training module 1 basic module

Developed by the Cyprus University of Technology

Training Module 1

Basic Module

2

1. Introduction (nZEB, definition).

2. Directives

3. Basic Physics

4. Insulation Materials and Current

Technology trends

5. Building Automation and HVAC

6. Practical Workshop

Material to be covered

Training Module 1: Basic Module

Session 1

Introduction

4 Introduction

What is nZEB ?

“nZEB” is defined by the EU Directive 2010/31

“A building with near zero energy consumption”: a Building with very high

energy performance, which is defined according to the annex I.

Need to stress that

The near zero or very low required energy for the building to function

should be covered (or recommended to be covered) by renewable energy

which is produced by the building or near the building.

5 Introduction

Buildings consume around 41% of

primary energy demand in Europe.

Residential buildings consume

around 67% of primary energy

demand in buildings in Europe.

Buildings are responsible for 30% of

CO2 emissions in Europe.

There is a great uncertainty in future

energy supply and the

corresponding prices.

There is a great potential in energy

savings in buildings, both in the

residential and non-residential

sectors.

Why nZEB?

6 Introduction

1970s: Efforts in improving efficiency rates

Introduction of natural gas networks

1980s: Emphasis in the reduction of emissions

New combustion technologies, operating in lower temperatures and emitting

less.

1990s: Introduction of Passive House standard

Reduction of heating load demand

First thoughts on indoor air quality

Increased cooling load demand, even in northern European countries

2000s: Optimization methods

Introduction of smart buildings and systems

Integration of renewables

Introduction of holistic view of buildings as an integrated system of multiple

elements rather than individual systems.

History – evolution of building energy use and efficiency

7

The first discussions appeared in 2002-2003 with the introduction of

directives for building energy consumption

In the subsequent years (2004-2006) we had the first numbers and targets

to reduce the energy consumption by 40% by the year 2020.

Re-evaluation of the above in 2013 for 20% reduction by (2013.C353E/28)

Reduction by 40% by 2050 for gross energy consumption (406.2009.EC)

Introduction

History – recent milestones

8

What is nZEB ?

“nZEB” is defined by the EU Directive 2010/31 as

«The Government of each country is responsible to define the nZEB building

and the subsequent minimum energy requirements for its function”

In other words EACH Government is obliged to define this term in its own

territory

Introduction


Session 2

Directives and National Legislation

10

RES

Directive 2009/28/EC on the promotion of the use of energy from renewable

sources (RES)

EPBD-recast

Directive 2010/31/EU on the energy performance of buildings (recast)


Directives

11

Driving factors:

Reduction of greenhouse gas emissions and compliance with the Kyoto Protocol to

the United Nations Framework Convention on Climate Change.

Increase security of energy supply.

Promotion of technological development and innovation.

Providing opportunities for employment and regional development.


RES Directive (1)

12

Overall Goal: to establish a common framework for the promotion of

renewable energy sources in the European Union, setting mandatory national

targets for achieving a 20% share of renewable energy in the gross final

energy consumption and a 10% share of energy from renewable sources in

transport by 2020


RES Directive (2)

13

A new national law N.112(I)/2013 was voted in September 2013

Mandatory target for the year 2020 of increasing the contribution of

renewable energy sources to:

13% of the gross final energy consumption.

10% in all forms of transport.

Current Status

9% (target: 5.93%) in final

energy consumption.

2.42% in all forms of transport.

Annual RES share and minimum trajectory defined on the Directive 2009/28/EC for Cyprus


RES Directive - Cyprus

14

RES Directive was integrated in the Greek legislation through the Greek

Law 3851/2010.

In order to achieve the target of 20% RES contribution to the total gross

energy consumption, the aforementioned law stipulates:

40% RES electricity share.

20% RES heating and cooling share.

10% RES transport rate.

Incentives were provided for achieving the goals set especially for the

photovoltaics.


RES Directive - Greece

15

The following table provides the installed Power per RES till end March

2014 and the targets that have been set till 2014 and 2020.

Technology

Installed Power

(MW) on March

2014

Target 2014

(MW)

Target 2020

(MW)

Wind power station 1,847 4,000 7,500

Biomass power station 47 200 350

Hydroelectric power plants 3,238 3,700 4,650

Small – scale (0-15 MW) 220 300 350

Large – scale (>15 MW) 3,018 3,400 4,300

Photovoltaic power plants 2,212 1,500 2,200

Installations from farmers by

profession 273 500 750

Other installations 1,939 1,000 1,450

Solar thermal power station 0.00 120 250


RES Directive - Greece

16

The development of renewable energy sources has been one of the priorities

of Italy’s energy policy for some time, together with the promotion of energy

efficiency.

The objectives of such a policy are:

energy supply security.

reduction in energy costs for businesses and individual citizens.

promotion of innovative technology.

environmental protection (reduction in polluting and greenhouse gas emissions).

sustainable development.

In the medium to long term, Italy aims to redress the balance of its energy mix,

which is currently too dependent on imported fossil fuels. This process will also

involve significant measures to relaunch the use of new-generation nuclear

power.


RES Directive - Italy

17

According to the baseline trend scenario of the PRIMES model, which the

European Commission has taken as a reference point, Italy’s gross final energy

consumption in 2020 could reach a value of 166.50 Mtoe, compared with the

value of 134.61 Mtoe recorded in 2005.

The 2009 update to the PRIMES model, which also takes into account the effect

of the financial crisis, estimates Italy’s 2020 gross final energy consumption at

145.6 Mtoe.

Italy’s primary objective is therefore to make an extraordinary commitment to

increasing energy efficiency and reducing energy consumption. This strategy

will also be a determining factor in reaching the targets for reductions in

greenhouse gas emissions and the proportion of total energy consumption to be

covered by renewable sources.



18

Italy has already been putting significant emphasis on the mobilization of

renewable energies for some time.

Numerous support mechanisms are therefore already available, ensuring

remuneration for investment in various renewable energy and energy efficiency

operations, and encouraging the growth of related industries.

Nevertheless, the targets and the scale of Directive 2009/28/EC do require a

renewed commitment, based on principles which will ensure balanced

development of the various sectors which contribute to reaching said targets,

and with consideration of the cost-benefit ratio.

Equally, there will be increased commitment in terms of infrastructure, research,

training and, in general, every element which could contribute to the balanced

growth in renewable energy use.



19

The Parliament has compiled implementation criteria for the directive.

By implementing all these measures effectively, and by combining the effects of

individual actions, we can reach our goal:

national measures alone are unlikely to be enough, and in order to achieve

efficiency these should be integrated into international cooperation schemes;

during this process action will be needed to overcome potential restrictions

and criticalities, modify or improve certain measures, adapt the support

schemes to the continually changing economic and energy-use situations,

and take advantage of new technological applications.

References: Ministry of Economic Development (MSE); National Network of Local Energy Agencies (RENAEL); National Agency for new technologies, sustainable energy and economic development (ENEA



20 Directives and National Legislation


22

In order to achieve its own national objectives, Italy intends to strengthen and

rationalize the existing support mechanisms, within a framework which

integrates:

- efficacy in concentrating efforts along routes which will make the maximum

contribution to achieving the objectives;

- efficiency in introducing flexibility in incentives, limiting their contribution to

what is strictly necessary to make up for market shortcomings;

- financial sustainability for the end consumer, the party which bears a large

part of the burden of incentive schemes;

- careful consideration of all measures to be promoted in the three sectors in

which action will be taken: heating, transport, electricity.




RES Directive - Portugal

The National Energy Strategy (NES 2020) attributes a pivotal role to renewable

energy in the energy strategy and the targets that have been delineated for this

sector, with a very significant impact on the Portuguese economy.

24

Key parameters of NEEAP/NEAPR together with EPBD requirements on plans

for increasing the number of nearly zero-energy buildings

Source: http://repositorio.lneg.pt/handle/10400.9/2283



25

The main objectives of the national energy policy include:

To guarantee compliance with Portugal’s commitments in the context of

European energy policies and policies to combat climate change, ensuring

that 31% of the gross final energy consumption, 60% of the electricity

produced and 10% of the energy consumption in the road transport sector

will be derived from renewable sources in 2020;

To reduce Portugal’s energy dependence on external sources, based on the

consumption and importation of fossil fuels, to around 74% in 2020, by

means of increasing use of endogenous energy resources (estimated

reduction using a Brent reference of 112 USD/bbl);



26

To reduce the balance of energy imports by 25% (around € 2 billion) with the

energy produced from endogenous sources, making it possible to reduce

imports by an estimated 17 million barrels of oil and 3 billion cubic meters of

gas;

To consolidate the industrial cluster associated with wind energy and to

create new clusters associated with new technologies in the renewable

energy sector, ensuring a Gross Added Value of 2.7 billion Euros and

creating 70,000 new jobs in addition to the existing 29,000 jobs associated

with the production of electricity from RES by 2020;



27

To promote sustainable development, creating the necessary conditions to

meet the commitments that Portugal has made with regard to reducing

greenhouse gases, by means of a greater use of RES and energy

efficiency.



28

Portuguese overall target for the share of energy from renewable energy

sources in gross final energy consumption in 2005 and 2020

A) Share of energy from renewable sources in gross final energy consumption in 2005 (%) 19.8

B) Target of energy from renewable sources in gross final energy consumption in 2020 (%) 31.0

C) Expected total adjusted energy consumption in 2020 ((ktoe) 16,623

D) Expected amount of energy from renewable sources corresponding to the 2020 target

(calculated as B x C) (ktoe) 5,153

Solar thermal for residential and non-residential buildings: increasing area from 1 million m2 to 2.2 million m2

Residential : 700,000 m2 in 2013 plus 800,000 m2 in 2016 and 1,2 millions in 2020.

Non-residential: 300,00 m2 in 2013 and plus 330,000 m2 in 2016 and 500,00 m2 in 2020.



29

Projections for Renewable Electricity in 2020 (PNAEE and PNAER)

MW

installed

RES Electricity Generation

(GWh)

% in Electricity

Consumption

Large Hydro 8,540 13,613

Hydro (below or equal to 10 MW) 400 916

Geothermal 29 226

Photovoltaic 670 1,039

Solar Thermal Electricity 50 100

Tidal, Wave, Ocean 6 15

Wind Onshore 5,273 11,601

Wind Offshore 70

Biomass (solid, biowaste, bioliquid) 4,306

Biogas 59 413

Total 15,824 32,300 59.6

Source: EREC road Map; DR 70/2013



30

Renewable Electricity Generation in 2014

RES Electricity Generation (GWh)

Large Hydro 15,314

Hydro (below or equal to 10 MW) 1,509

Wind 11,813

Thermal 2,697

Cogeneration 1,526

Solar 592

Source: REN



31

Source: REN

Energy supply in Portugal



32

Renewable Energy production share in Portugal

Source: DGEG and REN

0

10

20

30

40

50

60

70

80

90

100

%

Renewable Non-renewable



33

RES target, production and potential in Portugal

Source: ECOFYS



34

RES target, production

and potential in Portugal

Source: ECOFYS



35

Available local renewable energy

resources for Portugal

Distribution of potential renewable energy in Portugal

Source: DGEG

Contribution of Renewable Energy:

Solar collectors

Photovoltaic systems

Wind energy systems

Biomass

Geothermal

Hydro

Heat pumps



http://www.google.pt/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CDAQFjAC&url=http://www.res-legal.eu/search-by-country/portugal/&ei=Ld1RVaaPAYfTU_LcgIAM&usg=AFQjCNEWA51DvjeDCcRc9wxr1N9kORxp8A&sig2=DgSnAmk2xWBqw6m2hLgDsg&bvm=bv.92885102,d.d24

36

Production of electricity from renewable sources in Portugal (GWh)

Distribution of potential renewable energy in Portugal

Source: DGEG



http://www.google.pt/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CDAQFjAC&url=http://www.res-legal.eu/search-by-country/portugal/&ei=Ld1RVaaPAYfTU_LcgIAM&usg=AFQjCNEWA51DvjeDCcRc9wxr1N9kORxp8A&sig2=DgSnAmk2xWBqw6m2hLgDsg&bvm=bv.92885102,d.d24

37

Directive on the Energy Performance of Buildings (EPBD) - (Directive

2002/91/EC) first published in 2002

Directive on the Energy Performance of Buildings (EPBD) - recast

(Directive 2010/31/EU) adopted in 2010


EPBD Directive (history)

38

1. To promote the improvement of the energy performance of buildings

within the EU, taking into account outdoor climatic and local conditions,

as well as indoor climate requirements and cost-effectiveness.

2. Lay down requirements regarding:

a. A common general framework for a methodology for calculating the

integrated energy performance of buildings and building units.

b. The application of minimum requirements to the energy performance of new

buildings.


EPBD – Scope (1)

39

c. The application of minimum requirements to the energy performance of:

i. Existing buildings that are subject to major renovation.

ii. Building elements that form part of the building envelope, and have a significant

impact on its energy performance, when they are retrofitted or replaced

iii. Technical building systems whenever they are installed, replaced or upgraded

d. National plans for increasing the number of nearly zero energy buildings.

e. Energy certification of buildings.

f. Regular inspection of heating and air-conditioning systems in buildings.

g. Independent control systems for energy performance certificates and

inspection reports.


EPBD – Scope (2)

40

National (or regional) methodologies for assessing the energy performance

of buildings and Energy Performance Certification of buildings across EU

member states.

Building Energy Audits.

Mandatory inspection of boiler based heating systems as well as cooling

systems installed in buildings.

Overall view of the Building and treating all building components as

integrated parts of a larger system rather than individual components.

Establishing a correlation of building commercial value with its energy

performance .


EPBD – Major Outputs (1)

41

Definition of near Zero Energy Buildings (nZEB) and mandatory

introduction of nZEB buildings by:

31 December 2020 for all new buildings.

31 December 2018 for new buildings occupied and owned by public authorities.


EPBD – Major Outputs (2)

42

Implementation of the EPBD in Cyprus is ensured through 3 basic laws:

1. N.142(I)/2006 – Regulating the Energy Performance of Buildings

Law of 2006.

