A Guide To Residential Energy Efficiency In Florida

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A Guide To Residential Energy Efficiency In Florida
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Cook, Gary D.
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University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
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"Publication date: November 1991. Revised: August 1994."
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"EES-7"

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FactSheetEES-7 August1994 AGuidetoResidentialEnergyEfficiencyinFlorida1 GaryD.Cook2Thisguidelooksatvariousconstructionoptions thatcanhelpabuildermeetorexceedtheFlorida EnergyEfficiencyCode'sminimumEnergy PerformanceIndex(EPI)requirements.Approached sensibly,energyefficiencycanbeaccomplishedata reasonablecostandwithoutsacrificingaestheticsor livingstandards. Thisguidecanalsohelpbuyersandrealestate agentsidentifyhomefeaturesthatsaveenergyand evaluatethepotentialenergyperformanceofahome withrespecttoheating,airconditioningandwater heating. Eachconstructionfeaturethataffectstheenergy useinahomeisdiscussed.ENERGYEFFICIENCY-AFACTOFLIFEAsaresultoftheoilcrisesof1973-1974,1980 andthemorerecent1992GulfWar,manyAmericans havebecomeconcernedthatourdependenceon foreignoilcanbecounterproductivetoournational interest.PrioritieshavechangedasAmericanshave begunbuyingmorefuel-efficientcars,adjusting thermostats,addinginsulationandavoiding unnecessarydriving.UnitedStatesautomobile manufacturersfailedtorecognizethepublicconcern forenergyefficiencyand,asaresult,lostmillionsof dollarstoforeignmanufacturersofsmaller,fuelefficientcars(Figure1). Publicinterestinenergyefficiencyhasgrown Figure1. Isyourhomeanenergyguzzlerlikeanolder car?steadily,andpeoplenowwanthousesandcarsthat saveenergyandmoney.Contractors,builders,real estateagentsandfinancialinstitutionscanavoidthe mistakesoftheautomobileindustrybyrecognizing thisconsumerconcern.Someolderhomeshave energybillsashighasmortgagepayments.Many prospectivehomebuyersarenowaskingtoseeutility 1.ThisdocumentisFactSheetEES-7,aseriesoftheFloridaEnergyExtensionService,FloridaCooperativeExtensionService,Instituteof FoodandAgriculturalSciences,UniversityofFlorida.Publicationdate:November1991.Revised:August1994. 2.GaryD.Cook,EnergyExtensionSpecialistforBuildingConstruction,CooperativeExtensionService,InstituteofFoodandAgricultural Sciences,UniversityofFlorida,GainesvilleFL32611. TheFloridaEnergyExtensionServicereceivesfundingfromtheFloridaEnergyOffice,DepartmentofCommunityAffairsandisoperatedby theUniversityofFlorida'sInstituteofFoodandAgriculturalSciencesthroughtheCooperativeExtensionService.Theinformationcontained hereinistheproductoftheFloridaEnergyExtensionServiceanddoesnotnecessarilyreflecttheviewsoftheFloridaEnergyOffice. TheInstituteofFoodandAgriculturalSciencesisanequalopportunity/affirmativeactionemployerauthorizedtoprovideresearch,educational informationandotherservicesonlytoindividualsandinstitutionsthatfunctionwithoutregardtorace,color,sex,age,handicap,ornational origin.Forinformationonobtainingotherextensionpublications,contactyourcountyCooperativeExtensionServiceoffice. FloridaCooperativeExtensionService/InstituteofFoodandAgriculturalSciences/UniversityofFlorida/ChristineTaylorStephens,Dean

