building energy efficiency -...

Building Energy Efficiency

Student handbook

Edition EN1.0 - September 2010 Check IUSES project web site www.iuses.eu for updated versions. Disclaimer This project has been funded with support from the European Commission. This publication reflects the views only of the author and the Commission cannot be held responsible for any use which may be made of the information contained therein.

http://www.tetris-project.org/�

Authors: Sergio García Beltrán (CIRCE), Lucie Kochova (Enviros s.r.o.), Giuseppe Pugliese (CIRCE), Petr Sopoliga (Enviros s.r.o.) Layout Fabio Tomasi (AREA Science Park) About this handbook and IUSES This handbook has been developed in the frame of the IUSES –Intelligent Use of Energy at School Project funded by the European Commission - Intelligent Energy Europe Programme. The partners of the project are : AREA Science Park (Italy) CERTH (Greece), CIRCE (Spain), Clean Technology Centre - Cork Institute of Technology (Ireland), Enviros s.r.o. (Czech Re-public), IVAM UvA (Netherlands), Jelgava Adult Education Centre (Latvia), Prioriterre (France), S.C. IPA S.A. (Rumania) Science Centre Immaginario Scientifico (Italy), Slovenski E-forum (Slovenia), Stenum GmbH (Austria), University “Politehnica” of Bucharest (Rumania), University of Leoben (Austria), University of Ruse (Bulgaria) Copyright notes This book can be freely copied and distributed, under the condition to always include the pre-sent copyright notes also in case of partial use. Teachers, trainers and any other user or dis-tributor should always quote the authors, the IUSES project and the Intelligent Energy Europe Programme. The book can be also freely translated into other languages. Translators should include the pre-sent copyright notes and send the translated text to project coordinator ([email protected]) that will publish it on the IUSES project web site to be freely distributed.

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Key to symbols

Definition: this is to indicate a definition of a term, explaining what it means.

Notes: this shows that something is important, a tip or a vital piece of information. Watch out for these!

Learning Objective: these are at the beginning of each chapter and they explain what you will learn in that chapter.

Experiment, Exercise or Activity: this indicates something for you to do, based upon what you have learned.

Weblink: this shows an internet address where you can get more information

Reference: this indicates where some information came from.

Case Study: when we give an actual example or a real situation.

Key Points: this is a summary (usually in bullet points) of what you have covered, usually at the end of a chapter

Question: this indicates when we are asking you to think about a question, especially at the end of chapters

Level 2: this marks an in-depth section

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IUSES — building handbook

HANDBOOK ON BUILDING Energy Efficiency & Renewable Energies

INDEX 1. INTRODUCTION............................................................................................................................... 3

1.1. BUILDING CONCEPT.................................................................................................................... 3 1.2. BUILDINGS TYPOLOGY ................................................................................................................ 3

2. BUILDING STRUCTURES ............................................................................................................... 7 2.1. CONCEPT: A BUILDING IS LIKE A BREATH BOX ............................................................................ 7 2.2. ENVELOPE OF THE BUILDING ...................................................................................................... 9

2.2.1. Insulation and building materials ...................................................................................... 10 2.2.1.1. Reforming with thermal insulation: General examples ........................................................... 12

2.2.2. Windows, glazed surfaces and doors ................................................................................. 12 2.2.2.1. Windows rating ....................................................................................................................... 13

2.3. BIOCLIMATIC BUILDING DESIGN ................................................................................................ 14 2.3.1. Passive solar elements ....................................................................................................... 16

2.4. TIPS AND HINTS FOR BETTER BUILDING USE .............................................................................. 18 2.5. EXERCISE/QUESTIONS............................................................................................................... 19

3. CLIMATIZATION ........................................................................................................................... 23 3.1. HEATING .................................................................................................................................. 23

3.1.1. Internal microclimate and comfort..................................................................................... 23 3.1.2. Heating systems.................................................................................................................. 25 3.1.3. Type of heat carrier............................................................................................................ 25

3.1.3.1 Hot water..................................................................................................................................... 25 3.1.3.2 Air heating................................................................................................................................... 25

3.1.4. Energy sources ................................................................................................................... 25 3.1.4.1 Fossil fuels................................................................................................................................... 25 3.1.4.2 Electric energy ............................................................................................................................ 26

3.1.5. Renewable sources ............................................................................................................. 26 3.1.5.1. Biomass ................................................................................................................................... 26 3.1.5.2. Heat pumps ............................................................................................................................. 27

3.1.6. Solar energy ....................................................................................................................... 29 3.1.7. Heating elements................................................................................................................ 31

3.2. COOLING – AIR CONDITIONING ................................................................................................. 33 3.2.1. Introduction........................................................................................................................ 33 3.2.2. How does an air conditioner work?................................................................................... 35 3.2.3. Energy Label ...................................................................................................................... 36 3.2.4. Different air-conditioning system options.......................................................................... 36 3.2.5. Tips and hits on how to use an air conditioner .................................................................. 37

3.3. EXERCISE/QUESTIONS............................................................................................................... 39 4. DOMESTIC HOT WATER PREPARATION.................................................................................. 41

4.1. TYPES OF WATER HEATING APPLIANCES..................................................................................... 41 4.1.1. Electrical storage appliances............................................................................................. 42 4.1.2. Electrical instantaneous appliances................................................................................... 42 4.1.3. Gas direct instantaneous appliances.................................................................................. 42 4.1.4. Gas direct storage appliances............................................................................................ 42 4.1.5. Gas indirect storage appliances......................................................................................... 42 4.1.6. Other possibilities .............................................................................................................. 42

4.2. TIPS AND HINTS HOW TO SPARE WATER AND ENERGY ................................................................. 42 4.3. SOLAR WATER HEATERS............................................................................................................. 44 4.4. EXERCISE/QUESTIONS............................................................................................................... 44

5. LIGHTNING..................................................................................................................................... 46 5.1. DAYLIGHT................................................................................................................................. 47 5.2. ARTIFICIAL LIGHTING................................................................................................................ 47

5.2.1. Sources of light................................................................................................................... 48 5.2.2. Lamps................................................................................................................................. 49 5.2.3. Energy consumption........................................................................................................... 49

5.3. EXERCISE/QUESTIONS............................................................................................................... 50

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6. ELECTRIC APPLIANCES AND ELECTRONIC DEVICES (AND SOLAR PV) ......................... 52 6.1. OVERVIEW ................................................................................................................................ 52

6.1.1. General tips on how to save energy ................................................................................... 56 6.2. ELECTRIC APPLIANCES.............................................................................................................. 56

6.2.1. Refrigerators/ Fridges: ...................................................................................................... 56 6.2.2. Washing machines: ............................................................................................................ 58 6.2.3. Dishwashers....................................................................................................................... 58 6.2.4 Ovens ................................................................................................................................. 59 6.2.5 Small home appliances....................................................................................................... 59 6.2.6 Home electronic equipment – Entertainment and home office devices: ............................ 60

6.3. EXERCISE/QUESTIONS............................................................................................................... 62 6.4. PHOTOVOLTAIC ENERGY ........................................................................................................... 67

6.4.1 Solar energy ....................................................................................................................... 67 6.4.2 The process of turning sunlight into electricity.................................................................. 68 6.4.3 Photovoltaic applications .................................................................................................. 70 6.4.4 How much electricity can a PV system produce? .............................................................. 71

6.5. EXERCISE/QUESTIONS............................................................................................................... 74 7. EXERCISE - MONITORING ENERGY CONSUMPTION - HOME/SCHOOL FACILITIES ENERGY AU-DIT .......................................................................................................................................................... 77

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1 Introduction

Learning Objective: In this Chapter you will learn:

What is building

What are the types of buildings

1.1 Building concept

Definition: Building is a man-made construction used for supporting or sheltering any use or continuous occupancy. It is fully enclosed by external envelope (that means external walls, roof and floor) which creates its internal microclimate.

Buildings come in a wide amount of shapes and functions, and have been adapted throughout history for a wide number of factors, from building materials available, to weather conditions, to land prices, ground conditions, specific uses and aesthetic reasons. Buildings serve several needs of society - primarily as shelter from weather and as general living space, to provide privacy, to store belongings and to comfortably live and work. A building as a shelter represents a physical division of the human habitat into the inside (a place of comfort and safety) and the outside (a place that at times may be harsh and harmful). The first shelter on Earth constructed by a relatively close ancestor to humans is believed to be built 500,000 years ago by an early ancestor of humans, Homo erectus. To create required internal microclimate is very energy demanding. So, building construction and operation have an enormous direct and indirect impact on the environment. Buildings not only use resources such as energy and raw materials, they also generate waste and potentially harmful atmospheric emissions. As economy and population continue to expand, designers and builders face a unique challenge to meet demands for new and renovated facilities that are acces-sible, secure, healthy, and productive while minimizing their impact on the environment. Recent answers to this challenge call for an integrated, synergistic approach that considers all phases of the facility life cycle. This "sustainable" approach supports an increased commitment to environmental stewardship and conservation, and results in an optimal balance of cost, envi-ronmental, societal, and human benefits while meeting the mission and function of the intended facility or infrastructure. The main objectives of sustainable design are to avoid resource depletion of energy, water, and raw materials; prevent environmental degradation caused by facilities and infrastructure through-out their life cycle; and create built environments that are liveable, comfortable, safe, and pro-ductive. 1.2 Buildings typology To differentiate buildings in the usage of this book from other buildings and other structures that are not intended for continuous human occupancy, the latter are called nonbuilding structures or simply structures.

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Buildings can be sort by purpose for which they were built: 1) Residential building – apartment building, detached/semi-detached dwelling, row house, cot-tage, castle, yurt, igloo, mansion, condominium, dormitory

taken by Michael Gardner 2) Educational and cultural buildings – school, college, university, gymnasium, library, mu-seum, art gallery, theatre, concert hall, opera house,

3) Commercial buildings – bank, office building, hotel, restaurant, market, shop, shopping mall, store, warehouse

4) Government buildings – city hall, consulate, courthouse, parliament, police station, post of-fice, fire station

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5) Industrial buildings – brewery, factory, foundry, mining, power plant, mill

6) Medical building – hospital, policlinic, surgery 7) Agricultural buildings – for example: barn, chicken coop, greenhouse, silo, grainery, stable, sty, mills

Photo by Lars Lentz 8) Military building – barracks, bunker, citadel, fort, fortification 9) Parking and storage – garage, warehouse, hangar 10) Religious buildings – church, cathedral, chapel, mosque, monastery, synagogue, temple

11) Buildings for sports – sport stadium, pool, gymnasium, court

So there is a big variety of building and also there is a big variety of requirements for these buildings. All these types of buildings have to create suitable indoor microclimate for purpose

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for which they were built. The requirements are different for all types of buildings, for example in the warehouse you need lower indoor temperature and much lower humidity than in the in-door swimming pool.

Web links http://en.wikipedia.org/wiki/Building http://www.learn.londonmet.ac.uk/packages/clear/thermal/buildings/configuration/building_orientation.html http://lonicera.cz/awadukt_thermo/ http://www.vsekolembydleni.cz/clanek.php?id=166 http://www.passivehouse.co.uk/

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2 Building structures

Learning Objective: In this Chapter you will learn: The important role of building envelope and how energy can be wasted

(including “heat transfer fundamentals”)

An overview of the most common building and insulation materials

Basic concepts of the bioclimatic building design 2.1 Concept: A building is like a breathing box A building could be seen to be like a box, protecting its contents from climatic conditions, such as outdoor temperatures, wind, rain, etc. Indoor comfort, apart from being a subjective matter, depends mainly on two factors: indoor temperature and humidity. It is obvious that the least comfort is achieved when high temperature and high humidity works together. The skin of the building, named the envelope, works like an exchanger with the external climate conditions, gaining heat from exposure to solar rays and releasing heat towards the outside (due to ventilation and an inadequate envelope). The envelope, apart from having the task of wrapping and defending the building, should allow it to breath, in order to avoid indoor humidity and reach a proper balance between heat gains and losses*.

Fig.1 Energy balance of a building

This special photo (fig. 2, an infrared picture taken by a thermographic camera*) shows the ther-mal condition of the building, with the clearer areas (yellow) being the warmer parts, while the darker (red/blue) ones are the colder areas. It shows the clearest points where heat is escaping.

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In this picture, for example, the wall face has got a thermal gradient (a temperature) of 6.1 ºC at the thermal point of the floor framework (Sp2 = 6.2ºC). It is 1.1ºC at the wall (Sp1).

Fig.2 Thermographic picture of building

As is shown in the picture, heat is escaping through the windows and because of the thermal bridges caused by the blind box and the floors.

Fig.3 Thermographic picture of building

Why does it occur?

Definition: That is a physical phenomenon well known as “Heat Transfer”. According to this, “Heat always flows from a warmer to a cooler space”.

It means that in winter, the heat moves directly from all heated living spaces to the outdoors and to adjacent un-heated attics, garages, and basements – wherever there is a difference in temperature. During the summer, heat moves from the outdoors to the house interior (when the outside temperature is higher!). To maintain comfort, the heat lost in the winter must be replaced by the heating system, while the heat gained in the summer may be removed by an air conditioner. That means a large amount of energy is wasted in most build-ings. In Europe, 70% of the average energy household con-

Fig.3 Difference of Temperature and heat transfer

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sumption goes to keeping homes at a comfortable temperature. Typically, natural gas and elec-tricity are used for heating systems, and electricity for almost all cooling systems. The heat demand for heating the house in the cold season is the major energy-consuming service. If the heat demand is reduced by means of insulation, heat recovery, superwindows, passive solar gains and other measures, the heating system can be simplified step by step, and the energy re-quirement for heating is reduced, as well as the supplier bill and CO2 emissions. BOX Concept Heat transfer fundamentals

Fig.4 Heat transfer

Conduction occurs in a solid material when its molecules are at different temperatures. The hotter molecules transmit energy (heat) to the cold side of the material. For example, a spoon placed into a hot cup of coffee conducts heat through its handle and into the hand that grasps it. In buildings, conduction occurs primarily through walls and windows.

Convection is the transfer of energy by the movement of fluids and gases. Warm air rises and is replaced by colder air drawn in from outside. In multi-storey buildings* with inade-quate internal partitions, this can create powerful and wasteful draughts.

Radiation is where the energy is transported by electromagnetic waves*. Unlike the other mechanisms, radiation requires no intervening medium to propagate. Radiation into build-ings occurs mainly through glass windows and doors, but if walls are not well insulated, radiation falling outside may heat the inside by conduction.

2.2 Envelope of the building Most of the building energy loss is due to an inadequate envelope, which is composed of the walls, floors, roof, doors, and windows. The next picture shows from where the heat transfer typically acts, e.g., external walls and adjacent unheated spaces.

Note: Heat is always transferred from a warmer to a colder area by three mechanisms:

Note: Proper component and insulation materials allow a decrease in the heating or cooling needed by providing an effective resistance to the flow of heat, or said more simply, by creating a better conservation of the inside temperature.

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In addition, the colour of the external walls is important, due to their characteristic of reflecting or absorbing the light of the sun. White and lighter colours act as reflectors, while black and dark tones are sun absorbers.

Fig.5 Energy looses in a conventional building

2.2.1 Insulation and building materials

Definition: Insulation means all materials with a high resistance to heat flow.

Some commonly used materials for home insulation can be classified according to type:

Vegetable: cork, wood fibre, flax, straw, etc. Mineral: fibreglass, mineral-wool, expanded clay, metal carbides,

foamed glass, etc. Synthetic materials: expanded polystyrene, polyurethane and phe-

nolic foams, PVC, etc.

Furthermore, insulation materials are available in a variety of forms. Apart from rigid insulation, there are: blankets, in the form of mats or rolls, blown loose fibres, foam and spray insulation, etc.

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They can be used together, thus increasing insulation property, but this requires professional in-stallation and a proper mix. Good insulation can reduce the heat transfer through walls, roofs, windows, etc., giving the fol-lowing benefits:

Saves energy because it reduces energy losses during

cold days and allows lower refrigeration loads and tem-peratures during hot summer days.

Increases comfort by eliminating the “cold wall” effect* produced in exterior walls and windows (the temperature difference between the wall surface and the room should be no greater than 4°C).

Reduces the risk of condensation* which may cause damage to building insulation and structural materials, discolouration and unhealthy living conditions. The risk of condensa-tion increases with lower ambient temperatures.

Avoids sudden temperature changes, protecting the building from cracks and thermal ex-pansions.

Improves the building’s acoustics. Insulation material is usually rated in terms of thermal resistance (indicated with an R-value), which indicates the resistance of material to heat flow (see paragraph 2.2.1.2). The higher its re-sistance is, the greater the insulating effectiveness is. Of course, the thermal insulation property depends on the type of material, its thickness, and its density. As an example, look at the comparison between 10 cm of thermal insulation and other building materials.

Graph 1. Material comparison

Note: In winter, each square metre of uninsulated wall loses the equivalent energy of 3 to 6 litres of oil (referring to the oil which is theoretically consumed for heating the space without insulation). With good insulation, these losses are reduced to one-sixth. Doubling the insulation thickness of a blank wall from 45mm to 90mm can save about 30% of the energy1.

1 The energy standard of a building is commonly measured by the energy consumed for heating and cooling (kWh) per each square metre of building surface (m2) during one year. Thus, when we speak about energy losses or sav-ings due to insulation, we are referring to that energy (expressed by kWh or oil equivalent) which would be con-sumed or saved for heating and cooling.

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For any building more than 20 years old or insufficiently insulated, a retrofit is advisable for im-proving its insulation, by which a 50% energy savings is easily achieved for heating and cooling. In addiction to insulation, careful selection of construction materials is the key to achieving high comfort levels at a low cost, although it is more suited to the new building stage, or when impor-tant renovations are needed. For example, a hollow ceramic brick has very good insulating properties (or high thermal resis-tance), and other materials like thermal clay have an even better performance.

