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Copenhagen School of Design and Technology

Bachelor in Architectural Technology and Construction Management

Specialization Report

GEOTHERMALENERGY FORHEATINGAND COOLING

student: Elena Kalcheva

Class 7I

GGEEOOTTHHEERRMMAALL EENNEERRGGYY FFOORR

HHEEAATTIINNGG AANNDD CCOOOOLLIINNGG



7th semester-Specialization Report

Student: Elena Kalcheva

Supervisor: Finn Arne Pedersen

Hand in-Date: 15.10.2010


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Table of content:

1. Abstract.......................................................................................... .... 3

2. Introduction.................................................................................... ..... 4

2.1. Problem formulation ................................ .............................. .... 4

2.2. Argumentation......................................... .............................. .... 4

2.3. Structure................................................... ............................. .... 4

3. Geothermal systems...................................................................... ..... 5

3.1. Open loop systems..................................... ............................... 6

3.2. Closed loop systems 7

4. Geothermal energy use........................................ .............................. 8

4.1. Advantages and disadvantages ............................................... . 8

4.2. Sizing and installation............................................................. ... 10

4.3. Operation and maintenance .................................................... .. 12

4.4. Cost........................................................... ................................ 13

5. Case studies 14

5.1. Case study 1: Residential building 14

5.2. Case study 2: Educational building.. 20

6. Prospects...................................................................................... ...... 24

7. Conclusion..................................................................................... ..... 28

8. References.............................................. ...................................... ..... 29


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1. Abstract

Geothermal energy is a sustainable and clean resource that can be used at everylocation-from urban to remote. It is the energy contained in the heated rock and fluid thatfills the fractures and pores within the Earth's crust and originates from radioactive decaydeep within the Earth or from a solar gain.

Geothermal energy can be used directly or indirectly, depending on the temperature of thegeothermal resource. The technology is well proven , relatively uncomplicated, and involvesextracting energy via conventional wells, pumps, and/or heat exchangers. The simpleprinciple behind these highly efficient systems is that when the pressure of the fluid rises,the temperature also rises and vice versa. In combination with hot-water storage tanks,photovoltaics or forced-air systems, it can provide sustainable and cost effective radiantheat, air-cooling and hot water.

There are two basic types of geothermal systems: closed loop and open loop. In theclosed loop the temperature of the earth is transferred as a heat exchange through a coilfilled with biodegradable antifreeze (such as glycol or methanol) into a heat-pump system.The open loop system pumps surface water from a water well and then discharges it backinto the ground. It is more cost effective if certain soil conditions are in presence.

The geothermal systems have a great potential as a heating and cooling solution for thebuildings. This report explores the properties of the available solutions, their advantages,limitations and requirements, the cost effectiveness and the aspects of sustainability relatedwith this energy source. The issues discussed in the paper can provide useful views andarguments for designers, a rchitects, HVAC engineers and other specialists that areconcerned with the quality of the living and the protection of the environment.


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2. Introduction

2.1. Problem formulation

Geothermal energy has been used for centuries in areas with abundance of hot

springs. Nowadays the energy consumption is growing and so is the need for

energy sources that are sparing the environment. The latest geothermal

technologies are simple and cost effective alternative that can provide sustainable

heating, cooling and hot water in the buildings. The intent of this report is to explore

the operational principles of the basic geothermal systems and to review technical

characteristics, economical aspects and the range of application for the needs of

different residential and public buildings.

2.2. Argumentation

Recent technology advances has made the geothermal energy applicable within a

dramatic range. It can be the sustainable replacement of the traditional fossil fuels

methods for the supply of heating, cooling and hot water in the buildings. Their

operation is highly efficient and related with considerably less emissions of

greenhouse gases. Therefore the use of geothermal energy is both eco- and

socially sustainable.

There are a lot of variables when selecting the type of the system and its

components. Decisive are the soil type, the heated area, the heat losses of the

building, the overall energy demand and the limitations of the solutions that areavailable on the market. It is the intent of the report to provide through theory and

case studies a ground for the design decisions that the constructing architects and

the HVAC engineers have to make when defining the HVAC system of the building.

2.3. Structure

The report starts with an introduction of the topic and continues with a section about

the different geothermal systems and their principles of operation. The next section

analyses the advantages and disadvantages of the different solutions, certain

technical properties, the maintenance and the economic issues. Then case studies

illustrate the theory so far. The last section provides review of the current andexpected geothermal energy development.

The information is obtained from:

Internet

Books and publications


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Specialic ation Report

GEOTHERMALENERGYFORHEATINGAND COOLING

std dente ElenaKalcf

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It iscausedby ironbacteriaandoccursmostly in thereturnwellsasaorange-brown

slime. Inorder toprevent blockingof the system, thewaterlinesshouldbeunder

pressureand freeofair-contact. Thebacteriacanberemovedbyperiodiccleaning

withachlorinebleachsolution.

Erosion

Theheat pumpcan erode, if thewater isnot freeofsandorotherparticles. Some

manufacturersuseacupro-nickel heat exchangerbecauseof itshigherresistance

toabrasion. To reduce thecontent ofsand in thesystem, awell screenand filters

between the pressure tank and the heat pump can be installed. A replaceable

cartridge isalsoanoption.

It is recommended that awatersample isanalyzedbyaproper laboratory forpH,

highcontent of solids, iron, calciumetc. The lab can also calculate the angelier

Saturation Index, which isameasureofcorrosiveness.Thepossibilityofchange in

thewaterquality in timeshouldalsobeconsideredbefore installation.

Open loopsystemmalfunctionscancausegroundwatercon taminationordepleted

aqu ifers. ormally it isnot economical to treat thereturnwaterso ifwater treatment

is required, it would bemore cost-effective to use a ground-coupled closed loop

design.