2. N. 30(I)/2009 – Regulating the Energy Performance of Buildings

(amendment) Law of 2009.

3. N.210(I)/2012 – Regulating the Energy Performance of Buildings

(amendment) Law of 2012.


Transposition to national legislation – Cyprus (1)

43

On a second level of legislation control national regulations are

issued:

i. Regulations regarding the energy certification of buildings.

ii. Regulations regarding the energy performance of buildings

correlated with the “Roads & Buildings Law”

iii. Regulations regarding the inspection of HVAC systems

iv. Regulations regarding the inspection of boiler-based heating

systems



44

Finally, parameters and details are regulated through ministerial

orders:

i. Ministerial orders regarding the energy certification of buildings.

ii. Ministerial orders regarding the energy performance of

buildings correlated with the “Roads & Buildings Law”.

iii. Ministerial orders regarding the inspection of HVAC systems.

iv. Ministerial orders regarding the inspection of boiler-based

heating systems .



45

Law 142(Ι)/2006-On the energy performance of buildings basic

law and amending laws N30(I)/2009 & N210(I(/2012

KDP148/2013-On the energy performance of buildings (Inspection of boiler-based

heating systems of nominal power 20-100 kW) Ministerial Act of 2013.

KDP149/2013-On the energy performance of buildings (Inspection of boiler-based heating systems of nominal power >100

kW) Ministerial Act of 2013.

KDP 119/2011-On the energy performance of buildings (Inspection of

boiler-based heating systems) Regulations of

2011.

Inspection of boiler-based heating systems



46

Boiler-based heating system category

Frequency of inspection

Systems with boiler of nominal capacity 20-100 kW and use of solid, liquid or gaseous fuel

Every five (5) years following 31/12/2014

Systems with boiler of nominal capacity >100 kW and use of solid or liquid fuel

Every two (2) years following 31/12/2013

Systems with gas boiler of nominal capacity >100 kW

Every four (4) years following 31/12/2013




47

The inspection is performed from a qualified “inspector of boiler-based

heating systems”.

The inspection is performed according to the “Inspection of boiler-based

heating systems national guidelines” (KDP 238/2011).

An inspection certificate is issued to be presented to the national authority

when asked




48

Law 142(Ι)/2006-On the energy performance of buildings basic law and

amending laws N30(I)/2009 & N210(I(/2012


HVAC systems) Ministerial Act of 2009.


HVAC systems) Regulations of 2009.

Inspection of HVAC systems



49

HVAC system category Frequency of inspection

HVAC Systems of nominal capacity 12-250 kW

Every five (5) years following 31/12/2011 or five (5) years after their installation date

HVAC Systems of nominal capacity >250 kW

Every three (3) years following 31/12/2011 or three (3) years after their installation date

HVAC Systems of nominal capacity less than 12 kW but with the overall capacity installed in the building exceeding 50 kW

Every five (5) years following 31/12/2010 or five (5) years after their installation date




50

The inspection is performed from a qualified “inspector of HVAC systems”.

The inspection is performed according to the “Inspection of HVAC systems

national guidelines” (KDP 163/2009).

An inspection certificate is issued to be presented to the national authority

when asked.




51

Law 142(Ι)/2006-On the energy performance of buildings basic law and

amending laws N30(I)/2009 & N210(I(/2012

KDP 39/2014-On the energy performance of

buildings (Energy Performance Certification

of buildings) amending Regulations of 2014.

KDP 164/2009-On the energy performance of

buildings (Energy Performance Certification of buildings) Regulations

of 2009.

Energy Performance Certification of buildings



52

Related Ministerial Acts:

KDP432/2013: On the Energy Performance of Buildings regulating

Ministerial Act of 2013 (Minimum building energy performance

requirements).


Ministerial Act of 2015 (Methodology for the assessment of the energy

performance of buildings).


Ministerial Act of 2013 (Methodology for assessing the optimal cost level of

the Minimum building energy performance requirements).




53


Ministerial Act of 2013 (Performance requirements of building systems, in

current buildings or building units, that are newly installed, replaced or

upgraded).


Ministerial Act of 2014 (Minimum energy performance and technical

specifications requirements that must be met by a near Zero Energy

Building).




54

The energy performance of buildings is assessed based on the

corresponding national methodology.

Energy Performance Certificates (EPC) are issued only by qualified

experts registered in the records of the Cyprus Energy Service.

A valid EPC of minimum “Energy Category B” is required prior any new

building obtaining a building permit from local authorities.

A valid EPC is required for any building (new or old, residential or not

residential) used for commercial purposes (sale, rent, commercial space,

etc.).




55

Based on the ministerial order KDP 366-2014, the following minimum

requirements are set for defining an nZEB:

Maximum consumption of primary energy in residential buildings: 100

kWh/m2/year.

Maximum consumption of primary energy in non-residential buildings: 125

kWh/m2/year.

Maximum consumption of primary energy used for heating in residential

buildings: 15 kWh/m2/year.

At least 25% of total primary energy consumed in the building should

originate from RES

Parameter Definition of NZEB



56

Maximum thermal transmittance coefficient (U-value) of walls and

structural elements (columns and beams) of the building envelope: U≤0.4

W/m2K.

Maximum thermal transmittance coefficient (U-value) of horizontal

structural elements (rooftops, floor in pilotis, etc.) of the building envelope:

U≤0.4 W/m2K.

Maximum thermal transmittance coefficient (U-value) of doors and

windows that are part of the building envelope: U≤2.25 W/m2K.

Maximum mean installed lighting power in buildings dedicated as office

spaces: 10 W/m2.

Parameter Definition of NZEB



57

The EPBD Directive 2002/91/EC was integrated in the Greek legislation

through the Greek Law 3661/2008.

Based on the aforementioned law, the Regulation for Energy Efficiency of

Buildings (KENAK) was issued in 2010

The recast EPBD Directive 2010/31/EU was integrated in the Greek

legislation through the Greek Law 4122/2013.

EPBD Directive


Transposition to national legislation – Greece (1)

58

According to the Greek Law 3661/2008 and KENAK, relative legislation

came into force through ministerial orders regarding:

Guidelines to be followed during the construction / inspection of new build

buildings and fully renovated buildings the guidelines were issued by the

Technical Chamber of Greece.

Building legislation Greek Law 4067/2012.

Energy Performance Certificates

Required for new build buildings, fully renovated buildings and in case of

selling / renting a property (building).

EPBD Directive



59

Energy Inspectors are responsible in issuing the EPCs, for which there are 3

categories and 2 levels for each category (A and B):

o The Energy Inspectors for Buildings.

o The Energy Inspectors for Heating Systems.

o The Energy Inspectors for Cooling Systems.

o A- level License.

o B- level License.

Energy inspectors are qualified experts registered in a corresponding national

Registry.

EPBD Directive



Categories

Levels

60

General definition of nZEB concept, as per the recast EPBD Directive

Greek Law 4122/2013, however:

No minimum technical requirements and primary energy consumption for

nZEBs have been defined yet

No National Plan has been issued yet

No promotion actions have been done yet

EPBD Directive



61

In Italy the overall responsibility for the implementation of the Energy

Performance of Buildings Directive (EPBD) rests with the Ministry for

Economic Development.

The first decree setting the basis for the national legislative EPBD framework

was enacted in 2005.

After that, a number of legal acts (legislative, ministerial and presidential

decrees) have been issued to progressively define and specify all aspects of

the national EPBD transposition.

EPBD Directive – National implementation


Transposition to national legislation – Italy (1)

62

According to the Constitution, energy- related topics are a shared task

between the State and the 21 Regions and Autonomous Provinces.

Consequently, regional authorities may implement autonomous transpositions

of the EPBD, as long as they do not contradict the general principles and

requirements provided by national and EU regulations.

The national regulation stays in force for those regions which have not

published their own legislation.

At present, 11 Regions and Autonomous Provinces (Liguria, Emilia

Romagna, Toscana, Val d’Aosta and Lombardia, Friuli Venezia- Giulia, Puglia,

Sicilia, Toscana and the Autonomous Provinces of Trento and of Bolzano) out

of 21 have enacted their local transposition of the EPBD. All the others

follow the national legislation.




63

Except for the inspection of air-conditioning systems, the Legislative Decree

192/2005 has drawn the general framework for the transposition of the EPBD

at national level, setting the minimum requirements for the Energy

Performance (EP), and the U-values for windows, walls, floors and roofs, in

case of new buildings and major renovations.

In 2009, the Presidential Decree n. 59 extended the calculation

methodologies and minimum requirements to the summer EP of cooling and

lighting systems; it also updated the minimum requirements for the EP of

buildings and of heating systems.




64

With the Legislative Decree 28/2011 transposing the Renewable Energy

Services (RES) Directive, the requirements regarding the share of renewable

energy for new buildings and major renovations were increased, establishing

a calendar with a progressively larger share of renewable quota for Domestic

Hot Water (DHW), heating and cooling energy demand:

A. 20% renewable quota for all building permits requested between the 31st

of May 2012 and the 31st of December 2013;

B. 35% renewable quota for all building permits requested between the 1st

of January 2014 and the 31st of December 2016;

C. 50% renewable quota for all building permits requested from the 1st of

January 2017 onwards.




65

Since January 2010, after a transition phase with intermediate requirements,

new residential and non-residential buildings must fully comply with the

minimum requirements for winter performance, set by the Legislative Decree

192/2005.

EP values vary according to building type (EP for residential buildings is

expressed in terms of kWh/m2 year of primary energy, while EP for non-

residential buildings is expressed in terms of kWh/m3 year of primary energy),

climatic zone, local degree days, and surface area to volume ratio of the

building.

EPBD Directive – format of national transposition and implementation

of existing regulations



66

Table 1: Minimum EP requirements for heating in residential buildings

(kWh/m2)

Table 2: Minimum EP requirements for heating in non residential

buildings (kWh/m2)





67

Table 3: Minimum EP requirements for cooling in

residential buildings (kWh/m2)

Table 4: Minimum EP requirements for cooling in non

residential buildings (kWh/m3)

Table 5: Minimum required U values for

building elements (W/m2K)





68

In case of new buildings and major renovations, the designer is expected

to:

Introduce compulsorily window sun shades, and calculate their contribution

to the winter and summer performance;

Either check that the mass external walls, except North-East to North-

West, is larger than 230 kg/m2, or that their value for periodic thermal

transmittance (a dynamic parameter introduced with the Standard UNI EN

ISO 13786:2008) is lower than 0.12 W/m2K;

Check that the periodic thermal transmittance for North-East to North-

West external walls only, is lower than 0.20 W/m2K.





69

Minimum requirements are differentiated according to the degree of the

planned renovation. The minimum EP requirements for new buildings apply

fully in case of:

• Demolition/reconstruction or renovation of all the building elements (for

buildings with heated floor area >1000 m2);

• Building enlargements over 20% of the original volume, only for the newly

built section.





70

When designing their local EPBD implementation, regional governments and

Autonomous Provinces are allowed to set stricter minimum requirements.

Table 6 shows the state of EPBD implementation among Regions and

Autonomous Provinces.

Requirements for public buildings

Public authority buildings are expected to set an example, and to play a

leading role. Therefore:

EP and U-values are set 10% lower than those required for private

buildings;

Seasonal efficiency for heating systems should be higher than (75 + 4 log

Pn)%;

Only centralized heating systems are allowed.

EPBD Directive – Minimum requirements in specific Regions



71

Table 6: State of EPBD implementation among Regions and Autonomous Provinces




72

The leading role of public buildings in the progression to nearly zero-energy

performance has been emphasized in the National Energy Efficiency Action

Plan (NEEAP).

In order to promote and support energy efficiency measures in the public

sector, the NEEAP foresees that an observatory will be set up.

The aim of this observatory will be to build a reference framework on the

status of implementation of energy efficiency programs and their effectiveness

at local level, as well as to support the process of defining policies and

specifying the implementation measures in a system shared among

institutions and stakeholders, both public and private.




73

The Second National Energy Efficiency Action Plan, issued in July 2011, carried

some preliminary milestones for setting a national strategy for nearly Zero-

Energy Buildings (nZEB). It is stated that:

New minimum requirements for building EP and for building elements will be

set: the requirements should be laid down with a view to achieving cost-

optimality.

Economy and Finance, and the Ministry for Economical Development shall

join in a task force to program and manage a national incentive scheme.

Social housing: introduction of an incentive/bonus for projects adopting

innovative solutions (cool roof, active building envelope systems, etc.),

integration of renewables, use of ecologic components and materials,

optimization of local economic resources.

EPBD Directive – Action plan for progression to nZEB



74

Introduction of standardization in the use of Building Energy Management

Systems (BEMS) for public buildings.

Residential buildings: focus on the cluster of existing buildings built before

1976 (which sums up to more than 70% of all buildings). Provide incentives

through low interest rate revolving fund schemes for renovations leading to a

50% decrease in energy consumption.

Stakeholders involvement: the National Energy Agency (ENEA) will involve

stakeholders in working groups, with the goal of proposing new lines of

action.

An observatory will be set up in order to monitor the effectiveness of the

programs and schemes.

School buildings: simplified procedures to involve Energy Service

Companies (ESCOs).




75

According to the Constitution, energy-related topics (technical standards

and building regulations relating to energy) are a shared task between the State

and the 21 Regions and Autonomous Provinces.

Regional authorities may implement autonomous transpositions of the

EPBD, as long as they do not contradict the general principles and

requirements provided by national and EU regulations.

As a consequence, there are two levels of standards and regulations:

a national level that establishes the national minimum energy performance

requirements;

a regional or local level that could be more onerous.




76

A different consequence of the regional independence is that a number of

regions have not yet implemented a certification scheme. The majority of these

regions are in the South of Italy.