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AGuidetoResidentialEnergyEfficiencyinFlorida Page2billinghistories.Theywanttoknowwhattheycan expecttopayforenergy. Buildersandrealestateagentsarefindingthat energy-efficienthousesareeasiertosellthan conventionalhouses.Somelendinginstitutionsare Figure2. Floridaclimatezones.alsoconsideringenergyefficiencywhenqualifying prospectivehomebuyers,sincelowerutilitybillscan makemonthlymortgagepaymentsmoreaffordable. Almosteveryoneisfamiliarwiththe EnvironmentalProtectionAgency(EPA)mileage estimatesforautomobiles.Homesbuiltunder Section9oftheFloridaEnergyEfficiencyCodehave asimilarenergyindicator,theEnergyPerformance IndexorEPI.Carmanufacturersstrivetoachieve thehighestpossibleEPAmileageratingsfortheir automobiles.Forbuilders,however,alowEPImeans amoreenergy-efficienthouse. InordertocomplywithSection9ofFlorida's ModelEnergyEfficiencyCodeforBuilding Construction,newhomesmusthaveanEPIof100 pointsorless.Section9oftheCodefocusesonthree mainareasthataffecthomeenergyefficiency: thermalenvelope(seeGlossary)andthe associatedheatingsystem thermalenvelopeandtheassociateair conditioningsystem,and thehotwatersystem. SinceFloridaextendsthroughmorethansix degreesoflatitude,therearesignificantclimatic differencesbetweenthenorthernandthesouthern portionsofthestate.InpreparingSection9ofthe Code,thestatewasdividedintothreezonestoreflect theseclimaticdifferences(Figure2). SinceOctober1980,newhomesmustmeet requirementsofFlorida'sEnergyEfficiencyCode.By law,theCodeisreviewedeverytwoyears.Eachtime

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AGuidetoResidentialEnergyEfficiencyinFlorida Page3theEnergyCodehasbeenmodifiedithasbeenmade Figure3a. Manyhomesbuiltsince1980haveEPIratings.morestringent.Inmanycases,homesbuiltafter April1993withanEPIof90aremoreenergy efficientthanahomebuiltin1981withanEPIof60 points.(ThelowertheEPInumber,thehigherthe energyefficiency,asageneralrule.) TheEnergyPerformanceIndexisanexcellent Figure3b. SampleofResidentialEnergyPerformance RatingSheet.indicatorofthepotentialenergyperformanceofthe airconditioning,heatingandwaterheatingsystemsof ahouse.Itcanbeveryusefulwhencomparingthe potentialenergyefficiencyofonehousetothatof another.Consideringonlythesefactors,a50-point houseshouldusehalftheenergyofa100-pointhouse withthesamesquarefootageandnumberofbedroomsiftheywerebuiltunderthesameeditionofthe EnergyCode. However,afamily'slifestyleisamajorinfluence onrealenergyefficiency.Twofamilieslivinginthe samehomeatdifferenttimesmayuseenergyvery differently.Ingeneral,thenumberandageoffamily membersaswellastheamountoftimetheyspendat homeaffectenergyconsumption.Thewaylights, appliancesandequipmentareusedbyafamilyalso influencesenergyusage. Ifyouplantobuyanewhome,itisprudentto askthebuilderabouttheEPI.Remember,thelower theEPI,thebetter.Somenewhomesmayhavebeen builtunderthePrescriptiveSection(10)ofthe EnergyCode.Thismethodallowsbuildersto constructeachcomponenttoaprescribedstandard withouthavingtocalculatethetotalEPI.Generally, homesbuilttothesestandardswillhaveacomputed EPIoflessthan100points(Figures3aand3b). Currently,theFloridalegislatureandthe DepartmentofCommunityAffairsaredeveloping proceduresforadoptionofaBuildingEnergyRating System,whichissimilarinformattosomeofthe applianceratingsystemsthatpeoplehavebeen accustomedtoseeingonyellowtags.Theappliance ratingsystemsindicatehowmuchmoneywouldbe spenttooperatethemostandleastefficientappliance ofthatcategory,andthenindicateshowthat particularappliancecompares.TheBuildingEnergy RatingSystemwillconsiderenergyandusefactors suchasspacecooling,spaceheatingandwater heatingtodevelopthefinalFloridaBuildingEnergy