3.2. losed loopsystems:

The closed loop systemscirculate water or water and biodegradable antifreeze-

usuallypropyleneglycol, methyl orethyl alcohol, throughacontinuousunderground

pipe. The loopscanbe installed inseveral ways:

Horizontal Closed Loop

ainlyused innewconstructionswherea lot of land is

ava ilable, it is themost cost-effective solution forsma ll

installations. The pipe is inserted in trenches with

minimumseparationsof0.3mbetweenpipesand3 to

mbetween trenches. Up tosixpipes, usually inparallel

connections, are buried in each trench, which can be

dugwithbackhoesorchain trenchers.


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Vertical Closed Loop

Vertical closed loops are installed thewhen the soil is

toosha llow for trenchingor the land isnot sufficient.

A U-tube and, rarely, two U-tubes) is installed inawell

drilled30 to120mdeep. The lengthsof the loop can

vary from10 to30mperkW ofheat exchangebecause

of thedifferences in thesoil conditions. Usually inmost

of the installations the pipes are connected inparallel

andmultipledrill holesarerequired.

Pond Closed Loop

A pond closed loop is a special kind of closed loop

system.If there isapondorstreamwithsufficient depth

and flow, closed loopcoilscanbeplacedon thebottom.

Fluid is pumped in the same manner as in a

conventional closed loop ground system. The figures

are very positive for environmental impact and also

showgreat economicadvantages.

Slinky Loops

Increasingly, overlapping coilsofpolyethylenepipeareused to increase theheat

exchangepermeterof trench. The trench lengthdecreasesas thenumberofpipes

or theoverlap in the trench increases.3

. eothermal energyuse

eothermal systems can beused in residential, commercial and industrial buildings to

greatly reduce the consumption of electricity and fuels.Office buildingsand schoolsare

particularly good applications for geoexchange technology. They have relatively high

occupancy, fluctuating usage schedules, and widely varying heating and cooling

requirements within individual zones offices and classrooms) that are difficult to meet

efficientlywithconventional systems. FromWhisper Energy websitecanbeobtainedprosandconsas follows:

.1. Advantagesanddisadvantages

3Material fromhttp://www.whisperenergy.com/geoexhange-hvac-systems.asp


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The geothermal systems have numerous advantages regarding:

Low Operating Cost: heat pumps operating under moderate ground

temperatures have Coefficient of Performance (COP) from 3 to 4. It means

for every energy unit used, the pump will produce 3 -4 units of heat. Thus

every 1 DKK el-cost for heating/cooling will be reduced three or four times. In

commercial installations, systems can save money by recovering excess

heat from building interior zones and moving it to the perimeter of the

building.

Low maintenance cost: in both commercial and residential buildings.

Moreover, since the equipment is installed indoors or underground, it is not

exposed to vandalism or harsh weather conditions.

No Supplemental Heat Required:except in colder climates the heat pumps

can meet all of the space loads, including ventilation loads. Ventilation air

can be tempered by separate heat pumps and/or conditioned with heat

recovery equipment.

Low Cost Integrated Water Heating: The system can be designed to meet

hot water loads. It is particularly attractive when there is a large cooling load

relative to the heating load. By extracting some of the heat from the ground

loop for water heating, the ground heat exchanger size and cost can be

reduced.

Very w E vironmental Impact : No fossil fuels need to be consumed on

site.4

The operation is related with considerably less CO2 emissions:

Oil (new): 265 g per k h

Oil (old): 330 g per k h

Natural gas (new): 200 g p er k h

Natural gas (old): 250 g p er k h

Electricity: 540 g per k h

District heating: 125 g p er k h

Geothermal heat: 180 g p er k h5

However, geothermal systems have some downsides to be examined:

Hi her initial cost: Geothermal systems tend to have a higher first cost than

the conventional systems. In the presented case studies there are stated the

rates to which expenses can rise, although the second one is an example of

system that was actually cheaper than the conventional one. T he lower

energy and maintenance cost during the systems life cycle also compensate

4 Mate al from Whisper Energy

5 Lecture material from Finn Arne Pe ersen


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for size of the investment. Depending on the building type, system design,

operating parameters and energy costs, the simple payback for the marginal

cost of a geoexchange system usually is between 2 and 8 years

Dependent: Open-loop systems have more potential problems than eitherconventional systems or closed-loop geothermal systems because they bring

outside water into the unit. This can lead to clogging, mineral deposits, and

corrosion in the system. Open-loop systems also require a large supply of

clean water in order to be cost effective. This often limits their use to coastal

areas, and areas adjacent to lakes, rivers, streams, etc. In addition, there

must be an acceptable method of returning the used water to the

environment. This may be limited not only by environmental factors (such as

no suitable places to dump the water), but also by local and state

regulations.

Besides, in the same way that wind and hydro power rely upon certain windspeeds and certain levels of water, geothermal energy relies upon an area

having a certain level of activity. Areas with very stable geothermal

properties (or very unstable, such as near a vol cano) may not be able to

support a geothermal project. In areas where geothermal activity is present

but not at high rates, exhausting the supply of energy (at least temporarily) is

possible.

Many closed-loop systems use an antifreeze solution to keep th e loop water

from freezing in cold temperature conditions. Most antifreeze solutions have

very low toxicity, but many produce CFCs and HCFCs, that are not

sustainable. In addition, some antifreeze solut ions can obstruct the work ofthe system and add to the cost of pumping due to the increased fluid

viscosity.

Refrigerant Loop systems have several other disadvantages, including:

Environmental issues related to the system's use of refrigerant, Corrosion

issues since they use copper piping which needs anodi c protection, and the

need to maintain refrigerant temperatures within certain limits to keep from

freezing or baking the ground, Difficulty in finding and fixing a refrigerant loop

leak, should one occur.