In fact, according to the CTI report 2011 on the state of implementation of the

EPBD in Italy, 1,375,000 EPCs had been delivered in 18 of the 21 Regions and

Autonomous Provinces, 710,000 (more than the half) of which in Lombardia,

creating a marked difference in the level of expertise within the market

operators, and also in the level of awareness and trust within the population.

EPBD Directive – National/regional transposition



77

In the northern part of the Country almost all regions have implemented

specific schemes as to what concern the application of the EPBD.

At present, 11 Regions and Autonomous Provinces (Liguria, Emilia-

Romagna, Toscana, Val d’Aosta and Lombardia, Friuli Venezia-Giulia,

Puglia, Sicilia, Toscana and the Autonomous Provinces of Trento and of

Bolzano) out of 21 have enacted their local transposition of the EPBD.

At the end of 2012, 6 Regions (Liguria, Emilia Romagna, Toscana, Val

d’Aosta, Lombardia and the Autonomous Province of Bolzano) have

transposed the EPBD recast.




78

In the south those that have done

so are still the vast minority (just

Sicilia and Puglia).

The national regulation stays in

force for those regions which have

not published their own legislation,

so all the others follow the national

legislation.

Figure 1 In gray: regional EPBD regulations




79

The EPBD was transposed into national law through:

Decree-Law n.º 78/2006 of April 4th - National System Energy Certification

and Indoor Air Quality in buildings,

Decree-Law nº 79/2006, of April 4th - Regulation of Energy Systems and

Air-conditioning in buildings (for office buildings),

Decree-Law n.º 80/2006, April 4th - Regulation of Thermal Performance of

Buildings (for residential buildings).

This regulations promoted energy efficiency of buildings, and the acquisition of

relevant experience in this area → increasing of the efficiency of the energy

certification system, but also on the identification of relevant aspects of its

application.

EPBD Directive


Transposition to national legislation – Portugal (1)

80

The creation and operation of the certification system, along with the effort

employed in its application, contributed to highlight issues related to increasing

energy efficiency and use of renewable energy in buildings.

The 2006 Portuguese Building energy certification system and energy efficiency

codes were revised to transpose the 2010 recast EPBD (the process started in

2010 and the technical committees completed their work in 2012).

The transposition into national law of the Directive 2010/31/EU created an

opportunity to improve the systematization and scope of the energy certification

system and respective regulations, as well as align national requirements

impositions.

EPBD Directive



81

Decree-Law n.º 118/2013 ensures not only the transposition of the Directive

2010/31/EU, but also a review of national legislation, including in a single

document, the Buildings Energy Certification System (SCE), Rules of the

Energy Performance of Housing Buildings (REH) and the Regulation on Energy

Performance of Office and Commercial Buildings (RECS).

EPBD Directive



82

Building Thermal Legislation - Decree-Law 118/2013

Requisites

Thermal performance of opaque envelope Uelement ≤ Umax

Thermal performance of plane thermal bridges (PTB):

Umáx [W/m2.ºC]

Climatic zone

I1 I2 I3

Envelope elements and elements separating

useful and non useful areas (elevator shafts,

common circulation areas) with btr 0.7 (thermal

conditions similar to outdoors)

Vertical elements 1.75 1.60 1.45

Horizontal

elements 1.25 1.00 0.90

Construction elements between buildings and

non useful areas (elevator shafts, common

circulation areas) with btr ≤ 0.7 (thermal

conditions similar to indoors)

Vertical elements 2.00 2.00 1.90

Horizontal

elements 1.65 1.30 1.20

UPTB ≤ 0.9 W/m2.ºC

or UPTB ≤ 2 Uwall & UPTB ≤ Umáx

Maximum U-values, Umax [W/(m2.°C)]

Winter and Sumer climatic zones

EPBD Directive



83

Reference U-Values - Evolution of the Reference U-values, Uref, Mainland Portugal [W/(m2.°C)]

Note: These values might be updated until 2020 to take into account cost-optimal studies and nZEB requisites.

Envelope, Uref [W/(m2.ºC)] RCCTE REH 31 – Dez. - 2015

I1 I2 I3 I1 I2 I3 I1 I2 I3

Envelope elements and

elements separating useful

and non useful areas (elevator

shafts, common circulation

areas) with btr 0.7 (thermal

conditions similar to outdoors)

Opaque vertical

elements 0.70 0.60 0.50 0.50 0.40 0.35 0.40 0.35 0.30

Opaque horizontal

elements 0.50 0.45 0.40 0.40 0.35 0.30 0.35 0.30 0.25

Construction elements

between buildings and non

useful areas (elevator shafts,

common circulation areas)

with btr ≤ 0.7 (thermal

conditions similar to indoors)

Opaque vertical

elements 1.40 1.20 1.00 1.00 0.80 0.70 0.80 0.70 0.60

Opaque horizontal

elements 1.00 0.90 0.80 0.80 0.70 0.60 0.70 0.60 0.50

Windows (Uw) (doors and windows) 4.30 3.30 3.30 2.90 2.60 2.40 2.80 2.40 2.20

Elements in contact with the ground - 0.5 0.5

EPBD Directive - Building Thermal Legislation - Decree-Law 118/2013



84

In Portugal, the information needed for calculating the energy performance

certificate and the suggested energy savings measures, the general information

about the building and the expert is stored in a central register.

Examples of extracted added value from EPC data are:

average building stock label;

benchmarking for revision of building regulation;

dissemination of renewable DHW systems; and

most recommended energy-efficiency measures.

ADENE’s website provides detailed information on the SCE (training courses, a list

of qualified experts, and lists of valid EPCs) to licensing authorities, professionals of

the sector, property owners and developers, and also to the general public.

www.adene.pt

EPBD Directive



85

The energy performance of buildings is assessed based

on the national methodology (Decree-Law 118/2013 and

related mandamus and ordinances).

Energy Performance Certificates (EPC) are issued only

by qualified experts.

A valid EPC of minimum “Energy Category B-” is required

prior any new building or subjected to major renovation

works obtaining a building permit from local authorities.

A valid EPC is required for any building (new or existing

when on the market for sale or rent, residential or not

residential, commercial space, etc.).

EPBD Directive



86

Distribution of Energy Performance certificates

Source: http://www.buildup.eu/publications/38183

The application of EPBD to the new and renovated buildings is still limited

50,000 new buildings are build each year in Portugal

The impact of applying energy performance requirement for new buildings

is low compared to the whole building stock.

EPBD Directive



87

Energy label and Energy Performance Certificates distribution for new and existing buildings

Source: http://www.buildup.eu/publications/38183

EPBD Directive



88

The national action plan for the progression to nearly zero-energy buildings is

now under development, and the key targets and milestones defined.

The adopted definition of the nZEB, establishes a relation with cost optimal

evaluations.

nZEBs are defined as buildings that cumulatively offer:

components compatible with the upper level of the cost optimal

evaluations;




89

implementation of renewable energy (produced on site, whenever possible

and/or as nearby as possible) that covers a very significant fraction of the

reduced building energy needs. Numerical indicators are also being studied

and will be made available following the conclusion of the cost optimal

procedures.

The primary energy factors, that also play an important role, will be gradually

revised until 2020, to incorporate the effort made by Portugal to have clean and

renewable electricity.




90

Status of development of the nZEB definition

September 2014





Session 3

Basic Physics and the Building Envelope

92

1. The building envelope/shell

2. Thermal Losses

3. Mechanisms

4. Thermal Gains

Basic Physics & the building envelope


93

Every element of the building that connects the building’s conditioned

spaces with the external environment or any other adjoined constructions


Building Shell - Definition

94

Vertical structural building elements

Walls

Columns/beams

Horizontal structural building elements

Rooftops

Floors in touch with the ground or in “pilotis”

Doors/windows and glazing

Shading systems


Building shell / envelope elements

95

A building is loosing thermal energy to

the external environment:

through the roof.

through the walls.

through the windows.

through draughts due to insufficient

air-tightness.

into the ground.


Thermal losses through the building envelope

96

Conditioned Space, Ti

External Environment, To

To

Ti

Tsi

Tso

Air gap / thermal

boundary, hsi Air gap / thermal

boundary, hso

Structural element, λ

d

Q Q


Thermal losses through the walls (1)

Structural element thickness

97 Basic Physics & the building envelope

Thermal losses through the walls (2)

98

Conditioned Space, Ti

External Environment, To

To

Ti

Tsi

Tso

Air gap / thermal

boundary, hsi Air gap / thermal

boundary, hso

Structural element, λ

d

Q Q


Thermal gains through the walls (1)



0.00

5.00

10.00

15.00

20.00

25.00

1-27-2012 0:00 1-27-2012 12:00 1-28-2012 0:00 1-28-2012 12:00 1-29-2012 0:00

Te

mp

era

ture

oC

Time

Temperature distribution across a west-orientated wall section

Internal Room Temperature

Internal West Wall Surface Temperature

External West Wall Surface Temperature

Ambient Temperature

101

Thermal losses based on the typical convection-conduction-convection

mechanism (just like the wall presented earlier)

Thermal gains due to solar radiation in sunny days

Increased thermal losses due to radiation during clear-sky nights


Thermal losses/gains through the roof (1)



0.00

5.00

10.00

15.00

20.00

12-29-2011 12:00 12-29-2011 18:00 12-30-2011 0:00 12-30-2011 6:00 12-30-2011 12:00 12-30-2011 18:00

Te

mp

era

ture

(oC

)

Time

Temperature Distribution on Roof Section

Internal Roof Temperature

External Air Temperature

Intrnal Roof Surface Temperature External Roof Surface Temperature

104

Requirements for windows and shading systems:

Limit thermal losses to the external environment

Typical losses (just like the walls).

Losses through draughts.

Control direct solar radiation entering the building

Direct solar radiation provides heat gains to the conditioned building spaces

during the winter.

Direct solar radiation exposure increases cooling demand during summer time.

Visual contact to the external environment

Direct visual contact to the external environment (despite the existence of any

shading systems) is beneficial to the occupants psychological health.


Windows and shading systems (1)

105

Glare control

Depending on workspace, there might be restrictions to the desired light density

entering the building (e.g. office spaces with computers).

Internal space illumination

Artificial light increases internal gains as well as operating costs.

Natural light is beneficial to the occupants health.



106

Basic Mechanisms

Heat is transferred

through the windows

by direct solar

radiation.

Through convection

and conduction.



107

Low-e coating

Used in double or triple glazing

Coated in the external surface of the

internal glazing

Limits thermal losses from the

internal conditioned space to the

environment (acts as a heat barrier

– undesired effects for summertime).



Basic Mechanisms

108

Solar protective coating

Used in double or triple glazing

Coated in the internal surface of the

external glazing

Limits internal gains from direct solar

radiation (useful in the summer for

avoiding over-heating, undesired

effect for winter)

Limits space illumination

Basic Mechanisms



109

Fixed shading systems

Flexible shading systems

External shading systems

Internal shading systems

Window integrated shading systems

Categories of shading systems



110

Category of shading system based on installation origin

Shading system type

Externally installed shading system

Blinds Venetian blinds Awnings Screens

Window-integrated shading system

Blinds

Internally installed shading system

Blinds Vertical blinds Pleated blinds

Basic Mechanisms



111

Architectural Association with funding from BMU/UBA. Further Training C02-Reduction 1995 source: PACER; U. Fischer

External fixed shading

device External movable

shading devices

Examples of shading devices



112

fixed horizontal and vertical

elements

blinds/ venetian blinds

light controlling systems

/ roller-blinds

awnings

solar control glass

Examples of shading devices



113

+ effective shading devices

+ adjustable fins – controllability of

visual contact and light

incidence

+ shading even with opened

windows

- susceptible to wind – no shading

during high wind velocities

Window with external

adjustable blinds

External shading devices


Functional properties of different Shading Devices (1)

114

External shading systems can

provide efficient protection

from direct solar radiation

External shading devices



115

+ requires no cleaning, requires

little space

+ adjustable fins – controllability of

visual contact and light

incidence

- no shading with opened

windows

- joint controlling complex and

costly

Double-glazed window with

integrated blinds

Window –integrated Shading Devices



116

Integrated shading systems

can efficiently control glare

and illumination but on the

same time provide adequate

thermal protection

Window –integrated Shading Devices



117

Internal adjustable blinds

+ glare control

+ subsequent installation possible

- allows solar radiation to enter

the room and thus adding to

thermal load

Fixed roof curtains

Internal Shading Devices



118

Example of solar radiation entering the room and

thus adding to thermal load

Internal Shading Devices



119

Walls ~ 35%

Roof ~ 25%

Ground ~15%

Glazing ~ 10%

Draughts ~ 15%


Overall losses in a typical residential building

120

Overall building shell

construction affects:

Internal envelope surface

temperature

Internal temperature and

humidity

Direct solar radiation and

illumination


Building Shell

121

U

[W/m²K]

q

[W/m²]

θe

[°C]

θsi

[°C]

1.4 35 -5 15.45

0.5 12.5 -5 18.37

0.25 6.25 -5 19.18

Degree of insulation greatly affects internal

environment and temperature distribution, thus

affecting the perceived internal temperature and

heat direction


Thermal loss

122


Building Shell and Thermal loss


Session 4

Thermal Insulation Materials

124

1. Definition

2. Available materials & general

properties

3. Current trends

4. Future technologies

5. Thermal Insulation Construction

Techniques



125

Any material that limits heat transfer (primarily by conduction) from an

environment (body, element, building internal space, etc.) of high temperature

to an environment of lower temperature can be considered of being an

insulating material. Main thermal property for insulating material classification

is the thermal conductivity (k or λ).

As a rule of thumb, any material with a thermal conductivity k≤0.1 W/mK can

be classified as an insulating material.


Definition

126

Inorganic materials

Foamy

o Foam glass

Fibrous

o Glass-wool

o Rock-wool

Organic materials

Foamy

o Expanded polystyrene

o Extruded polystyrene

o polyurethane foam

Foamy expanded

o cork

o Melamine foam

o Phenol foam

XPS

EPS

Cork

Glass wool

Glass foam


Insulating materials categories (1)

127

Organic materials (cont.)