These bricks have an internal structure of air chambers, helping to achieve good thermal and acoustic insulation. In summary, in addition to construction materials, it is important to use insulation-layered mate-rial in order to achieve better energy saving results and comfort. 2.2.1.1. Reforming with thermal insulation: General examples 1. Insulation of facade (walls and windows): By installing thermal insulation material on external or internal walls, or injecting it inside the wall, and replacing glass and windows with more efficient ones. 2. Insulation of roof, floor and ceiling: By installing thermal insulation material between tie-beam,* wall,* with tile* adhered onto insu-lation material, etc., and by insulating ceilings which are in contact with living spaces and roofs in contact with no living spaces. 3. Insulation of plumbing system: By installing thermal insulation material around water pipes in order to reduce heat loss in the transport of hot water.

2.2.2 Windows, glazed surfaces and doors

This is due to air leakages, infiltrations and thermal bridges* along the frame of the components, and is also due to the heat transfer through the component materials. Common windows usually come with a low resistance to heat flow, which is inefficient.

Fig.6 Example of a hollow brick with excellent in-sulating properties

Fig.7 Examples of clay bricks

Note: These are the weakest parts of the building envelope, responsible, on average, of one-third of a home’s heat loss in winter and cooling loss in summer.

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Windows and glazed surfaces, which cover a relevant part of a building surface, as well as working like the other envelope parts to avoid heat loss, play another important role: they provide natural daylight and, thanks to sunlight, allow heat gains for indoor space (mainly in cool countries or cool seasons).

They usually need to be insulated and sealed, mainly at the bottom with weather-stripping* or insulating rope to prevent air leaks. Or, if the doors are quite old, it would be good to change them for new ones made of some good thermal insulation material (wood, double-layered alu-minium filled with insulation foam or blanket, etc.). For this, there are two crucial main steps:

The proper shaping and correct positioning of windows and glazed surfaces;

Checking for energy-efficient windows (which provide a great resistance to heat flow). 1. Large windows should be positioned on the south side, in order to al-

low the winter sun to warm internal spaces. Conversely, during the summer, when the purpose is to keep out the hot summer sun, some sort of shading device should be used, indeed, by putting up a proper eave or veranda over the window. Conversely, windows located on the cold north side of the house should be kept to a smaller size, in order to avoid the cold from the north entering.

2. Several efficiency degrees of windows are available, mostly depend-ing on frame material and glass characteristics. For instance, a win-dow with an aluminium or iron frame permits a great amount of heat flow (low thermal resistance), whilst a wood frame is better since it is an insulating material. Equally, systems with double-glazing or a dou-ble window cut heat loss by almost 50% in comparison with single glazing, as well as reducing air leaks, condensation of moisture and frost formation.

2.2.2.1. Windows rating

Windows are rated with the heat-transfer coefficient U-value. Remember that the U is the inverse value of R (thermal resistance) and the lower the U-value, the better the energy efficiency of the window.

Note: Similarly, external doors are responsible, on average, for 10% of a home’s heat loss.

Note: Double-glazed windows have up to 75% lower U-values than single-glazed units. The most efficient double-glazed win-dows allow about 80% of the sunlight received to enter and have U-values of approximately 2. Windows with U-values of 1 or lower are sometimes called “superwindows”. Many of the com-mercially available high-efficiency windows may include multiple layers of glazing, low-emissivity (low-e) coatings, inert gas-fill between glass layers and insulating spacers.

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The following figure shows typical U-values of different types of windows.

Fig.8 Windows Rating: U-values of different types of windows

2.3 Bioclimatic building design The energy efficient model for building counts more than all the above technical solutions and design principles and many others, as it is capable of increasing energy savings, indoor healthiness, help-ing to reduce the greenhouse emissions from fossil-fuel energy use,

as well as reducing household running costs. Furthermore, the energy-efficient con-cept also includes the elements of the well known the “Bioclimatic Building Design” to provide a naturally comfortable home all year round.

Definition: The Bioclimatic Building Design consists of adapting the building to par-ticular weather conditions and getting the greatest comfort with the minimum support from auxiliary energy sources. The sun is the main energy provider in bioclimatic design.

It is not a new discipline. Most traditional architecture followed bioclimatic principles when arti-ficial heat and cold sources were expensive and limited.

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Fig.9 Main bioclimatic Active and Passive elements

Definition: Bioclimatic elements are commonly classified as passive and active. Active solar systems are directed towards solar energy capture by mechanical

and/or electrical systems: solar collectors (for space or water heating) and photovoltaic panels (for producing electric energy), as dealt with in the next chapter.

Passive solar design maximizes the benefits from the sun using standard con-struction features, while operating with little or no mechanical assistance. The natural movement of heat and air or just making the optimum use of the sun, for instance in terms of daylight and heat, maintain comfortable temperatures.

Fig.10 Active and passive solar elements in a building.

Active systems

Solar collectors

Photovoltaic pannelsBioclimatic elements

.....

Direct solar gainThermal walls with air preheating

Passive systems

Indirect solar gain Trombe walls

Isolated systems: Sunspaces and Atria

Mass walls

Collectors and grave fills

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2.3.1 Passive solar elements As the above chart shows, passive solar systems are usually further divided into three main ele-ments, according to the method of gaining solar benefits; they are:

Direct solar gain

Indirect solar gain

Isolated systems

Direct solar-gain systems are basically composed of a south-facing glazing surface that traps the sun’s heat into the space made by the internal wall and the glazed surface. It is a spe-cial wall (called a thermal mass) composed of proper materi-als able to trap and store solar heat and give it off during the night. Temperatures of up to 27°C can be reached. Glazing is usually the most important factor in obtaining en-ergy savings. In south-facing buildings with glazing surfaces of 60%, sav-ings due to direct solar gain range between 15% and 40%, depending on the insulating material. The inconvenience is that the same surface demands 55% more air conditioning over the summer. Thus, it is usual to place eaves and trees around the building.

They provide shade in the summer and solar gain in the winter. Then, facilitating crossed ventilation is a very important factor (even more than thermal insula-tion) when trying to avoid air conditioning in the summer. Indirect solar gain uses the same materials and design principles as direct gain systems, but places the thermal mass (the internal wall) between the sun and the space to be heated. With indirect solar-gain passive elements, temperatures up to 70°C can be reached (remember that direct solar-gain elements can reach 27°C). These systems are thus great energy-storing sur-faces. The high temperatures are slowly attained and slowly lost being the thermal delay between six and eight hours. During the summer period, they use eaves to avoid overheating. These systems affect the global design of the building, so they are recommended for pre-designed structures. Among the several types of indirect solar-gain systems, the most common element is the Trombe walls.

Fig.12 Operating principle of a Trombe Walls.

Solar radiation is collected and trapped between the large external window and the thermal mass (the wall) and heats the air in between. The particular element is that such vents are located at the top and bottom of the wall. The top one allows the heated air to flow into the room, while cooled air then moves to take its place from vents at the bottom of the wall (remember that warm air re-

Fig.11 Operating principle of a pas-sive solar surface.

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mains higher, due to being lighter than cold air). The thermal mass (the wall) continues to absorb and store heat to radiate back into the room after the sun has gone. Dampers can be placed in the vents to prevent warm air from escaping through them at night. Isolated systems, such as sunspaces and atria (respectively for dwellings and for larger buildings) represent additional space with attractive architectural qualities. In certain climates, they can also offer protection against adverse weather at an acceptable cost. These systems result from a combination of direct and indirect gain systems. They are made up of a large glazed surface enclosing a thermal mass (greater than the ones in Trombe walls), lo-cated between the exterior wall of the building and the glazed surface. The principle of operation is similar to Trombe walls.

Fig. 13 Operating principle of atria

What are the benefits? A new building that is planned and constructed following bioclimatic criteria can become self-sufficient from an energy point of view. However, these are exceptional cases and cannot be ap-plied to most projects.

The energy standard of a building is commonly measured by the energy consumed for heating and cooling (kWh) per square metre of building surface (m²) and usually over a year. Table 3 shows a comparative example between the consumption of a traditional building and a bioclimatic one. As seen, savings can be up to 67%.

Tab.3 Consumption of traditional versus bioclimatic building

Note: Any building can obtain energy savings of up to 60% by applying bioclimatic techniques – without running into extra expense and still keeping the final aesthetic of the project.

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Each building, depending on the materials used, should have its own energy demand value To have an estimation of a building energy demand, and knowing its energy demand per square me-tre, you need to multiply that value by the habitable surface of the building.

2.4 Tips and hints for better building use Building design, its envelope materials, windows and doors used, are decisive in having a com-fortable living standard. As the greatest part of building energy consumption is due to heating and cooling (more than 50%), and considering the long life of a building, attention must be paid to all those structural issues in order to be really cost effective. Follow the tips below to increase energy efficiency and to save money. Envelope and insulation Good thermal insulation should always be planned during the design process of new or re-

stored buildings. For existing buildings, modifying the structure to improve insulation is usually difficult

and not always cost effective. However, for older buildings, if you are considering building work, don't forget that correct thermal insulation can make significant energy and money savings. Reduce the heat losses by using double panes (for windows) and insulation in the walls. Energy consumption could be reduced by half (50%).

Remember that dark surfaces absorb more solar radiation. Make sure of the envelope seal, filling cavities and slits wherever air leakages are found. Doors and Windows If you cannot replace older doors and windows, there are several things you can do to

make them more efficient: Open the curtains and the sunshades in southern windows to allow the sun to pass into the

interior. Do not use drapes or blinds to cover the windows and glazed faces during winter days, be-

cause the windows provide the indoor space with natural daylight, and allow sun heat to enter (solar gain).

Make sure the door is sealed and have door sweeps at the bottom to prevent air from leak-ing out. Applying weather-stripping and caulking around doors and windows can signifi-cantly reduce air leakage.

Keeping windows and doors closed when heating or cooling systems are operating to avoid losses.

Bioclimatic Building Design and Systems Building design and structure elements mostly belong to building construction or large-

scale reform phase decisions; nonetheless, teenagers should be concerned. There are three bullet points needed to be learned:

For example, having a surface of 240 m2 (example in note) and an energy de-mand of 169 kWh/m2 (as shown in the table), we obtain: 240 m2 x 169 kWh/m2 = 40,560 kWh (being approximately the energy demand of the entire building).

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acquiring an awareness and knowledge of proper design, materials and use of technologies could be useful when choosing a home to live in, or simply for giving suggestions to your parents or school headmasters;

There are small-scale, low-cost repairs, which can be carried out, such as sealing cracks, adding interior movable shades (such as Venetian blinds), installing ceiling fans, using plants for shade, etc.

there are non-technical measures, even the simplest of which can have energy benefits for our buildings without added costs, such as ensuring the rational operation of the building and its systems, the correct use of windows (for sun penetration during the winter, shading and night ventilation during the summer), and the rational use of appliances so as not to place a heat burden on the building (for example, not cooking during the hottest part of the day).

2.5 Exercise/Questions

1. What is the direction of the heat transfer? a) From warmer to cooler ¨ b) From cooler to warmer ¨

2. Which colours do you think are the best at absorbing the light from the sun and which at reflecting them?

....................................................................................................................................................

.................................................... 3. Quote three of the most common insulation materials: ........................ .............................

................................ .................................. 4. Which of the construction solutions would make the best insulator?

10 cm of thermal insulation ¨ or 20 cm of hollow brick ¨ 5. Can you think of any materials which would not be good insulators?

Why? ........................................................................................................................................................................................................

6. Where do the most losses due to air leaks occur?

....................................................................................................................................................

.................................................... 7. What can be done to stop the drafts?

..................................................................................................................................................

.................................................. 8. Where should larger windows be positioned in a building?

South side ¨ North side ¨ 9. What device or system could be used to keep hot sunlight from the windows during the

summer? .....................................................................................................................................................................................................

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10. What kind of window shows the best performance and how much range of U-value should it have? .....................................................................................................................................................................................................

11. Select whether the following techniques are Solar Active (A) or Passive (P)

Photovoltaic panels [ ] [ ] Atria [ ] [ ] Indirect solar-gain systems [ ] [ ]

12. Try to define “bioclimatic building design” and say what could be considered its main en-

ergy source. .....................................................................................................................................................................................................

13. What is the inconvenience of solar passive elements during the summer? And how can this

be easily solved? .....................................................................................................................................................................................................

14. Tick the functions of the thermal mass (the internal wall) of a passive solar system: Heat absorption and storage ¨ Protection against climate adversity ¨ Radiating heat after the sun is gone ¨ Allowing air ventilation ¨

15. According to the building energy-demand measurement (kWh/m²), and supposing that

your school has a demand of approximate 150 kWh/m² per year: Get (or estimate) the school’s habitable surface (m²) = ............... Calculate the global energy demand (kWh) = ................

Glossary Thermographic camera: also called an infrared camera, is a device that forms an image using infrared radiation, similar to a common camera that forms an image using visible light. It is able to reveal temperature variations on the surface of a body. Heat Gain – an increase in the amount of heat contained in a space, resulting from direct solar radiation, heat flow through walls, windows, and other building surfaces, and the heat given off by people, lights, equipment, and other sources. Heat loss – a decrease in the amount of heat contained in a space, resulting from heat flow through walls, windows, roof and other building surfaces and from ex-filtration of warm air. Solar heat gain – heat added to a space due to transmitted and absorbed solar energy. Multi-storey buildings: buildings composed of different floors.

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Electromagnetic waves: are formed when electric fields couple with magnetic fields, which propagate through space carrying energy from one place to another. Cold wall effect: the chilly discomfort experienced by a person in a building as his or her body radiates heat to the cold surface of an uninsulated wall. Condensation: is the change of the physical state of aggregation (or simply state) of matter from a gaseous phase into a liquid phase. For instance, water vapour condenses into liquid after mak-ing contact with the surface of a cold bottle. Balk: one of several parallel sloping beams that support a roof. Piling stick: a stick or strip of wood used to separate courses in a stack, and thus improve air cir-culation. Tile: a thin flat slab of fired clay used for roofing. Kelvin degree: is a unit measure of temperature and is the same size as the Celsius degree; hence, the two reference temperatures for Celsius, the freezing point of water (0°C), and the boil-ing point of water (100°C), correspond to 273.15°K and 373.15°K, respectively. Expanded polystyrene foam: is a plastic material that has special properties due to its structure. Composed of individual cells of low-density polystyrene, EPF is extraordinarily light and can support many times its own weight in water. Fibreglass: also called glass fibre, is a material made from extremely fine fibres of glass. Thermal bridge: is created when materials that are poor insulators come into contact, allowing heat to flow through the path created. The bridging has to be eliminated, and rebuilt with a re-duced cross-section or with materials that have better insulating properties, or with an additional insulating component. Caulk: a soft, semi-solid material that can be squeezed into non-movable joints and cracks of a building, thereby reducing the flow of air into and out of the building. Weather-stripping: material that reduces the rate of air infiltration around doors and windows. It is applied to the frames to form a seal with the moving parts when they are closed.

Web links

http://www.energysavingcommunity.co.uk/ http://www.proudcities.gr/ http://www.eurima.org/ http://www.energytraining4europe.org/ http://www.need.org/ http://apps1.eere.energy.gov/consumer/your_home/designing_remodeling/index.cfm/mytopic=10250 http://www.cres.gr/kape/energeia_politis/energeia_politis_bioclimatic_eng.htm

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References

VV. AA.: Guía práctica de la energía para la rehabilitación de edificios. El aislamiento, la me-jor solución’ (Practical Guide for the Energy Reform of Buildings. The insulation, the best solution), Instituto para la Diversificación y Ahorro de la Energía (IDAE), Asociación Nacional de Industriales de Materiales Aislantes (ANDIMA), 2008.

Key points: Building design, its envelope materials, windows and doors used, are decisive in having a comfortable living standard. As the greatest part of building energy con-sumption is due to heating and cooling (more than 50%), and considering the long life of a building, attention must be paid to all those issues in order to be really cost effective. Good insulation can reduce the heat transfer through walls, roofs, windows, etc., giving the following main benefits: Saves energy and increases comfort. According to “Heat Transfer” principle, heat always flows from a warmer to a cooler space. Windows, glazed surfaces and doors are the weakest parts of the building envelope, responsible, on average, of one-third of a home’s heat loss in winter and cooling loss in summer. Any building can obtain energy savings of up to 60% by applying bioclimatic tech-niques – without running into extra expense and still keeping the final aesthetic of the project.

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3 Climatization

Learning Objective: In this Chapter you will learn: What the thermal comfort is and how to achieve it. Heating systems fundamentals What renewable energy sources are being used for heating Cooling systems fundamentals How to use properly the heating systems and air conditioning and save energy.

3.1 Heating

3.1.1 Internal microclimate and comfort The key task of the heating is to maintain the thermal comfort in the internal space.

Definition: Thermal comfort is one of the most important factors which provide opti-mal internal environment for people. It’s a condition when the thermal balance be-tween the man and his surroundings is preserved. It means that the heat which man produces is taken away from the body.

You can simply change the heat flow from your body by changing clothes (increasing the ther-mal resistance of the body) or activity (with more activity increase the thermal production of the body).

There are recommended values of air temperature for each activity to provide thermal comfort. However in short-term staying in the space where the required temperature is not, people usually don’t feel the discomfort, because differences between produced and taken heat are balanced by internal thermoregulation system. This thermo regulating processes have connection with age, health condition, nutrition and activity of the person and are influenced by the temperature, hu-midity and air velocity in the internal environment. It is proven that thermal comfort has got bigger influence on the sub-jective comfort feeling and working activity than air pollution or dis-turbing noise. Some studies proved that person achieves 100 % work output (soft job) in temperature 22 °C. In 27 °C the output falls to 75 % and in 30 °C the output is only 50 % of the maximum. The humidity is closely associated with the temperature. In winter the relative humidity falls to 20 % or lower. So the mucosa membrane of the respiratory system become dry, the striking power of the organ-ism falls down and harmful substances can get in the respiratory sys-tem. However the thermal comfort depends on many other factors, e.g. the temperature of the sur-roundings surfaces. These surfaces emit the radiation component of the operative temperature and can be positive or negative. People are very sensitive on radiation. Even though a person has a sensation of thermal neutrality, parts of the body may be exposed to conditions that result in thermal discomfort. This local thermal discomfort can not be removed by raising or lowering the

Note: The basic criterions connected with thermal comfort are operative temperature (that is the air temperature influenced by the radiation from surrounding surfaces), hu-midity and air velocity.