Since accessibility to terminal units is important in geothermal systems,architects and mechanical and structural designers must carefully coordinate

their work. Each unit requires both electrical and plumbing service .

4.2. Sizing and installation


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Geothermal heating and cooling equipment is readily ava ilable in the

marketplace and can be installed by any qualified HVA contractor.The

manual from one of the biggest air conditioning manufacturers cQuay6

givesacomprehensivepictureof theprocess. It involves installing the indoor

unit, thedistributionsystem whetherforcedhot airorhydronic), and then the

outside pipe loop. oop installation can be planned together with other

construction activities, so the overall construction schedule not to be

affected.

Heat pumps come in all shapesand sizes to mee t space requirements.

Weight ranges from 00 to30000kg. Theycan be locatedabove theceiling,

inacloset or in theoccupiedspace.

Heat pumpsystemswithproperlydesignedven tilationsystemsprovidevery

good indoorairquality IAQ). Theunitscanbesuppliedwithdouble-sloped,

cleanabledrainpansandclosedcell insu lation.

In the residential sector, typically the heat pumpsareproduced in larger

series and in standard heating capacities from ca. to 20 kW are used.

Installations for thecommercial sector includingheat pumps, manifolds, are

much larger and have a capacityca. 0 kW upwards that are usually

constructed individua lly or in smallernumbers, adapted to the specific site

conditions. Themaximumdelivery temperatures typicallyarebetween 0-

55C with new developments offering increased values of 60- 5C for

refurbishment ofolderbuildings), and incoolingmodeca. 6-7C.

Thepurposeof the loopdesign is toestimate therequired loop length. This

is best done with computer software, but a basic understanding of the

process ishelpful. Thedesigneruses theheatingandcooling loads todefine

energy transfer rates for sizing the loop. The design supply fluid

62002, McQuaysGeothermalHeat PumpDesignManual,McQuayInternational

Pic. 2 Large ground source heatpump (ca. 400 kW) and manifold for

larger project

Pic. 1 Small, packaged heat pump forsingle family house, with DHW storage

tank


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temperatures must also be estimated. The larger the loop for a known load,

the cooler the supply fluid temperature will be. Lower fluid temperatures

improve the heat pump performance and capacity. The designer must find a

balance between heat pump fluid supply temperature and the capital cost of

the ground loop.

At steady-state conditions, there is heat transfer from the heat pump fluid to

the ground that can be calculated as follows:

Qc = (tg tw)/R

here

Qc is the heat load

L is the pipe length

tg is the ground temperaturetw is the fluid temperature

R is the thermal resistance to heat transfer

The challenge in loop design is that the ground temperature does not stay

constant. For horizontal loops, where the pipe is near the surface, the ground

temperature can change seasonally with the weather. In all cases, the loop

itself affects the ground temperature. For loop design, it is common to break

the effects into three parts: long term effect, annual effects and short-term

effects that have to be estimated to find the required pipe length. The length

may be established by the winter heating load requirement or the summer

cooling load requirement. If a winter peaking load establishes the length, thedesigner should go back and evaluate the cooling performance with the

longer length. This will improve the summer performanc e and may allow

smaller heat pumps to be used for some spaces .

4.3. Operation and maintenance

The O&M key figures depend on the system and the building ty pe, location,

system and the building size, year installed, service provider and etc.

Current surveys give a comprehensive picture of the average components

failures, the number of corrective actions - scheduled and unscheduled , and

how is this performance compared to that of the conventional HVACsystems. To summarize survey data from Cane and Garnet paper7, the most

frequent scheduled or preventive maintenance is change of filters, check ing

the units, lubrication, fan belts, antifreeze concentration, fen motors, clean

refrigerator, clean evaporator, pressure, clean heat exchangers, back wash,

7Cane,Douglas,Eng P,Garnet, JeremyM.,Update on Maintenance and Service Costs of Commercial Building Ground-

Source Heat Pump Systems


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duct sanitizer, voltage and amperage checking and less often- refrigerant

change, thermostat calibration, isolation valve inspections, grilles cleaning

and water filters replacement. The failures of components occur mostly

within the compressors (at the average 0.53 and 1.30 corrective actions per

100 unit-years respectively for ground water and closed -loop system), the

blowers, belts and motors, refrigerant leak ( average 2,58 corrective actions

per 100 unit-years for closed-loop systems), as well as within switches or

solenoids, thermostats and electric wiring, shaft seals, expansion valves,

piping and pipe materials (1,47 and 0,16 per 100 unit -years respectively for

open and closed-loop systems), insulation and within the hoses .

Transformers, reversing valves, air vents; heat exchangers and the line

dryers, sediment filters and etc. have negligible number of failures and need

for repair.

4.4. Cost

The initial cost of a geothermal heat pump system varies greatly according to

local labor rates, lot geology and size, type of system installed, and

equipment selected. In general the geothermal systems are more costly to

install than air source heat pumps. For either system, the cost of installed

ducts should be identical. Equipment costs can be 50-100% more expensive

for a geothermal heat pump system when the circulating pump, indoor

tubing, and water source heat pump are considered. This equals $1,000 -

$2,000 per k for the equipment.

The ground loop is generally the most expensive component of a geothermal

heat pump system and is highly dependent on local labor rates and drilling

conditions. An installed ground loop stubbed o ut in a home can cost between

$300 and $850 per installed k . Finally, experience shows that it costs

between $1,500 and $3,500 more per 1k GHP system than for an air

source heat pump system8.

