Download - EFFECT OF BUILDING MATERIALS ON THERMAL LOAD AND … · effect of building materials on thermal load and thermal comfort of building and cfd analysis of radiant cooling techniques

EFFECTOFBUILDINGMATERIALSONTHERMALLOADANDTHERMALCOMFORTOFBUILDINGANDCFDANALYSISOFRADIANTCOOLINGTECHNIQUESONSOLARLABOFUNIVERSITYBUILDINGLOCATEDINCOMPOSITECLIMATEOFINDIA

1SARVESHKUMARSINGH,2ANKITKUMARSHUKLA,2SAIFUDDIN,2AFJAULANSARI,3ABHISHEKJATAV

1Student,DepartmentofMechanicalEngineering,SureshGyanViharUniversity,Rajasthan,INDIA

2Students,DepartmentofMechanicalEngineering,SureshGyanViharUniversity,Rajasthan,INDIA

3AssistantProfessor,DepartmentofMechanicalEngineering,SureshGyanViharUniversity,Rajasthan,INDIA

ABSTRACT

Making the building energy efficient and improving thermal comfort inside the buildingis drawing attention of theresearchersduetothelimitedstockofconventionalresources.About40‐60%ofenergyintheformofelectricityisconsumedby thebuilding itself. About 43‐45% energy can be saved by implementing the normssuggested by Energy ConservationBuildingCode(ECBC)duringtheconstructionofthebuilding.Presentstudy investigatetheeffectof improvingthebuildingmaterialonthesolarlaboftheISBMblock,SureshGyanViharUniversitytherebyapplyingthedifferenttypesofradiantcoolingtechniques suchas radiant floor cooling ,radiantwall coolingand radiant ceiling cooling to improve the thermal comfortinside the roomanddecreasing cooling load. It is shown thatabout82%heatgain through the roof,57%solarheatgainthroughwindow can be reduced by using energy efficientmeasures (EEM) and 25% fangerPMV can be improved.Aftercomparisonradiantfloorcoolingisfoundtobebestsuitedforthesolarlab.

KEYWORDS:Radiantcooling,CFDanalysis,fangerpmv,airtemperature,solarheatgain

1.INTRODUCTION

Today because of the energy consumption the wholeworld is inclined towards finding new techniques andmethods to downsize as well as efficient utilization ofenergy for sustainable development. From variousresearches it has been found that about 40‐60% ofenergy is consumed by buildings in the form ofelectricity [4]. For making an energy efficient building(EEB)somebuildingparameterssuchasmaterialsusedduring construction, fenestration, insulation, locationofairconditioners,chillersetc.areinvestigated.

Variousresearchersarefocusingonoptimuminsulationthickness so that rate of heat transfer through thebuilding envelope can be minimized and thermalcomfortcanbemaintainedspecially in summerseason.MorelOzel[3]investigatedinhisresearchthatoptimumthickness of insulation for east, west, north and southwallshouldbe4,4,3.1,3.6cmrespectively.Ithasbeenfound that limestone, concrete and terracotta are themost efficient materials for housing. Apart from theseconventional materials COFALIT, a material made byvitrificationofasbestoswhichhaveremarkablethermalstorage property is suggested as a energy efficientbuildingmaterial[6].

Aftermakingthebuildingenergyefficientthesecondarything is minimizing electricity consumption andimproving thermal comfort. Thermal comfort isgenerally measured by predictive mean vote (PMV)whichvariesfrom‐3to+3.ThermalcomfortismaximumwhenthevalueofPMVliesbetween‐0.5to+0.5.Radiantcoolingmethodsare implemented inresidentialaswellas commercial buildingsdue to its efficient coolingandhigh level of thermal comfort. This technique is moreefficient for dry and hot climatic conditions but can beimplemented in other zones as well with minor

modifications such as dehumidifier. From variousresearches it has been found that cooling panel areashouldbe30to50%oftheceiling[2].Furtherincreasingtheareawouldnotbebeneficialasnoconsiderabledropin temperature were found. The supply air should befrom ceiling to floor for maximum thermal comfort.Relative humidity should be between 50‐60%.Implementing displacement ventilation system electricenergycanbesavedupto13.2%forthechillersand8%forthewholecoolingsystem[1].