Fibrous

o Sheep-wool

o Cotton-wool

o Coconut fibers

o Cellulose

Combined materials

Siliconated Calcium

Gypsum foam

Wood-wool

Cement composites

o With glass fibers

o Foam cement boards (e.g. with polyurethane foam)

o etc.

Gypsum

foam Cellulose

Cement foam

boards

Glass fiber reinforced

composite



128

State of the art materials

Vacuum Insulation Panels (VIP)

Gas Filled Panels (GFP)

Aerogels

Reflective materials and radiant barriers

Phase Changing Materials (PCM)

Future materials & technologies

Vacuum Insulation Materials (VIM)

Gas Insulation Materials (GIM)

Nano Insulation Materials (NIM)

Dynamic Insulation Materials (DIM)



129

Physical properties

Density

Mechanical strength

Thermal insulation ability – thermal conductivity

Resistance to moisture

Resistance to heat

Resistance to fire

Sound absorption

Aging

etc.

Environmental impact properties

Primary embodied energy

Gas emissions during production

Use of additives against biological impacts


Insulating materials properties (1)

130

Environmental impact properties (cont.)

Re-usability

Recyclability

Classification of their treatment as waste

Environmental impact based on LCA approach – environmental labelling.

etc.

Public health (during production, use and final stage of disposal) properties

Dust and fibers emissions

Biopersistence

Toxicity in case of fire

etc.


Insulating materials properties (2)

131

Covers the family of glass wool and rock wool

Produced in the form of mats, boards, as well

as filling material.

Light and soft mineral wool products are used

for cavity insulation and frame houses.

Harder mineral wool boards with high mass

densities are used in cases where thermal

insulation is intended in carrying loads (e.g.

floors, roofs, etc.).


Traditional thermal building insulating materials (1)

Mineral Wool

132

Typical thermal conductivity values are

between 30 and 40 mW/mK

(0.03 W/mK ≤ k ≤ 0.04 W/mK).

thermal conductivity increases with moisture

increasing content (from 37 to 55 mW/mK for

a moisture increase from 0% to 10%).



Mineral Wool

133

Made from small spheres of polystyrene (from crude

oil) containing an expansion agent.

Casted as boards or continuously on production line.

Partly open pore structure.

Typical thermal conductivity values are between 30

and 40 mW/mK (0.03 W/mK ≤ k ≤ 0.04

W/mK).


increasing content (from 36 to 54 mW/mK for a

moisture increase from 0% to 10%).



Expanded polystyrene (EPS)

134

produced from melted polystyrene (from crude

oil) by adding an expansion gas (e.g HFC,

CO2, C6H12).

Produced in continuous lengths which are cut

after cooling on a production line.

closed pore structure

showing relatively high resistance to humidity

(especially compared to EPS).



Extruded polystyrene (XPS)

135

Installed on roofs and wall parts which are in

contact with the ground.


between 30 and 40 mW/mK (0.03 W/mK ≤ k ≤

0.04 W/mK).






Extruded polystyrene (XPS)

136

Manufactured from recycled paper or wood

fibre mass.

Production process gives the material a

consistence similar to wool.

Boric acid (H3BO3) and borax (sodium

borates) are added to improve product

properties.

Produced mainly as a filler material but boards

and mats are also produced.



Cellulose – polysaccharide (C6H10O5)n

137

Typically installed by blowing in cavities and

frame houses.



0.05 W/mK).







138

Made primarily by cork oak

Produced both as a filler material, as well as

boards.



0.05 W/mK).

Exhibits also good acoustic properties for

sound insulation.




139

Formed by reaction between isocyanates and

polyols (alcohol containing multiple hydroxyl

groups).

During the expansion process the closed

pores are filled with an expansion gas (HFC,

CO2, C6H12).

Usually produced as boards, sandwich panels

or in the form of an expansion.



Polyurethane (PUR)

140

Used in external thermal insulation or most commonly

in the form of an expansion foam on site to insulate

difficult to reach cavities, frame houses, etc.

Typical thermal conductivity values are between 20

and 30 mW/mK (0.02 W/mK ≤ k ≤ 0.03 W/mK).

thermal conductivity varies with temperature,

moisture and mass density.

e.g. increases with moisture increasing content (from

25 to 46 mW/mK for a moisture increase from 0% to

10%).



Polyurethane (PUR)

141

safe in its intended use but raises serious

health concerns and hazards in case of fire

during burning phase, PUR releases

hydrogen cyanide (HCN) and isocyanates,

which are highly toxic and very poisonous,

and can prevent cellular respiration



Polyurethane (PUR)

142

Material Thermal

conductivity

k (W/mK)

Resistance

to heat

Resistance

to fire

Moisture

permeability

aging Resistance to

parasites

Mineral wool 0.03-0.04 Excellent Excellent High Excellent Excellent

EPS 0.03-0.04 Good Poor High Excellent Vulnerable to

rats

XPS 0.03-0.04 Good Poor Medium Excellent Vulnerable to

rats

Cork 0.04-0.05 Good Poor High Excellent Vulnerable to

rats

Polyurethane 0.02-0.03 Medium Poor Small Excellent Excellent

Cellulose 0.04-0.05 Medium Poor High Good Vulnerable to

rats and insects



Typical properties overview

143

+ Relatively cheap and easy to handle

+ Can be perforated, cut or adjusted on construction

site without any loss of thermal resistance or other

physical properties

- Susceptible to moisture and temperature fluctuations

(thermal properties worsen with moisture penetration

and temperature increase)

- Thermal properties deteriorating with aging

- Requirement for increased insulation material

thickness to achieve low U-values



Pros and Cons

144 Thermal Insulation Materials

Market Evolution (1)

146

Building

Structural

Elements

EnEV 2007 EnEV 2009 Tightening

(%) Umax (W/m2K)

External Walls

(external

insulation)

0.35 0.24 31

External

Windows,

French Windows

1.7 1.30 24

Slabs, roofs and

inclined roofs

0.30 0.24 20

Cellar Slabs

(cold-sided

cladding)

0.40 0.30 25



Evolution of Energy Saving Ordinance (EnEV) in Germany

147

Equivalent insulation effect

10x less thickness

Direct comparison of a traditional insulating

material versus a Vacuum Insulation Panel (VIP)



148

Consisting of an open porous core of fumed

silica, enveloped in several metallized polymer

layers (single, double or triple layer structure).

Manufactured primarily as boards/panels.


State of the art building thermal insulating materials (1)

Vacuum Insulation Panels (VIPs)

149

Typical thermal conductivity values are between 3 and 4

mW/mK (0.003 W/mK ≤ k ≤ 0.004 W/mK).

Due to the VIP’s material core nature of an open porous

structure, they are susceptible to:

Cuts, punctures and other external induced wear (thermal

conductivity can rise up to five times – 20 mW/mK in such

cases).

Moisture and air penetration from the envelope layer to the

core material (thermal conductivity can double after 25 years

reaching values up to 8 mW/mK).




150

As a result, VIPs cannot be cut or adjusted on site and their thermal

properties worsen with age.




151

Similar structure to VIP.

Constructed by a barrier foil and an internal

baffle structure where a gas (e.g. Argon – Ar,

Krypton – Kr or Xenon - Xe) less thermally

conductive than air is applied.

Typical theoretical thermal conductivity values

are less than 10 mW/mK (k ≤ 0.01 W/mK),

even though prototype GFPs measured

exhibit thermal conductivities of up to 40

mW/mK.



Gas-filled Panels (GFP)

152

Compared to VIP, they exhibit a higher

thermal conductivity but have an advantage

on the fact that due to the presence of the

filling gas do not have to maintain a vacuum,

thus making them less susceptible to moisture

and air penetration.

Additionally, low emissivity surfaces inside the

GFP reduce radiative heat transfer.

Similarly to VIP, they are vulnerable to cuts,

punctures and other external induced wear.



Gas-filled Panels (GFP)

153

They are practically dried gels with very high

porosity.

Synthesized by traditional low-temperature sol-

gel chemistry.

Most commonly used material is silica.

Synthesis and gel preparation: silica solid

nanoparticles, dispersed in a liquid,

agglomerate together to form a continuous 3D-

network. Then, by drying out the gel, the solid

framework is isolated from its liquid medium.



Aerogels

154

Theoretical thermal conductivity values can reach as low as 4 mW/mK

(k ~ 0.004 W/mK) at a pressure of 50 mbar.

Currently, commercially available

state-of-the-art aerogels have been

reported to achieve thermal

conductivities in the range of 13-14

mW/mK .

They exhibit high compression

strength but are very fragile due to

very low tensile strength.



Aerogels

155

Aerogels exhibit a very high

resistance to fire and heat.

Matches on top of an aerogel cylindrical

disc are protected from the beneath lit

fire.



Aerogels

156

They can be produced as either opaque, translucent or transparent

materials, thus exhibiting a great variety of potential building applications.



Aerogels



Aerogels

158

Reflective materials and radiant barriers are materials used to reduce

the transport of energy across air spaces in a building envelope.

They include surfaces with low emittance and high reflectance in the

thermal spectrum 2-50 μm (i.e. near infra red and mid infra red).

Reflective insulation systems are characterized by having enclosed air

spaces adjacent to low-emittance surfaces.

Radiant barrier systems are associated with large ventilated or

unventilated spaces.

Reflective insulation materials usually consist of one or more aluminum

foils or metallized aluminum films bound to substrates.



Reflective Materials & Radiant Barriers

159

Radiant barrier materials are most commonly single sheet materials

consisting of aluminum foils or film bonded to reinforced plastic or paper

or in some cases wood sheathing.

Reflective insulation materials usually consist of one or more aluminum

foils or metallized aluminum films bound to substrates.

Aluminum products are relatively cheap and can exhibit emittance factors

as low as 0.03.

The performance of radiant barriers and reflective materials is based on a

reduction in heat transfer by radiation between hot and cold surfaces.




160

If surface one is hot and surface 2 is cold, then the net radiative transfer Q12 is

given by the following equation:

The net radiative transfer between parallel surfaces

depends on the temperatures of the surfaces, the

emittances of the surfaces and the orientation of the

surfaces.

For large parallel surfaces (such as the applications of reflective insulation

systems in building envelopes) with emittances ε1 and ε2 F12 is given by

equation:




161

Ιn building applications the temperature differences (T1-T2) are relatively small

with the result that the radiative heat flux Q12/A can be approximated as

follows:

The heat flux for the convection-convection term is represented by hc with the

resulting total heat flux being the sum of the two terms as shown below:




162

A combination of the former equation with the definition of R-value gives an

expression for the equivalent thermal resistance of the enclosed air space:

The term hc depends on the heat flow direction since it includes buoyance

driven free convection. Thus, it can be derived that reflective materials and

radiant barriers thermal insulation performance is orientation based.




163

It can also be observed that, since R-value is inversely proportional to E, the

lower the value of E the higher the value of the thermal insulation system’s

resistance R.

Thus, the lower the emittance factor of the reflective surface (the higher E

becomes), the higher the value of the thermal insulation system’s resistance R.




164

Reflective materials and radiant barriers are met in single or double brick walls

insulation systems, or used for thermal insulation of roofs or floors. Other

applications include roof solar reflectance coatings to reduce building thermal

gains in hot climates.




165

The main property of phase change materials is the storage of heat

energy in a latent form, leading to greater heat storage capacity per

unit volume than that of conventional building materials.

They are not really considered to be insulating materials (but they are

similarly applied in structure surfaces – walls, roofs, etc.).

They provide solutions especially in buildings with low thermal mass

due to extensive use of light-weight materials (thermal energy storage

in buildings seems to provide better thermal comfort for occupants).

PCMs change phase from solid state to liquid when heated, thus

absorbing energy in the endothermic process.




166

When the ambient temperature drops again, the liquid PCMs will turn

into solid state materials again while giving off the earlier absorbed heat

in the exothermic process.

Such a phase change cycle stabilizes the indoor building temperature,

cuts-off peak cooling loads and decreases the heating loads.

Desired properties (thermal, physical, kinetic & chemical) of PCMs:

From a thermal point of view, a suitable phase change temperature range

(melting temperature), a high latent heat of fusion (melting enthalpy) and a

good heat transfer towards the PCM are desired. The desired phase

change temperature will depend on climatic conditions and the desired

comfort temperature.




167

From a physical point of view, a favourable phase equilibrium, i.e. no phase

segregation, a high density and small volume changes at the phase

change are desired for easy incorporation in existing building materials or

structures.

From a kinetic point of view, no supercooling and a sufficient crystallization

rate are desired to make optimal use of the properties and possibilities of

PCMs. Supercooling, i.e. the process of lowering the temperature of a

liquid below its freezing point without becoming a solid, could strongly

affect the performance of the PCMs based on the chosen suitable phase

change temperature by influencing this temperature.




168

From a chemical point of view, a long-term chemical stability of the PCM

despite cycling, compatibility with construction materials, non-toxicity and

no fire hazard is desired.




169

PCM categories:

Organic compounds:

o Paraffins.

o Non-paraffins.

Inorganic compounds.

Inorganic eutectics or

eutectic mixtures.




170

+ Very low thermal conductivity values resulting in ultra low

requirement in insulating material thickness

+ Substantial space saving which can make them financially

profitable in areas of very high cost-sale value/m2.

- Thermal properties deteriorating with aging (even though

much less compared to traditional insulating materials)

- Very expensive at the moment

- Vulnerable to cuts, punctures and/or other external induced

wear, thus cannot be perforated or adjusted on construction

site without major loss of thermal properties



Pros and Cons

171

Nanotechnology is expected to be applied as a scientific tool to make high

performance thermal insulation materials. Even though the normal focus in

nanotechnology is to control matter (typical particles, of dimensions between

0.1 nm and 100 nm, i.e. at an atomic and molecular scale), in the case of

thermal insulation materials, the focus is shifted from particles to controlling

pores in the nano range.