However geothermal heat pumps offer high efficiency and low operating

cost. According to the EPA ( S Environmental Protection Agency),

geothermal heat pumps can save homeowners 30 to 70 percent on heating

and 20 to 50 percent on cooling costs over conventional systems. This

information, as well as, reports that have been made by builders who monitor

their in-place systems indicates that heating and cooling savings can range

between $358 and $1,475, annually.

Maintenance cost are relatively low-in the S they are about $ 1 ,9 per

square meter unless there is an initial problem with the installation or a lack

8Material fromAllim n t En o o t o m l o

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of local maintenance providers. Table 1 from a Bl{ { |

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comparison between the maintenance costs of geothermal and conventional

HVAC systems:

5. Case studies

The report presents two case studies that make evident the broad application range andthe flexibility of the geothermal systems. The data proves that these kinds of systems arehighly efficient (COP of 4 for the house) and have very short payback period. Both casestudies are also examples for easy maintenance and operation, although there areconcerns that the design of the school HVAC could have been more adapti ve.

5.1. CASE ST DY 1: Residential building10

9Bloomquist, R. Gordon, 2010, Theeconomicsof

eothermalheat

mpsystems forcommercialand instit

tional

ildings,

Washington State

niversity Energy Program 10

2004, Raymondhousecasestudy, Water Energy Distribution

Table 1 Maintenancecost $/m2/Year(# ofdatapoints)

Weightedaverage: GeoExchange Conventional HVAC Savings

All Web sites andRefferences

$1.40 (13) $ 3.60 (15) 61%

B ildingtypeSchools $1.30 (10) $ 3.70 (11) 65%Office buildings $ 2.70 (1) $ 3.40 (1) 21%Retirement $ 1.00 (1) $ 2.50 (2) 60%

Prisons $ 1.50 (1) $ 4.80 (1) 69%Conventional HVACRooftop DX with gas heating $ 1.10 (1) $ 3.30 (1) 67%Air source heat pump $ 1.10 (1) $ 3.00 (1) 63%Water source heat pump $ 1.50 (4) $ 2.30 (1) 36%Central variable air volume $ 1.10 (1) $ 3.50 (1) 69%Four-pipe fan coil unit $ 1.70 (5) $ 4.00 (5) 58%Two-pipe fan coil unit $ 80 (1) $ 3.10 (1) 74%


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RaymondMaine, USA - Ground-source heatpump

SummaryThe building is a two-storey single-family house with cathedral ceilings and large glazedareas located at Raymond, Maine, where the annual temperature differences aresignificant. Instead of using town water, a water well supplies low cost heating and coolingvia a geothermal heat pump throughout the year. Two reversible water -to-water heat pumpsare run in parallel to share the overload from the common well pump in winter and summer.The heat is distributed via a hydronic radiant floor heating system and fan coil units. Theoverall measured COP of 4 includes the well pump and the circulators. The cost of spac eheating is one third that for an oil -fired boiler. The heat pump system provides also usefulcooling. The performance of the heat pump has been continuously monitored since 1998.

Buildinganddesign values

Operational experienceandothercomments

The performance of the heat pump has been continuously monitored since 1998. The

radiant floor heat allows different water temperatures depending on outside temperature,which gives a COP ranging from 4 to 5. The overall COP, including well pump andcirculators, was measured as 4. In the four years of operation there have been no reliabilityproblems. The only maintenance required involves periodic flushing of the supply waterfilter.

Off-peak electricity with geothermal radiant heat from the pipes i n the concrete under thefloor gives storage. This precludes heating at other than off -peak time.

Building type: Single-family house

Location: Raymond, Maine, USA

Year of construction: 1997

Number of storeys: 2

Heated floor area (m2): 400

% of total floor area (%): 100

Design outdoor temperature (C) Heating: -9 Cooling: 35

Design indoor temperature (C) Heating: 20 Cooling: 24

Degree days Heating: 4 230 Cooling: No data

Base temperature for degree days

(C)

Heating: 18 Cooling: No data


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Theheatingcostswith theheat pumpare three times lower thanwithanoil-firedboiler inthispart of the USA.

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Heatingandcooling

Application: Space heating and cooling and DHW

Heat pump type(s): Water-to-water

Heat pump installed capacity (kW) Heating: 24.7 Cooling: 24.7

Refrigerant: R22

Heat source Groundwater

Details (circulating pumps): Two heat pumps: 10.6 + 14.1 kW (3 + 4 ton) and two fractional horse

power (FHP) circulators.

a) Type of ground heat exchanger: Water/refrigerant, standing column well

b) Borehole depth (m): Well depth 237

c) Pipe length (m): Column length 190

d) Heat transfer fluid: Water

e) Flow rate (l/h): Well water at 3.23 l/kW (3 gal/ton). Total 4,800 l/h (21 gal/min)

Distribution system(s): Radiant floor/fan coils. The heating circulators supply radiant floor andthe fan coils for winter heat. The cooling is done in the summer only with

the fan coils.

Supply and return temperature (C) Heating: 43/-1 Cooling: 5.5/-1

Auxiliary system: None required for geothermal radiant

Heat pump design:100% heating. For DHW there is s desuperheater on only one of the heat

pumps.

Supplementary system: Back-up for DHW is propane-fired boiler

Heat pump system completion date: October 1997

1Return temperature depends on the instantaneous loading. Depending on the month of the year the heating

temperature is varied.

Additional notes

The details of the well design:

y Static at around 9 m (30 ft)y Well pump at 31 m (100 ft)


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y Return pipe at 210 m (700 ft)y Bottom of the well at about 229 m (750 ft)

This is a standing column well of about 183 m (600 ft) for 24.7 kW (7 tons) of heat pump

capacity, about 26 m/3.5 kW (85 ft/ton). When the heating system is running the totalmeasured power consumption for the well pumps, heat pumps, circulators, controls etc. is 8kW. This gives a nominal 24.6 kW (84,000 BT /h) heating.