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AGuidetoResidentialEnergyEfficiencyinFlorida Page4RatingGuide.Currently,thisprogramisvoluntary Figure4. TheBuildingEnergyRatingSystemGuide.forresidentialapplications,butmayberequiredfor allnewresidentialbuildingsinthenearfuture(Figure 4).FACTORSAFFECTINGENERGYUSEEachhouseisunique.Design,functionandcost willbegivendifferentemphasesbydifferentbuilders andbuyers.Energyefficiencycanbesatisfiedwithout excessiveexpenseandwithoutsacrificingaesthetics. Constructioncostswilldependontheroutetakento achievethepointgoal. Theenergyuseofahouseisaffectedbymany factors(Figure5)including: floorplans(locationofkitchen,bedrooms,etc.)* north-southorientation windowtypeandfunction man-madeshadingoroverhangs treesandshrubbery insulationandconstructionmaterials waterheatingmethod characteristicsandefficiencyofairconditioning andheatingunits doorselection useoffans locationofwasheranddryer. *Nocreditgiveninenergycode.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page5 Figure5. ManyfactorsaffectEPI.USINGTHEGUIDEThisguideexaminesvariousconstructionfeatures. Eachhasseveralcharacteristicsthatinfluenceenergy efficiency.Forexample,theenergyefficiencyofa windowmaybeaffectedbyitssizeandtheareathat opens,aswellasbytinting,shading,insulationvalues andorientation.Eachofthesemainfactorswillbe examinedwithrecommendationsoffered.HEATTRANSFERCONCEPTSAND COMFORTBeforelookingatenergyefficientdesignand constructiontechniques,abriefdiscussionofthe physicsofheattransferandthephysiologyofcomfort mightbehelpful.Heatalwaysflowsfromhottocold. Heatistransferredbyconduction,convection, radiationandchangeofstate(heatsofvaporization andfusion).Thegreaterthetemperaturedifference, thegreaterthepotentialforheattransfer.Oneway todecreasetemperaturedifferenceswouldbeto adjustthethermostattoalevelrequiredforcomfort. Utilitycompaniesrecommendsettingsof78to82F insummerand65to68Finwinter.Ifthe temperatureoutsideis92Fandthethermostatisset at75F,thereisa17Ftemperaturedifference. Settingthethermostatto78Fmeansonlya14F temperaturedifference,almostan18%reductionof conductiveheattransfer. Conductiveheattransfer occursbetweensurfaces ofdifferenttemperaturesthatareincontactwithany substanceorcombinationofsubstancesbetween them.Itisthetransferofenergybetweenagitated moleculesoratoms.Metalsaregoodconductors becausetheytransferheatrapidly.Insulationsare poorconductors.Conductiveheattransfercanbe reducedbyinsulationmaterialssuchasbatts,fill,or foamplastics.Conductiveheattransferoccursin directproportiontothetemperaturedifference betweentheoutsidesurfaceandinsidesurface,i.e., wallorceiling.Conductiveheattransferisless extensiveinFloridathaninnorthernstateswhere temperaturedifferencesaremoreextremefrom wintertosummer. Convectiveheattransfer occurswhenagasor Figure6. Heattransfermodes.liquid,suchaswaterorair,atonetemperatureis replacedwithagasorliquidhavingadifferent temperature.Risingwarmairreplacingcoolerairis anexampleofconvection.Inthewinter,warmair leaksoutofcracksandholesinthehouseandis replacedbycoldair.Inthesummer,hotmoistair replacescoolerdryairthroughthesamecracksand holes.Thisprocessiscalledinfiltration.Convective heatlossisreducedbymakingthehomereasonably air-tightthroughsealing,weather-stripping,caulking andproperdesign.Convectionoccursattheouter skinofastructureviawind,whichisusuallygreater inwinterthansummer. Radiantheattransfer occurswhen electromagneticwavestravelthroughavacuumorair betweensurfaceswithdifferenttemperatures.The earthreceivesallitssolarheatthroughradiation. Generally,dark,roughsurfaceswillabsorbradiant heatandbecomewarm;smooth,shinysurfaceswill