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temperature of the enclosure. It is necessary to remove the cause of the localised over-heating or cooling.

Note: Generally, local thermal discomfort can be grouped under one of the following four headings: 1. Local convective cooling of the body

caused by draught 2. Cooling or heating of parts of the body

by radiation. This is known as a radiation asymmetry problem.

3. Cold feet and a warm head at the same time, caused by large vertical air temperature differences.

4. Hot or cold feet, caused by uncomfort-able floor temperature.

Remember, only when both the local and general thermal comfort parameters have been investi-gated, the quality of the thermal environment can be judged.

Tab. 1 - Recommendations for winter thermal comfort

Relative air humidity has to be between 30-60%

Air velocity – in winter max. 0,15 m.s-1; in summer max. 0,25 m.s-1

Room Air temperature (°

C) Intensity of air changes (h-1)

Air amount (m3 . h-1)

Habitable room 18-22 3 3 on 1 m2 floor

Kitchen 15 Gas 3 150

Kitchen corner Electricity 3 100

Bathroom 24 - 60

Bathroom with toilet 24 - 60

Toilet 16 - 25

Lavatory 18 0,5 -

Cloak-room 18 1 -

Pantry 15 1 -

Hall, staircase 10-15

Note: So the recommended temperature for long-term staying of persons is 19-24 °C. For small children, elder people and sick or undernourished people the temperature should be higher – about 23-24 °C.

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3.1.2 Heating systems There are different types of standard heating systems. We can sort them by the source, place of the source, type of heat carrier, temperature of the heat carrier, type heating element etc. Local heating means that the source of the heat (e.g. fireplace) is in the room which should be heated. Central heating is often used in cold climates to heat private houses and public buildings. Such a system contains a boiler, furnace, or heat pump to heat water, steam or air, all in a central location such as a furnace room in a home or a mechanical room in a large building. In big cities district heating is often used. 3.1.3 Type of heat carrier Typical heat carrier is hot water or air, but there can be used also other as electricity, steam, etc. 3.1.3.1 Hot water This system can be low or high temperature. Traditional hot water system with radiators is much extended in Europe, because this system is optimal for solid buildings with brick or stone walls and natural ventilation which were the most common in the past. This traditional system is also optimal for solid fossil fuel sources which are not much flexible.

3.1.3.2 Air heating Air heating system of residential buildings is not in contrast to office or industry buildings often used in Europe. The main reason is the climate conditions, historical development and the con-nection of the heating system to the construction of the building. The heat carrier in this system is air. In comparison with water, air has got lower heat capacity so it’s worse heat carrier than water.

3.1.4 Energy sources 3.1.4.1 Fossil fuels Solid fossil fuels, such as hard coal, brown coal, anthracite or coke, were usually used in past.

In past these sources were hardly controllable and not flexible. Also the combustion efficiency was low and amount of emissions was high. Modern boilers have got higher efficiency and pro-

Note: This system can be applied also in low energy buildings, but there are some dif-ferences between traditional system and system for new buildings. The output of radia-tors is essentially lower, so the system reacts more flexibly on the change of the internal gains.

Note: The modern conception of this system is connection of air heating and ventila-tion. This is usable mainly in the well insulated buildings with low energy demand. In contrast to circulation system there is controlled fresh air supply which provides the hy-gienic air interchange.

Note: Heating with solid fossil fuels is one of the main sources of air pollution. Burning of these fuels generates emission of sulfur, nitrogen and carbon oxides, dust emissions, emissions of organic and inorganic compounds and others.

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duce less emission. But you should remember that fossil fuels are non-renewable source and there is limited reserve of the fuels. Liquid fossil fuels are also popular in some countries. But today’s most used fossil fuel is gas. Gas has got many advantages in comparison with other fossil fuels. Burning gas instead of solid fossil fuel emits much less pollutants – emissions of dust and sulfur dioxides (SO2) are almost insignificant and also amount of carbon oxide (CO) is much lower. The only problem is that burning gas emits nitrogen oxides (NOx), but nowadays manufacturers lower NOx emissions to 10% of former values. European standards divides heaters in to 5 groups according to amount of NOx emissions. Gas, like any other carbon fuel, is the source of carbon dioxide (CO2) which is nowadays considered to be the substance most responsible for greenhouse effect. 3.1.4.2 Electric energy Electrical heating belongs to most comfortable sort of heating from the view of installation, ser-vice, thermal comfort or response rate. It is also available everywhere. But today the price of electricity rises, so this type of heating is suitable mostly for well insulated buildings where the energy demand is low. You also shouldn’t forget that mostly fossil fuels are burned to produce electricity. 3.1.5 Renewable sources 3.1.5.1. Biomass

Definition: Biomass is the organic substance. In the en-ergy context it’s usually wood and wood waste, straw, grain and other agricultural remains. Biomass may also include biodegradable wastes (such as dung, sewage etc.) that can be burnt as fuel.

Basic technologies of the manufacturing are the dry process – combus-tion, gasification and pyrolysis and wet process – biochemical transfor-mation, such as methane fermentation, ethanol fermentation and produc-tion of the bio-hydrogen. To the special group belongs mechanic-chemical transformation – oil pressing and its modification, e.g bio-fuel.

Note: Wood or straw are, if they are combusted well, the second most environmentally friendly fuels. The only pol-lutants emitted by combustion are nitrogen oxides and some solid pollutants. The carbon dioxide is consumed by plant growing, so the no problem with these emissions. The wood contains almost no sulfur, in straw there is about 0,1% so also these emissions are very low.

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Combustion and gasification The combustible gases are emitted from dry biomass by high temperature. If the air is present, the biomass is burning normally, but if the air is not present gas is combusted similarly like other gas fuels. The output can be easily controlled, emissions are lower and efficiency is higher. Biomass is very complex fuel, because the part of the gasification is high (wood - 70%, straw - 80%). These gases have got other burning temperatures, so very often only a part of fuel is burn-ing. The main condition of the well combustion is high temperature, efficient mixing with air and enough space in furnace for burning whole fuel.

Fuel value of the wood and other plant fuels varies with type of wood or plant and with humid-ity. The energy amount in 1 kg of the dry wood is about 5,2 kWh, but in praxis you can dry the wood completely, the moisture is about 20 % of the weight of the dry wood. So the energy amount of this wood falls down to 4,3 – 4,5 kWh.

Nowadays biomass is combusted not only in residential building but also in power plants or heat-ing plants. The furnace in the one family house gasificates the fuel first and then burns it. This system is very well controlled and it is comparable with gas furnaces. Disadvantage is the ma-nipulation with fuel and its storage. Also transport and supply can be problem – depends on the locality. From technical point of view biomass is not much suitable for small low energy build-ings, because there are problems with low output and regulation. Also the protection against low temperature corrosion should be installed. Very useful is using accumulation and combine it with preparing domestic hot water.

Heaters in family houses usually burn wood chunks, briquettes, wood chips or wood waste. Biogas Biogas rise from organic substances (dump, mulch, sewage) in closed tank without air presence. The biomass is heated to 37 – 60 °C in biogas facility and the bacteria transform the biomass to biogas. Fermentation The ethanol is created from sugar water, from turnips, grain, corn, fruits or potatoes. Theoreti-cally you can create 0,65 l of 100 % ethanol from 1 kg of sugar. This clean ethanol is very good fuel for gas-engines. 3.1.5.2. Heat pumps Nowadays heat pumps become slowly usual heat source. The increas-ing price of energy helps expansion of heat pumps to residential (especially one family) buildings.

Definition: A heat pump is an electric device with both heating and cooling capabilities. It transforms the natural low temperature heat from water, soil or air into heat with higher temperature which can be used for heating.

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How heat pump works

The evaporator takes the low potential heat from the outside environment (air, soil, wa-ter), so the outside environment become cooler, and heat is carried by the compressor to the condenser. In condenser the heat is emitted to the environment with higher tem-perature (heating system, domestic hot water) and this internal environment becomes warmer. The heating output of the heat pump is the sum of the electrical energy of the com-pressor and low potential energy of outside environment.

Heating factor usually varies between 2,5 to 3,5. It means that from 1 kWh of electrical energy we can get from 2,5 to 3,5 kWh of thermal energy. In special cases we can get more – about 4-5 kWh. The heat pump is efficient when the thermal difference between environments is high. It uses 60-70 % of natural energy. The heat pump itself doesn’t produce any emissions.

Sources of low potential energy for heat pumps 1. Water We can use both underground water and surface water. The only condition is that it has to be clean, the lowest temperature has to be over +8 °C, and there has to be enough amount of the water. When using underground water two wells should be constructed - one for collection and the other for infiltration. The used water mustn’t be emitted into a sewage system or stream, because the ecologically more valuable underground water would become into less valuable surface water. 2. Geothermal energy The heat from the soil can be easily used by the pipe absorber. The heat is taken indirectly – there has to be a car-rier medium between the evaporator and soil, usually it’s a refrigerant. Ab-sorber is composed from plastic pipe-line which is installed vertically in the wells or horizontally in the surface col-lector. The output is regulated with the length of the pipeline.

1

inputelectrical

outputheatingfactorheating

Note: The major part of the heat pump is the cooling circuit with electrical compressor. Other parts are two heat exchangers – evaporator and condenser.

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3. Air The external air, which contains the low potential heat, flows through evaporator. This source is easily accessible, unlimited and doesn’t influence the external environment, because the heat taken from the air is put back by heat losses of the envelope. But with varying of external air temperature the output of the heat put varies. 3.1.6 Solar energy Climate change, atmospheric pollution and, in general, the alarming environmental situation, mainly caused by the continued use of fossil energy sources, are slowly becoming growing con-cerns and are leading to the development of new alternatives for supplying electricity, well-known as Renewable Energies.

What is Solar Energy? Every day the sun sends out an enormous amount of energy in the form of radiation. Like others stars, the sun is a large ball of gases, mostly hydrogen and helium atoms, in a constant combus-tion process, or said better, in a combining process among those atoms called nuclear fusion. Simply said, the hydrogen atoms combine or fuse to form helium in the sun’s core under ex-tremely high temperature and pressure conditions. Precisely four hydrogen nuclei fuse to become a helium atom which contains less matter than the previous four of hydrogen. This loss of matter is what is emitted into space as radiant energy, the first source of life on the planet earth.

Fig.14 Energy radiations

Only a smart portion of the energy radiated hits the earth, one part in two billon, the remainder being spread into space. Of that small portion, about 15% of the sun rays are reflected back into space, another 30% cause water evaporation which is stored in the atmosphere producing rain-fall, and finally, solar energy is also absorbed by plants, the land and the oceans, allowing vege-

Note: One of them is solar energy, the source of which is simply the sun; it is available for free, is inexhaustible and can be used in different ways.

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table life through the photosynthesis mechanism. Only the rest could be used to supply our en-ergy needs, yet this amount of energy is enormous. How can we use solar energy?

We have many options for using solar energy at home, school and building in general. The three main ways are: 1. Passive heat: it consists of getting use by the heat naturally received from sun. The main

application is in the design of buildings where less additional heating is required (look at the chapter on building design).

2. Solar thermal: where we use the sun’s heat to provide hot water for homes or swimming pools or also heating systems (look at the chapter on water).

3. Photovoltaic energy (PV): The direct transformation of solar energy into electricity, able to run appliances and lighting. A photovoltaic system requires daylight – not only direct sunlight – to generate electricity.

Solar system has to be connected with other heating source (e.g. gas boiler, electrical boiler etc) in case that there is no or a little sunshine (cloudy, night etc). In summer the heat carrier can be water, but in the year-long operation the non-freezing liquid has to be used.

Note: Active systems use vari-ous types of solar collectors and can be additional source for heating – percentage of using depends on the geo-graphic latitude, times and in-tensity of the sunshine. It’s always system with heat accu-mulation, mainly to the water tank but it can be also pool, or gravel storage, then the accu-mulated energy is used usually for heating or mainly for do-mestic hot water. But a rule proceeds that longer accumu-lation means higher costs.

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For guaranteeing maximal efficiency of the system is necessary to find suitable combi-nation of the solar panel, heat accumulator and the working temperature of heating system. The regulation of the system is very important. There are many sensors connected to main part of the system and regulating system. When the sensor on the solar panel discovers that temperature of the panel exceeds the temperature of the tank, the regulation switches the pump on and the heat from panel is carried into the storage. When temperature in the tank reaches temperature of the panel, pump is switched off. So the heat losses are pre-vented. 3.1.7 Heating elements

Definition:The main task of the heating ele-ments is to put enough heat to the internal space to create thermal comfort. The quantity can be regulated by the type, size and way of installation of the heating element.

Devices that direct vents away from windows to prevent "wasted" heat defeat this design intent. Cold air drafts can contribute significantly to subjectively feeling colder than the average room temperature. Therefore, it is important to con-trol the air leaks from outside in addition to proper design of the heating system.

Radiator next to the window

A – floor convector, B – intensive zone of underfloor heating,

C – underfloor heating

Note: The heating elements (radiators or vents) should be located in the coldest part of the room, typically next to the windows to minimize conden-sation and offset the convective air current formed in the room due to the air next to the window be-coming negatively buoyant due to the cold glass (see picture).

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On contrary when the element is integrated into the internal surface (e.g. underfloor heating), the cold air from the window falls down to the floor and creates unpleasant convective flow with velocity about 0,3 - 0,5 m/s. The floor heating near window should be intensified or floor con-vector should be installed to deflect the unpleasant flow. Types of heating elements 1. Radiators It’s a mistake to think that you can use only underfloor or wall heat-ing in the low temperature heating systems. The modern radiators can be used also in the low-energy building without any problem connected with volume of the radiator. However it’s important to choose carefully the suitable type heating body. Radiator transmits heat by radiation and convection. Sectional radiators are composed from several sections and are manufactured from the different materials – usually from steel

sheets, cast-iron or aluminium. These type of radiator has got very good hydraulic characteristics. The water con-tent and weight is high so the radiator doesn’t react enough quickly. That can be a disadvantage in case of using flexible source of heating and automatic regulation. Sectional radiators are characterized by the long lifetime - some types about 80 years without corrosion. Board radiators belong to the most common radiators. These radiators are composed from plain or wavy steel boards (from 1 to 3).

Tubular heating body is mostly installed in the bathroom, toilets or hall. They consist of several small steel of copper tubes welded together. They are usually very aesthetical, and are available in many shapes, sizes and col-ours. It is possible to install it inside the space like the parting wall. This type of heating element is ideal for drying laundry but hasn’t got enough high output to heat big room. And also in bathroom it’s recommended to use it as additional source.

2. Convectors Convector is a heating element, which transmits heat by convection. It consists of the exchanger and the case with grating on the upper side.

It can be placed on the wall, built into plinth or floor. The inbuilt con-vector has got small output so the ventilator has to be installed to increase the output.

Note: Compared to sectional radiators board radiators contains only 1/3 of water, so they are much more flexible and can be easily regulated by thermostatic valve.

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3. Underfloor heating

Definition: Underfloor heating is the large-area radiation heating. There are two types of underfloor heating - hot water or electric.

Using this type of heating element you need lower temperature to main-tain the thermal comfort in the interior so low potential source as heat pump, condensing boilers or solar panels can be used for hot water heat-ing. Electric heating is mainly used as additional element to maintain higher comfort. 4. Wall heating system Wall heating system has got the same development as underfloor heating, but is not used so usu-ally. The cost of investments is higher, but it brings some advantages. It creates an ideal climate; it is flexible in designing and using and brings new possibilities in heating old houses. External walls emit cold to the room when you use heating system. That turns round with wall heating system and external wall emit heat to the internal space. So we need low temperature for heating and the low potential sources can be used. And in contrast to underfloor heating the tem-perature of the wall is not limited. The construction is similar to underfloor heating. 3.2 Cooling – Air conditioning 3.2.1 Introduction Air-conditioning systems allow the maintenance of a pleasant temperature in buildings during the warmer season. It is a relatively recent luxury to choose the desired temperature at which to keep our homes. In fact, in the last few years, the relevant price drop of those cooling devices has widely spread their use in more and more residential buildings. Furthermore, in the great majority of cases, buildings don’t come with central systems, which would make them more efficient, while air-conditioning units are installed in single apartments..

Before explaining how an air conditioner works and its typology, the following question needs reflection.

Note: As a consequence, air conditioners are shooting up the summer utility bills of industries, hotels, hospitals, institutional buildings, schools, etc. and, in many warmer European regions, the household energy consumptions are becoming greater during summer than winter, due to the ex-tended use of such cooling systems.

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What is a comfortable temperature?

Definition: Thermal comfort is very difficult to define because you need to take into account a range of factors when deciding what will make people feel comfortable. The most commonly used indicator of thermal comfort is air temperature, although other factors, like humidity and air movement, together affect the thermal comfort feeling.

A comfortable environment is one in which the occupants do not express any sensation, either cold or hot, because the ambient conditions produce an ade-quate and sufficient feeling of well-being. Why define comfort? An air-conditioning device needs to have a working temperature set, usually from a remote con-trol, above which temperature it starts to cool. Thus, it is advisable to select an appropriate tem-perature, because if it is too low, the device will be running for too long, but if it is too high the device will work for only a little time and therefore not be cooling enough. Often we don’t appropriately consider the necessity of a cooling device or its power and con-sumption. Thus, defining comfort will allow the selection of the suitable temperature on the ther-mostat. What is more comfortable? The following example clarifies what has been said: On a summer’s day, the temperature in my town at 15:00 is 38ºC, what is more comfortable?