There are several ways to configure standing column wells depending on the depth andflow capacity of the well.

In this case the geothermal well is geothermal only and there is no concern of drawdown,which might uncover the pump. As an economy move the pump was located near the top ofthe well with the return to the bottom of the well. This saves a heavy duty copp er wire to thepump and simplifies the maintenance. Locating the pump at the top also works forcombined geo/domestic heater wells where there is a high capacity flow rate.

Typically in Maine, for lower yield wells of the order of about 7.6 -15 l/min (2-4 gal/min) thepump is located at the bottom for residential wells of up to about 152 m (500 ft).

In this installation the two heat pumps are run in parallel to share the overload from thecommon well pump in winter and summer. The common hydronic storage tank controls thewater temperature from the separate heating and cooling aquastats on the tank.

Performance

Heating energy Heat pump Aux. heating

system

Auxiliaries1

Energy input (kWh/year): About 16 000 - Included in heat pump

Energy output (kWh/year): About 48 000 - n/a

Energy cost (USD/year): 800 - Included in heat pump-

Cost tariff (USD/kWh): 0.052 - Included in "heat pump"

1 Circulation pump ground loop, fans, circulation pump heat distribution

2 On-peak tariff 0.26 USD: Monday to Friday 7.00-12.00 and 16.00-20.00, off-peak tariff 0.05 USD. Heating isessentially at the off-peak rate of 0.05 USD because the storage is concrete and because of the control strategy. The

latter includes a time-dependent 2-stage thermostat approach for hydronic tank temperature control. It also includesthe differential temperature off-peak heat storage in the basement concrete.

Cooling energy Heat pump Aux. heating

system

Auxiliaries

Energy input (kWh/year): 2 400 - Included in "heat pump"


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Energy output (kWh/year): No data - n/a

Energy cost (USD/year): 240 - Included in "heat pump"

Cost tariff (USD/kWh): 0.11 - Included in "heat pump"

1 Average of peak and off-peak rates for cooling: level load average of 73% at 0.05 USD and 27% at 0.26 USD.Cooling is supplied whenever needed both at peak and off-peak times. The cooling is automatically disabled during

the peak time. However, by manually overriding, cooling can be turned on during the peak time when it is really

needed.

Coefficient of performance (COP)

Heating: 4.6 and 4.0, for 14.1 and 10.6 kW heat pump respectively

Test conditions: Heat sink at 38C

Cooling: No data

Test conditions: No data

Heat pump cost breakdown

Heat pump only (USD): 5,431 (two heat pumps)

Installation (USD): No data

Capital cost (excluding heat pump)

(USD):No data

Maintenance: No data

Alternative system (if has been

considered)Propane boiler

Fuel cost 3 000 USD/year

Payback Estimated simple payback of heat pump system over a propane boiler is

about two years.

CO2 emissions No data


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5.2 CASE STU Y 2: Educational building11

CANYON VIEW HIGH SCHOOL

CEDAR CITY, UTAH

Location & ackground:TheCanyon ViewHigh School is located inCedarCity, UT, about0 miles 145 km) northeast of the point of

intersectionof Utah, Arizona, and evada. It isa two-story building with 233,199 ft2 21,665m2) of floor space and construction wascompleted in2001. Averagehigh temperaturesin the region in July are about 93F 33.9C)andaverage low temperatures in Januaryareabout 15F -9.4C). Thereareapproximately6100 3390C-day)heatingdegreedaysand700 390C-day)coolingdegreedaysperyear[65F 18C)base].

The Canyon View ground-source heat pump system is considered the first large geoexchangesystem in theCentral ocky ountain egion.System Description

round Source System:Thegroundsourcesystem Figure1) is thevertical closed looptypeconsistingof300vertical boreholes, each300 ft 91.4m)deep, fora total lengthof90,000 ft 27,432m). Theboreholes, installedundertheschool playing field, areplaced ina15 x 20 grid pattern with a 20-ft 6.1-m) borehole spacing and 25-ft 7.6-m) spacingbetweenrun-outs.

11Geothermal direct use-case studies, 62-66, Geo-Heat Center, Oregon InstituteofTechnology KlamathFalls

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A singleu-tubeheat exchangeris installed ineachborehole, and theborehole field ispipedina reverse-returnarrangement. Themeanannual ground temperature in this location is

approximately53F 11.7C). An in-situ thermal conductivity test revealed that theaveragethermal conductivityof thesoil toadepthof300 ft 91.4m) is1.19 Btu/hr-ft-F 2.06 W/m-C). The loop fieldwas installed inbasin-fill typesediments, consistingofcoarsesandandgravel withclaystringersand tracevolcanic.

Interior System: The total installedheat pumpcapacityat theCanyon ViewHigh School isapproximately550 tons 1953kW). Spaceconditioning isaccomplishedbyover100water-airheat pumps, whichare installed in ceiling spaces to serve individua l classroomsandother zones. Outdoorair is introduced through heat recovery ven tilator HRV)units. Theoriginal designcalled for totalenergyrecovery ERV)units, butHRVswere installeddue totheir lower cost. There is little use ofdomestic hot water in the school, and thus it isgenerated partially by water-water heat pumps and natural-gaswater heaters. The fluid

distributionsystemconsistsofacentral pumpingsystemwithavariable frequencydrive.

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ProjectCosts: The Canyon View High School is an example of a building where a ground -source heat pump system was cheaper to install than a conventional boiler chiller system.