Future building thermal insulating materials (1)

Employing Nanotechnology

172

As an advancement to VIPs, VIM is basically a homogenous material

with a closed small pore structure filled with vacuum, with an overall

thermal conductivity of less than 4 mW/mK in pristine condition.

Due to its nanostructure nature, it is not susceptible to moisture and air

infiltration to the nanopores, thus it will present excellent ageing

characteristics.




173

The VIM can be cut and adapted at the building site with no loss of low

thermal conductivity.

Perforating the VIM with a nail or similar would only result in a local

heat bridge, i.e. no loss of low thermal conductivity.




174

As an advancement to GFPs, GIM is basically a homogenous material

with a closed small pore structure filled with a low conductance gas

(e.g. Argon – Ar, Krypton – Kr or Xenon - Xe), with an overall thermal

conductivity of less than 4 mW/mK in pristine condition.

Due to its nanostructure nature, it is not susceptible to moisture and air

infiltration to the nanopores, thus it will present excellent ageing

characteristics.

Similar to the VIM, with the only difference being that the vacuum is

replaced by a low-conductance gas.



Gas Insulation Materials (GIM)

175

Originating from the idea of VIP and VIM, NIM is basically a

homogenous material with a closed or open small pore structure, with

an overall thermal conductivity of less than 4 mW/mK in pristine

condition.

unlike VIMs and GIMs, the grid structure in NIMs do not need to

prevent air and moisture penetration into their pore structure during

their service life (greater than 100 years). NIMs achieve their low

thermal conductivity without applying a vacuum in the pores by utilizing

the Knudsen effect. The gas thermal conductivity λgas taking into

account the Knudsen effect may be written in a simplified way as:



Nano-Insulation Materials (NIM)

176

λgas=gas thermal conductivity in the pores (W/(mK))

λgas,0=gas thermal conductivity in the pores at STP

(standard temperature and pressure) (W/(mK))

β=coefficient characterizing the molecule–wall

collision energy transfer efficiency (between 1.5

and 2.0)

kB = Boltzmann's constant ≈ 1.38 × 10−23 J/K

T=temperature (K)

d=gas molecule collision diameter (m)

p=gas pressure in pores (Pa)

δ=characteristic pore diameter (m)

σmean=mean free path of gas molecules (m)




177

These result that the smaller the pores diameter, the lower is the value

λ of the NIM thermal conductivity.

Since NIMs are not affected by moisture or air infiltration to the nano-

pores, they are expected to present excellent ageing characteristics.




178

A dynamic insulation material (DIM) is a material where the thermal

conductivity can be controlled within a desirable range. One can control

thermal conductivity by being able to change in a controlled manner:

The inner pore gas content or concentration including the mean free path

of the gas molecules and the gas-surface interaction.

The emissivity of the inner surfaces of the pores.

The solid state thermal conductivity of the lattice.




179

DIMs can provide solution to thermal insulation issues in southern

climates where a very low (as low as possible depending purely on

economical aspects) U-value is required to minimize thermal losses

during winter time but, on the other hand, a significantly higher U-value

is required as optimal insulation level to minimize cooling load demand

(it has been observed that ultra-low U-values can have reverse effects

on cooling demand and the corresponding seasonal energy

consumption – for Cyprus a U-value close to 0.3-0.4 W/mK is

considered to be at optimal insulation level regarding cooling demand).




180

Advantages

Minimization of thermal bridging.

Taking full advantage of wall’s thermal mass.

Conditioned space remains heated/cooled substantial time after

switching off the heating/cooling system.

Protection of envelope structural elements from contraction and

expansion due to temperature differences.

Buffering sudden temperature changes and load peaks.

Disadvantages

Increased installation cost.

Susceptible to installation errors.

Difficulties in application in buildings with non uniform exterior

shape design.


Thermal insulation Construction Techniques (1)

External insulation in both walls and beams/columns

181

Advantages

Simple and fast construction.

lower costs.

Protection of insulation materials from external

environment (rain, solar radiation, heat, etc.).

Immediate response of heating/cooling system.

Disadvantages

Reduces conditioned space area.

Quick cooling/heating of conditioned space after switching

off the heating/cooling system.

Possible moisture problems.



Internal insulation in both walls, beams/columns and roof

182

Double brick wall with thermal insulation in

between two layers and external insulation in

beams/columns

Thermal bridge on the joint of wall and pier.

Part of wall’s thermal mass is not utilized.

Thermal insulation interruption

Thermal bridge on the balcony projection where

thermal insulation is interrupted.



Combination/Other

183

Alam, M., Singh, H. and Limbachiya, M.C., 2011. Vacuum Insulation Panels (VIPs) for

building construction industry – A review of the contemporary developments and future

directions. Applied Energy V.88(11), pp. 3592-3602.

Beatens, R., Jelle, B.P., Thue, J.V., Tenpierlk, M.J., Grynning, S., Uvslokk, S. and

Gustavsen, A., 2010. Vacuum insulation panels for building applications: A review and

beyond. Energy and Buildings V.42(2), pp.147-172.

Beatens, R., Jelle, B.P. and Gustavsen, A., 2010. Phase change materials for building

applications: A state-of-the-art review. Energy and Buildings V.42(9), pp.1361-1368.

Beatens, R., Jelle, B.P., Gustavsen, A. and Grynning, S., 2010. Gas-filled panels for

building applications: A state-of-the-art review. Energy and Buildings V.42(11), pp.1969-

1975.

Beatens, R., Jelle, B.P. and Gustavsen, A., 2011. Aerogel insulation for building

applications: A state-of-the-art review. Energy and Buildings V.43(4), pp.761-769.


Bibliography (1)

184

Escudero, C., Martin, K., Erkoreka, A., Flores, I. and Sala J.M., 2013. Experimental

thermal characterization of radiant barriers for building insulation. Energy and Buildings

59, pp. 62-72.

Hall Matthew R., 2010. Materials for energy efficiency and thermal comfort in buildigs.

Woodhead Publishing (United Kingdom).

Jelle, B.P., 2011. Traditional, state-of-the-art and future thermal building insulation

materials and solutions – Properties, requirements and possibilities. Energy and

Buildings V.43(10), pp.2549-2563.

Papadopoulos, A.M., 2005. State of the art in thermal insulation materials and aims for

future developments. Energy and Buildings V.37(1), pp.77-86.

Papadopoulos, A.M., Oxizidis, S. and Papathanasiou, L., 2008. Developing a new library

of materials and structural elements for the simulative evaluation of buildings’ energy

performance. Building and Environment V.43(5), pp.710-719.


Bibliography (2)


Session 5.0

HVAC

186

Some years ago, people had to rely only on their clothing for their thermal

comfort. Today however, people rely on the building environment and the

mechanical systems for this comfort.

HVAC

The Need (1)

187

HVAC

The Need (2)

Under normal condition the human internal body temperature is around

36.6oC, while changes ranging from 36.1oC to 37.3oC are considered

normal. The outside body temperature is around 33oC.

188

HVAC

The Need (3)

189

The body mechanisms that are employed to reject heat are :

1. By Radiation (40–50%). Thermal energy from the body surface

temperature is radiated to the surrounding.

2. By conduction (2-3%). This mechanism takes into account the loss/gain of

energy that is transferred to/by the human body by its direct contact with

other surrounding bodies.

3. By convection (25-30%). The air that is coming in contact with the body

may absorb/add heat. This process depends largely on the velocity of air,

the temperature of the air and the clothing.

4. The evaporation (25-30%). This is the only active mechanism that the

body employs in order to reject heat. On average a human body may

reject around 700W of thermal energy by this mechanism.

HVAC

The Need (4)

190

The parameters which affect the thermal comfort in a space/room and can

be adjusted by and HVAC system are:

The surrounding air temperature.

The radiation temperature of the surrounding surfaces.

The humidity of the space.

The air movement in the space (velocity).

The human metabolism and activity.

The clothing.

HVAC

The Need (5)

191

Human Metabolism

(Source: ASHRAE Handbook of Fundamentals 2009)

*1 met = 58,1 W/m2

Activity W/m2 met*

Resting

sleeping 40 0.7

laying 45 0.8

Sitting 60 1

Standing 70 1.2

Walking on leveled surface

0,9 m/s 115 2.0

1,34 m/s 150 2.6

1,79 m/s 220 3.8

Office activity

Reading) 55 1.0

Writing 60 1.0

Typing 65 1.1

Filing/Archiving (sitting person) 70 1.2

Filing/Archiving (standing person) 80 1.4

Walking 100 1.7

shelving 120 2.1

Driving

Car 60 - 115 1.0 – 2.0

Airplane 70 1.2

Airplane-landing 105 1.8

Airplane-military 140 2.4

Heavy Vehicle 185 3.2

Professional Activity

Coking 90 - 115 1.6 – 2.0

House cleaning 115 - 200 2.0 – 3.4

Sawing 105 1.8

Light industry 115 - 140 2.0 – 2.4

Heavy industry 235 4.0

Free time activity

Dancing 140 - 255 2.4 – 4.4

Gymnastics 175 – 235 3.0 – 4.0

Tennis 210 - 270 3.6 – 4.0

Basket ball 290 - 440 5.0 – 7.6

Wrestling 410 - 505 7.0 – 8.7

HVAC

The Need (6)

192

The surface of the human body (AD) can be estimated by the so called

DuBois equation as :

AD = the body surface, m2

w = the body mass, kg

h = the height of the human, m

HVAC

The Need (7)

193

Recommended design temperatures for winter

Category Temperature (oC) Rel Humidity(%)

Residences 22 30-50

Office Buildings 21-23 30-35

Libraries-museums 20-22 40-50

Hospitals 24 30

Restaurants and similar place 21-23 30-40

Recommended design temperatures for summer

Category Temperature (oC) Rel Humidity (%)

Residences 25-26 40-50

Office Buildings 25-26 40-50

Libraries-museums 22 40-55

Εστιατόρια, κέντρα διασκέδασης 23-26 50-60

Hospitals

- Rooms 24 45-50

- Operating theater 20-24 50-60

- Patient rooms 24 50-60

HVAC

The Need (8)

194

The heat rejection by the human body is achieved in part by skin

evaporation. At temperatures of 20 to 22C, this heat is rather small. At this

temperature level and relative humidity less than 30% (static electricity is

generated and the throat gets dry) while at the upper limit of 70% odors are

easily generated (very unpleasant) and mould is formed.

If the temperature is higher, the humidity levels are getting very important

as the evaporation from the skin is getting higher. It is very important to

avoid situations that prohibit the evaporation from the human skin. At the

level of 24 to 26°C the levels of the relative humidity can be within the

40% to 60%. According to ASHRAE, the relative humidity should never get

outside the region of 30% - 70%.

HVAC

The Need (9)

195

For thermal comfort, the value of the speed of air within the room is very

important. The range of this speed is between 0,1 and 1 m/s. If the speed is

less than 0.1m/s then this indicates a natural non-forced circulation.

HVAC

The Need (10)

196

Air Temperature (oC)

Air

velo

cit

y in

(m

/s)

sensitive

body areas

General

HVAC

The Need (11)

197

Recommended values of air velocities for interior areas.

(ΤΟΤΕΕ 2423/86)

Velocity

(m/s) Effect Rec. Use

0-0.08 Complains about stagnant air none

0.125 Ideal Condition For all

applications

0.125-0.25

Very satisfactory, but the upper

limit approaches the maximum

recommended. (especially for

sitting persons)

For all

applications

0.325

Unsatisfactory for office space.

The air may remove light material

from the room and desks Commercial

spaces 0.375

Maximum Recommended for

moving people in the room.

0.373-1.5 Allowed only for industrial places * The above velocities refer to moving-working areas and up to the height of 2 m from

the floor.

HVAC

The Need (12)

198

“clo” values, depending on the clothing used

Clothing type (category) Clo

Naked 0

With shorts 0.1

Light clothing (for tropical areas) 0.3

Light summer clothing 0.5

Light summer -working clothing 0.6

Heavy winter clothing 1.2

Winter -working clothing 1.0

Clothing for the artic 3-4

Practically as heavy as possible 5

HVAC

The Need (13)

199

Thermal comfort in a room or a place depends on a number of parameters.

There have been efforts to combine those parameters into a single thermal

one either for commercial purposes or just to make our life easier.

So, in the past a number of those “combined parameters” have been

developed.

HVAC

The Need (14)

200

The globe temperature ranges between the dry bulb of the air and the

mean radiation temperature of the air in the room. This can be calculated

by the following equation:

tg = Globe temperature(oC)

tr = mean radiation temperature (oC)

ta = dry bulb temperature(oC)

V = velocity of air, m/s

HVAC

The Need (15)

The Globe temperature (spherical thermometer temperature) , tg

201

Effective temperature (ΕΤ), is the combination of the moisture, dry bulb

temperature and velocity of air in a room resulting in a single value. This

value is the older one developed and is based on the experimental work of

YAGLOU. This value does not take into account the radiation and a new

version called CET- Corrected Effective Temperature is usually used.

HVAC

The Need (16)

Effective Temperature, ET

202

This indicator was first used in 1935 by Missenard. Today is used in two

different variations, the first with the dry bulb and the second by wet bulb

temperatures. It takes into account the air temperature, the radiation, the

velocity of the surrounding air (the second takes into account the moisture as

well). The measurement of the dry resultant temperature is done by using a

special thermometer which consists of a black cooper sphere, 0.2mm thick and

of 10cm diameter. In the center, the bulb of a mercury thermometer is

measuring the particular temperature.

HVAC

The Need (17)

Resultant Temperature, tres

203

tg = temperature of spherical thermometer (oC)

tr = mean radiant temperature (oC)

ta = dry bulb temperature (resultant temperature)

v = velocity of air, m/s

When the air velocity is 0,1 m/s, then :

The resultant temperature (tres), can be used as a very good indicator of the

thermal comfort “for the whole body” in most heated spaces. The following

criteria can be used for people with normal clothing, in office work, and where

the thermal convection and radiation is around 65W ~ 83 W. Under the above

condition the criteria of the resultant temperature are:

19 oC ≤ tres ≤ 23 oC

Air velocity ≤ 0,1 m/s

Relative humidity 40% to 70%.