A) Entering and exiting a building whose interior temperature is 18ºC?

B) Entering and exiting a building whose interior temperature is 24ºC?

In option A, the body experiences a sharp jump in tem-perature of 20ºC, while in option B, this jump is reduced to 12ºC. According to the comfort definition, in this case it is much more comfortable to set the air conditioning to 24ºC.

Note: In summer, the temperature setting of an air conditioner should be such that, en-tering the building, a feeling of cold is not experienced. Despite the fact that the air con-ditioning allows you to select temperatures below 18ºC, the operating temperature in the summer must be between 23ºC and 25ºC.

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And ...What is this for? To select the suitable air-conditioning temperature gives us four main linked advantages:

Increasing the comfort;

Cutting down the hours of equipment operation, thus consuming less energy;

By consuming less energy, we reduce our electricity bill;

Having temperatures in the house too low is not healthy; it produces a sudden thermal jump causing the majority of slight summer colds.

3.2.2 How does an air conditioner work?

Definition: The function of any refrigeration or air-conditioning system is to transport heat from one station to another with a cer-tain amount of work, i.e., electricity consumption. It is like an exchange where heat is absorbed from inside the home, getting cooled, and transported to the exterior where is released.

To do this, the cooling device uses a vehicle substance, well known as “refrigerant”, with suit-able physical characteristics. It is a special substance that passes from the fluid to the gas phase over low temperature conditions. During that phase change , the changed heat is trapped. A cooling system consists of four basic parts (compressor, condenser, expansion device, and evaporator), within which the refrigerant fluid is continuously circulated. The basic system is divided into four steps as is shown in figure 14. Steps 4–1: The refrigerant passes through the evapora-tor (situated indoors), where it removes heat from the warmer space (the inside room), being cooled. This heat absorption process results in the vaporization of the refrigerant, which means it passes into the gas phase (as said above, it passes into the gaseous phase to trapping heat). Steps 1–2: The refrigerant leaving the evaporator (in a vapour low-pressure state) is compressed into a rela-tively high pressure and temperature by the compres-sor. It is in the compressor device where electricity is consumed. Steps 2–3: Next, the higher pressure and temperature refrigerant passes through the condenser (situated out-doors), where it condenses due to contact with a cooler medium such as the outdoor air, thereby there is a heat transfer from the refrigerant to the cooler surroundings. Steps 3–4: Finally, the higher pressure and temperature refrigerant is reduced in pressure by an expansion valve for delivery to the evaporator. Obviously, the evaporator device is situated indoors and the condenser outside the building.

Fig. 14 Basic scheme of a vapour-compression refrigeration system

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What about their efficiency? In recent years, concern for the conservation of energy has led manufacturers of air conditioners to significantly improve their devices to become more energy efficient. The efficiency of an air conditioner is indicated by the Energy Efficiency Ratio (EER). It defines “what you get for what you have to put in”, where the useful effect (what we get) is the removal of heat from the indoor space and what we have to “put in” is the electricity consumption by the compressor. The higher the EER is, the more efficient the air conditioner is.

Table 4 Energy efficiency scale

Therefore, the older air conditioners can have an EER of about 2.2, while the new ones can have a value of approximately 3.5. It means that, comparing these two devices, as the amount of heat to be evacuated is the same, the device with less EER consumes 60% more energy than the high-est EER in performing the same function (3.5/2.2 = 1.60). 3.2.3 Energy Label With the objective of saving energy to reduce CO² emissions, the European Union regulates the energy labelling of all air conditioners.

The label for energy efficiency reports on the energy consumption of air conditioners. They are graded on a scale from A–G, where A represents the best equipment that is widely available and G the worst (see figure). The energy label will also show the estimated annual energy consumption in kWh. Equipment with a higher rating may cost a little more initially, but G-rated equipment will use 50% more electricity under normal operating conditions compared to A-rated units.

3.2.4 Different air-conditioning system options First of all, before acquiring an air-conditioning system, you need to make sure that you really need it. Air conditioners are quite expensive when compared to fans and, most importantly, they consume large amounts of electricity.

EER

A 3.20 < EERB 3.20 ≥ EER > 3.00C 3.00 ≥ EER > 2.80D 2.80 ≥ EER > 2.60E 2.60 ≥ EER > 2.40F 2.40 ≥ EER > 2.20G 2.20 ≥ EER

Energy Efficiency Scale

requiredEnergy

movedHeatEER

_

Re_

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Are you sure you cannot reach a comfort level using an inexpensive fan?

If you have finally decided that you need an air conditioner, choose the type of system that matches your needs. Shown below are the main air-conditioning sys-tem options. Room Air Conditioners They are used to cool single rooms rather than an entire building. They are less expensive to operate than central units, but their efficiency is generally lower.

The most commonly used are “Split System” ones (as in fig-ure), meaning that the coil (Evaporator) is located indoors and the condenser, outdoors. Both units are connected to each another through a conduit, through which cooling fluid circulates.

When the evaporator and the condenser are both located in the same case, the system is called a “packaged system” or “combos”. Central Air Conditioners Central air conditioners use supply-and-return ducts distributed throughout the building, through which the cooled air and the later warmer air circulate. Most central air conditioners are split systems (see above). Heat Pumps A heat pump can serve as a heater and as an air conditioner. In the winter, a heat pump draws heat from the outdoor air and circulates it through ducts into the building. During the summer, it reverses the process and draws heat from the interior air and releases it outdoors. These systems can make significant energy savings, as they work both as heaters and as air conditioners.

Note: In most cases, a fan will produce the same comfort feeling as an air conditioner. They lead to temperature feelings of 3°C to 5°C lower than the actual temperature and have a lower electricity consumption (usually less than 10% of air-conditioner electrical consumption).

Packaged system

Note: During the summer, air conditioning can account for 50% or more of your total electric bill.

Evaporator Condenser

Split system

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3.2.5 Tips and hints on how to use an air conditioner Follow the tips below to increase energy efficiency and save money. Avoid using air conditioners when possible:

In most cases, a fan will produce the same comfort feeling as an air conditioner.

Avoid unnecessary heat flows, such as excessive lighting, hot equipment, etc. Switch off when unused.

Eaves and awnings are good tools that avoid the entry of sunlight during the summer (see the chapter on windows below).

Properly sized and correctly use of your air conditioner:

Table 5. Guidance for dimensioning

N.B. Indicative values such as construction materials, orientation and design of the building sig-nificantly influence cooling needs. For example, if the room to cool is very sunny or if it is an attic, we should increase the table cooling power values by 15%. If there are heat-source devices, as in the kitchen, power will be increased by 1 kW.

Set an acceptable level of comfort (between 23ºC and 25ºC, the second one being the best level) and install control devices (thermostats) to regulate the air-conditioning system according to the required temperature. With each degree below the comfort temperature, you are wasting 8% more energy.

Keep doors and windows closed when the air conditioner is running.

Good insulation is very important in avoiding cold leaks (follow the same advice given in the Heating systems section and look at the Insulation section).

Make sure the cold flow is well distributed throughout the space, avoiding areas with too cold or too hot air streams (near windows, doors, etc). If your air conditioner has adjustable louvres, adjust them towards the ceiling, since cool air falls.

Look carefully at the energy rating of the new air conditioner, where A represents the best equipment and G the worst.

Correct installation and proper maintenance of your equipment:

Place the condensing unit outside and in a well-ventilated area away from solar ra-diation.

In room air conditioners, place the system in a window or wall area near the centre of the room and on the shadiest side of the house.

Surface to cool (m2) Cooling Power (KW) 9 – 15 1.5 15 - 20 1.8 20 - 25 2.1 25 - 30 2.4 30 - 35 2.7 35 – 40 3 40 – 50 3.6 50 – 60 4.2

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Clean and check your air conditioner every few months. Dirty filters and coils can block the normal air flow and impair the heat-absorbing capacity of the evaporator, reducing the efficiency of the system. Savings can range between 3% and 10%.


1. What can create local discomfort? ……………………………………………………………………………………… 2. What heat carrier is often used in heating system? ……………………………………………………………………………………… 3. Explain how does the heat pump work? ………………………………………………………………………………………. 4. Why should the heating factor of the heat pump be higher than 1? ………………………………………………………………………………………. 5 Name components of the solar heating system: ………………………………………………………………………………………. 6 What are the three main factors affecting thermal comfort?

– ........................ – ........................... – ............................

7 What should the operating air-conditioner temperature be set at in the summer season in order to feel comfortable and to avoid a sudden thermal jump? .....................

8 In an air-conditioning system, in what device/part is electricity consumed? (Tick the

correct one) Compressor – Evaporator Condenser

Web links

http://www.rerc-vt.org/solarbasics.htm

http://www.price-hvac.com/media/trainingModule.aspx

http://www.idae.es/

References

Greg Pahl: Natural Home Heating: The Complete Guide to Renewable Energy Options, Chelsea Green Publishing, 2003

ASHRAE, Fundamentals Handbook (SI), GA, ASHRAE, 2001, Atlanta.

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Moran, M. J. and H. N. Shapiro, Fundamentals of Engineering Thermodynamics: SI version, John Wiley & Sons, Inc., 2006.

VV. A. A.: Guía Práctica de la Energía. Consumo Eficiente y Responsable (Practical Guide for Energy: Efficient and Responsible Consumption), Instituto para la Diversificación y Ahorro de la Energía (IDAE), 2007, Madrid.

Key points: Thermal comfort is one of the most important factors which provide optimal

internal environment for people. The best way how to provide thermal comfort without increasing energy con-

sumption is to achieve just the recommendations - temperature especially - not overheating or overcooling

There are several possibilities and combinations of heat source and heating ele-ments. It is important to choose optimal combination and proper regulation.

There is a good possibility to use effectively renewable sources - solar, bio-mass, heat pumps

Air conditioners are shooting up the summer energy bills of industries, hotels, hospitals, institutional buildings, schools, etc. of many warmer European re-gions.

The function of any refrigeration or air-conditioning system is to transport heat from one station to another with a certain amount of work, i.e., electricity con-sumption. It is like an exchanger where heat is absorbed from inside the home, getting cooled, and transported to the exterior where is released.

Air conditioner operating temperature in the summer must be between 23ºC and 25ºC (the second one being the best level). With each degree below the comfort temperature, you are wasting 8% more energy.

In most cases, a fan will produce the same comfort feeling as an air condi-tioner. They lead to temperature feelings of 3 °C to 5 °C lower than the actual temperature and have a lower electricity consumption.

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4 Domestic hot water preparation Domestic hot water preparation is usually the second highest amount in the heat consumption of the house. Consumption depends on the user’s habits and differs in every country and every household.

In houses with central heating system the same source is used for heating and hot water prepara-tion. In houses with local heating system electricity is used most.

During the heating period domestic hot water is usually prepared together with heating. In sum-mer the water preparation should be separated, because you don’t use whole input of the heater. Especially, efficiency of an old heater can drop to 40 %, modern heaters can switch into the sum-mer mode, so the efficiency can be 80 % or higher.

Table 1. How much potable water we need/consume?

4.1 Types of water heating appliances There several systems to prepare hot water – instantaneous water heaters or storage system, di-rect or indirect heating. And all can be sorted by the source of energy. Direct heating means that the water is in contact with the source of heating (electricity, flame etc). Indirect means that wa-ter for consumption is heated through heat exchanger. Storage system is the oldest system of preparation potable water. The inequality of the consump-tion and production is covered by the storage. When the uncontrollable heater for solid fuel is used, the storage is even required. The calculation of the proper size of the storage depends on the time of heating the water, and then using use this time you calculate input of the storage. This type of boiler has got low take-off for long time. The disadvantage is that the heat loss can be quite high (new types have got the loss printed on the energy label). When you use instantaneous heater, the water flows throw the heat transfer surface and get warmer. Instantaneous heaters are not suitable for places where the consumption is often and it’s in small amounts (e.g. washing hands). The temperature changes with the outflow, so it can be problem sometimes. This type of heaters has got on contrary high take-off for shot time. But this type is quite sensitive to earthy water.

Washing hands 3 - 6 l 37 ° 0,1 - 0,2 kWh

Daily body care 9 - 12 l 37 ° 0,3 - 0,4 kWh

Dishes (1 person) 4 - 7 l 60 ° 0,3 - 0,5 kWh

Taking a shower 30 - 50 l 37 ° 1,0 - 1,7 kWh

Taking a bath 150 - 180 l 27 ° 5,0 - 6,0 kWh

Washing hands 3 - 6 l 37 ° 0,1 - 0,2 kWh

Note: Is said that minimum consumption is about 40 litres per one person and day what is about 2 kWh. Average consumption is about 3,4 – 4 kWh per person and day (this number includes the losses in the piping). .

Note: To avoid heat losses the pipeline should be as short as possible and well insu-lated. Temperature should be about 45-60 °C.

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4.1.1 Electrical storage appliances Electrical heating is usually the direct heating. Water in this type of appliance is usually heated at night, when the electricity is cheaper. So the advantage is the lower price of electrical energy and also low input of the appliance. The heating spiral connected to the heating system can be in-stalled in the storage, so in winter you can heat water by cheater heat from the heater. This type of appliance is called combination (or ‘combi’) boiler. The disadvantage is limited volume of water you can heat. When you consume whole storage, you have to wait quite long (sometime to the next day) for next hot water. 4.1.2 Electrical instantaneous appliances This type is usually placed under the sink. When you use this type of appliance the hot water is available every time, but on contrary it brings disadvantage is that the installed input of this ap-pliance is quite high. So you need better circuit breaker and that means higher costs and bills. 4.1.3 Gas direct instantaneous appliances This type of appliance was common in the past. Today the gas storage appliances are usually used. Main advantage of this type is simple construction and operation, and also small propor-tions. On contrary the efficiency is low and temperature varies with the flow. 4.1.4 Gas direct storage appliances This type eliminates disadvantage of the instantaneous heater. Input of the burner can be lower, temperature doesn’t depend on the flow and efficiency is higher even if you take out only small amount of water. But it’s bigger and price is higher. In comparison with electrical heater, gas heater can operate during whole day; the input is higher, so the size can be smaller. This water heater can also be connected with the heater or there are a lot of heaters with integrated storage in the market. 4.1.5 Gas indirect storage appliances These are connected to the gas heater and heat the water through the exchanger installed inside the tank. This solution is suitable when you use other source in addition to the gas heater. 4.1.6 Other possibilities The storage with heat exchanger is the universal system of water heating and can be used with any other source of energy, e.g. fossil fuels, bio-mass, wood, solar energy, heat pump etc. Also geothermal energy can be used. Counter-flow exchangers are used recently, but mostly to accu-mulate the energy into the water is preferable. With solar system or heat pump accumulation is necessary. 4.2 Tips and hints on how to spare water and energy It’s not pleasant to pay bills especially when the price rises constantly. So it’s better to spare en-ergy and water. In fact you spare two times – water and also energy needed for the heating. Preparation potable water presents about 25 % of the energy consumption.

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Next step is to lower the consumption. There are a lot of possibilities. Take a shower or bath? Cheaper is taking a short shower because only one third of water is consumed in comparison with taking a bath. Also using the showerhead for washing hands or dishes can spare water, be-cause the water is enriched by air and so the higher flow is made. With economical showerhead in the shower you can spare other 30-35 % of potable water. Using single handle faucets which reduce time of regulating temperature can spare almost 20 % of energy needed to heat the water. If you comply with all these principles you can spare 30 – 40 % of energy needed to heat the wa-ter, that’s about 7 – 10 % of single family household consumption of energy. And that’s not a small amount.

So look at possible spares in detail:

Mixing A great loss of water and energy presents time of mixing water from the tap. A huge amount of water flows off without any use till you mix water with suitable temperature. So there is one sim-ple trick: open the hot water first and wait till it flows. Then open the cold one which has tem-perature about 20 °C because it’s warmed in the pipeline and mix it. After a while cold water from the source (10 °C) flows and brings down the temperature. If you only wash your hands it doesn’t matter, if you are taking a shower simply increase the temperature. When you finish close the hot water first. It may appear to be a pettiness but in households with small children these are thousands of long lasting mixings of water. When you spare a decilitres or litres of wa-ter in every washing, yearly savings can reach several cubic metres.

Single handle tap Problem with mixing is partly solved using the single handle faucet. When you use this type of faucet you have to learn which position of handle brings the suitable hot water. During washing dishes it’s useful to close the tap several times, prepare another part of dishes and open it again. Other tip: with short handle you can’t regulate the flow of the water fluently. The regulation is usually jumping so it’s better to buy a tap with longer handle. An ideal solution is to use the thermostatic tap in whole flat, because you can simply set up the temperature and then the flow of water. There is no need to worry about to hot water.

Shorter water plumbing When you move the heater from the cellar to the bathroom or as close as possible you can lower heat losses from the pipeline. Bathroom today becomes representative part of the flat and archi-tects don’t want to have a boiler inside, but you can simply put it in the cupboard.

Change your habits Taking shot shower can spare almost 70 % of water compared to taking bath. There is no need to give up relaxing in the bath only to reduce this habit. A bath contains about 150 litres of water on the other hand you need 50 litres to take a shower.

Reduce wasting We usually waste water and let if flow off to the sanitary plumbing because we don’t turn off the faucet when we soap our hands, brush teeth, shampoo hair, shave ourselves, etc. There is also one good example of the usual wasting. We usually wash our hands in very little amount of wa-

Note: First step is to prevent all leakages of the hot water. Dripping 10 drops in one minute represents 40 litres per week.