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AGuidetoResidentialEnergyEfficiencyinFlorida Page6reflecttheradiation.Dark,roughsurfacestypically aremoreeffectiveatradiatingheatthansmooth, shinysurfaces.Radiantheattransfercanbelimited byshadesanduseofradiantbarrierssuchas aluminumfoil(Figure6). Ourfeelingsofwarmthorcoldnessareinfluenced bythesurfacetemperatureofobjectsaroundus,air circulationandhumidity.Dependingonourlevelof activity,wefeelcoldwhenobjectsaroundusarecold, whenairisblowingaroundus(windchillfactor)and whenthehumidityishigh. Keepinginmindthewaysheatistransferredand howourcomfortisaffectedwillaidinthe understandingofhowenergysavingdesignand constructiontechniqueswork.FLOORPLANANDGEOMETRY GeometryThedesignofahousewillinfluencebothitscost anditsenergyefficiency.A1600-square-foothouse withalength-to-widthratioofone-to-one(square) willhave25%lessmaterialinitsexteriorwallsthan acomparablehousehavingafour-to-oneradio(long rectangle).Reducingwallareausuallytranslatesinto reducedenergylosses. Somedesignersbelievethatahousewitha length-to-widthratioof1.7to1isbestforFlorida's hot,humidclimate.Thisistrueonlyifthelongsides facenorthandsouthandifthehousehasadequate overhangs.Ifalongrectangularhomeisdesired,it isbesttoorientthelongsidessotheyfacesouthor north(Figure7).FloorPlanThefloorplanofahomeshouldbecarefully considered.Ahousethatiscompactlydesignedis moreefficientonasquarefootbasisthanonethat rambles.Floorplandesigncanreducelossesthrough thethermalenvelopeandimprovethewaterheating efficiencyofahouse.Forexample,unconditioned areassuchastheclosets,workshopandgaragecan provideathermalandinfiltratingbarrieriflocated adjacenttotheexteriorwalls,especiallyontheeastor westsidesofthehouse.TreesandShrubberyAhouseconstructionsiteshouldbecarefully selected.Treescansavelargeamountsofenergythat wouldotherwiseberequiredtocoolorheatahouse. InsouthFlorida,deciduousorevergreentreesthat shadeahousecansubstantiallyreducetheamountof energyneededforairconditioning.Incentraland northFlorida,itpaystotakeadvantageoftreeswith deciduousleaves.Theyprovideshadeinsummer, and,afterlosingleavesinthefall,allowthewarming raysoftheruntostrikethehouseinthewinter. Deciduoustreesontheeast,southeastandsouthwest sidesofahousesaveenergythatwouldotherwisebe spenttocoolthehouseinsummer,yetdonot interferewiththesun'snaturalwarminginwinter. Ifyouareabletochooseyoursiteorchooseyour Figure8. Landscapingcansaveenergyrequiredtocoolor heatahome.landscapingthatwillbenearthehome,selectwind resistanttrees.Thelesswindresistanttreesshould beplacedataconsiderabledistancefromthehome, ifpractical. OneofthemostdurabletreesisourFloridastate treetheSabalpalm.Palmtreesingeneralare veryresistanttohighwinds.Otherwindresistant treeswereshowntobehickory,pecan,liveoak,bluff oak,baldcypressandAmericanash.Treesthatdo notdowellinhighwindsandcouldcausedamageto homesandbuildingswereidentifiedtobelaureloak, wateroak,sweetgum,sugarberry,cherrylaureland pinetrees.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page7Plantingfast-growingtreesonabarelotcan Figure7. Orientationandgeometry.providesavingsinjustafewyears.Evergreens locatednorthandnorthwestofahouseareabarrier againstcoldwinds.Shrubberycanbestrategically plantedtochannelprevailingsummerbreezesintothe homeorplacedclosetothehouseonthenorthside tohelpreduceinfiltrationandthewindchillfactor. Thissavesenergythatwouldotherwisebeneededfor heating(Figure8).YourcountyCooperative ExtensionAgentwillbeabletoadviseyouaboutthe typeandlocationoftreesandshrubberybestsuited foryourneeds.GLASSWhileglassisnecessaryforaesthetics,ventilation andlighting,itisthemajorcauseofenergyloss throughthethermalenvelope.Generally,about55% ofthetotalenergyusedinaFloridahouseisfor heatingandcooling.Approximately20%ofthe energyusedisforheatingwater;theremaindergoes foroperatingequipmentorappliances.Windows, skylightsandglassdoorscanaccountforupto60% oftheenergyusedforheatingandcooling.GlassAreasMinimizingglassareas,whilemaintainingdesign andventilationrequirements,canbeenergyefficient. Gooddesignpracticeprovidesnomorethan10%of