HVAC

The Need (17)

Resultant Temperature, tres

204

Thermal comfort is a very objective term and very difficult to measure. Various

studies however have shown that “thermally comfortable” environment is one

where 90% of the people in it feel comfortably. With tis assumption in mind a new

indicator was established, known as comfort temperature, tcomf. To calculate this

indicator, one takes into account the temperature of the surrounding air, the mean

radiant temperature, the humidity and the velocity of air.

ta = dry bulb temperature(oC)

tr = mean radiant temperature(oC)

v = velocity of air (m/s)

φ = relative humidity (%)

The above equation is valid provited:

tcomf : 21 – 24 oC

ta - tr : 3 Κ

v : 0 – 0.25 m/s

φ : 35 – 75%

HVAC

The Need (18)

Comfort Temperature, tcomf

205

As humans use different clothing to accommodate for the seasonal changes

and their personal activities, ASHRAE developed ASHRAE 55 which defines

the “zones of thermal comfort” for people dressed in typical summer or winter

clothing and sitting activity. This is shown in the following diagram.

HVAC

The Need (19)

Thermal Comfort Chart - ASHRAE

206

The operative temperature, top is the combination of the temperature of the

surrounding air, the mean radiant temperature and their respective convection

coefficients.

hc = clothing convection coefficient, W/m2K

hr = coefficient of the linear heat radiated by the clothing, W/m2K

tr = mean radiant temperature, oC

ta = dry bulb temperature of the surrounding air, oC.

HVAC

The Need (20)

207

The value of the coefficient hr ranges between 3.1 και 5.1 W/m2K depending

on the air velocity and the human activity, while the value of hc for room

conditions is 4.7 W/m2K. For a more precise calculation of the values

ASHARE suggests various values depending on the velocity of air and the

person's’ activity.

HVAC

The Need (21)

208

In a room with a large glass window the air temperature is 23oC, the mean

radiation temperature is 27oC, the velocity of the air 0.15 m/s and the relative

humidity 50%. Calculate the operational temperature of the room and check for

the thermal comfort conditions.

From the ASHRAE thermal comfort chart we observe that for operative

temperature of 24.8 oC and relative humidity 50% the room is within the zone of

thermal comfort. For the winter season however this zone is barely within the

comfort limits.

HVAC

The Need (22)

Example


Session 5.1

Heating and Cooling

210

Buildings and rooms receive sensible heat in the summer and loose sensible

heat in the winter. This obvious result is due to the air movement and

radiation. They can also gain or loose latent heat due to moisture. Energy can

also be due to human activity and devices within the building/room. Lighting

can only produce sensible heat in a room/space.

HVAC

The Need

211

Cooling load is defined as the quantity of heat that has to be removed from a

building in order to keep the various rooms/spaces under certain temperature

and humidity levels (other parameter may also be selected). The difference

between the term “gain” and load is the heat that is entering the building. The

load of the building is what usually need to be removed by an HVAC system

in order to keep the space/room under the pre-defined conditions. Cooling

load are measure in units of power, i.e. W.

HVAC

Cooling Load

212

Internal Thermal Gains

The main sources of internal thermal gains are the lighting, the people, and

possible devices that operate within the space to be conditioned.

Lighting

Usually lighting is the main source of internal thermal gains within a space.

Part of the energy used to provide lighting is in the form of radiation.

Florescence lights are considered to provide 59% of their rated power as

radiation and the rest as thermal load, while the usual tungsten type lighting

typically provides 80% radiation and 20% as thermal.

HVAC

Thermal Load

213

The instantaneous rate of thermal gain by electrical lighting can be estimated

as :

W = the total installed lighting power, W

Fu = coefficient of use

Fs = coefficient of special addition (if

fluorescent and halogen lights are

used)

HVAC

Thermal Load

214

The thermal gains due to the tenants has two basic elements. The so called

sensible and the latent. The total amount of heat gains is directly related with the

activity of the tenants. Special attention is required in designing a system and the

thermal gains as the places are getting populated. In places such as theaters,

museums, amphitheaters, is always reasonable to design for more people than

the full capacity of the space.

The sensible thermal gain is calculated by the following equation:

N = maximum number of people in a room

Fu = coefficient of use (unique for a specific space)

HVAC

Thermal Load

Tenants

215

If there is equipment driven by an electrical motor within the space to be air

conditioned then an equivalent thermal power is taken into account in the

calculation of the required cooling load.

HVAC

Thermal Load

Electrical Devices

216

Generally the solar gains depend on the characteristics of the building

surfaces and the direction of the sun’s radiation. To fully define this reality one

needs to take a look at the basic parameters that relate the sun’s radiation in

relation to the building’s position. The basic parameters are

The position of the building on the earth’s surface.

The date of year.

The time of date.

HVAC

Thermal Load

Solar gain thru transparent surfaces

217

General Geometry of the falling Sun radiation: αs = solar altitude angle, γs = solar azimuth angle, β = surface angle 0≤β≤0

0 180

HVAC

Thermal Load

γ = surface azimuth, θ = angle of incidence: the angle of the radiation to the perpendicular to the surface,, θz = the zenith

angle of the sun (=the angle between the rays and the perpendicular to the horizontal level (source: Duffie & Beckman).

218

Declination (δ) Approximate dates

+23o 27’ June 22

+20o May 21, July 24

+15o May 1, August 12

+10 o April 16, August 28

+5 o April 3, September 10

0 March 21, September 23

-5 o March 8, October 10

-10 o February 23, October 20

-15 o February 9, November 3

-20 o January 21, November 22

HVAC

Thermal Load

219

The optical characteristic of a surface are estimated by:

τ = transmittance, the percentage of the radiation passing through the surface

ρ = reflectance, the percentage of the radiation that is reflected

α = absorptance, the percentage of the radiation that is absorbed.

HVAC

Thermal Load

220

The value of each one of the above parameters changes significantly the solar

thermal gain. For transparent surfaces, such as the window in the drawing, the

solar energy that penetrates thru the surface , in Watts, can be calculated as:

It = solar radiation, W/m2

N = percentage of the absorbed radiation that was transferred with conduction and radiation to the

room interior.

HVAC

Thermal Load

221

Under equilibrium conditions N = U/ho, where ho is the convection coefficient of

the external side of the wall in W/m2 K. Thus the equation becomes:

HVAC

Thermal Load

222

This coefficient is used to accommodate for the values of SHGF for other kinds

of glass or take into account the shading due to a shading device.

HVAC

Thermal Load

Shading coefficient, SC

223

Type of glass

Glass

thickness

(mm)

Coefficient of Shading

No

external

shading

Viennese Rollers

Medium Light colored Dark colored Light colored

Single glass

- clear 3 1.00 0.64 0.55 0.59 0.25

- clear 6-12 0.95 0.64 0.55 0.59 0.25

- Heat absorbent

6 0.70 0.57 0.53 0.40 0.30

10 0.50 0.54 0.52 0.40 0.28

Double

- clear 3 0.90 0.57 0.51 0.60 0.25

- clear 6 0.83 0.57 0.51 0.60 0.25

-Reflective 6 0.2-0.4 0.2-0.33 - - -

HVAC

Thermal Load

224

The solar radiation that passes thru the window is:

HVAC

Thermal Load

225

Calculate the position of the sun (angles) in relation to a building in Limassol

at 14.00 on Oct 20th, based on the sun path diagram shown before.

HVAC

Thermal Load

Example

226

Limassol’s position is at a width of 35ο and we can use the previously

presented diagram. From the table we can estimate that the angle

(declination) on Oct 20 is -10ο. The exact location of the sun can then be

estimated on the common point which is:

- Solar angle αs = 38ο

- Azimuth γs = 218ο or 38ο SW.

HVAC

Thermal Load

Example

227 HVAC

Thermal Load

Example

228

Heating is the process of adding heat to the surrounding air of a space for the purpose of increasing its temperature or keep its temperature at certain levels.

Cooling is the process of removing heat from the surrounding air of a space for the purpose of lowering its temperature or keep its temperature at certain levels.

Humidification is the process of the addition of moisture to the surrounding air of a space for the purpose of increasing the relative humidity or keeping it at certain level.

Dehumidification is the process of removing moisture from the surrounding air of a space for the purpose reducing its relative humidity or keeping it at certain level.

Renewal is the process of getting fresh air and damping quantities of internal air of a space for the purpose of increasing or keeping the quality of air at certain levels.

Cleaning is the process of removing solid particles and biological molecules from the air, for the purpose of increasing or keeping the quality of air at certain levels.

HVAC

Thermal Load


Session 5.2

Heating and Cooling Systems

230

Air Conditioned

space


HVAC – Basic Unit

231

In these systems the air is conditioned in the central unit and then brought via ducts to the rooms/spaces to be conditioned. The necessary external air is brought into the system and mixed into a mixing chamber with the returning filtered air. Subsequently, the air returns to the rooms/spaces filtered, conditioned and with a percentage of fresh air.


HVAC – Systems (1)

Systems with air

232

These systems provide conditioned air and water at the supply points. These systems require thus, a dual system consisting of a separate air and a separate water systems, operating in parallel.



Systems of air and water

233

These systems control the air temperature thru devices in which cold/hot water is passed. These devices include fans which force the air to pass thru the cold/hot water exchanger and the room environment is kept at a required set temperature. There is no central air conditioning in those systems and the supply of fresh air is a separate system by itself.



Systems with water only

234

These systems are totally independent systems which use cooling media to cool/heat the surrounding air. They are of two types self contained and split units.

Larger systems with a central control unit and several distribution units are can also be found in the market today.

All the units can offer cooling and heating by reversing the their cycle operating thus as a refrigerator (cooling) and as a heat pump (reversed cycle).



Independent systems

235

ΗS = The sensible heat gain that needs to be removed from a space/room

ΗL = The latent heat gain that needs to be removed from a space/room

ΗΤ = The total heat load that that needs to be removed from a space/room



Room condition line

The room condition line is a straight line on a psychrometric chart which

connects the points that represent the initial air conditions and the conditions

under air treatment. The slope of this line is an indicator called factor of

sensible heat (SHF) and is defined as :

236



237 Heating and Cooling Systems


Air Conditioned

space

Mixing

chamber

Filter

Heating

Unit Heating

Unit

Adiabatic

spray

Fan

238

(1) Conditioned air, (2) Recycled air, (3) Fresh Air, (2)+(3) mixture of fresh and recycled (4), (4)(5) cooling

and dehumidification, (5)(6) sensible heating process, (6)(1) Air heating due to thermal gains (ducts,

fans etc.), (Α) apparatus dew point temperature, ADP.


HVAC – Typical Summer Condition (1)

239

Point (5), i.e. the condition of the exiting air id due to:

apparatus dew point , ADP (point Α) , and

The by-pass factor, B.F of the cooling unit which is calculated by:


HVAC – Typical Summer Condition (2)

240


HVAC – Typical Winter Condition (1)

Winter Time Air Conditioning Process

During the winter time, some of the thermal losses are recovered by the solar

radiation and the special internal thermal gains (persons present, lighting,

heat generating devices etc.). The main thermal gains are actually due to the

people in the room while the specific humidity of the outside air is usually low

(the relative humidity can be high).

241

(1) Entering air, (2) recycled air, (3) fresh air, (4) mixture of fresh and recycled air (5) preheated air, (6) exiting from spray chamber air, (7) heated air.

Air Conditioned

space

Mixing

chamber

Filter

Heating

Unit Heating

Unit

Adiabatic

spray

Fan



242



The respective processes of the typical winter air conditioning on a

psychrometric chart are shown below.


Session 5.3

HVAC - Air Supply Systems

244 HVAC - Air Supply Systems

Systems of Constant Air Supply

The main systems of constant air supply are:

i. one circuit system of constant air supply.

ii. system of constant air supply with after-heating.

iii. two circuit system of constant air supply.

iv. multi circuit system of constant air supply.

245

Single Circuit constant air supply system


Air Conditioned

space

Mixing

chamber

Filter

Heating

Unit Heating

Unit

Adiabatic

spray

Fan

246

Central Air Conditioning Unit

Air Conditioned spaces

Fresh Air

Damped air

Filters

Cold Water in Hot Water in

Returning Air


Internal

space Internal

space

Constant air supply system with after-heater

247

Mixing

chamber Fresh

Air

Returning Air

Hot Air Duct

Cold Air Duct

Humidifier Fan

Fan

Cooling

Unit

Heating

Unit

Filter

Zone 1 Zone 3 Zone 3


Dual-duct system (1)

248

The dual duct systems are usually the choice for hotels, office buildings,

hospitals, schools and laboratories. The common characteristic of these

buildings is the large variation in the sensible heat load. With the

simultaneous supply of both hot and cold air in every supply unit this system

offers flexibility and instantaneous response to any demand.


Dual-duct system (2)

249

Cooling

Unit

Heating

Unit Fan

Pre-cooling /

Pre-heating

Unit

Filter

Mixing

chamber

Fan

Returning Air

Zone A

Zone B

Zone C

Fresh Air


Multi-circuit system of constant air supply

250

Cooling load Profile Cooling load Profile

Hours Hours

Load, % Load, %


Systems of variable air supply (1)

251

The main systems of variable air supply (VAV) are:

i. The single system of variable air supply.

ii. The dual system of variable air supply.

iii. The VAV system with units with embedded fan.



252

Simple system of variable air supply - VAV

Cooling

Unit

Heating

Unit

Filter

Mixing

chamber Fresh Air

Fan

Fan

Returning Air

Room A

Room B

Room C



253

Fresh Air

Damped Air

Central VAV Unit

Filter

Conditioned Spaces

Returning Air

Cold Water Hot Water



Dual system of variable air supply - VAV

Internal

space

Internal

space

Internal

space


Session 5.4

HVAC - Water Systems

255 HVAC – Water Systems

Water only systems

The Water Only system are distinguished in:

Two pipe system

Three pipe system, and

Four pipe system.