Present study reveals the effect of energy efficientbuilding materials as well as insulation in context ofmaking the building energy efficient. Further variousradiant cooling techniques viz. radiant floor cooling,radiant ceiling cooling and radiant wall cooling areanalyzedandcomparedonEnergyplussoftware.

2.LITERATUREREVIEW

MeralOzel in his study found that the highest coolingloadisoneastandwestwallwhereasthelowestcoolingloadisonnorthwallandthecoolingloaddecreaseswiththe insulation of wall. The value of optimum thicknesswasfoundbydegreehouranddegreedaymethodwhichisalreadymentionedearlier.

Shivraj Dhaka suggested that by implementing energyconservation measures which is recommended byenergy conservation building code (ECBC) 43% energysaving can be done as compared to conventionalmethods.Healso found that16%energy saving canbeachievedbyusingthermaladaptationtechnique.

L.L. Sun and H.X. Yang analyzed the concept of usingbuilding integrated photovoltaic (BIPV) as shading andfound thatmore electricitywere generatedwhen BIPVcladdings were installed on south façade. He prioritize

SARVESH KUMAR SINGH et al. DATE OF PUBLICATION: AUG 05, 2014

ISSN: 2348-4098 VOLUME 2 ISSUE 7 JULY 2014

INTERNATIONAL JOURNAL OF SCIENCE, ENGINEERING AND TECHNOLOGY- www.ijset.in 1027

shorter photovoltaic module over longer one as theearlieroneresultsinmoreenergysavingeffectperunitarea.

Wei‐Hwa Chiang and Chia‐Ying Wang present variousparametersinradiantcoolingsystemsuchasshape,size,weightandsurfaceareaofcoolingpanel.Healsofindthesurface temperatureofceiling,bestpositionofdiffuser,supplyairtemperature,velocityandairdensity.

NestorFonseca investigatedvariousmethodsofradiantcooling for a classroom with uniform and convectiveenvironment. He found that horizontal asymmetry inhumanbodyismaximuminlateralradiantpanelcoolingsystemwhereasverticalasymmetryismaximuminfloororceilingtyperadiantcoolingsystem.

Nestor Fonseca in his another experimental studycooling power in case of radiant ceiling cooling can bedecreased by circulating uniform air near the ceilingwiththehelpofmechanicaldriver.Thishappenbecausethecoefficient

RobertoAnsuiniandRobertoLarghettiintegratedphasechangematerial(PCM)withradiantfloortoprovidetherequired thermal inertiawithout increasing the overallmass.PCMareusedtostorelatentheatandcanbeusedaccording to the requirement in both summer andwinterseason.

3.RESEARCHMEHODOLOGY

3.1BUILDINGLOCATION

SolarlaboftheGyanViharUniversityJaipur(Raj.)whichis on the top loor of the ISBMbuilding is taken for theresearch and analysis. The domain is located at 26.8 ͦ,75.80 ͦ and is 390m above the sea level. In summerseason temperature varies between 45‐48 ͦC and inwinterseason theminimumtemperaturecanbeeven4ͦC.Humidityisverylowinsummerandwinterseasonascompared to monsoon season. Jaipur comes incompositezoneinfiveclimaticzonesofIndia.

3.2BUILDINGDETAILS

Solar lab is situated at 14m from the ground level andthe total surface area of the room is 217.434m2. Thesurfaceareaoftheeast‐west,north‐south,ceiling‐flooris20.227m2, 31.872m2, 56.618m2 respectively. Doublebrick, cement‐sandplaster, gypsumplasterandpaint isused for making the walls whereas steel sheet withpartiallypitchedroof,concrete,andcementsandplasterisusedformakingroofandwindowglassismadeupof6mmgenericclearglass.Itisonthewestwalloftheroom.Thereare twodoors in theroomfacingeastandsouth.OccupancyisgivenasperthescheduleoftheUniversity.Construction details are mentioned in table 2.1 to 2.3.Table2.4showstheECBCstandardsvalue.PhotoA&Boffig 2.1 shows construction layer of wall and roof oforiginal building. Fig 2.2 &2.3 shows geographicallocation of university and considered building. Fig 2.4,2.5& 2.6 shows the simulated photo of building, blockandoriginalphotoofblock.