thewallareasofsingle-storyhousesshouldbeallocatedforwindowsandglassdoors;intwo-storyhouses, nomorethan6%.Inadditiontosavingenergy, reducingglassareaswilllowerconstructioncosts. Horizontalglassprovidesmorepanoramicviewsand betterventilationthanverticalwindowsofthesame squarefootage.Windowsextendingbelow3feetor above61/2feetinheightaddlittletofunction.Orientation,Overhangs,Shading/TintingTheamountofsolarradiationcomingthrough glassareasisdirectlyaffectedbyregionalfactorssuch asthebrightnessandangleofthesun.Asmuchas 270Britishthermalunits(heatunitscalledBTUs)of directanddiffusedsolarradiationcanenterahome orbuildingthrougheachsquarefootofglass.In otherwords,ifsunlightstrikesone6x8footclear glasswindowonthewestwallofaroom,thecooling effectofmorethanonetonofairconditioningis requiredtoremovetheheatgainedfromthissource alone.Thisismorethaneighttimestheheatgain duetoconductionandinfiltrationthroughtherestof thewall.Windowsfacingotherdirections,suchas northorsouth,maystillhavetwiceasmuchindirect radiantheatgainthanconductionandinfiltration lossesthroughtherestofthatwall. Houseorientation,overhangsandshadingor tintingareinterdependentcharacteristicsthataffect theenergygainedandlostthroughglass.The directionwindowsface(orientation)willgreatly influencetheenergyrequiredforheatingandcooling. Asaresultofseasonalvariationsinthesun's declination,properlydesignedoverhangs(about21/2 feet)canalmostentirelyeliminatedirectsolar radiationthroughsouth-facingglassinthesummer, yetstillallowthesun'sheattoenterahouseinthe winter.Newhurricaneconcernsmayeffectivelylimit overhangstobetween18and24inches.Ifso,

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AGuidetoResidentialEnergyEfficiencyinFlorida Page8awningscanprovideadualfunctionofshadingglass andprovidinghurricaneprotection.West-facingand east-facingwindowsandglassdoorsshouldbekeptto aminimum.Thisisbecausethesun'sdirectradiation isdifficulttocontrolinthesummerand,therefore, overhangsmustbeexcessivelylong(andexpensive)to beeffective(Figure9). Awningsplacedjustabovewindowscanbehelpful Figure9. Orientationandwindowshadingareimportantto energysavings.incontrollingthesun'sdirectradiation.Ifproperly designed,awningscanalsoprovideprotectionagainst winddamagefromhurricanes. Installingsolarscreensortintedwindowshaving alowshadingcoefficient(Sc)maybeanattractive energysavingoption.Thelowertheshadingcoefficient,themoreefficientthescreenortintisat reducingsolarradiation.ClearglasshasanScof1, whilesomeofthebettersolarscreensorfilmshave anScaslowas0.2.AnScof0.2wouldreducethe directsolarradiationby80%. Ifasignificantnumberofeast-orwest-facing windowsaredesired,itmaybenecessarytousesolar screenorwindowtinttoreducetheEPItoan acceptablevalueandtomaintaincomfort. Disadvantagesofsolarscreenortintedglassare reductionofnaturallightingandsolargaininthe winter.Useofsolarscreenortintedglassonnorthandsouth-facingwindows,whileprovidingsome benefitinsouthFlorida,isnotconsideredcost effective.VentilationInFlorida'smoderateclimate,therearebetween 90and120daysoftheyearwhenoutside temperaturesandhumiditylevelsfallwithinthe comfortzone,ifhumiditylevelspermit(ifdewpoint isbelow60F).Duringthismildweather,useof naturalventilationcanresultinlargeenergysavings. Glassareasshouldbedesignedsonaturalventilation isprovided.CrossVentilationAhousethatprovidescrossventilationduring periodsofmildweathercanachieveconsiderable energysavings.Eachroomdesignedforcross ventilationshouldhaveoperablewindowslocatedin themiddleofadjacentwallsoronoppositewalls. Properlydesignedwingwallscanprovidenatural ventilationthroughthewindowsonthesamewall (Figure10). Ingeneral,atwo-storyhouseoffersbetteropporFigure10. Glassareasshouldallownaturalventilation.tunitiesthanasingle-storyhouseforincorporating ventilationintothedesign.Ifpicturewindowsor clerestorywindowsareused,theyshouldbedesigned toopen.InsulatedGlassandInfiltrationControlGlassisapoorinsulatoragainstcoldandheat. Double-panewindowsarebetterthansingle-pane windowsbecausetheyprovideaninsulatingairspace