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ter and turn on the hot water, but from the tap flows the water with 20 °C and when the hot water arrives we usually turn off the tape and let this hot water cool down in the pipeline. So try to wash your hands with cold water because this water also stayed in the pipeline and is warmed to 20 °C. Another tip how to reduce wasting of water is using single use gloves for dirty work, us-ing cups for brushing teeth or shaving. 4.3 Solar water heaters

These active solar systems accumulate collected sun energy into the storage (can be water tank, but also pool, or gravel storage) and then the accumulated energy is used usually for domestic hot water or heating. But a rule proceeds that longer accumulation means higher costs. Solar sys-tem has to be connected with other heating source (e.g. gas boiler, electrical boiler etc) in case that there is no or a little sunshine (cloudy, night etc). In summer the heat carrier can be water, but in the year-long operation the non-freezing liquid has to be used.


1 Which is the suitable temperature of the domestic hot water? ……………………………………………………………………………………….. 2 What does consume less water? Taking a bath Taking a shower

3 What part of the domestic hot water can be annually prepared by solar system? ………………………………………………………………………………………..

Note: This type of domestic water preparation belongs to the most usual using of solar energy. The main advantage is that the solar energy is accessible, operation of this sys-tem cost almost nothing and can be installed additionally. But the costs of investments are quite high so the pay-off period long and the whole system depends of the sunshine which is unpredictable.

Note: Advantages of the solar hot water preparation: Provides 50 % to 70 % of your annual hot water needs

20-30 years life expectancy

Solar water heaters will halve your annual hot water bills

Summer hot water is almost completely provided

Functions when overcast

Simple planning considerations

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References

Greg Pahl: Natural Home Heating: The Complete Guide to Renewable Energy Options, Chelsea Green Publishing, 2003

Web links

http://www.engineeringtoolbox.com http://www.rerc-vt.org/solarbasics.htm http://www.diydoctor.org.uk/projects/domestic_hot_water_systems.htm

Key points: Domestic hot water preparation is usually the second highest amount in the

heat consumption of the house. Minimum consumption is about 40 litres per one person and day what is about

2 kWh. Average consumption is about 3,4 – 4 kWh per person and day. There is a problem in summer period when losses from pipeline turn into un-

wanted internal gains. To avoid heat losses the pipeline should be as short as possible and well insulated. Temperature should be about 45-60 °C.

First step is to prevent all leakages of the hot water. Dripping 10 drops in one minute represents 40 litres per week.

Saving is taking a short shower because only one third of water is consumed in comparison with taking a bath. Also using the showerhead for washing hands or dishes can spare water, because the water is enriched by air and so the higher flow is made.

There is a good possibility to use effectively renewable sources - solar espe-cially

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5 Lighting

Learning Objective: In this Chapter you will learn: The importance of light for humans How use daylight and artificial light An overview of the possible artificial light sources What is light, how to measure and recommendations for its intensity in buildings

We need proper lighting for seeing and working. Main demand on the internal space (from this the point of view) is the visual comfort.

Definition: It means that the lighting environment has to satisfy physiological, psychological and aes-thetical needs of human.

Lighting includes use of both artificial light sources such as lamps and natural illumination of interiors from daylight.

When it’s not possible to use the day lighting you can use mixed lighting or in worst-case only artificial lighting.

To provide the demanded illumination of the space the artificial lighting is usually needed. So, artificial lighting represents a major component of energy consumption, accounting for a signifi-cant part of all energy consumed worldwide.

Artificial lighting is most commonly provided today by electric lights, but gas lighting, candles, or oil lamps were used in the past, and still are used in certain situations.

Proper lighting can enhance task performance or aesthetics; while there can be energy wastage and adverse health effects of lighting. Indoor lighting is a form of fixture or furnishing, and a key part of interior design. Lighting can also be an intrinsic component of landscaping.

Note: Daylight is very important for human being. Without daily stimulation of the day-light the human vision can degenerate. So day lighting (through windows, skylights, etc.) is used as the main source of light during daytime in buildings where people live or work.

Note: Using daylight during the daytime also brings down the energy demand and also the costs.

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5.1 Daylight Source of daylight is direct rays of sunlight or sunlight dispersed by sky. Intensity and colour of daylight vary during the day and the year and also depends on geographical latitude and the weather condition. Daylight belongs to main factors of the environment and has got a huge im-pact on the man’s physical and psychical condition. So there are some quantity and quality de-mands in standards or recommendations. Quantitative criterion is the level of intensity of daylight, quality is described by luminous flux and the direction of the light, equability of illuminance and brightness and glare. The glare is caused by high brightness or high contrast e.g. roof windows oriented to the sky. So it is neces-sary to regulate direct rays of daylight in internal spaces. There are many ways to regulate day-light. You should choose these instruments which suit best and are eco-nomical. Firm window covering – are situated on the external side of window (e.g. terrace blinds) Moveable window covering – (e.g. window blind, curtains, movable terrace blinds) can regulate as necessary and can be placed on both sites. On external sited also eliminates the gains from the sun.

5.2 Artificial lighting Artificial lighting is realized by artificial lighting sources in time when day lighting is no possi-ble. Modern sources can create in internal space lighting which is similar to day lighting.

The lighting is usually divided into central and local lighting. There is main principle in designing lighting – the light has to be there where is needed (e.g. floor, working place etc.). Also the way of lighting is important. It can be direct, semi direct, mixed or indirect. Direct lighting means that the light falls down on working place or the floor. Direct lighting uses whole emit-ted light so it’s very economical, but on contrary the dark shadows with sharp edges originate and caused the glare. Also the ceiling and upper part of wall are dark.

Semi direct lighting means that the source emits the light not only down but also up to the ceiling or walls. The room appears more comfortably. The light reflected from the ceiling makes shadows lighter and the glare is more acceptable. The semi direct lighting is optimal and is used most often. Mixed lighting emits light in all directions, so the illuminance of all surfaces (floor, ceiling, walls) is same.

Note: Intensity of the light should react on the visual activity. Lower for basic activity and higher for visual demanding activity. And also lighting has to create suitable and pleasant environment.

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Indirect lighting means that all light falls on the ceiling and upper part of walls. Bright ceiling appears like the source with low inten-sity, so the whole room is illuminated uniformly without any glare. Disadvantage of this lighting system is its high light loses caused by the reflection.

5.2.1 Sources of light There are two main groups of sources - thermal sources and luminescent. In thermal sources (e.g. Sun, common bulb) the light is emitted by heating on very high temperature. In luminescent source (fluorescent bulbs) the light springs from luminescence. There is a list of technical data which characterizes source which determines the quantity and quality of the light: voltage (V) input (W) luminescent flux (lm) lumen per watt (lm/W) temperature (K)

Bulbs are most common and most uneconomical sources. Only about 3-4 % of the inputted energy transform into the light, the rest is the waste of the heat. Advantage is the low price and easy application without need to install other facilities. The col-our rendition is very pleasant and approximates to the daylight. The lifetime is quite short, about 1000 hours. The input varies from 15 to 200 W and lumen per watt from 6 to 16 lm/W.

Halogen bulbs are quite new sources. Because of its shape they are preferred for decorative and intimate lighting. The lumen per watt is higher from 11 to 25 lm/W. And the lifetime is longer, about 2000 - 3000 hours. These bulbs are manufactured in 2 types, for low voltage (12 V) with input from 5 to 75 W and for line-voltage with input from 60 to 2000 W. They have got the highest colour index from all sources. When you use it don’t for-get that they are suitable for low voltage, the temperature of this source is high and they warm surroundings.

Today standard fluorescent lamps are most common. They belong to the low-pressure sources. The light is emitted by incidence of the UV light on the layer of luminophore which covers the internal side of fluorescent lamp. The lamps are manufactured in many colour tones from rose to daylight. The colour index is quite good. The lumen per watt is higher from 35 to 60 lm/W. The lifetime is quite long, 5000-8000 hours. But often switching brings down the lifetime.

There is some anxiety about negative influence of these lamps on human organism (headache, dry eyes, hair loss etc.) but the research has proved that this fear is idle.

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We recognize two types of fluorescent lamps: linear and compact. Linear sources are manufac-tured in the length 60, 120 and 150 cm and with inductive stabilizer (INDP) the fused starter for 230 V or without starter with electrical stabilizer (ELP). These sources have got about 10 times longer lifetime and 5 times higher output than common bulbs. Compact fluorescent bulbs belong to the group of most modern sources. Some types of these sources are produced with the same thread as common bulbs, so you can replace bulbs easily. The lifetime is about 8 times longer and the input about 6 times higher than bulbs.

Table 1. How much energy can be saved with replacing bulbs by fluorescent lamps?

It’s percentage of not used energy.

5.2.2 Lamps The important parts of the lighting are also the lamps. Different sources required different lamps, for example the lamps for linear fluorescent bulbs have got different shape and construction than lamps for bulbs. Lamps consist of the lighting part and construction part. Lighting part can be diffusor (which disperse the light), reflector (which reflects the light) or refractor (which refract the light). The lamp is characterized by the ef-ficiency of the lamp which means the ratio between lumen flux of the lamp to the flux of the source. Lamps which are opened on the bottom have got the highest efficiency. Common problem of the lamps is the glare from visible source. Sources should be covered, so it shouldn’t be possible to see them from usual angles. Good choice of the lamp brings higher working efficiency, comfort, better vision and health. 5.2.3 Energy consumption Artificial lighting consumes a significant part of all electrical energy consumed worldwide. In homes and offices from 20 to 50 percent of total energy consumed is due to lighting. Most im-portantly, for some buildings over 90 percent of lighting energy consumed can be an unnecessary expense through over-illumination. The cost of that lighting can be substantial. A single 100 W light bulb used just 6 hours a day can cost over 28 € per year to use (the calculation is the same as another electric appliance). Thus lighting represents a significant component of energy use today, especially in large office buildings where there are many alternatives for energy utiliza-tion in lighting.

There are several strategies available to minimize energy requirements in any building: Specification of illumination requirements for each given use area.

Analysis of lighting quality to ensure that adverse components of lighting (for example, glare or incorrect colour spectrum) are not biasing the design.

Type of source replacing bulb Savings Linear fluorescent bulb Ø 38 mm with INDP

62 %

Linear fluorescent bulb Ø 26 mm with INDP

72 %

Compact fluorescent bulb with INDP 76 % Compact fluorescent bulb with ELP 79 % Linear fluorescent bulb Ø 26 mm with ELP

82 %

Linear fluorescent bulb Ø 16 mm with ELP

88 %

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Integration of space planning and interior architecture (including choice of interior surfaces and room geometries) to lighting design. Design of time of day use that does not expend unnecessary energy. Selection of fixture and lamp types that reflect best available technology for energy conser-vation.


1 What are quantitative and qualitative criterions of the light? ……………………………………………………………………………………….. 2 Why is it necessary to regulate direct rays of daylight in internal spaces? ……………………………………………………………………………………….. 3 What is direct lighting? ………………………………………………………………………………………. 4 Which technical data does characterize source? ……………………………………………………………………………………….

References

Fetters, John L.: The Handbook of Lighting Surveys & Audits, CRC Press, 1997

Web links

http://www.iesna.org/ http://www.enlighter.org/ http://www.newbuildings.org/ALG.htm http://www.lrc.rpi.edu/ http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/97/970109.html http://www.lightingmanual.com/ http://www.vgklighting.com/

Note: Training of building occupants to utilize lighting equipment in most efficient man-

ner. Maintenance of lighting systems to minimize energy wastage. Use of natural light - some big box stores are being built with numerous plastic

bubble skylights, in many cases completely obviating the need for interior artifi-cial lighting for many hours of the day.

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Key points: We need proper lighting for seeing and working. Day lighting (through win-

dows, skylights, etc.) have to be used as the main source of light during day-time in buildings where people live or work

Intensity of the light (illuminance) should react on the visual activity. Lower for basic activity and higher for visual demanding activity. This is closely con-nected with electric input and consumption of artificial sources of light; higher intensity higher input higher consumption.

It is possible to save 60 - 80 % of energy with replacing bulbs by fluorescent lamps.

The simplest and most obvious way to eliminate useless energy consumption is to switch off lights when not necessary.

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6 Electric appliances and electronic devices (and solar PV)

Learning Objective: In this Chapter you will learn: The unit of electricity measurement and how to calculate it How to read the European Energy Label for electric appliances An overview of the characteristics of the main appliances used in households

and how to save energy using them properly.

6.1 Overview In our homes, we are surrounded by all kinds of electrical and electronic equipment that we use regularly to meet our needs. We consider their use as being so elemental that sometimes we for-get the associated energy cost. In Europe, electrical appliances account for about 8% of a typical household’s energy consump-tion.

Main appliances include the follow-ing:

Refrigerator and deep freeze Washing machine and tum-

ble dryer Dishwashers Immersion heater Hairdryer Room air conditioners Electric oven

Apart from the purchase price, which normally is the driver in the criteria for choosing, the cost of operating the appliances during their lifetimes should also be seriously considered, that is the cost of the utility bill every month for many years (depending on the lifetime), due to their elec-tricity consumption. Models with high energy-efficient performance usually have a higher initial purchase cost, but they permit the saving of significant amounts of energy costs over their life-time (and thus save money). Do you know what an Energy Label is? One of the main aims of the EU Energy Label is to help householders make informed decisions about the purchase of energy-consuming appli-ances. It is also an incentive for manufacturers to improve the energy performance of their products. The Energy Label is compulsory only for a certain group of products, light bulbs, cars and most electrical appliances (e.g., refrigerators, stoves, washing machines, as listed above). The other appliances, which have

Note: The percentage is much higher if we refer to a household’s electricity consump-tion. Consumption by all-electrical appliances and lighting represents about 55% of the electricity used by households. The appliances include the six large consumers of elec-tricity (refrigerators, deep freeze, washing machines, dishwashers, TV and dryers), and many small appliances.

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lower power in general, are not covered by the Energy Label. Some of them are: toasters, fans, clothes irons, blenders, etc.

Definition:The Energy Label is a sticker providing clear and easily recognizable in-formation about the energy consumption and performance of products and must be attached visibly to new appliances displayed for sale. An important part of an energy label is the energy-efficiency rating scale, which pro-vides a simple index composed of a code of letters and colours ranging from green and the letter A, the most efficient, to the colour red and the letter G, the least effi-cient.

The energy consumption figure shows you the units of electricity use in kWh to allow comparisons between models. Each letter that is lower in the scale, away from A, means an increase in energy consumption by about 12–15% more than the letter that pre-cedes it. Thus, we can say that, for instance, a washing machine of ”Class A” consumes up to 24% less than one of equal benefits and class C, and up to 36% less than a Class D. Only in the case of cold appliances (refrigerators, freezers, etc.), must you add two rows from the top, to include Class A+ and A++, express-ing an even lower relative consumption. Therefore, if you consider that the useful life of a home electrical appliance is more than ten years, the energy savings to be gained are very important. How do you estimate appliance electricity consumption? How much electricity do appliances use? The first step to making your home more energy efficient is to understand where you use energy. You can make the greatest impact on reducing your electric bill by focusing on the areas where you use the most energy. But to do that it’s useful to know the following two basic concepts!! 1. Electric Power The electricity consumption of an appliance firstly depends on its “electric power” or the wattage, that is to say the maximum power drawn by the appliance. You can look at the wattage of most appliances stamped on the bottom or back of the appliance, or on its nameplate.

Usually it is expressed by watts (W) or kilowatts (kW) (Remember that 1 kilowatt (kW) = 1,000 Watts)

Thus, if you have 500 Watts, it means 0.5 kW (obtained by dividing

500/1,000). Some examples of the wattage range for various electrical appliances are shown here, bearing in mind that they can vary much according to type, size and working conditions.

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Table 6 .Typical Wattages of Various Appliances

2. Electricity Consumption When you use electricity to watch television (or just keep to it on without watching!) for 1 hour,

you use 150 watt-hours of electricity. And, 1,000 watt-hours equals 1 kilowatt-hour (1,000 Wh = 1 kWh). But, it is important to bear in mind that, since many appliances have a range of settings (for ex-ample, the volume on a radio, the temperature se-lected on an air conditioner), the actual amount of power consumed depends on the setting used at any one time. It means that if an appliance is not running at its maximum wattage (for example not the maxi-mum air-conditioning temperature), the electricity consumed does not exactly equal power per time, but rather, less. This is obtained by multiplying by the so-called “demand factor”,* which is a number equalling 1 (running at maximum wattage) or less (not at maximum wattage). Consumption Calculation: First of all, you already know that the consumption of electricity by elec-tric appliances is measured in a unit termed “kilo-Watt-hours” (kWh). In order to estimate the electricity consumption of an appliance, these few steps can be followed:

Appliance Wattage Appliance Wattage

Coffee maker (4/10 cups)

700–1200 Air conditioner (room) 1000 +

Toaster 1000 Aquarium 50–1210

Blender 300 Dehumidifier 800

Microwave oven 700 - 1500 Electric blanket 200

Clothes Iron 750 - 1200 Water heater (150 litre) 4500-5500

Clothes washer 900 CD player 30

Clothes dryer 2000 - 5000

Personal computer + moni-tor

120 - 160

Dishwasher 1200 - 1500

Lap top 50

Fan (table) 20 - 250 Television (25” / 19”) 150 - 80

Fan (ceiling) 10 - 50 Radio (stereo) 50 - 300

Vacuum cleaner 1200 Fryer 1200

Hair dryer 1000 + Refrigerator 200 - 800

Note: In other words, consumption is obtained by multiplying power by time.

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1. Look at its wattage (the plate gives you its installed power in watts or kilowatts). 2 Make an estimation of how many hours* it runs per day (for instance, TV 3 hours, refrig-erator 24 hours). Multiply the wattage by the hours the appliance is used (run per day).

The formula is: Power (kilowatts) x Time (hours used Per Day) = Energy consumption (kWh).

