Comparative study of HVAC systems in an office … · Comparative study of HVAC systems in an office building in Greece based on energy simulations Ilia Lampro email: [email protected]

ComparativestudyofHVACsystemsinanofficebuildinginGreecebasedonenergysimulations

IliaLamproemail:[email protected]

D.Koubogiannis

EinB2017- 6th InternationalConference“ENERGYinBUILDINGS2017”

• The building sector is responsible for the greatest part of energy consumption in Europe andUSA. The greatest percentage of energy consumption in buildings is due to air conditioning.Hence, the air conditioning system selection and performance are crucial for the operationalenergy of the building. The selection of an air conditioning system depends on variousparameters (e.g. weather conditions, the building applications, etc).

• In this study various air conditioning systems are compared on the same reference buildingfor the different climatic zones in Greece. The systems are:

Split Unit Air Conditioners (SPLIUs),Air to water Heat Pump with FCUs (AWHP-FCUs),Water to water Heat Pump with FCUs (WWHP-FCUs),Air to air Variable Refrigerant Flow system (AAVRF),Water to Air Variable Refrigerant Volume system (WAVRF),Air Handling Unit with air-source heat pump (AHU-AWHP) andAir Handling Unit with water-source heat pump (AHU-WWHP).

MotivationEinB2017- 6th InternationalConference“ENERGYinBUILDINGS2017”

• Techno-economical comparison among the air conditioning systems.• Hourly analysis of cooling and heating loads of the reference buildingfor the different climatic zones in Greece.

For each system:• Design (equipment selection, installation design etc.)• Energy consumption analysis.• Financial analysis.• Environmental analysis.• Discussion on the selection of the most efficient air conditioningsystems in typical Hellenic building for the climatic zones in Greece.

Aims&ObjectivesEinB2017- 6th InternationalConference“ENERGYinBUILDINGS2017”

MethodologyBuildingselection

(casestudy)

Locationselection

Loadsanalyzing

• ClimatezoneA– Irakleio Crete• ClimatezoneB– Athens• ClimatezoneC– Thessaloniki• ClimatezoneD– Florina

• Worstcasescenario• Hourlyanalysis

Conclusions

Systemselection

Systemscomparison

• Splittypeunits (SPLIIUs)• A/WheatpumpwithFCUs(AWHP-FCUs)• W/WheatpumpwithFCUs(WWHP-FCUs)• A/AVRVsystem(AAVRF)• W/AVRVsystem(WAVRV)• AirHandlingunitwithA/Wheatpump(AHU-AWHP)• AirHandlingunitwithW/Wheatpump(AHU-WAHP)

Systemdesign

Drawingscreation

Energyconsumpti

onsimulation

Economicanalysis

Environmental

analysis

100% 80% 60% 40% 20%

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

20 15 10 7 5 2 0 -5 -7 -10 -15 Load

(%)

COP(W

/W)

TOA(oC)

DiagramA3.4:COP(W/W)- TOA(oC)- Load(%)diagramofRAS-13N3AV2-E 6.00-

7.00 5.00-6.00 4.00-5.00 3.00-4.00 2.00-3.00

Coolingloadsandenergysimulation

Heatingloadsandenergysimulation

• Costofenergy(hourly,monthly,annual)

• Costofinstallation• Cashflow(20years)• Paybackperiod

• Economic• Technical• Environmental

• Carbondioxideemissions

• Refrigerantcontent

• Sizeselection


Results– Thermalloads(heating,cooling,annual)

0.00

20.00

40.00

60.00

80.00

A.Irakleio B.Athens C.Thessaloniki D.Florina

Thermalload

inM

Wh

Annualthermalload(MWh)ineachclimatezoneofGreece

Energyloadincooling(MWh)Energyloadinheating(MWh)Totalenergyload(MWh)