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AGuidetoResidentialEnergyEfficiencyinFlorida Page9betweenlayersofglass.Cracksaroundwindowframes areanotherwayunwantedcoldorhotairentersa house.Stormwindowscanbeeffectivelyusedas addedinsulationandasanextrabarrieragainst infiltratingwinds. Double-panewindows,becauseoftheirexpense, generallyprovideapooreconomicpaybackin Florida.However,tolowertheEPIofahousewith largewindowareasortoreduceoutsidestreetor airportnoise,itmaybenecessarytoinstalldoublepanewindows.Wherealargeexpanseofglasscauses aninfiltrationproblem,propercaulkingorweatherstrippingwillhelp.Do-it-yourselfstormwindowsmay bethebestoptioninthecostvs.benefitequation. Itshouldbenotedthatdouble-panewindowswill stillallow15to20timesmorecoldorhotairtobe transmittedintooroutofahousebyconductionand infiltrationthanawell-insulatedwallofequivalent size.Sincetherearemanycharacteristicsaffecting theenergyefficiencyofglass(orientation,overhangs, shadingcoefficient,insulationandinfiltration),the bestoverallsolutionistoreducewindowareasas muchaspossible(Figure11). Figure11. StormwindowsshouldbeconsideredinNorth Florida.INSULATION-GENERALCONSIDERATIONSInsulationmaterialscomeinmanyformsand types.Somehavelongchemicalnamessuchas ureaformaldehyde,polyisocyanurate,polyurethane andpolystyrene.Othermaterialssuchasmineral woolandcellulosearealsocommon.Eachtypeof insulationhasdistinctcharacteristicsthatshould beevaluated:somearelessexpensivethanothers; somewillshrink,thusreducingperformance;and somemayproduceunpleasantodors.Inthepast, someinsulationmaterialswereattackedbyinsects andprovidedarefugeforvermin,andsomewerenot properlytreatedorinstalled,causingfirehazards. Newstandardshaveeliminatedmanyoftheabove problems.Somefoil-backinsulationboardscanbe usedasradiantandvaporbarriers,ifappliedcorrectly withanairgap.Insulationshouldbeselectedforits quality,characteristicsand,mostimportantly,its insulatingcapabilitycommonlyreferredtoas"R" value.R-10insulationistwiceaseffectiveasR-5 (Figure12). Properselectionandinstallationofinsulationare Figure12. Tableofinsulationvalues.veryimportantifthetheoreticalR-valueofthe insulationistobeattainedandretained.Tests supervisedbytheAmericanSocietyofTestingand Materials,Owens-CorningandtheUniversityof FloridahaveshownthatwallsinsulatedwithR-11 battsoftenperformedatonlyR-7orlessbecauseof shoddyinstallationtechniques.Forexample,anR-11 fiberglassbattwillperformatlessthanR-6if compressedtohalfthedesignedthickness(31/2 inches).Also,ifinsulationisblownorpouredintoan attic,itwillnotperformasexpectedunlessitisevenly rakedtotheproperdepthanddensity. Gapsthatareoftenfoundaroundwiring, electricaloutletboxesandpipingruns,andnextto framingmemberscreateareasofhighheattransfer andconvectivethermaldrafts.Thiscausesa disproportionatedegradationoftheinsulationsystem. Infact,researchhasshownthatgapsininsulation

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AGuidetoResidentialEnergyEfficiencyinFlorida Page10withinwallcavitiesamountingtoonly3%ofthetotal Figure13. Insulationtypes.areawillreducetheactualperformanceupto20%. Installationofinsulatedexteriorsheathingwill significantlyimprovetheoverallperformanceby insulatingstudsandgaps(Figure13).InfiltrationControlandVaporBarriersTheEnergyCodeencouragestheuseofan "infiltrationbarrier"ontheexteriorsideofthe insulation.Thispreventswindfromcirculatingair withintheinsulation.Ifproperlysealedattheseams andends,plywoodandbuildersfeltwillserveasan