3 Then, multiply the daily consumption by the number of days the appliance is used during the week, month or year (depending on the period of consumption you want observe). Finally, you can calculate the annual, monthly or daily cost to run an appliance by multiplying the electricity consumption (kWh) by the price of a unit of kWh (i.e., 9 cents€/kWh).

The formula is: Energy consumption (kWh) x Electricity price (cents€ / kWh) = Cost (€).

Reading the utility bill Your utility bill usually shows what you are charged for the kilowatt-hours you use, and shows also how many kilowatts hours (kWh) have been consumed. The multiplication between these two factors, plus the addition of others elements (taxes, administrative costs, etc.) gives you the amount to pay.

Examples of Calculation: Clothes Iron:

Electric Consumption = (850 Watts × 1 hour/day × 3 days/week × 4 weeks/month) ÷ 1,000* = 10.2 kWh/month Money Cost = 10.2 kWh × 13 cents€/kWh = 132.6 cents€/month (.........× 12 month/year = 1,591 cents€/year = 15.91 €/year).

Personal Computer and Monitor:

Electric Consumption = (120 + 160 Watts × 4 hours/day × 365 days/year) ÷ 1,000* = 408.8 kWh Money Cost = 408.8 kWh × 13 cents/kWh = 5,314 cents€/year = 53.14 €/year.

*Remember that 1,000 Wh = 1 kWh. In the above formulas, division by 1,000 is done to transform watt hours (Wh) into kilowatts hours (kWh), which is a more suitable way to express electricity consumption. Observe: if, in the ex-ample, electricity consumption was expressed by watts, the result would be = 10,200 Wh (for the clothes iron) and 408,800 (for the PC and monitor). It would mean larger and uncomfortable numbers!! Note that: the electricity price is variable among European countries. Check your utility bill for your price!!

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6.1.1 General tips on how to save energy Two basic and simple points to be observed: Take care when buying electrical appliances. Purchase energy-efficient products (such as

Class A) and get used to looking at the electric power (wattage). Operate them efficiently: try not to use appliances if they are not necessary, and switch off

them when not used.

Most phantom loads will increase the appliance’s energy consumption by a few watt-hours. These loads can be avoided by unplugging the appliance or using a power strip and using the switch on the power strip to cut all power to the appliance. 6.2 Electric appliances 6.2.1 Refrigerators/ Fridges: Nowadays, refrigerators are necessary devices in homes for better preservation of food.

Although these appliances are relatively low-power, their high number of running hours makes them greater consumers of energy than others with much greater power. Compare:

As can be seen, a refrigerator consumes more energy than an air conditioner that has wattage 10 times higher. As mentioned, cold appliances (refrigerators, freezers, etc.) are rated with two more energy-efficiency levels in the “Energy Label”, i.e., Class A+ and A++, expressing an even lower rela-tive consumption.

A++ A+ A B C D E F G

<30 <42 <55 <75 <90 <10

0 <11

0 <12

5 >125

Note: In Europe, the average residential rate is 20 cents per kWh, varying from 9 cent€/kWh (Bulgaria) to 32 cent€/kWh (Denmark). A typical European household consumes about 4,500 kWh per year, costing an average of €900 annually.

Note: Because they are machines that operate 8,760 hours a year (all year), their consumption is the highest in a home.

Note: Many appliances continue to draw a small amount of power when they are switched “off”. These “phantom loads” occur in most appliances that use electricity, such as VCRs, televisions, stereos, computers, and kitchen appliances.

Air conditioner: Electric Power = 2 kW

Refrigerator: Electric Power = 0.2 kW

Hours of operation = 480 hours/year Electricity consumption = 2 x 480 = 960 kWh/year

Hours of operation= 8,760 hours/year Electricity consumption = 0.2 x 8,760 = 1,752 kWh/year

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A new refrigerator with an A+ label uses at least 42% less electricity than conventional models (Class D or E), and even less than 30%, if the new refrigerator is labelled with A++. In cold appliances, it is very important to avoid losses of cold air, as they will need to produce the lost cold air again. The main causes of cold losses are: Insulation: the heat transfer through the material that makes up the walls of the refrigera-

tor. Food: the heat transfer from the food (as food deposited initially has a greater temperature

than refrigerator). Door seals (gasket): the heat transfer through the board which is responsible for maintain-

ing airtightness. Door open: the heat transfer caused when the door is opened.

Graph 2 . Cause of cold losses

Refrigerator and Freezer Energy Tips: Look for the ENERGY LABEL when buying a new refrigerator and select class A+ or

A++. Select a new refrigerator that is the right size for your household needs. The bigger it is,

the higher the energy consumption gets. Do not put in hot food. When you have to thaw food from frozen, do it in the refrigerator compartment and not

outside of it, as that will exploit the colder temperature of the frozen food. Make sure your refrigerator door seals are airtight. Test them by closing the door over a

piece of paper. If you can pull the paper out easily, the seal may need replacing. Keep the doors open the shortest time possible. Do not install a refrigerator in warm places and with little ventilation. Don’t keep your refrigerator or freezer too cold. Recommended temperatures are 5°C for

the fresh food compartment of the refrigerator and -18ºC for the freezer section. Regularly defrost a manual-defrost refrigerator and freezer; frost decreases the energy effi-

ciency of the unit. Don’t allow frost to build up more than 3mm thick.

8%9%

15%

68%

Door open

Door seals

Food

Insulation

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6.2.2 Washing machines:

This is an essential appliance present in almost all European homes. The number of times it is used depends on the users’ habits, but can be esti-mated, on average, to between three and five times per week. After the re-frigerator and TV, it is the appliance that consumes more energy than any other in European homes. The machine washes clothes by using hot water and detergent in a process of spinning on a drum load.

The other important consumption factor is related to water use, which can be approximated to 30–50 litres. The Energy Label for washing machines shows all these issues: effectiveness of washing, effec-tiveness of spin, water and energy consumption per cycle.

Advice on their use:

Buy machines with a Class A Energy Label. Wash full loads. If you are washing a small load, use the appropriate water-level setting,

or better, wait until you have more dirty clothes. Wash using cold water or use a low temperature setting whenever possible. 30ºC would be

sufficient!!! Avoid using the dry function – for that there is the sun and wind!

The new bi-thermal machines operate with two sources of water, hot and cold. The hot water is taken from the hot water system that is preheated and allows less energy con-sumption.

6.2.3 Dishwashers:

The use of this appliance is growing day by day, according to the in-crease in our level of comfort demand and the decrease of family spare time.

One out of four European families has got a dishwasher and uses it al-most every day, making it one of the most energy-using consumer ap-pliances.

Currently, there are devices with many setting programs which are capable of selecting medium-capacity and low-temperature modes, allowing an energy consumption reduction.

Note: The largest energy consumption is not in moving cargo, but in heating the water, which is done by electrical resistance, using about 85% of the total energy.

Note: As in the washing machine, approximately 70–80% of the electricity used goes to heating the water.

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Tips on its use: When shopping for a new dishwasher, look for the Energy Label Class! Be sure your dishwasher is full, but not overloaded, when you run it. Set the water heater in your home to a lower temperature. Let your dishes air dry; after the final rinse, leave the door open so the dishes will dry

faster. 6.2.4 Ovens: There are two main types of ovens, gas and electric. The first ones are the most recommended from the standpoint of efficiency, but electric ovens are more widespread in European families, although they are more energy consuming. Although ovens consume a lot of energy according to their wattage, over a year, the total energy consumption is relatively low, thanks to their lower employment in terms of time (hours).

Tips on their use: Leave the oven door closed during cooking. To know the status of the cooking food, sim-

ply use the light. Each time you open the door, you lose about 25–50 degrees of heat. Try to get used to its maximum capacity and not use the oven only to heat a little food. For

this, use the microwave instead of the conventional oven, it can save between 60 and 70% of the energy and is, in addition, faster.

Turn off the oven a little before the food is cooked, as the residual heat will be enough. 6.2.5 Small home appliances: They can be divided into two groups: those which do some mechanical work, such as to beat, to cut up, to squeeze, and in gen-

eral are of low power; those which produce heat, such as irons, toasters, hair dryers, electric blankets with higher

power, and thus, lead to significant consumption.

Look at the power of the following devices: Vacuum cleaner = 1,300 Watts Iron = 1,000 Watts Hair dryer = 1,200 Watts Food mixer = 1,800 Watts

Tips on their use: Do not leave appliances on unnecessarily. Use your hands to do work like squeezing an orange or beating eggs. Choose with care when shopping for appliances. Look at their wattage and not only at price.

Note: These electric appliances are not covered by the Energy Label, but they are not for that reason energy innocuous!!

Note: Only the intelligent use of this range of products can prevent energy waste!! Thus, do not dry clothes using a tumble dryer!! ...unfortunately some people do that. .

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6.2.6 Home electronic equipment – Entertainment and home office devices: These are devices that are increasingly widespread and are being employed more and more hours a day. Every year, electronic products manufacturers emerge with more sophisticated equipment, and thus, offer more attractive en-tertainment.

The vast majority is consumed by home entertainment systems and home office equipment. But small energy users, includ-ing portable devices with battery chargers, add a significant weight, not because they use a lot of energy individually, but be-cause of their numbers and the many hours of activity.

In this group are: televisions and home cinemas, VCRs and DVD players, combination units (TV/VCR; TV/DVD), home audio, com-puters, video game consoles, etc.

Power modes All these products incorporate various operating modes. One of them is the stand-by mode that can be turned on and off via a remote con-trol. This is virtual disconnection, because devices on stand-by con-sume roughly between 10 and 15% of normal conditions. Thus, it is recommended to switch off completely if you are not going to be used them. Operation modes are as following:

Table 7 Operating modes

Mode Definition Examples

Active (In-Use) Appliance is performing its primary function.

TV displays picture and/or sound. VCR records or plays back tape. Printer prints document.

Active standby Appliance ready for use, but not performing primary function. Appears on to consumer.

DVD player on but not playing. Cordless appliance charging.

Passive standby Appliance is off/standby. Appears off to consumer, but can be activated by remote control or is performing peripheral function.

Microwave not in use, but clock is on. CD player off, but can be turned on with re-mote control.

Off Appliance is turned off and no function is being performed. Consumer cannot activate with re-mote control.

Computer speakers are off, but plugged in. TV is not functioning and cannot be turned on with remote.

Note: The energy use of electronic equipment often goes unnoticed. Instead, an estimated 10% to 15% of all electricity used in European homes can be attributed to the running of electronic devices.

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Below is a table of common electronic equipment and the average energy used in each mode and per year (in order from the most energy-intensive to the least). In the last two columns, the rela-tives annual energy consumption costs are showed, considering the lowest and highest European electricity price.

Table 8 Electronic equipment and average energy consumption

External Power Adapter Electronic products run on low-voltage direct current (DC), and therefore require a power adapter to transform the 120-volt alternating current (AC) supplied at the power outlet. Some larger products, like TVs, stereos and set-top boxes, incorporate the power supply into the body of the product. Others use external power supplies, the familiar “wall packs” that increasingly com-pete for space in our sockets and power extension strips.

Product Passive

Standby or Off (watts/

year)

Active Standby (watts/year)

Active (watts/year)

Average Annual Energy

Use (kWh)

Annual En-ergy Cost (Euro) EU lower price

(0,09 €/kWh)

Annual En-ergy Cost (Euro) EU

higher price (0,32 €/kWh)

Home Entertainment Plasma TV (<40") 3 - 246 441 39,69 141,12 DVR/TiVo 37 37 37 363 32,67 116,16 Digital Cable 26 26 26 239 21,51 76,48 Satellite Cable 12 11 16 124 11,16 39,68 LCD TV (<40") 3 - 70 77 6,93 24,64 Video Game Console 1 - 24 16 1,44 5,12 DVD 1 5 11 13 1,17 4,16 Home Office Desktop Computer 4 17 68 255 22,95 81,6 Laptop Computer 1 3 22 83 7,47 26,56 LCD Monitor 1 2 27 70 6,3 22,4 Modem 5 - 6 50 4,5 16 Wireless Router 2 - 6 48 4,32 15,36 Printer 2 3 9 15 1,35 4,8 Fax 4 4 4 26 2,34 8,32 Mutli-Function Printer/Scanner/Copier 6 9 15 55 4,95 17,6

Rechargeable Devices Power Tool 4 - 34 37 3,33 11,84 Cordless Phone 2 3 5 26 2,34 8,32 Electric Toothbrush 2 - 4 14 1,26 4,48 MP3 Player 1 - 1 6 0,54 1,92 Cell Phone 0 1 3 3 0,27 0,96 Digital Camera 0 - 2 3 0,27 0,96

Note: These power supplies consume electricity whether or not the product is on or off, and even if it is disconnected! You’ll know a wall pack is using energy when it has been plugged in for a while and it is warm to the touch.

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Tips and hints: There are several steps you can take now to minimize the energy used by the electronics in your home: Unplug It. The simplest and most obvious way to eliminate power losses is to unplug

products when not in use. Search the wall sockets in your house for hidden unconnected chargers and other devices that don’t need to be plugged in. When you detach your cell phone or similar device from its charger, unplug the charger too.

Use a Power Strip. Plug home electronics and office equipment into a single power strip with an on/off switch. This will allow you to turn off all power to the devices in one easy step.

Especially for Computers: When not using the computer, even for short periods, switch off the screen. Use screensaver black, as this consumes less energy. Remember, you must enable the power management features (low-power “sleep mode”)

on your computer. It is standard in Windows and Macintosh operating systems. Simply touching the mouse or keyboard “wakes” the computer and monitor in seconds.

Energy Star Under an agreement reached between the United States and the Euro-pean Union, an energy label called “Energy Star” is used for many electronic devices (monitors, computer equipment and imaging equip-ment). This label indicates equipment which has the ability to disconnect and go into a low-power “sleep mode” after a period of inactivity. Thanks to this mode, a reduction of energy consumption is achieved by 75% compared to the performance of normal “off” functions. The ENERGY STAR label ensures a low standby power use for these appliances — in most cases, only 1 watt or less.

Tips and hints: There are several steps you can take now to minimize the energy used by the electronics in your home: Look for the ENERGY STAR label when purchasing a new TV, DVD Player, VCR, audio sys-tem, computer, printer, fax, and copier.


1 How much do electrical appliances account for a typical household’s energy and electric-

ity consumption (in %)? ........................................... 2 What information is provided in the EU Energy La-

bel? .................................................................................................And what letter/colour rate is the most efficient rate?

................................................................................................ 3 What kind of appliances have been given two more energy ranges (A+ and A++)? ................................................................................................ 4 According to the Wattage Table, write how much power do the following devices use

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(expressed by kW): Blender =..................... Vacuum cleaner =..................

5 Electricity consumption calculation. Fill in the gap:

6 How much electricity will the following appliances consume if they are used for 2.5 hours each?

Blender = kWh..................... Vacuum cleaner = kWh.................. And if are they used 0.5 hour a day during 12 days a month? Blender = kWh/month..................... Vacuum cleaner = kWh/month.................. 7 How much electricity does a typical European household consume approxi-

mately? ........................................; and how much does it cost? ......................... 8 Which is the household appliance using the highest consumption (on average) per year?

And why? .................................................... 9 Where would be the best place to site a refrigerator? (Tick the Wrong answer/s): Close to the oven ¨ In a small storage room without windows Wherever it is far from warm spaces ¨ 10 In which task do washing machines, like dishwashers, consume the largest amount of elec-

tricity? ......................................................................................... 11 Answer the following statements with right (R) or wrong (W): Ovens don’t lose energy by opening their doors during cooking ........ Small home appliances are covered by the Energy Label....... Some small home appliances have a large wattage........ 12 How much electricity do home electronic equipment account for in EU homes on average

(%)? ............................ 13 Check for at least two electric or electronic household appliances that, even if they have

lower wattage, register large electricity consumption during a year: – ............................ – ............................... Explain why: .........................................................................

Power (W) X Time (h)

= Electricity (W) X Price (cent€/kWh)

= Cost

1100 X 4 = X 15 = 100 X 10 = X 15 = 600 X 4 = X 15 = 800 X 4 = X 15 = 150 X 4 = X 15 =

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14 What is the average cost of a kilowatt-hour of electricity for residential customers in your country?

.................................................. Glossary Demand Factor: the ratio of (a) the maximum real power consumed by a system to (b) the maximum real power that would be consumed if the entire load connected to the system were to be activated at the same time.

Web links

www.energystar.gov/ http://www.energysavingtrust.org.uk/ http://www.energylabels.org.uk/eulabel.html http://www.energysavingcommunity.co.uk/

References

VV. AA.: Guía práctica de la energía. Consumo Eficiente y Responsable (Practical Guide for Energy. Efficient and Responsible Consumption), Instituto para la Diversificación y Ahorro de la Energía (IDAE), 2007.

Key points: The purchase price of electric appliances and electronic devices, usually is the

driver in the criteria for choosing, however models with high energy-efficient performance have a higher initial purchase cost, but they permit the saving of significant amounts of energy costs (and thus, of money).

The electricity consumption of an appliance firstly depends on its “electric power” or the wattage, that is to say the maximum power drawn by the appli-ance. Then consumption is obtained by multiplying power by time of appliance use.

The Energy Label is a sticker providing clear information about the energy consumption and performance of products. For instance the energy-efficiency rating scale, which provides a simple index composed of a code of letters and colours ranging from green and the letter A, the most efficient, to the colour red and the letter G, the least efficient.

The largest electricity consumption in appliances such as washing machines and dishwashers is in heating the water, which is done by electrical resistance, using from 70% up to 85% of the total energy.

Home electronic equipment and entertainment and home office devices are in-creasingly being employed more and more hours a day. Their energy use often

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goes unnoticed; instead, an estimated 10% to 15% of all electricity used in European homes can be attributed to them.

The simplest and most obvious way to eliminate power losses is to unplug products when not in use.