The project costs are summarized as follows:

Conventional Mechanical System Bid: $17.00/ft2 ($183.00/m2) Canyon View High School Ground Source System Bid:

Mechanical/Plumbing bid: $2,457,000Loop Field bid: $778,000Total Ground Source bid: $3,235,000Mechanical Cost/ft2 (m2): $13.87/ft2 ($149.30/m2)Cost Savings: $3.13/ ft2 ($33.69/m2) = $729,000

Additional cost savings may be realized if one considers architectural savings in themechanical room floor space in the ground-source system over the conventional system.

For the Canyon View High School, the mechanical room for the ground-source system is2,680 ft2 (249 m2), or 1.15% of the total floor space. Comparing this value to 3.80% ofmechanical room floor space to total floor space for average schools, and assuming $50/ft2($538/m2) cost of new construction, an additional sav ings of $309,000 may be realized.

SystemPerformanceandOperatingCost: The system has performed as designed.Maximum ground loop temperatures observed in the summer are about 92 oF (33.3oC) andminimum loop temperatures in the winter are 40 -42oF (4.45.5oC). Annual utility costs for2001-2002 are summarized as follows:

Annual tility Costs for Canyon View High School:

Electricity: $135,886.54 (96%)Natural Gas: $5,446.87 (4%)Total: $141,333.41Cost/ft2 (m2): $0.61/ft2 ($6.57/m2)

tility Costs for a Comparable School:

Cost/ft2 (m2): $0.86/ft2 ($9.26/m2)(77% electrical, 23% gas)

Operating Cost Savings: $0.25/ ft2 ($2.69/m2)= $58,300 (or 29%)/year

Operating Experiences: Although the geoexchange system at the Canyon View HighSchool is performing well, it is a large system, and the designer admits that there are waysthat the pumping system could have been designed to optimize energy consumption. Forexample, systems of similar size are being designed with primary/secondary pumping,


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multiple loop pumps to utilize only as much of the ground loop as necessary, anddistributed pumping in the building.

Most heat pumps are installed in ceiling spaces, and access has been a bit tight. Dirt and

sand was a problem in the system for about 6 months after start -up, which was attributed toa damaged header pipe, likely caused by landscaping work.

Overall Summary:Building Description:Location: Cedar City, UtahOccupancy: SchoolGross Floor Area: 233,199 ft2 (21,665 m2)Number of Floors: 2Type of Construction: NewCompletion Date: 2001

July Avg. High Temp.: 93F (33.9C)Jan Avg. Low Temp.: 15F (-9.9C)Annual Heating Degree Days: 6100F-day (3390C-day)Annual Cooling Degree Days: 700F-day (390C-day)

Interior System:Total Installed Heat Pump Capacity: ~550 tons (1,935 kW)No. of Heat Pump Units: 100+Pumping System: Central with VFD

Ground-Source System:Geologic Materials: Basin-fill sediments

Mean Ann. Ground Temp.: 53F (11.7C)Type: Vertical closed loop, single U-tubeConfiguration: 300 boreholes (15x20 grid pattern)300 ft (91.4 m) deep,20 to 25 ft (6.1 to 7.6 m) spacingBorehole per ton: ~164 ft/ton (14.2 m/kW)

Economic Analysis:Installed Geothermal HVAC Capital Cost: $3,235,000 ($13.87/ft2)($149.30/m2)Conventional HVAC Capital Cost Bid: $3,963,363 ($17.00/ft2)($183.00/m2)Annual HVAC Energy Cost (2001 -2002): $141,333 ($0.61/ft2)($6.57/m2)Annual HVAC Energy Cost of Comparable Conventional School: $200,500 ($0.86/ft2), ($9.26/m2)

Annual HVAC Energy Savings: 29%Estimated Simple Payback Period: Immediate


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6. Prospects

Thepresentedcase studiesexemplify two possible types of installation for two differentbuildings typologies, but that is just asmall fraction fromall theapp lication thegeothermaltechnology finds. At present thegeothermal resourcesareused forelectricitygenerationinpower plants, district heating, industrial process heat, agricultural and aquaculturepurposes.

According to Geothermal Education Office12 in every part of the world there are longestablished traditions and/or emerging trends. Since geothermal energy is a complexurban, industrial and economic issue, the development of this sector is showing greatvariety by countries and regions. evertheless, by legislation and regulations thegovernmentsare intending toprotect theaquifersandprevent sideeffects likemanmaidseismicity. Guidelines for thedesignand theproperoperationsareconstantlyupdated, butin Europe and not only) governments often lack clear energy policies and environmental

policy does not address energy sources but rather the mitigation of their effects. Geothermalenergy in general and geothermal resources in particular, is usually not well defined in legalterms, and the regulation of their development andutilization is correspondingly diffuse .

13

Fig. 5 Geothermalcapacityinstalledandpotential14

12Material fromhttp://www.geothermal.marin.org/geomap_1.html

132010, EGEC, Keyissue 3:Regulations forgeothermalenergy, 7-8

14Material fromIslandsbankissustainableenergyteam,Canada eothermal nergy arketReport, 7


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In EUROPE hot water from wells up to 1800m deep and 45 -85 degrees and similar areheating houses in France (1470 GWh/yr), Belgium (28 GWh/yr), Germany, Denmark (12.5GWh/yr), as well as in Netherland and England where heating systems are tested. Another

field of exploration is Hot-Rock Projects that have been tested in England, France andGermany, in order to figure out if water injected in the hot rocks can be heatedeconomically. Besides for dwellings in some regions in France, Germany, Austria andSweden heat pumps are extracting there are thermal spas. Still the strategies of theauthorities for future development are as various as the European countries itself. InDenmark for instance there is positivism and legislation in place, but no incentives as publicfunding for geothermal plants. The driving force is the market, where there are high taxeson fuel heating and periods with lower prices for heating by electricity and power plants.Thesaleofheat to districtheatingsystems isregulated toprotect thecustomersagainst

theotherwiseerystrongposition the limitednumberof localproducerscouldhaveon local

price setting. enerally the price is thus only allowed to include certain well definedelements aspay backofnormal loans tonecessary investments inplants, purchaseoffuels, maintenance.15

In Switzerland on the other hand the fiscal barrier for the use of geothermal energy is verylow and the industry is very active in the promoting. One way to do it is invented by SwissEKZ (Electricity Company of Canton Zurich) which provides Energy Contracting orotherwise the EKZ installs, owns, and operates the system in buildings and sells the heat (domestic hot water) at a fixed price to the owners. But if the geothermal installation involveswater as a heat carrier (as in the open loop systems), permit and concession are neededaccording to the water management legislation, because shallow and deep ground waterbelongs to the cantons.