infiltrationbarrier,butnotasamoistureretardant. Avaporbarrier/retarderwillessentiallystopmoisture transmissionofdiffusioninadditiontoservingasan infiltrationbarrier.Commonvaporbarriersor retardersare6-milpolyethylenesheetandaluminum foil-backedpaperorboards.Contrarytonorthern constructionpractices,avaporbarrier,includingvinyl wallcoverings,installednexttotheconditionedspace isnotrecommended.Otherwise,watermaycondense onthevaporretardersurfacewithinthewallcavity whentheinsidetemperatureisbelowtheoutsidedew pointinthesummer.Thiscouldwetanddegrade insulation,deterioratewallcomponentsand contributetomoldandmildew. Vaporbarriersare notrecommendedontheconditionedsideofwallsin Floridabuildings (Figure14). Ifahouseistobeconstructedonaconcreteslab, avaporbarrierofplasticsheetingshouldbeplaced undertheslab.Withoutavaporbarrier,moisturewill migratefromthegroundthroughtheporousslaband intothehouse.Ifahouseistobebuiltoff-grade,a sheetof6-milpolyethyleneplasticshouldalwaysbe placeddirectlyonthegroundunderthehouseto preventmoisturefrommovingupwardfromthesoil. Ifavaporbarrierisnotusedontheground,higher thannormalhumiditylevelswilloccurinthecrawl spaceandmoisturewillinfiltrate(Figure15). Groundandunder-slabvaporretardersthatare installedwithsealseamsandwithoutholesortears willalsorestrictradonentryintoahome. Tofurthercontrolairandmoistureinfiltration, Figure14. Condensationtemperatureoccurringatvapor barrier(studwall).windowsanddoorsshouldfitsnuglyintheirframes. Weathersealsshouldbeused,andwindowanddoor framesshouldbecaulked.Ifframeconstructionis used,thesoleandtopplateshouldbesealedwitha high-gradecaulkorfoamsealant.Holesdrilledfor electricalwiringandplumbingshouldbesealedalso. Low-costfoamcoversforwalloutletsmaybeadded inexistinghomes.Ifpossible,kitchenandbathroom exhaustfansshouldbedesignedwithautomatic dampersandtimerswitches.Gasandoilheating systemsshouldhaveautomaticfluedampersiflocal buildingcodespermit.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page11Sincemostofthemoistureenteringthehomein Figure15. Properplacementofinsulationandground covervaporbarriers.thesummerandexitinginthewinteroccursthrough infiltration,takingstepstocontrolinfiltrationwill makethehousemorecomfortable.Keepinghumidity atmanageablelevelsalsoeasescontrolofmoldand mildew. Humidity,airmovementandtemperature determinecomfortlevels.Highhumidityhelpsour bodiesholdheat.Dryairabsorbsmoisturefromthe skinatarapidrateandproducesachillingeffect whichcanonlybeoffsetbyincreasingair temperature.Inthewinter,forexample,aproperly humidifiedhouseisascomfortableat68Fasadry oneisat72F.Byloweringthetemperaturefour degrees,upto20%canbesavedonheatingbills.WALLSNexttoglass,wallsgenerallyaccountforthe largestamountofenergylostfromahouse--about15 to20%.Thereareseveralmajorfactorsaffectingthe energyperformanceofwalls.Theseincludeinsulating characteristics,surfacearea,infiltrationandthermal mass. Insulatingtheexteriorwallsisimportanttoenergy performance.Wallinsulationwithavaluebetween R-11andR-19isrecommendedforFlorida.Thisis equivalentto31/2to51/2inchesoffiberglassbattor about11/2to21/2inchesofexpanded polyisocyanurate(Figure16). Figure16. Framewallinsulation.Sealingtheopeningswherewiringandpipingrun throughfloorsandceilingsatthesoleandtopplates isveryimportant.Inresidentialconstruction,upto 20%ofinfiltrationheatlossesarecausedbythis problem.Thereareavarietyofcaulkingandfoam productssuitableforthispurpose.Somelocalcodes forbiduseoffoamsealantsbecauseoffiresafety concerns. Forbuildersdesiringtosuper-insulatetheirwalls, usinga2x4inchstudsystemwithR-11battsandR5.4or7.2foil-backrigidinsulationassheathing providesanexcellentsystemcompletewithinfiltration andmoisturecontroliftheseamsarecaulkedor sealedproperly(Figure17).Thissystemwillbe superiortoa2x6inchstudsystemwithR-19batt insulationbecausethestudsandgapsinthebattsare insulatedbytheinsulatedsheathing,i.e.,the sheathingwillprovidebetterinfiltrationcontrol.ThermalMassThermalmassreferstotheabilityofbuilding materialstostoreheat.Thermalmasstendstodelay theeffectoflargetemperaturevariationsoccurring overshortperiodsoftime.