256

Fresh air

Fan

Filter

Returning air Water from Boiler/Cooler

Water to Boiler/Cooler

3-way valve

Room Thermostat

Heat Exchanger

soundproofing

HVAC – Water Systems

Two-pipe fan-coil unit (FCU)

drain

Common

cooling/

heating

Unit

257

1 Thermostat

2 Cold water valve

3 Hot water valve

4 Heater/cooler

5 Hot water inlet

6 Cold water inlet

7 Common return

diagram


Three-pipe water system (1)

258

1 Cold Water

2 Hot water

3 Thermostat

4 6-way valve

5 Cooler/Heater

6 2 or 3-way cold water valve

7 2 or 3-way hot water valve

8 Heater

9 Cooler


Three-pipe water system (2)


Session 5.5

HVAC - Mixed Systems

260

In these systems the basic operation includes the supply of cold or hot water in suitable air moving devices, located in the room to be conditioned. So, circuits of both air and water need to be erected. There are cases where the supply of air is achieved by a separate independent ducting system.

If the water system is a 3 or 4-pipe one, then the system can supply simultaneously hot and cold water to the local units, making thus feasible the instantaneous and simultaneous heating and cooling of the rooms as required.

The centrally conditioned air is brought to the units and is called primary air while the recirculated air which is re-used is called secondary air.

The main air-water systems are:

the system with Fan-coil units and central distribution of primary air, and

the system with local production.


HVAC – Air/Water Systems

Air-Water Systems

261

To other circuits

Fresh air

Returning air

Cooling unit

Heating unit



Chiller

Primary water

circuit Pump

secondary water

circuit Pump

Zone re-heating

unit

FCUs

nozzles

262



System with local units

263

This system employs an external unit (or an number of units) which can supply a number of delivery (room) units. Depending on the supplier these may be found as VRV (Variable Refrigerant Volume) or as VRF (Variable Refrigerant Flow). In both cases the system operates in a mode of variable refrigerant volume.

External

unit

Internal units

Refrigerant piping


HVAC – VRV Systems

Variable Refrigerant Volume (VRV) Systems

264

Hea

t

Reje

ctio

n

Hea

t

Su

pp

ly

Cooling



Cooling Cooling Cooling

Heating Heating Heating Heating

Cooling Cooling Heating Heating

265

The maximum power of an external unit is around 30 kW and can serve up to eight internal units of around 2,5-15 kW each. There are limitations to the maximum distance of the piping between the external unit and the internal ones and this is usually around 100m, with a maximum height difference of 50m.




Session 5.6

HVAC - Energy Recovery Systems

267

When air at a different temperature is damped in the environment, then there is room for heat recovery. When fresh air has to be supplied to a space/room then conditioned air is damped in exchange for that air. For the process of conditioning the fresh air by heating or cooling there is room for savings. These savings are usualy done by special systems called recovery systems.

HVAC – Energy Recovery Systems

Energy Recovery Systems

268

Fresh air

Damped air

Recycled

air

Supply

air

HVAC – Energy Recovery Systems


Fixed plate exchangers

1. Air supply fan

2. Water droplet collector

3. Humidifier

4. Heating Unit

5. Cooling Unit

6. Drain basin

7. Filters

8. Fresh air damper

9. Filter bags

10. Air to air heat exchanger

11. Rejected air dampers

12. Recycled air damper

13. Recycled air fan

269 HVAC – Energy Recovery Systems


Finned tube/coil exchangers

Fresh air

Damped air Recycled

air

Supply

air

1. Air supply fan

2. Water droplet collector

3. Humidifier

4. Heating Unit

5. Cooling Unit

6. Drain basin

7. Filters

8. Air to water heat exchanger

9. Recycled air fan

10. Recycled air damper


Session 5.7

HVAC - Air supply systems

271

Ventilation is the process of supplying fresh air in a space/room in order to keep the necessary conditions for comfortable living in the room/space. This supply has first to satisfy the demands for breathing/survival in the space.

These requirements dictate the following:

Removal of CO2 Removal of the all body odors, Removal of all unnecessary heat, Removal of the excess humidity, Removal of all unwanted chemicals and smoke.

HVAC – Air Supply Systems

272

Under normal resting conditions man requires 0.10 to 0.12 l/s of air, while only

5% is led to the lungs as oxygen. The inhaled air mixture has 3-4% of CO2

which represents around 0.004 l/s. The upper limit of CO2 in an inhabited

space is 0.5% (by volume) for an 8-hour exposure.


273

Activity

Minimum Requirements for Fresh Air

(l/s per person)

0.10% CO2 0.25% CO2 0.50% CO2

Resting 5.7 1,8 0.85

Light work 8.6 – 18.5 2,7 – 5,9 1.3 – 2.8

Average work - 5,9 – 9,1 2.8 – 4.2

Hard Work - 9,1 – 11,8 4.2 – 5.5

Very Hard Work - 11,8 – 14,5 5.5 – 6.8


274

The odors form the human body are necessary to be removed from a

space/room. The minimum requirement for air removal to satisfy this

requirement is 5 l/s per person, but the usual number used is around 8

l/s per person. In large audiences (restaurants, theaters etc.) is safer to

assume 10-15 l/s per person.


275

This Criterion is usually used in simple designs of ventilation. The following

table indicates the recommended (empirical) air changes depending on the

space/room usage. The amount of air required can easily be found by

multiplying the number of the table by the volume of the space/room.


Hourly air changes

276

Type of Room air changes per hour

Conference rooms 6 – 8

Operation Theaters 15 – 20

Theaters 8 - 10

Rest rooms 4 - 8

Libraries 4 – 5

Offices 4 - 8

Malls 4 – 6

Restaurants 4 - 8

Shops 6 – 8

Cinemas 4 – 6

Κολυμβητήρια 3 – 4

Kitchens

- Large 8 - 12

- average 10 - 20

- small 15 - 30

Baths 5 – 8

Bedrooms 1 - 2

Schools 3 - 6


277

Type of Building

People per 100

m2 of room

floor area

Required ventilation

(m3/h)

minimum recommended

Single House

- Sitting room, bedrooms 5 8,5 12 - 17

- Kitchens, showers - 34 50 - 85

Multi Story buildings

- Sitting room, bedrooms 7 8,5 12 - 17

- kitchens, bathrooms - 34 50 - 85

Educational Buildings

- Lecture/teaching rooms 55 17 17 - 26

- Amphitheaters 110 17 26 - 34

- Libraries 22 12 17 - 21

- Laboratories 32 17 17 - 26

Hospitals

- Operating Rooms 55 34 42 - 51

- Surgery rooms - 34 -

- Patient rooms 22 17 26 - 34

Offices

- General 10 25 25 - 42

- Computer rooms 22 8,5 12 - 17

- Drafting rooms 22 12 17 - 25

Hospitals

- Bedrooms 5 12 17 - 25

- Showers - 34 51 - 85

- Corridors 22 17 25 - 34

Museums 75 12 17 - 25

Restaurants 75 17 25 -34

Cafeterias 110 51 60

Bars 150 51 68 - 85 * For more places see ΤΟΤΕΕ 2425/86


278

This method is applicable in special places where the rate of evaporation or

rate of injection into the environment of dangerous substance takes place.

Place such as paint shops, or places where there is exhausting of gases are

common place where this method is most appropriate.

The required quantity of air V results from the following equation:

Κ = The generated quantity of dangerous substance (m3/h)

Κa = Ratio of the dangerous substance to the air intake (m3 of dangerous substance per m3 of intake

air)

MAC = maximum allowable concentration of the dangerous substance in the space/room (m3 of

substance per m3 of air)


Calculation according to air pollution

279

Substance

Molecular

weight

(Μ)

Density

(kg/m3)

Death

(mg/l)

Dangerous

if inhaled for

½ to 1h

(mg/l)

Dangerous if

inhaled for

extended

periods

(mg/l)

Detectable

(mg/l)

Maximum allowable

in working

environments (MAC)

mg/l cm3/m3

Ammonia 17,03 0,7 3,5 -

7 1,5 – 2,7 0,1 0,035 2,4 1000

Benzene 100,2 4,2 - 30 - 40 5 - 10 1,25 2,0 500

Chlorine 70,91 2,9 2,5 -

3 0,1–0,15 0,01 0,01 0,0003 0,1

CO2 44,01 1,8 360 -

550 90 - 120 20 - 30 odorless 9,0 5000

CO 28,01 1,2 6 - 12 2 - 3 0,2 odorless 0,055 50 * For more substance look at ΤΟΤΕΕ 2425/86


280

These can be found in two main categories, depending on the circulation

mode employed. The first type is the so called “natural ventilations” systems

and the second is the so called “mechanical ventilation” system.


Ventilation Systems

281

In this kind of systems the air in the room/space is changing by natural

phenomena, and mainly due to the difference in pressure between the internal

and external environment. This change in pressure can be achieved either due

to the difference in temperature or due to the difference created by the local

wind conditions.

The volumetric flow of the air qv thru the various openings (junctions) can be

found from:

V = air volumetric flow, l/s

k = coefficient of intrusion, l/s m Pan

L = length opening, m

ΔP = pressure difference between openings, Pa

n = flow power


Natural Ventilation Systems

Ventilation Systems

282

Depending on the pressure in the building and the pressure of the wind outside

the building we may have air removing from the building interior to the

environment outside. The velocity of the wind is generally accepted that is

higher at higher levels, and as buildings are getting taller, the pressure around

the buildings are getting different as well. The velocity of air (v) in z meters

above the ground can be estimated by the following equation (Faber and Kell’s):

v = the average velocity at elevation z from the ground (m/s)

vm = the average velocity of air at 10 m from the ground (m/s)

z = elevation above the ground (m)

ks = coefficient

a = power depending on the building height



Ventilation Systems

283

Building position ks a

Level ground,

outdoors

0,68 0,17

Outdoors, non level

ground

0,52 0,20

Large city area 0,35 0,25

City area 0,21 0,33



Ventilation Systems

284

A = area of openings, m²



Ventilation Systems

C = coefficient of outflow(0,65 – 0,70)

g = 9,81 m/s²

h = differential height, m

Ti = mean internal temperature, K

To = external temperature, K

285

Calculate the natural ventilation achieved due to temperature difference in a

heated room with room temperature of 22 oC while the environmental

temperature is -2 oC if there are two openings in the room walls of 0,3 m2 each

in a vertical distance of 4 m from each other in opposite walls of the room.


Natural Ventilation Systems - Example

Ventilation Systems

286

In rooms with a large number of people (such as theaters, cinemas,

conference rooms, etc.) or places where unwanted odors are produced

natural ventilation is not the way to go. In such cases mechanical ventilation

is necessary.

There are three basic types of systems of mechanical ventilation, shown in

the subsequent diagrams. Το σύστημα φυσικής προσαγωγής φρέσκου αέρα

με μηχανική εξαγωγή αέρα

The system of natural intake and mechanical exhaust of the air

The system of mechanical intake and natural exhaust of the air, and

The system where both intake and exhaust are achieved with mechanical

means.


Mechanical Ventilation Systems

Ventilation Systems

287

(a) natural intake and

mechanical exhaust of the

air

(b) mechanical intake and

natural exhaust of the air

(c) both intake and exhaust

with mechanical means

Fan

Room

Fan

Room

Fan

Room

Fan



Ventilation Systems

288

Air distribution in the room

Room

Air supply

Duct

Air nozzle



Ventilation Systems

Ceiling Fins

289

The air flow is due to the difference in pressure between two points. This

difference in pressure led to force on the air molecules and subsequently a

motion of the molecules from the high pressure point to the low one. The

volume flow (Q) and the velocity of flow (v) are following the equation: Q = v A,

where Q the rate of flow (m3/s), v the velocity of air (m/s) and Α the area of the

section that the flow occurs (m2). This basic equation relates the flow of air

under all circumstances.



Ventilation Systems

290

The motion of air in a particular velocity will create a pressure known as velocity

pressure. These two values are related as:

pv = velocity pressure (N/m2)

v = velocity (m/s)

ρ = air density (1.2 kg/m3)



Ventilation Systems

291

Impeller: The rotary part of the fan, (the part that gives air the motion)

Axial Fan: A fan where the air is entering the impeller in a cylindrical

manner and exits parallel to the impeller axis.

Centrifugal fan: A fan where the air is leaving the impeller perpendicular

to the rotating axis.

Casing: The stationary parts of the fan, which guide the air.

Multi-stage fan: Fan with two or more Impellers in series.



Ventilation Systems

292

Measuring the Fan Total Pressure, pT,

And the Fan Static Pressure, ps.



Ventilation Systems

293

The operation of fans of the same type is governed by relations usually called

laws. These relations/laws relate the rotational speed, (N), the volumetric flow

rate (Q), the static pressure (p) and the power (P) for a fan.