Results– Totalenergyconsumption

0.0

4.0

8.0

12.0

16.0

20.0


Energycon

sumptioninM

Wh

Energyconsumptionofcoolingseason ineachclimaticzoneofGreeceandpersystem

AHU-AWHP AWHP-FCUs SPLIUs AAVRF

AHU-WWHP WWHP-FCUs WΑVRV

0.0

4.0

8.0

12.0

16.0

20.0


Energycon

sumptioninM

Wh

Thetotal(annual)energyconsumption ineachclimaticzoneofGreeceandpersystem

AHU-AWHP AWHP-FCUs SPLIUs AAVRFAHU-WWHP WWHP-FCUs WΑVRV

0.0

1.0

2.0

3.0

4.0

5.0


Energycon

sumptioninM

Wh

Energyconsumptionofheatingseason ineachclimaticzoneofGreeceandpersystem

SPLIUs AHU-AWHP AWHP-FCUs AAVRF



y = -0.1248x + 8.6558R²=0.98504

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

0 10 20 30 40 50

EER(W

/W)

TOA (oC)

EER - ΤΟΑ diagram

Results– Totalenergycost

0.0

800.0

1600.0

2400.0

3200.0


Energycostin€

Totalcostofcoolingseason ineachclimaticzoneofGreeceandperuseandsystem



0.0

200.0

400.0

600.0

800.0


Energycostin€

Totalcostofheatingseason ineachclimaticzoneofGreeceandperuseandsystem

SPLIUs AHU-AWHP AWHP-FCUs AAVRF


0.0

1000.0

2000.0

3000.0


Energycostin€

Thetotal(annual)energycost ineachclimaticzoneofGreeceandperuseandsystem




EnergyCost=EnergyconsumptionxCostofenergy**Costofenergy=0,165€/kwh*Source:PowerpubliccorporationS.A.- Hellas– DEI,2015

Results– EnvironmentalimpactsFuel CO2 emissions(kgCO2/kWh)

Oil 0,298

Natural gas 0,212

Biomass- Pellet 0,027

Electricity* 1,120

ELECTRICITYPRODUCTIONFROM* PARTICIPATION (%)

COAL 47,69

OIL 8,20

NATURALGAS 23,93

R.E.S 10,55

LARGEHYDRO 6,21

INTERCONNECTIONS 3,42

*Source:PowerpubliccorporationS.A.- Hellas– DEI,2015

WAVRV AAVRF SPLIUs AHU-AWHP

AWHP-FCUs

AHU-WWHP

WWHP-FCUs

kgofR410A 21.2 15.0 10.5 9.9 8.8 7.9 6.8

0.0

5.0

10.0

15.0

20.0

25.0

Refrigeran

tR41

0Ain(k

g)

Contentofrefrigerantfluid(R410A)persystem


Results– CostofeachsystemA/CSystem

MainunitcostOtherparts

costInstallation

costTOTAL(Investment)

costServicecost

in€SPLIUs 7719 360 840 8919 420

AWHP-FCUs 11485 280 400 12165 225WWHP-FCUs 22175 5000 2000 29175 225

AAVRF 10713 300 400 10713 240WAVRV 17980 5000 2000 24980 225

AHU-AWHP 26379 5850 1500 29009 250AHU-WWHP 37069 1130 2500 45419 250

SPLIUs AAVRF AWHP-FCUs WAVRV WWHP-

FCUsAHU-AWHP

AHU-WWHP

TOTALCOST 8919 10713 12165 24980 29175 29009 45419

0

15000

30000

45000

60000

Totalcost(€)

TOTAL(INVESTEMENT)COST


Results– TechnicalcomparisonTable9.2.1:Airconditioningprocessesperairconditioningsystem

Airconditioningsystem

Noncentralsystem

Semicentralsystem Centralsystem

Processes SPLIUs AWHP-FCUs WWHP-FCUs AAVRF WΑVRVAHU-AAHPorAHU-WWHP

Cooling √ √ √ √ √ √Heating √ √ √ √ √ √

CoolingwithDehumidification

√ √ √ √ √ √

Ventilation* - - - - - √Wetting - - - - - √

Coolingwithwetting - - - - - √

Heatingwithwetting - - - - - √

Heatingwithdehumidification

- - - - - -

Dehumidification - - - - - -


Results– Simplepaybackperiod

0.0

20000.0

40000.0

60000.0

80000.0

100000.0

120000.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Cash(€

)

Year

Cumulativepresentvalue- Αclimaticzone(Irakleio)