Table2.1Constructiondetailofoutsidewalls

Table2.2Constructiondetailofflatroof

Table2.3Constructiondetailofwindow

Table2.4ECBCsuggestedU‐value(W/m2K)

WALL ROOF GLASS

0.440 0.409 3.30

Fig.2.1(A)LayerofouterwallsFig.2.1(B)Layerofroof




Fig.2.2Geographicallocationofsolarlab

Fig2.3GeographicallocationofwholeUniversity

Fig.2.4overallModeledBuilding

Fig2.5ConsideredblockFig2.6Originalblock

3.3DATACOLLECTION

In this study, temperature of the four walls, floor andceiling is measured by using infrared thermometerwhereas the temperature of air is measured by usingnormal thermometer. Inlet air temperature of thewindow,southdoorandairtemperatureatthemiddleofthe room ismeasured. Inlet air velocity of thewindowand south door is measured by using anemometer. Allthe readingswere taken for the 40 hours in the collegeworkingdays.

3.4MODELDESCRIPTION

Solar lab (domain) which is under analysis isconstructed by using design building software. First ofall the actual parameter such as wall thickness,fenestration and the building materials is given andresultweresimulated.Afterthatseveralenergyefficientmeasures according to the norms of EnergyConservationBuildingCode(ECBC)weregiventogettheimprovedresult.

Different types of radiant cooling systems such asradiant floor, ceiling and wall cooling is given andcompared and finally the best is found out by usingdesign builder. The details of the materials used formaking energyefficient building as well as the layerthicknessandoverallheattransfercoefficient(Uvalue)is given in table 2.5 and2.6 and layers ofwall and roofareshowninphotographAandBoffig2.7

Table2.5ConstructiondetailofoutsidewallwithEEM

Table2.6ConstructiondetailofroofwithEEM




Fig.2.7(A)LayersofwallwithEEM(B)LayersofroofwithEEM

4.RESULTANDDISCUSSION

4.1 ENERGY EFFICIANCY BY USING EFFICIENTBUILIDNGMATERIALS

Comparison of heat gain through roof, solar heat gainthrough window, air temperature and Fanger PMV oforiginal building and building with EEM are shown intable4.1to4.4andgraphicalcomparisonisshowninfig4.1 to 4.4. It is calculated that by modifyingbuildingmaterialheatgainthroughroofisreducedupto82% in month of May, 57.24% and 8.4% reduction isseen in solar heat gain through window and airtemperaturerespectivelyduringpeakloadmonthwhichis found to be in month of May. 25% improvement isnoted in average fangerpmv value which is ameasurementofthermalcomfort.

Table4.1Monthlyheatgainthroughroof

Fig4.1heatgainthroughroof

Table4.2Monthlysolarheatgainthroughexternalwindow

Fig4.2Solarheatgainthroughexwindow




Table4.3Monthlyairtemperature

Fig4.3Airtemperatureofroom

Table4.4MonthlyfangerPMV

Fig4.4FangerPMVofsolarlab

4.2 EFFECT OF RADIANT COOLING ON VARIOUSMEASURESOFBUILDING

Two horizontal slices H1 at 1.1 m and H2 1.75m aretaken from the floor because the sitting and standingheightofhumanbeingisapproximately1.1mand1.75mrespectively.Table4.5to4.8showstheaveragevalueofthese slices at four different cases i.e. basic building,floor radiant cooling, north wall radiant cooling, roofradiant cooling. Figure 4.5 to 4.11 shows the differentslicesrepresentingtemperatureandvelocitycontourforeach of the four cases. Fig4.12 & 4.13 shows thegraphicalcomparisonoftemperatureoffourcases.Ithasbeenfoundinthisstudythatgiving10ͦCand15ͦCradiantloor cooling, reduction in temperature is 9.4%&5.6%forH1and8.4&5.9%forH2respectively.Bygiving10ͦCand15 ͦCradiantroofcooling,reductionintemperatureis 5.8% & 3.8% for H1 and 7.3% & 5.4 % for H2respectively and bygiving 10 ͦC and 15 ͦC radiant northwall cooling, reduction in temperature is 5.5%& 2.1%forH1and6.4&4.8%forH2respectively.