To develop the relation we can easily use the dimensional analysis:

The size of a fan is governed by its diameter, D

The speed of a fan by its rotational speed, N

The medium property density, ρ


Fan Laws

Ventilation Systems

294

Following a small analysis one easily obtains the so called fan laws as follows:


Ventilation Systems

Fan Laws

295

Fans can be categorized in a number of ways and usually according to their

basic characteristics. One way they are usually categorized is according to

the flow direction thru the impeller. Basically, when it comes to room

ventilation, there are three types of fans:

Propeller fans

Axial flow fans

Centrifugal fans


Ventilation Systems

Types of fans and fan characteristics

296

rotor

motor

Volumetric air flow rate

Me

ch

an

ical p

ow

er

Sta

tic P

ressu

re

Eff

icie

ncy


Ventilation Systems

Typical fan characteristics

efficiency

Power fan static pressure

297

rotor Tip

Power

Efficiency

Static

Pressure

rotor blade

(airfoil section) motor

Volumetric air flow rate

Me

ch

an

ical p

ow

er

Sta

tic P

ressu

re

Eff

icie

ncy


Ventilation Systems

Axial fan

298

Impeller

Blades

Air outlet

Casing

Volumetric flow rate

Static Pressure

Power efficiency


Ventilation Systems

Centrifugal fan

rotation

Pre

ssu

re, e

ffic

ien

cy,

po

we

r

299

radial blades backward curved


Ventilation Systems

Volumetric flow rate

Static Pressure

Power

efficiency

Pre

ssu

re, e

ffic

ien

cy,

po

we

r Volumetric flow rate

Static Pressure Power

efficiency

Pre

ssu

re, e

ffic

ien

cy,

po

we

r

300

Two fans in series

Single fan


Ventilation Systems

Two fans in series

Volumetric flow rate (Q) P

ressu

re (

P)

301 HVAC – Air Supply Systems

Ventilation Systems

Two fans in parallel

Two fans in parallel

Single fan

Volumetric flow rate (Q)

Pre

ssu

re (

P)


Session 5.8

HVAC - Basic Thermodynamics and Energy

303

energy = work (sum of all energies equals sum of all work).

energy cannot be destroyed or produced, but only transformed

(conservation of energy).

the energy of an isolated system is constant.

HVAC – Basic Thermodynamics and Energy

Basics

First Law of thermodynamics

304 HVAC – Basic Thermodynamics and Energy

Basics

Second Law of thermodynamics

all natural processes are irreversible.

by itself, heat can only transfer from a higher to a lower temperature

reservoir.

any kind of work or energy, can be transformed completely into heat.

however, heat cannot be completely converted into work energy.

305

DEmechanical

-IN

DEmechanical

-OUT

DEthermal-IN

DEthermal-

OUT

system boundary

DEsteady


Basics

306

t [°C]

(1)

][kWQ

(1) heating of ice

(2) melting of ice

(3) heating of liquid water

(4) evaporating of water

(5) heating (overheating) of water vapour

(2) (3) (4) (5)


Basics

307

medium r [kJ/kg] remark

ice/water 333.5 melting heat at 0°C

water 2452.8 evaporation heat at 20°C



NH3 (ammonia) 1260.66 evaporation heat at 0°C

R134a 197.2 evaporation heat at 0°C

R407C 223.29 evaporation heat at 0°C

methanol 1167 evaporation heat at 20°C


Basics

308

medium cp [kJ/kgK] remark

water 4.183 at 0°C, 1bar

ice 2.060 at -5°C

water vapour 1.875 at 0,01bar, 20°C

water vapour 2.020 at 1bar, 120°C

air 1.007 at 20°C, 1bar

monoethylene glycol/water

(30%/70%) 3.696 at -10°C

oil 2.540 mobiltherm 603 bei 200°C

steel 0.460

concrete 0.880


Basics


Session 5.9

HVAC - Basic Cooling

310

4

Q0 = condensing capacity

Pel

1

2

QC = vaporising capacity

3

HVAC – Basic Cooling

Ideal Cooling Cycle

311

s

T

critical point

liquid

liquid / gaseous

gaseous

p = const.

p = const.

GYKT00_54

t = const.

t = const.

t = const.


312

s

T

critical point

liquid

liquid / gaseous

gaseous

p = const.

p = const.

GYKT00_54

t = const.

t = const.

t = const.


313

h

log p

critical point

liquid

liquid / gaseous

gaseous

GYKT00_55

p = const.

p = const.

p= const.


314

h

log p

critical point

liquid

liquid / gaseous

gaseous

GYKT00_55

p = const.

p = const.

p = const.


315 HVAC – Basic Cooling

Cascaded Systems

316

h (kJ/kg)

0,8

h (kJ/kg)

P

(MPa)

h3=h4

0,14

R134a

0,32

1

23

4

67

58

h7=h8h1 h5

h6h2

A

B

h (kJ/kg)

0,8

h (kJ/kg)

P

(MPa)

h3=h4

0,14

R134a

0,32

1

23

4 1

23

4

67

58

67

58

67

58

h7=h8h1 h5

h6h2

A

B


Cascaded Systems

317

performance factor: COP, EER

«efficiency» of refrigeration cycles and heat pump cycles.

EER (Energy Efficency Ratio) refers to cooling output.

COP (Coefficent of Performance) refers ot heating output.


Definitions

318

parameter: SEER

SEER (Seasonal Energy Efficency Ratio); ratio of cooling output to energy

input.

efficiency factor (g)

ratio of the actually achieved COP to the maximum possible

efficiency of an ideal process.

e.g. the COP of a refrigerating machine using the Carnot-cycle.


Definitions

319

h

log p

GEJO01_013

condensating deheating

Q 1

= m 1 . D h

evaporator

(with sub cooling)

Q C

= m . D h condensor

losses in

suction line

losses in

iquid line

losses in

compressor

losses in

compressor

1

2

3 4 5

6 7

8

effective evaporising temperature

9 10

losses in

pressure gas

line

effective

sub-cooling

prior

expansion valve

11

pressure losses

in distributor


Real Cycle

320

At to= 0°C and at tc= 40°C, a refrigeration system using R 134a, is to provide

a cooling output of Qo= 50kW:

determine the required mass flow rate of the refrigerant.

what is the theoretical power input?

what is the theoretical condenser output?


Example

321

Enthalpy [kJ/kg]

140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560

Pre

ssu

re [

Ba

r]

0,50

0,60

0,700,800,901,001,00

2,00

3,00

4,00

5,00

6,00

7,008,009,00

10,00

20,00

30,00

40,00

50,00

s =

1,7

0

s = 1

,75

s = 1

,80

s = 1

,85

s = 1

,90

s = 1

,95

s = 2

,00

s = 2

,05

s = 2

,10

s = 2

,15

s = 2

,20

s = 2

,25

-40

-40

-30

-20

-20

-10

0

0

10

20

20

30

40

40

50

60

60

70

80

80

90

100

100

120 140 160

0,00

15

0,0020

0,00300,0040

0,00500,0060

0,0070

0,0080

0,0090

0,010

0,015

0,020

0,030

0,040

0,050

0,060

0,070

0,080

0,090

0,10

0,15

0,20

0,30

0,40

0,50

0,60-40

-30

-20

-10

0

10

20

30

40

50

60

70

80

90

10

0

x = 0,10 0,20 0,30 0,40 0,50 0,60 0,70 0,80 0,90

s = 1,00 1,20 1,40 1,60

v= 0,0020

v= 0,0030

v= 0,0040

v= 0,0060

v= 0,0080

v= 0,010

v= 0,015

v= 0,020

v= 0,030

v= 0,040

v= 0,060

v= 0,080

v= 0,10

v= 0,15

v= 0,20

s in [kJ/(kg K)]v in [m^3/kg]T in [°C]

R134a Ref :D.P.Wilson & R.S.Basu, ASHRAE Transactions 1988, Vol. 94 part 2.


Example

322

from log p,h-Diagram: h1= 401 kJ/kg, h4= 257 kJ/kg

from log p,h-Diagram: h2= 428 kJ/kg


Example

323

log p,h-Diagram: h3= h4= 257 kJ/kg


Example

324

Enthalpy [kJ/kg]

120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580

Pre

ssu

re [

Bar]

0,50

0,60

0,700,800,901,001,00

2,00

3,00

4,00

5,00

6,00

7,008,009,00

10,00

20,00

30,00

40,00

50,00

s =

1,7

5

s =

1,8

0

s =

1,8

5

s =

1,9

0

s =

1,9

5

s =

2,0

0

s =

2,0

5s

= 2

,10

s = 2

,15

s = 2

,20

s = 2

,25

s = 2

,30

s = 2

,35

s = 2

,40

-4 0 -2 0 0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0 1 6 00,0

020

0,0030

0,00400,0050

0,00600,0070

0,0080

0,0090

0,010

0,015

0,020

0,030

0,040

0,050

0,060

0,070

0,080

0,090

0,10

0,15

0,20

0,30

0,40

0,50

0,60

0,70

0,80

-50

-40

-30

-20

-10

0

10

20

30

40

50

60

s = 1 ,0 0 1 ,2 0 1 ,4 0 1 ,6 0 1 ,8 0

x = 0 ,1 0 0 ,2 0 0 ,3 0 0 ,4 0 0 ,5 0 0 ,6 0 0 ,7 0 0 ,8 0 0 ,9 0

DTU, Department of Energy Engineering

s in [kJ/(kg K)]. v in [m^3/kg]. T in [ºC]

M.J. Skovrup & H.J.H Knudsen. 08-03-05

R407C Ref :DuPont SUVA AC9000


Example - data


Session 5.10

HVAC - Refrigeration Liquids

326

refrigerant = working substance of the refrigeration cycle

HVAC – Refrigeration Liquids

Definition & Common substances

Definition

CFCs: chlorofluorocarbons (perfluorinated)

HCFCs: hydrochlorofluorocarbons

HFCs, FCs: chlorine-free hydro-fluorocarbons

Common substances

327

CFCs: such as R11, R12 use banned (federal official journal

309/1990 of 17/05/1990).

HCFCs: such as R22 use prohibited for new systems from

01/01/2002 (federal official journal 750/1995).

HCFCs: use prohibited also for systems in use from 01/01/2015 .

HFCs, FCs: such as R134a, are prohibited for air-conditioning of

vehicles.


Restrictions of use

328

coefficient of performance

volumetric cooling performance

discharge temperature

compression ratio

boiling pressure

condensation pressure

Oil-miscibility

thermal stability


Selection criteria (1)

329

Safety

Inflammable

Explosive

Toxic

Environment

ODP (Ozon Depletion Potential)

GWP (Global Warming Potential)


Selection criteria (2)

330

refrigerant ozone depletion

potential ODP

global warming

potential GWP100

boiling

temperature °C

R134a (CFCH2F) 0 1.300 -26,4

R125 (CF3CHF2) 0 3.200 -48,6

R32 (CH2F2) 0 580 -51,6

R143a (CF3-CH3) 0 4.400 -47,4

R404A (CF3CHF2-CF3CH3-

CF3CH2F) 0 3.800 -46,5

R407C (CH2F2-CF3CHF2-

CF3CHF2F) 0 1.600 -44,0

R507A (CF3-CHF2-CF3CH3) 0 3.800 -47,2


Various refrigerants & basic properties (1)

331

refrigerant name ozone depletion

potential ODP

global warming

potential GWP100

boiling

temperature °C

ammonia R717

(NH3) 0 0 -33,6

propane R290

(CH3 CH2 CH3) 0 3 -42

Isobutane R600a

(C4H10) 0 3 -11,9

carbon dioxide R744

(CO2) 0 1 -78,4

water R718

(H2O) 0 0 100


Various refrigerants & basic properties (2)


Session 5.11

HVAC - Parts (heat exchangers, components and parts)

333

GEJO01_014

condenser

accumulator

evaporator

expansion

valve

Filter/dryer

Sight glass

magnetic

valve

compressor

HVAC – heat exchangers, components & parts

Components

334

open compressors

Motor is not integrated in the compressor casing

hermetic compressors

Motor is integrated in the compressor casing, casing is hermetically

welded or soldered

semi-hermetic compressors

Motor is integrated in the compressor casing; casing is bolted = can be

disassembled


Components

335

The motor of hermetic compressors is fully integrated in the casing.

Therefore, it is in general not possible to discharge the waste heat

directly to the surrounding area. Without cooling, the compressor motor

would burn. Most commonly, the suction gas is used for cooling. Before

reaching the cylinder, the suction gas passes the motor. Hence, the

motor is cooled, while the suction gas temperature will rise.


Components

Suction gas cooled compressors

336 HVAC – heat exchangers, components & parts

Compressors

reciprocating

piston

sliding vane roll piston rotary piston


Compressors

scroll single-screw twin-screw


Compressors

two-stage open compressor

339

A…rotor D…piston G… shell

B…stator E…piston rod H…electrical connections

C…cylinder F…sliding crank


Compressors

340

semihermetic, cooled screw compressor


Compressors

341

capillary tube: thin copper tube - in appropriate length - causing the needed pressure drop.

thermostatic expansion valve: controlling the superheating at the outlet of the evaporator (mechanical).

electronic expansion valve: controlling the superheating at the inlet of the evaporator (electronically).

float valve: modulates the flow of liquid refrigerant to the evaporator or to the collector (when a flooded evaporator is used, the filling level is modulated in the evaporator).

orifice plate: for high capacities (steady operating point).


Throttling devices

342

Internal pressure equalisation


Throttling devices


Throttling devices

345

Real Comercial Valves


Throttling devices

346

counter flow

parallel flow

cross flow

cross parallel flow


Heat Exchangers

347

DTE DTA

t [°C]

length [m]

DTG

DTK

t [°C]

length [m]


Heat Exchangers

348

De-superheating

Condensing

Sub-cooling

Q

CQ

0Q

T

P

Vaporising

Superheating


Heat Exchangers

349

Heat Exanger internal tubing


Heat Exchangers

350

Plate type Heat Exchangers


Heat Exchangers


Evaporators


Condensers


Accumulators

356

temporary storage of refrigerant.

protects from overflowing.

secures sub-cooling at condensator outlet.


Accumulators

357

removes humidity (water) from the refrigerant

residual moisture when assembling, or repairing

oil

Refrigerant

humidity in refrigerants can cause acidification

frosting around expansion valve at temperatures below 0 °C

obstruction of nozzle low pressure fault


Dryers


Liquid Coolers


Air Coolers


Cooling Towers


Cooling Tower - Calculations

362

Advantages:

great performances.

low re-cooling temperature possible.

Disadvantages:

water demand (evaporation, elutriation).

Water treatment (hardness stabilisation, softening, chemicals needed).

legionella risk (biocidal treatment).


Cooling Towers


Cooling Towers

training module 1 basic module

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