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6.4 Photovoltaic energy

Learning Objective: In this Chapter you will learn: Solar energy fundamentals and how solar energy is transformed into electricity

Main types of photovoltaic cells

A basic sizing of a photovoltaic system 6.4.1 Solar energy Climate change, atmospheric pollution and, in general, the alarming environmental situation, mainly caused by the continued use of fossil energy sources, are slowly becoming growing con-cerns and are leading to the development of new alternatives for supplying electricity, well-known as Renewable Energies.

What is Solar Energy? Every day the sun sends out an enormous amount of energy in the form of radiation. Like others stars, the sun is a large ball of gases, mostly hydrogen and helium atoms, in a constant combus-tion process, or said better, in a combining process among those atoms called nuclear fusion. Simply said, the hydrogen atoms combine or fuse to form helium in the sun’s core under ex-tremely high temperature and pressure conditions. Precisely four hydrogen nuclei fuse to become a helium atom which contains less matter than the previous four of hydrogen. This loss of matter is what is emitted into space as radiant energy, the first source of life on the planet earth.

Fig.14 Energy radiations

Only a smart portion of the energy radiated hits the earth, one part in two billon, the remainder being spread into space. Of that small portion, about 15% of the sun rays are reflected back into space, another 30% cause water evaporation which is stored in the atmosphere producing rain-fall, and finally, solar energy is also absorbed by plants, the land and the oceans, allowing vege-table life through the photosynthesis mechanism. Only the rest could be used to supply our en-ergy needs, yet this amount of energy is enormous.

Note: One of them is solar energy, the source of which is simply the sun; it is available for free, is inexhaustible and can be used in different ways

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How can we use solar energy? We have many options for using solar energy at home, school and in buildings in general. The three main ways are: Passive heat: it consists of getting use by the heat naturally received from sun. The main

application is in the design of buildings where less additional heating is required (look at the chapter on building design).

Solar thermal: where we use the sun’s heat to provide hot water for homes or swimming pools or also heating systems (look at the chapter on water).

Photovoltaic energy (PV): The direct transformation of solar energy into electricity, able to run appliances and lighting. A photovoltaic system requires daylight – not only direct sunlight – to generate electricity.

sizing of a photovoltaic system

6.4.2 The process of turning sunlight into electricity. “Photovoltaic” comes from the two words: “photo”, from the Greek root word, meaning light, and “voltaic”, from “volt”, which is the unit used to measure electric potential.

Definition: Photovoltaic systems use cells to convert solar radiation into electricity. The cell consists of one or two layers of a semi-conducting material.* When light shines on the cell, it creates an electrical field across the layers, causing electricity to flow. The greater the inten-sity of the light, the greater the flow of electricity is.

Currently, commercial PV cells convert only between 6% and 15% of the radiant energy into electricity. Nonetheless, although it may not seem so, it is a good result and great possibilities are inherent in this technology, thanks to important ad-vances achieved by scientific re-search in the last few years, mainly in the field of new materials which are able to achieve the photovoltaic conversion.

The most common semi-conductor material used in photovoltaic cells is silicon, an element most commonly found in sand. There is no limitation to its availability as a raw material; silicon is the second most abundant material on earth mass. A photovoltaic system, therefore, does not need bright sunlight in order to operate. It can also generate electricity on cloudy days. Due to the reflection of sunlight, slightly cloudy days can even result in higher energy yields than days with a completely cloudless sky.

How does a PV cell work? The most important parts of a PV system are the cells which form the basic building blocks of the unit, collecting the sun’s light, the modules which bring together large numbers of cells into a unit (and in some situations, the inverters used to convert the electricity generated into a form suitable for everyday use).

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Fig.15 Solar cell functioning

Regardless of size, a typical silicon PV cell produces about 0.5–0.6 volts DC (Direct Currency). The current (and power) output of a PV cell depends on its efficiency and size (surface area), and is proportional to the intensity of sunlight striking the surface of the cell.

Note: For example, under peak sunlight conditions, a typical commercial PV cell with a sur-face area of 16 cm² will produce about 2 watts peak power. If the sunlight intensity were 40 % of peak, this cell would produce about 0.8 watts. However, 2 watts are not enough to run any electrical devices. But hundreds of cells composing a PV module, sometimes also called a panel, running for more time, will re-sult in a power output from 10 watts to 300 watts, depending on the technology used – even more if several modules are connected together (called arrays).

Fig. 16 Photovoltaic elements

For example, a typical commercially available 160-watt-power PV module could have a surface area of 1.2 square metres (1.5 m x 0.8 m).

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Cell-production process There are several kinds of available technology, mainly differentiated by the type of raw material composing the cell and the method of building the modules. The most common are as follows. PV cells are generally made from Crystalline Silicon, with two main possibilities: from thin slices cut from a single crystal of silicon (monocrystalline) or from a block of silicon crystals (polycrystalline), or mixing silicon with others semi-conductor materials (amorphous); their effi-ciency ranges between 12% and 17%. This is the most common technology representing about 90% of the market today.

Fig.17 Types of PV cells

The other type available is the Thin Film technology. The modules are constructed by depositing extremely thin layers of photosensitive* materials onto a low-cost backing such as glass, stainless steel or plastic. Thin film manufacturing processes result in lower production costs compared to the more material-intensive crystalline technology, a price advantage which is cur-rently counterbalanced by substantially lower efficiency rates (from 5% to 13%). There are several other types of photovoltaic technologies developed today and starting to be commercialized, or still at the research level, such as the Flexible Cells, based on a similar production process to thin film cells – when the active material is deposited in a thin plastic, the cell can be flexible.

In recent years, scientific research has achieved important improvements in the PV cell technology by achieving 40% efficiency with a multi-junction solar cell made out of various elements (Gallium, Indium, Arsenic and Germanium), but the high production costs made it not commercially avail-able.

6.4.3 Photovoltaic applications The photovoltaic technology can be used in several types of applications. The first and probably most “high tech” applications have been developed for

spacecrafts.

Already familiar is the sight of solar-powered calculators, toys, lighting and phone boxes, and many others consumer goods using solar cells.

Where no mains electricity is available, off-grid applications are used to bring access to electricity to remote areas, such as remote telecommunica-tion stations, mountain huts, developing countries and rural areas.

It is also ever more common to see medium and large power plants that lie in countryside fields, so-called grid-connected power plants.

Here, it is our prime interest to throw light on the buildings which inte-grate photovoltaic systems.

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These PV systems can cover roofs and facades, thus contributing to the reduction of the energy which buildings consume. They don’t produce noise and can be integrated in very aesthetic ways. European building regulations have been and are being reviewed to make renewable energies a required energy source in public and resi-dential buildings. This action is accelerating the development of ecobuildings and positive energy buildings (E+ Buildings), which open up many opportunities for a better integration of PV systems in the built environment.

Regarding their functioning scheme, usually these systems carry a connection to the local electricity network which allows any excess power produced to be fed into the electricity grid and to be sold to the utility. Electricity is then imported from the network when there is no sun. An inverter is used to convert the direct current (DC)* power produced by the system to alternative current (AC) power for running normal electrical equipment.

6.4.4 How much electricity can a PV system produce? Depending on the location of the solar facility, more or less energy is available, and therefore, more or less electricity can be produced. Thus, the answer lies in several factors, and the main steps to take into account are as follows: 1. the amount of energy that reaches a certain location; solar irradiation and hours of sun;

2. the correct position and inclination of the modules; 3. technology employing photovoltaic modules. 1. Energy coming from the sun is measured by the “solar irradiance”, that is defined as the en-ergy power of the sun which a certain place receives per unit area (expressed in watts or kWs per square metre). Multiplying irradiance data (the power) by the sunshine hours of a given place (time duration), we obtain the sum of irradiation (energy). In other words, the irradiation indicates the quantity of solar energy (kWh) received on a square metre of surface (kWh/m²) during a given time. For ex-ample, multiplying by the daily sunshine hours averaged in a given place (or hours/day), we ob-tain the daily irradiation (kW·h/m²·day). Graphically, the following map shows the yearly irradiation for Europe. 2. Another crucial step is the PV modules position with respect to the sun, with the objective of getting as long a radiation exposure as possible. The longer the hours of direct solar exposure, the more electricity production is achieved. Three aspects have to be considered for positioning: Orientation: a system for solar power should be oriented as much as possible to the south

(if you are located in the northern hemisphere). Inclination (angle): the PV modules should have an inclination

which allows perpendicular facing towards the midday sun. This coincides, as general rule, with the latitude of the geographic lo-cation. In Europe, the optimum inclination angle of PV modules to maximize yearly energy yield goes from 26º in the south of

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Greece to 48º or even more in the north of Europe. The reason for this is, in the south, the sun travels quite perpendicularly, and thus, modules assume a quite horizontal inclination in order to get as long a use as possible from the irradiation. In contrast, the opposite hap-pens to the north, where the sun has a lower trajectory with respect to the horizon, and thus, modules need to be inclined more vertically. The same concept is valid for the sea-sons: the sun is higher in summer than in winter.

Fig.18 Sun positions

Shadow and wire: these should be avoid as much as possible, such as any shadows made by buildings, mountains or trees. Any shadow will affect the electricity output by reducing it. 3. The third step regards the technology used for which, as mentioned above, there are several options depending mainly on the material composing PV cells. Here the key factor is represented by the “conversion efficiency” that can reach as much 17% for the better technology commer-cially available. This means that a small portion of the irradiation received can be transformed into electricity. Nowadays, Solar Maps and interactive application services are available for each country. They include all those above-listed factors and deliver a comprehensive estimation of the amount of electricity production achievable in a certain place. Thanks to these tools, we can know our re-gion and local potential, and thus, are able to calculate how much electricity could be produced by a given solar facility. One of those tools is the Photovoltaic Geographical Information System (PVGIS) available online with a very friendly and funny application. Visit the website of the Joint Research Centre to discover how much solar energy strikes your region (http://re.jrc.ec.europa.eu/pvgis/).

Let’s calculate together... The following map (from the PVGIS) shows the amount of electricity gener-able in the European regions by photovoltaic systems. It already takes into account: quantity of solar irradiance, average hours of sun and other factors, such as conversion efficiency of PV technology, optimal modules orientation and inclination, and wire losses. In brief, it allows a good estimation of the solar energy potentiality of a given site.

73


Fig.19 Photovoltaic Geographical Information System (PVGIS)

The more red-coloured a given site is, the better energy performance there is. At the bottom of the map, the same colour legend shows two important indica-tors: The yearly sum of irradiation incident on a square metre of photovoltaic

modules, expressed by kWh/m2 (Global irradiation).

The early sum of potential solar electricity generated by a 1 kWp system

installed, or kWh/kWp (Solar electricity). The first row of data (Global irradiation) refers just to the irradiation on one square metre of surface per year. Note that it doesn’t mean that 1 m2 actually produces the value indicated. As said before, not all of the sunshine that strikes a PV cell will be converted into electricity, due to the technological limitations (“conversion efficiency”) and other losses.

74



1 What does the word photovoltaic mean? .................................................................................................

................................................................................................. 2 How efficient are PV cells today? Explain what the conversion efficiency means? .................................................................................................

................................................................................................. 3 Do PV cells produce AC (alternate current) or DC (direct current) cur-

rent? .................................................................................. 4 Estimate how much electricity a PV system installed in your school facility could produce

(please look at the solar map), and calculate how large it would be. Repeat the example al-

The second row of data (Solar electricity) directly informs how much electric-ity a 1 kW PV system could generate, installed in a given place. The estima-tion value already includes various losses and technology limitations. What you need is just to search for your city and check the right value...... Example: A one-kilowatt (kW) PV system installed in Sardinia (Italy) can produce

approximately 1,350 kWh of electricity per year (look at the map). Obviously, for a two-kilowatt system, it is (1,350 x 2) 2,700 kWh per year of electricity. Note that: This is almost the load of a typical European customer. The aver-age residential customer uses 3,200 kilowatt-hours (kWh) of electricity per year (average in Europe is 27). How large will the PV system be? To obtain a one-kW rooftop system and considering the installation of 200-watt power modules: About 5 modules would needed (obtained by: 1 kW (or 1,000 W)/200 = 5). But note that module banks (arrays) must never count with uncoupled mod-ules, which means that a total of at least 6 modules are suitable. In addition it is even better to over-dimension the system, due to different kinds of losses. Finally, if each module is 2 square metres, the surface covered by PV modules will be 12 square metres (resulted from: 2 m2 x 6 modules).

75


ready developed, adapting to your school’s geographic location. Given data:

5 kW system to install Modules chosen of 160 watts power each Dimension of each module: 2 square metres

Glossary Semi-conductor: a semi-conductor is a substance, usually a solid chemical element or com-pound, that can conduct electricity (electrical conductivity) intermediately between metals (conductors) and insulators (no conductors). It conducts under some conditions but not others, making it a good medium for the control of electrical current. Photosensitivity: is the amount to which an object reacts upon receiving photons (solar radia-tion), especially visible light. Direct current (or DC electricity): is the continuous movement of electrons from an area of negative (−) charges to an area of positive (+) charges through a conducting material such as a metal wire. Direct current was supplanted by alternating current (AC) for common commercial power in the late 1880s because it was then uneconomical to transform it into the high voltages needed for long-distance transmission. Techniques developed in the 1960s overcame this obstacle, and di-rect current is now transmitted over very long distances, though it must ordinarily be converted into alternating current for final distribution.

References

de Francisco G. A. et al. Energías Renovables para el desarrollo, (Renewable Energies for Development), Cooperación Internacional, Thomson-Paraninfo, Madrid, 2007.

Web links

http://www.epia.org http://www.soda-is.com/eng/index.html http://re.jrc.ec.europa.eu/pvgis/ http://www.pvsunrise.eu/Pictures.asp

Key points: One of the most important sources of renewable energy is solar energy, whose

source is simply the sun; it is available for free, it is inexhaustible and can be used in different ways.

We have many options for using solar energy at home, at school and in build-ings in general. The three main ways are: passive heat, solar thermal and photo-voltaic energy.

76


PV cells are generally made from Crystalline Silicon, in three main ways: from

thin slices cut from a single crystal of silicon (monocrystalline) or from a block of silicon crystals (polycrystalline), or mixing silicon with others semi-conductor materials (amorphous); This is the most common technology repre-senting about 90% of the market today.

A typical commercial PV cell with a surface area of 16 cm² will produce about 2 watts peak power only. However hundreds of cells composing a PV module will get an interesting electrical generation and have a power output from 10 watts to 300 watts, depending on the technology used – even more if several modules are connected together (called arrays).

The amount of electricity that a PV system can produce depends mainly on three factors: the amount of sun energy that reaches the location; the position and inclination of the modules and their technology.

77


7 Exercise - Monitoring Energy Consumption - Home/school facilities Energy Audit Grade Level: Secondary Subject areas: Sciences, Mathematics, Economics, Social studies, Language, Art Methodology In this activity, students will apply the energy conservation measures they have learned about from the “Handbook on Buildings” to perform a comprehensive energy audit of the school or home building. The following activity should be performed step by step, following the 6 steps below and the fur-ther activity variations suggested, although each step works/is worthwhile as an individual sepa-rate exercise. Tables and formats are suggested for each step, although further tables, figures and data, photos and graphic representations can be used. The entire work activity can be performed with:

Pen/paper, and/or

PC (all tables and calculator sheets are available in Excel format on the IUSES web page and DVD multimedia).

The students can work individually, in pairs or in small groups to work out their energy con-sumptions and find some energy saving solutions. Goal(s) To perform an energy audit, as the first step in assessing how much energy a building consumes and in evaluating what measures you can take to make it more energy efficient. (You can per-form a simple energy audit yourself, or have a professional energy auditor carry out a more thor-ough audit.)

To estimate energy requirements/consumptions of both electrical and thermal appliances;

To calculate energy costs;

To understand CO2 related emissions and how to calculate them;

To take action to reduce energy loss and consumption.

Summary 1st step – Checking all sources of energy consumption (Appliances – Lighting – Heating and Cooling) 2nd step – Register and calculate the consumption

2a – Electricity consumption 2b – Fuel consumption

3rd step – Graphic representation 4th step – Calculating CO2 (equivalent) emissions 5th step – Building inspection 6th step – Make recommendation for savings * Supplementary Step – Variations and combination with other activities:

78


1st step Checking all sources of energy consumption (Appliances – Lighting – Heating and Cooling) Make an inventory of all energy consumer appliances you can find in your school or home. This can be done (using tables like those below) following two main criteria: checking room by room (gymnasium, refectory, classroom – kitchen, bathroom, living

room, etc.); and checking by type of consumption charge (electric and electronic appliances, lighting, etc.). Divide them between Electricity and Fuel fired (natural gas, fuel oil, coal, wood) equipments.

Check list Electrical Equipment (Appliances – Lighting) Check list Fuel-fired Equipment (Heating-Cooling, etc.)

Extend the lists as you need. 2nd step

Register and calculate the consumption

2a – Electricity consumption Make a comprehensive list of all electrical appliances (in your home or school), then register their power consumption (wattage) and estimate for how long they are used (amount of time each one is on). The students may ask their parents or teachers about the use of appliances that the students do not use themselves and together estimate the hours of use. In a case where it is not possible to find the wattage plate on a given appliance, then use the figures shown in the Handbook or in the example below. Then calculate the amount electricity consumption by multiplying the wattage of each appliance by the number of hours used. Energy used (kilowatt hours) = Power (kilowatts) x Time (hours). Finally, calculate the cost of the electricity consumption by multiplying consumption by the price of a unit of electricity (as located in the electricity bill). Cost (€) = €/kWh × kWh.

Room/Space Name of Appliance Type (Lighting; Electric, Electronic appliance)

Room/Space Name of Appliance Type (Space heating and cooling; Water heating; Cooking; etc.)

Fuel type (natural gas, oil, etc.)