Germany, ironically, lack political acceptance for the development of its geothermalresources but some local governments are deviating from the official coarse and areintroducing financial incentives for the business. This is the reason why Bavaria, Baden-

Wrttemberg, Brandenburg and Nordrhein -Westfalen hold about 78 % of the heat pumpmarket with only 52 % of the population living there.

In EASTERN EUROPE there are thermal spas that have been exploited for hundreds ofyears like the famous Czech therm al spas Carlsbad and Marienbad. In Czech Republic andPoland hot water containing mineral salts from the crystalline rocks has long been used forhealth and recreational purposes. In Bulgaria (220 GW/yr), in Hungary (1630 GWh/yr),Slovakia (502 GWh/yr), Romania (360 GWh/yr), Poland (206 GWh/yr) and the formerYugoslavia (1085 GWh/yr) 16, hot water from 500 to 2000 m wells is used mostly used inswimming pools, greenhouses and health spas. In Hungary most of the 80% of thegreenhouses (42 % of all the geotherm al wells) are heated by geothermal waters, but only3 % of the existing wells are used for space heating. Like in Switzerland, the geothermalenergy is a subject of the Water Management Law, however there has been complains thatit does not include any relevant terms and regulations. Environmental protection issueshave also been found perplexed. Similar is the situation in Bulgaria which is very rich in hotmineral springs, but lacks administrative and practical expertise in geothermal development

152010,EGEC, Key issue3:Regulations for geothermalenergy,28

16Material from http://www.geothermal.marin.org/geomap_1.html


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in addition to very complicated and time consuming procedures for obtaining waterconcessions.

In EASTERN AND SOUTHERN MEDITERRANEAN a complex plate boundary between

Turkey and Greece (37 GW/yr) forms several high-temperature geothermal prospects. TheKizildere field in western Turkey operates since 1984 and a plant for dry ice is using CO2from the geothermal wells for the Middle East. At Ankara, Izmir and other regions lowtemperature springs (552 GWh/yr) are developed for heating and greenhouses. It isestimated that ifTurkeyutili

esallofhergeothermalpotential, shecanmeet4%ofher

totalenergyneed heatandelectricity) fromgeothermalsources .17What can be a setbackis the lack of legislation particularly regulating the geothermal energy, nevertheless taxexemption and third -party funding are present, in order to exploit the sector.

In Israel and ordan hot springs (100Co) are used for bathing and heating. Israel produces332 GWh annually. In Algeria (460 GWh/yr) and Tunisia (400 GWh/yr) the geothermalenergy is used for recreational and agricultural purposes .

ITALY has probably the most notable record in using geotherma l energy for heating andbathing. The Roman baths spread from North Afri ca to northern England, Spain andTurkey. The fumaroles at the Campi Flegrei near Naples are so impressive that it is said tohave inspired the picture of Dantes inferno. In 1904 the Larderello field in Tuscanyproduced the worlds first geothermal electricity.

Today the country produces around 1120 GWh/yr or 0,65% of the total energy output that isconsidered very limited part of what Italy could actually exploit . At Castelnuovo low-pressure steam heats water for greenhouses and district heating. At Monte Amiata, a largegreenhouse complex is heated by waste heat from a geothermal plant. The greatestdevelopment is expected in Tuscany, but many private developers naturally are interestedin the potential for spas across the country.

ISLANDhas also been using for centuries its geothermal resources at the residential andthe agricultural sector . The country is a volcanic island with an abundance of high and lowtemperature geothermal systems that produces around 5900 GWh/yr and heat 85% of thehouses. In Reykjavik, ("Bay of Steam"), the capital with more than 145,000 people, everyhouse supplied with hot water cheaper than the cold.There are plenty of hot baths, soilheated crops, fish farming and industry that is based on the geothermal resources of thecountry. New geothermal power stations are under construction and it is expected that thecountry will double its geothermal capacity thus continuing to decrease its dependence onimported fuels.

JAPAN is notorious for its volcanic activity that has been present for the last 20 millionyears. The country is located on the Pacific ring of fire and has cold winters, during whichhot bath has become a national ritual. Today apan is the world largest consumer of direct

geothermal heat with more than 8730 GWh/yr for bathing, with another 1940 GWh/yr spaceheating, manufacturing, agriculture and aquaculture (includi ng raising alligators). A longterm goal is 100 to 500 kW binary power plants for the small communities of mass

172009,Erdogdu,Erkan,A SnapshotofGeothermalEnergyPotentialandUtilization in Turkey,1,EnergyMarket

RegulatoryAuthority,Republic ofTurkey


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produced to a projected total of 23.7 MWe. In general the areas available for drilling aresmall with no more than 40 MWe average.