SplittypeairconditionersAirtowaterheatpumpWatertowaterheatpumpAirtoairVRFsystemWatertoairVRFsystemAHUwithairtowaterheatpumpAHUwithwatertowaterheatpump

0.0

20000.0

40000.0

60000.0

80000.0

100000.0

120000.0

140000.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Cash(€

)

Year

Cumulativepresentvalue- Bclimaticzone(Athens)

SPLIUsAirtowaterheatpumpWatertowaterheatpumpAirtoairVRFsystemWatertoairVRFsystemAHUwithairtowaterheatpumpAHUwithwatertowaterheatpump

0.0

20000.0

40000.0

60000.0

80000.0

100000.0

120000.0

140000.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Cash(€

)

Year

Cumulativepresentvalue- Cclimaticzone(Thessaloniki)

SplittypeairconditionersAirtowaterheatpumpWatertowaterheatpumpAirtoairVRFsystemWatertoairVRFsystemAHUwithairtowaterheatpumpAHUwithwatertowaterheatpump

0.0

20000.0

40000.0

60000.0

80000.0

100000.0

120000.0

140000.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Cash(€

)

Year

Cumulativepresentvalue- Dclimaticzone(Florina)

Splittypeunits

AirtowaterheatpumpwithFCUs

WatertowaterheatpumpwithFCUs

AirtoairVRF

WatertoairVRV

AirhandlingunitwithAWHP

AirhandlingunitwithWWHP

PV = IC + OC ∗ 1 + r , + SC ∗ 1 + r ,

PV:Presentvalue,IC:Investmentcost,OC:Operationalcost,SC:Servicecost,r:interestrate(3,5%),n:year

11,3yrs(⊠)

9,3yrs(√)

9,5yrs(√)

9,5yrs(√)

9,7yrs(√)

10,0yrs(√)

(√)


Conclusions• A parametric comparative study of seven types of air conditioning systemsimplemented in a reference floor of an office building in the four climaticzones of Greece was carried out.• Annual thermal building loads are about the same independent the climaticzone.• Simulation of system operation is necessary since the results aren’tpredictable. The climatic zone with the highest thermal loads doesn’tinvolve the highest energy consumption. While maximum cooling loadsoccur in zone Α, for air source systems maximum energy consumption incooling occurs in zone B.• Climatic zone B has the highest annual (cooling & heating) energyconsumptions and this is pronounced in the case of systems consuming moreenergy. Climatic zone C is second, zone D is third and the zone with the leastenergy consumption is A (B<C<D<A).


Conclusions• Geothermal systems (WWHP-FCUs, WWVRV, AHU-WWHP) involve a largecapital cost. This could be significantly decreased in case there is nogeothermal heat exchanger (e.g. if a dry cooler is utilized and the heatrecovery comes from waste heat from industrial processes, lakes, rivers etc).• Complexity in installation: simplest installationà SPLIUs

complicated installationà AHUs• Energy consumption: highestà AHU-AWHP

lowestàWΑVRV• Most viable solutions by zone (from economical point of view) :

climatic zones A & Dà AAVRFclimatic zones B & CàWAVRV


Conclusions• Environmental impact: CO2 emissions highestà AHU-AWHP

lowest àWΑVRVRefrigerant content: highestàWΑVRV

lowest àWWHP-FCUs• Which system must I select ?

What is the criterion?- Energy cost- Investment cost- Environmental impact- Simplicity of installation- Location of building


Futureresearch• Examine some alternative scenarios for the systems (e.g. utilization of drycooler instead of geothermal heat exchanger with or simulation with heatrecovery from waste water, use of rooftop mono-block AHU instead ofAHU-AWHP system, etc).• The same study can be conducted in an Europe-wise level, i.e. consideringthe building to be located in some European capitals or big cities (wherelocal values for climatic data, price of electricity, carbon dioxide emissions,cost of installation etc. are important).• Comparison of the systems under consideration in terms of Life CycleAssessment.


IliaLamproe-mail:[email protected]


Documents

Comparative study of HVAC systems in an office … · Comparative study of HVAC systems in an office building in Greece based on energy simulations Ilia Lampro email: [email protected]