79


Name:Subject of measurement:Place/Location:

Hours per day

5

Days of use X

Week 6

Hours per w eek 7 =

5 x 6

Lighting Incandescent light bulb 40W 40 1 0 0Incandescent light bulb 60W 60 1 0 0Incandescent light bulb 75W 75 1 0 0Incandescent light bulb 100W 100 1 0 0Fluorescent lamp 13W 13 1 0 0Fluorescent lamp 17W 17 1 0 0Fluorescent lamp 20W 20 1 0 0Fluorescent lamp 32W 32 1 0 0Fluorescent lamp 40W 40 1 0 0

Electric Appliances 0Air conditioner (room) 800 0,7 0 0Air conditioner 2000 0,7 0 0Fan (table) 200 0 0Fan (ceiling) 50 0 0Clothes Iron 1000 0,9 0 0Water heater (50 litre) 1500 0,9 0 0Motor or pump 0,3 0 0Clothes washer 600 0,4 0 0Dishwasher 1500 0Refrigerator 200 0,6 0 0Freezer 100 0,6 0 0Hair dryer 1000 1 0 0Clothes dryer 2500 1 0 0Blender 600 1 0 0Mixer 200 1 0 0Microwave oven 800 1 0 0Juicer / squeezer 50 1 0 0Toaster 700 1 0Vacuum cleaner 1200 1 0 0Coffee maker 1000 1 0 0Fryer 1200 0 0Electric blanket 200 0 0Dehumidifier 800 0 0Aquarium 1000 0 0

Electronic AppliancesPersonal computer + monitor 140 0,9 0 0Radio (stereo) 150 1 0 0Television 120 1 0 0VHS 60 1 0 0Lap top 50 0,9 0 0Equipo de sonido completo 300 1 0 0Nintendo 5 1 0 0CD player 30 0,9 0 0Extractor 500 1 0 0

0000000

04,3

00,00

Untill 200 kWh 200Between 201 and 1100 kWhMore than 1101 kWh 12 c€/kWh

Sub-total:Range consumptionsTotal electricity

consumption cost:20 c€/kWh15 c€/kWh

Electricity Price (Residential):

8 TOTAL Wh x Week:Number of Weeks a Month = 30/7=

10 Transforming to kWh x Month = 9 /10009 Wh x Month = 7 x 4,3

Register and calculate the electricity consumption

Wh per

Week

2 x 3 x 4 x 7

1

Hours of use per Week

CHARGENº of

Charge 2

Power (W) 3

Dem and Factor

4

80


Demand Factor: since many appliances have a range of settings (for example, the volume on a radio, the temperature selected on an air conditioner), the actual amount of power consumed de-pends on the setting used at any one time. It means that if an appliance is not running at its maxi-mum wattage (for example not max air conditioning temperature) the electricity consumed not exactly equals power per time but less. Thus it is used a so called “demand factor” which is a number by multiplying with and depends on the tipe or use of the appliance. Obviously, factor equals 1 means the appliance runs always at its maximum wattage, while less than 1 do not. In the table are reported the tipical Demand Factor for each appliance. 2b – Fuel consumption

The object of this exercise is to convert fuel consumption into kWh, in order to better understand these kinds of consumption and make comparisons with electricity consumption. In order to obtain the amount of fuel consumption, it is easier to register them directly by looking at bills or by asking parents or teachers. This is because, in contrast to the procedure followed for electricity consumption (step 2a), it is quite complicated to calculate fuel energy consumption of equipment starting from their own power (commonly expressed by CV, kcal, therms, etc.). Transform the consumption (amount of fuel: kg – m³ for natural gas – litres for fuel oil) into kilowatts by using the following conversion factor table (valid for the most common fuels used in Europe). (Available the Excel Calculator data sheet)

Fuel ConsumptionsEnergy content of selected fuels for end use — Conversion Table

Name:

Subject of measurement:

Place/Location:

Converting fuel types to kWh (1)

Fuel TypeAmount consumed

(per month)Units Units X Total kWh

Natural Gas (2) kg m³ × 13,1 kWh/kg 7,85 kWh/m³ 0

Liquefied petroleum gas (Butane/Propane)

kg litre × 12,78 kWh/kg 7,65 kWh/l 0

hard coal kg × 6,65 kWh/kg 0

Gasoil kg litre × 11,75 kWh/kg 9,87 kWh/l 0

Wood (25 % humidity) kg × 3,83 kWh/kg 0

Pellets/wood bricks kg × 4,67 kWh/kg 0

TOTAL (Source: DIRECTIVE 2006/32/EC of 5 April 2006 on energy end-use efficiency and energy services )

(2) 93 % m ethane.

(1): Mem ber States m ay apply other values depending on the type and quality of fuel m ost used in the respective Mem ber State.

Conversion factor (1) (kWh per unit)

Calculated on a Net Calorific Value basis

81


3rd Step Graphic representation Group all energy charges and appliances detected (now you have all of them in terms of kWh) by summarized group, as in the table below. Convert the consumption (kWh) into percentage (%). Then draw a pie chart to show graphically how the energy consumption is shared in your school/home. Fill in the pie chart by using the Excel application or by painting the empty chart manually.

Share of Energy Consumption (Example)

Consumption Sub-groups / Energy Service

Consumption (kWh)

Percentage (%)

Space heating & cooling 300 18,98%Water heating 100 6,33%Lighting 380 24,04%Cooking 125 7,91%Refrigeration 100 6,33%Electric Appliances 255 16,13%Electronic Appliances 234 14,80%Standby / ghost power 57 3,61%Other 30 1,90%

Total 1581

Pie Chart of Energy Consumption

18,98%

6,33%

24,04%

7,91%

6,33%

16,13%

14,80%

3,61%

1,90%

Space heating & cooling

Water heating

Lighting

Cooking

Refrigeration

Electric Appliances

Electronic Appliances

Standby / ghost power

Other

Manual Chart

82


4th step Calculating CO2 (equivalent) emissions The objective of this exercise is to calculate approximately the Green House Gas (GHG) Emis-sions related to your energy consumptions. The most important GHG is the CO2, which represents the great majority, from a quantity point of view. While the concept of “CO2 equivalent” means including the other GHGs, such as Meth-ane (CH4) and Nitrous Oxide (N2O), they represent only a small amount compared with just CO2. In the table below, the “emissions factors” of a range of fuels (the ones used for heating in the residential and tertiary sectors) are shown, as well as the emission factor of the electricity taken by the public grid. Emission factor = Quantity of emissions per unit of energy (Joule or kWh) or per unit of mass (kg, m³, litre). In the case of CO2 only, factors for different mass units are given, in order to simplify calcula-tion and to allow the insertion of Energy Consumption expressed by the units available to you. For CO2 Equivalent, only the Energy input in kWh is allowed. Note that: The emission factor of Electricity depends on the Electricity Mix of each country (that is, the composition of different kinds of energy sources used for electricity production), and may vary yearly and for each country. Emission factors of Fuels: An accurate estimation of emissions (mainly for CH4 and N2O) de-pends on combustion conditions, technology, and the emission control policy, as well as fuel characteristics. Therefore, the average and most common factors have been considered here. How to do the exercise: 1. Insert your energy consumptions by using the Unit you have available. 2. Multiply by the related emission factor. For example:

if your energy consumptions are expressed by kg of coal, multiply by 1.9220 to obtain CO2 emissions only;

if they are expressed by kWh of natural gas, multiply by 0.2019 to obtain CO2 emissions only, and by 0.2178 to obtain CO2 equivalent;

if all energy consumptions are expressed by kWh, obtained thanks to the previous 2b exer-cise, just multiply by the factors in the two columns of CO2 and CO2 equivalent per kWh. (Note that the Excel calculator uses the last one multiplied as default.)

3. Observe your total emissions by remembering that, in graphic terms, one Ton of CO2 approxi-mately equals one swimming pool of 10 metres wide, 25 metres long and 2 metres deep.

83


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84


5 th step

Building inspection...Check your building This step will show you problems which, if solved, may save you significant amounts of money over time. During the checking, you can pinpoint where your house or school is losing energy. An audit also determines the efficiency of your home’s heating and cooling systems and shows you ways to conserve hot water and electricity. You can easily conduct a home energy audit yourself. When auditing your home, keep a check-list of areas you have inspected and problems you found. This list will help you prioritize your energy-efficiency upgrades. Student assignment: Identify whatever helps or hurts energy conservation in a specific building. Look for "bad elements" that waste energy and money.

Energy Audit Data Sheet

Degree of implementation

Basic Standards Noth-

ing Start-ing

Imple-mentin

g Exten-sively

Lights and Equipment When adequate light is available from the sun, or when rooms are unoccupied, all

lights are to be turned OFF. X

Are lights in passage places (i.e., corridors, toilet, etc.) turned OFF when not in use ? X

Are electronic ballasts installed to provide the proper starting and operating electri-cal condition to power lamps? X

Computer monitors are either turned OFF, or computers are put into Sleep mode when not in use. X

Computer peripherals such as printers, scanners and other electronic equipment are to be turned OFF when not in use. X

All outside lights are to be turned OFF during daylight hours. X All outside lights are to be turned OFF at night. X Portable heaters may only be used as a short-term emergency measure. Principals

must authorize their use in these circumstances. X

Small “bar” refrigerators are prohibited unless there are compelling reasons for their use in exceptional circumstances. X

Only the most energy-efficient equipment is purchased (e.g., Highest Energy Label and Energy Star). X

An equipment consolidation program is implemented to ensure that energy is not wasted by using more equipment than is necessary (e.g., unplugging and/or remov-ing unnecessary refrigerators and reducing the number of computer printers through networking).

X

Are there lighting Control Systems such as: power stabilizers of lighting depending on the sunlight (light sensors) or automatic switch while a space is occupied by someone (Occupancy Motion Sensors), or simply timers.

X

A cleaning lighting fixtures programme is in practice. X Are walls and ceiling lights enough in colour to reflect light well? X Incandescent lightings has been removed and replaced with compact fluorescent. X Etc. ..Extend the list...

85


The above table includes just a limited list of items to be checked, so that it is recommended to extend it freely according to your facility characteristics.

Degree of implementation

Basic Standards Noth-

ing Start-ing

Imple-mentin

g Exten-sively

Heating and Cooling Windows and curtains are closed at the end of the school day. X Space around vents on walls or window sills is kept free of obstruction. X Doors to the outside of the building are not left open longer than necessary. X Internal gym doors are kept closed. X Mechanical equipment is checked regularly and problems are reported promptly. X Are hot water faucets free from drips? X Are the ceilings insulated? (ask the headmaster or professor) X Is heating and cooling equipment (ducts, radiators, grilles) blocked by curtain, fur-

niture, blankets, etc.? X

Are insulating drapes or other tight window treatments such as framed shades in place? X

Have all heating boilers been checked and are well insulated? X Exhaust fans off if not needed (gym, restrooms). When it is hot in a room, is opening windows done rather than regulating radiators

by thermostat valves? X

Is there effective weather stripping on doors? X Etc. ..Extend the list... General Awareness and Management Are there posters that favour energy savings spread around the school facilities

(such as “Do not leave the lights on”, or “Close the door to avoid heat losses”, etc.)? X

Is student participation promoted through Workshops or Awards? X Has a sort of Energy or Environment Board been created, composed of students and

teachers engaged in fostering best energy practice? X

Etc. ..Extend the list...

86


6th step Make recommendations for energy saving

As the final step, after having collected data and information about energy performance for your school or home, it is time to take action and establish energy-saving measures. This step aims at drawing up a list of recommendations, behavioural and technical, which will help you to reduce energy consumption and losses. Obviously, the range of changes proposed should derive from energy weakness and faults detected by the previous building inspection (step 5); with the objective of improving and solving them. Consequently, numerous measures could be put in place. Here the task is to consider only the most important measures or the ones which you consider to be technically or economically feasible for your case.

Please follow these steps: a. Propose a range of measures/changes/interventions (freely extend the list); b. Calculate the energy savings (estimate approximately the potential percentage of

savings for each measure with respect to the electricity and/or fuel consumption); c. Estimate the costs of actions and the pay-back period (search for the market price

of the action proposed; then divide it by the economic savings to know the pay-back period);

d. Calculate the CO2 avoided (use the same emission factors previously used in the CO2 table – exercise step 5).

The following table includes just a few examples of recommended measures. Please freely ex-tend the list according to your facility’s characteristics. Insert here your consumptions and the proper data for emissions and prices, according

to the type of Fuel used and local energy Prices. For emission factors and units, use the same data as in the previous CO2 emission sheet.

Then use these data for proceeding to the calculations required for filling in the table below.

Example

Example: If you are considering changing “light bulbs”, the type of saving is “Electricity”:

1. energy saving affects Electricity = 15% (estimated % saving) of 3.500 kWh (your elec-tricity consumption);

2. CO2 emissions avoided are to be calculated = multiplying electricity saved (525 kWh) by the emission factor of the electricity (0.54 kg of CO2/kWh – “it changes for any country”);

3. Economic savings = electricity saved (525 kWh) x electricity price (0.19 €/kWh – “search for local price”).

If you are considering “installing double-glazed windows”, it is a “heating measure”, conse-quently:

Energy Type

UnitConsum pti

on per m onth

Em ission Factors

(kg CO²eq/.....)

Price €/.....

Electricity (from grid) kWh 3500 0,54 0,19

Fuels for Heating

Natural Gas kWh 3200 0,22 0,20

Liquef ied Petroleum Gas (Butane, Propane) litre 0

Coal kg 0

Gasoil litre 0

Other Fuels 0

87


1. the percentage of savings is calculated over the amount of Fuel used (10% x 30.000 kWh);

2. the emission factor of CO2 emissions is the Natural Gas one (0.2 kg/kWh); 3. the economic savings are calculated with the Price of Natural Gas.

Type of E-

nergy

MEASURES PROPOSED

Type Beha-vioral/

Te-chnica

l

% of Sa-

vings Energy Savings

CO2 avoi-ded kg/month

Econo-mic Sa-

vings (€/

month)

Cost of the

Action (€)

Pay Back period

(months)

Recommenda-tions about feasibility

Thermal

Heating

Improving thermal insulation of the walls T 30% 960,00 209 192

5-0.000

260,4 In the case of rehabilitation

Installation of double glass windows T 15% 480,00 105 96

2-6.000

270,8

Whenever the existing win-

dows are single pane and not recently in-

stalled

Apply weather-stripping and caulking around doors

T 20% 640,00 139 128 1.500 11,7 Always

Installation of self-closing systems for external doors

T 5% 160,00 35 32 2.000 62,5 Always

Install Thermoregula-tion systems (thermostatic valves and timers)

T 5% 160,00 35 32 1.500 46,9 Always

Keep windows and doors closed when heating or cooling systems are operating

B 5% 160,00 35 32 0 0,0 Always

Do not use drapes or curtains to cover the windows during win-ter days (solar gain) And Close them at the end of the school day (avoiding heat loss)

B 5% 160,00 35 32 0 0,0 Always

In Winter set tempera-ture at 15ºC for bath-room and corridors, while 20-21ºC for rooms

B 5% 160,00 35 32 0 0,0

Always, unless a partucularly

strong cold season

Do not leave open Doors to the outside of the building longer than necessary.

B 2% 64,00 14 13 0 0,0 Always

Start the heating sys-tem (boiler) one hour before school activity begins and turn off at elast one hour before the end

B 5% 160,00 35 32 0 0,0 Always, unless a strong cold

season

Do not block heating and cooling equip-ments (ducts, radia-tors, grilles) by cur-tain, furniture, blan-kets, etc.

B 2% 64,00 14 13 0 0,0 Always

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Type of E-

nergy

MEASURES PROPO-SED

Type Behavio-ral/ Te-chnical

% of Sa-

vings Energy Savings

CO2 avoi-ded kg/month

Econo-mic Sa-

vings (€/

month)

Cost of the

Action (€)

Pay Back period

(months)

Recommenda-tions about feasibility

E-lectricity

Lightings and Equi-pments

Replace Incandes-cent lighting with low consumption compact fluores-cent ones

T 15% 525,00 283 100 800 8,0

Always, wher-ever the fre-quency of

switch on and off is not so

frequent

Install lightings Control Systems (light sensors, oc-cupancy motion sensors or timers) especially in corre-dors and bath-rooms.

T 10% 350,00 189 67 500 7,5

Always, mainly in corredors,

bathrooms and places where

switch on/off is do frequent

Install electronic ballasts to fluores-cent lamps

T 6% 210,00 113 40 700 17,5 Always

Use Power Strips. Plug home electron-ics and office equipment into power strip with an on/off switch.

T 2% 70,00 38 13 200 15,0 Always

When adequate light is available from the sun, or when rooms are unoccupied all lights are to be turned OFF.

B 4% 140,00 75 27 0 0,0 Always

Put in place a fre-quent a programme for cleaning lumi-naries

B 2% 70,00 38 13 0 0,0 Always

All lights, including the outside ones, are to be turned off at night

B 10% 350,00 189 67 0 0,0 Always

Computer monitors are either turned OFF, or computers are put into Sleep mode when not in use.

B 3% 105,00 57 20 0 0,0 Always

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Variations and combination with other activities: “Energy label detectives” – Investigation of the difference between the energy consumption of the best and worst available product in the shops. “Standby power in my home/school” – Investigation of the standby power consumption at home or school. Carbon footprint: Get the pupils to calculate their family’s carbon footprint by using an on-line calculator such as www.carbonfootprint.com. Get really creative: Ask the pupils to imagine life without electricity. Try one day without elec-tricity. What did our forefathers do before electricity was discovered? Even looking 100 years ago can be an eye-opener for children. A bit of History: Make a large timeline showing approximately when certain electrical appli-ances were introduced. Start with the light-bulb. Introduction of a competitive element: Challenge! Can you save 500 Watt in a week? Get the students to plan how to do this, preferably with their parents/teachers help.

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