UNITED STATES exploit the west coast boundary and the volcanic hot spots inYellowstone and Hawaii. The most geothermal electricity is generated in California (824MWe) at the Geysers, still highly under its full capacity but nevertheless the worlds largestoperating field. There are numerous other littl e power plants and the direct use ofgeothermal energy is rising rapidly to 4000GWh/yr with a great deal of positivism towardsthe technology. Hundreds of buildings are heated individually and through district heatingprojects (Klamath Falls, Oregon; Boise , Idaho; San Bernardino, California etc.) Largegreenhouse and aquaculture facilities in Arizona, Idaho, New Mexico, and tah use low -temperature geothermal waters . The private Davenport niversity got certified by LEEDafter installing geothermal system f or heating and cooling and is one of the many examplesthat this technology gives great advantage and its market is growing (even though S isslowly focusing on wind power as a main green energy).

InCANADA, there are plans for geothermal power project s at Mount Meager. In NovaScotia factories are heated using water from the flooded Springhill coal mines. In the Yukongeothermal protects city water pipes from freezing. More than 30 000 buildings includingCarleton niversity in Ottawa are heated direct ly or with heat pumps using 10 -20 Co groundwater.

In RUSSIA the subduction boundary at Kamchatka is a part of the ring of fire and the onlyplace in Russia with geothermal electric power (11 MWe). nder construction is 80 MWeplant at Mutnovsky and the waste water will be used to heat the town 80 km away. Howeverit can be expected that the traditional use of geothermal waters for district heating, woolwashing, greenhouses and production of paper and concrete blocks will make the most ofthe emerging technology.

ANDEAN VOLCANIC BELT is thinly populated and the e lectrical demand is low, so thegeothermal resources are poorly developed. In Chile the first major geothermal project - ElTatio- is realized by the nited Nations in 1965 for the needs of a great copper mine atChuquicamata. Argentina has a power plant producing electricity, and the rest of thegeothermal megawatts are produced for heating and bathing.

There is an active rift EASTAFRICA RIFT SYSTEM that runs through Zambia, Malawi,Tanzania, ganda, Kenya, Ethiopia and Djibouti and near six other countries. Anexperimental 200 kWe electrical generator operates in Zambia, and at Olkaria, Kenya thereis a 48 MWe geothermal power plant and an additional 64 M We one.Intensiveexplorationis under way in Kenya to increase electricityproduction to keeppa ce withpopulation

growth. Indrypartsof thearea, nomadic tribescondensesteam from fumaroles towatersheepandgoats.18 South Africa is ready to introduce advance rating systems to boostgeothermal heating in new projects.

18Material from GeothermalEducation Office


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7. Conclusion

Geothermal energy is a clean and sustainable resource that has been developed the lastdecades to find application in almost every type of building. Since it is very advantageousboth ecologically and economically , and available everywhere, its potential is great, eventhough that in the developing countries the initial cost is still a barrier. The design andefficiency are constantly being improved along with the gain of experience; in most of theworld in process is proper legislation and regulations.

For heating and cooling there are two principle types of systems -open and closed loop.Some principle concerns like source water quality, maintenance and runoff managementmake the closed loop more advanced solution, but the open loop is still a good and moreaffordable option provided that the site conditions are suitable.

The system design can be very flexible due to the variety of manufactured components.Heat pumps are produced in a great variety of sizes and can be installed at different placesin the building. Geothermal system mechanical rooms require very little space for circulatingpumps, the main header and so me chemical treatment equipment which leaves morespace for occupant needs.

The performance of the installed geothermal pum ps is a subject of various surveys. Twocase studies-with relatively small and relatively large size and capacity have been quoted inthis report. They provide measurable evidence for the adequate operation of theinstallations at a significantly lower cost than that of a conventional HVAC system. It is alsoimportant that the service supply proves to be fuel-independent, stable and flexible. Thebiggest advantage of the geothermal systems is their efficiency -they use up to 60% lesselectricity than a conventional system which depending on the consumption results in returnof investment within 2 to 8 years.

At present the geothermal systems are used to heat homes, swimming pools, greenhouses,and health spas. They are having place both in the industry and the agriculture. In remote,off the grid locations often they can be the only smart solution. In the urban context to makethe balance between large district projects and individual systems will be a challenge forurban planners, architects, as well as for the engineers and researchers in the next twentyyears. It can certainly be concluded that the geothermal energy can provide the buildingswith advance modes for heating and cooling, thus representing another important trend inthe pursuit for sustainable living.


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8. References

Literature:

Ryker, Lori, 2007, Off thegridhomes. Case studies for sustainable living,Gibbs Smith

Internet

EnergyTrainingforEurope , accessed 26-02-2010

WisperEnergy, accessed 28-02- 2010

Geothermal EducationOffice, accessed 28-02- 2010

Toolbase Services, accessed 28-02- 2010

Alliant Energy-Geothermal, accessed 28-02- 2010

Naturalresources Canada , accessed 10-09-2010

Publications

Bloomquist, R. Gordon, 2010, The economics of geothermal heatpumpsystems for commercial and institutional buildings, Washington State

niversity Energy Program

2004, Raymondhousecasestudy,Water Energy Distribution

2005, Geothermaldirectuse-casestudies, 62-66, Geo-Heat Center, OregonInstitute of Technology Klamath Falls,


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2002, McQuays Geothermal eat Pump esign Manual, McQuayInternational

Cane, Douglas, Eng P, Garnet, eremy M., Update on Maintenance andService Costsof CommercialBuildingGround-Source

eatPump Systems,

Caneta Research Inc

2010, EGEC, Key issue 3: Regulations forgeothermalenergy, 7-8

2009, Erdogdu, Erkan, A Snapshot of Geothermal Energy Potential andUtili

ation in Turkey, , Energy Market Regulatory Authority, Republic ofTurkey

2010, Islandsbankis sustainable energy team, CanadaGeothermal EnergyMarket Report, 7, Islandsbanki

Lecturematerials fromFinn Arne Pedersen

geothermal reporta

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