Table4.5Basicbuilding

HI H2

AVGTEMP 34.56 34.87

AVGVELO 0.63 0.72

Fig.4.5Temp.&velocitycontourath1&h2




Table4.6Buildingwithfloorradiantcooling

FLOORTEMP HI H2

10 AVGTEMP 31.25 31.93

15 32.59 32.79

10 AVGVELO 0.36 0.54

15 0.54 0.63

Fig.4.6Horizontalcontouroffloorcoolingwith10˚C

Fig.4.7Horizontalcontouroffloorcoolingwith15˚C

Table4.7Buildingwithnorthwallcooling

NORTHWALLTEMP HI H2

10 AVGTEMP 32.63 32.63

15 33.19 33.19

10 AVGVELO 0.54 0.54

15 0.63 0.63

Fig.4.8Horizontalprofileofnorthwallcoolingat10˚C

Fig.4.9Horizontalprofileofnorthwallcoolingat15˚C

Table4.8Buildingwithroofradiantcooling

ROOFTEMP HI H2

10 AVGTEMP 32.51 32.29

15 33.19 32.96

10 AVGVELO 0.54 0.45

15 0.63 0.54

Fig.4.10Horizontalprofileofroofcoolingat10˚C




Fig.4.11Horizontalprofileofroofcoolingat15˚C

Fig.4.12Temperaturegraphat10˚Cradiantcooling

Figure4.13TemperatureGraphAt15˚CRadiantCooling

5.CONCLUSION

Followingconclusioncanbedrawnbythisstudy‐

1. It is calculated that bymodifying buildingmaterialheat gain through roof is reduced up to 82% inmonthofMay,57.24%and8.4%reductionisseeninsolarheatgainthroughwindowandairtemperaturerespectivelyduringpeakloadmonthandtheisfoundto bemonthofMay. 25% improvement is noted inaveragefangerpmv.

2. In case of radiant loor cooling (10 ͦC), 9.4% and8.4%reductionintemperature(atH1&H2)isfoundas compared to theoriginal condition.At 15 ͦ C thereductionisfoundtobe5.6%and5.9%.

3. In case of radiant roof cooling the reduction intemperatureat10 ͦC is foundtobe5.8%and7.3%andat15ͦCitwas3.8%and5.4%.

4. In case of north wall cooling reduction intemperaturewasfoundtobe5.5%and6.4%at10ͦCand2.1%and4.8%at15ͦC.

5. If we compare the three types of radiant coolingsystems, it can be concluded that radiant floor

coolingisthebestoptionforthesolarlab.

ACKNOWEDGEMENT

WewouldliketothanktoHariSingh,AssistantProfessorfrom the Mechanical Department of Suresh GyanViharUniversity Jaipur and Dr. P.B.L. Chaurasia, Dean ofSureshGyanViharUniversityJaipurfortheirguidance.

REFERENCE

1. Wei‐ Hwa Chiang, Evaluation of cooling ceilingandmechanicalventilation systemsonthermalcomfort using CFD study in an office for subtropicalregion(2012)

2. Watson RD, Chapman KS. Radiant heating &cooling hand book. New York:McGraw‐Hill companies.Inc.;2002.

3. MeralOzel,determinationofoptimuminsulationthickness based on cooling transmission load forbuildingwallsinahotclimate(2013).

4. Shivraj Dhaka, Combined effectof energy efficiencymeasures and thermal adaptation of air conditionedbuildinginwarmclimaticconditionofIndia.(2012)

5. L. L. Sun, impacts of the shading type buildingintegrated photovoltaic claddings on electricitygenerationandcoolingloadcomponentthroughshadedwindows(2010).

6. AnaisJeanjean,selectioncriteriaofthermalmassmaterialsforlowenergybuildingsconstructionsappliedtoconventionalandalternativematerials(2013).

7. Ne´storFonseca,Experimentalstudyofthermalcondition in a room with hydronic cooling radiantsurfaces(2011)

8. RobertaAnsuini,Radiant floors integratedwithPCMforindoortemperaturecontrol(2011)

9. Ne´stor Fonseca, Experimental analysis andmodeling of hydronic radiant ceiling panels usingtransient‐stateanalysis.




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