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page12InallclimatezonesinFlorida,theaveragedaily Figure17. Blockwallinsulationoninside.temperaturesforbothsummerandwinterarejusta fewdegreesaboveorbelowthecomfortzone. Floridawintersmayproduceanearlymorning temperatureof35Fwhichoftenclimbsto70Flater intheday.Concretewallsandslabs,throughtheir thermalmass,candampentheeffectofthislarge fluctuationintemperature.Ifinsulationisplacedon theoutsideofamassivewall,thepositiveeffectof thermalmasscanbemaximized.Houseswithlarge thermalmasswilluselessenergyforheatingand coolingthanaframehouseoflightconstruction insulatedtothesamevalue.Takingadvantageofthe temperaturestabilizationeffectofthermalmass, heatingandcoolingsystemscanbedown-sizedto providebetterhumiditycontrolandlowerinvestment costs. Earth-shelteringorbermingahomewillprovide energysavingsthroughthermalmassandtemperature stabilization,butitisusuallymoreexpensivethan conventionalconstruction.Nevertheless,theremay becaseswhereitisappealingandcosteffective.An architectorengineershouldbeconsultedaboutthe feasibilityofearth-shelteringbecauseofspecial structuralandmoistureproblems. Useoffiberglassbattinsulationbetweenfurring stripsisnotrecommendedonblockwalls,especially ifplasticsheetingisusedtoholditinplacebefore thedrywallisinstalled.Thisinsulationislikelyto becomedampfrommoisturecondensation,thereby degradingitsperformanceandcausingmildew problems.Inaddition,moisturemayalsocause corrosionorrottingofmetalandwoodbuilding components.Thepreferredmethodistoinstall3/4to one-inchfoil-backrigidinsulationdirectlytothe block,nailingthefurringstripsthroughthisinsulation intotheblockandapplyingthegypsumboardover thistomakeanexcellentwallsystemcompletewith vaporandradiantbarrier(Figure17).CEILINGBetween10and25%oftheenergylostfroma houseislostthroughtheceiling/roofsystem.The surfaceareaofaceilingalsoaffectstheEPIrating. Onceagain,theshapeofahomewillinfluenceheat transfer.Giventhesameairconditionedsquare footageandinsulationvalues,atwo-storyhousehas upto50%lessofitsceilingandfloorareasexposed totheoutsideenvironmentasaone-storyhouse. Thismeansreducedenergylosses.Atwo-storyhouse mayhaveslightlymoresurfacearea,buttherewill stillbeanetgaininenergyefficiency. Adequateceilinginsulationisimportantin Florida.Ceilinginsulationshouldhavean"R"value between19and30.R-19isequivalenttoabout6 inchesoffiberglassbatts,3inchesofexpanded polyurethaneor6inchesofblowncellulose. Conductiveinsulationisparticularlyenhancedby installationofradiantheatbarriers(Figure18). Figure18. Ceilinginsulationshouldhave"R"values between19and30.RadiantHeatBarriersFloridaSolarEnergyCenterstudiesshowthatuse ofradiantheatbarriersprovidesexcellentsavingsin bothsummerandwinter.Thisisespeciallytruewhen installedintheattic.Aradiantheatbarrierismaterialthateitherreflectsradiantheatorinhibitsthe emissionofradiantheat.Aluminumfoilorplastic withareflectivefilmcoatingareexcellentexamples.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page13Radiantbarriersarenotveryexpensive.Thecost variesbetween6and20centspersquarefoot.This compareswith12to50centsasquarefootfor conventionalconductiveinsulationsuchasfiberglass batt,celluloseandrigidfoam. Radiantbarriersareeffectivebecauseradiation heatgainisoftenlargerthaneitherconductiveor convectiveheatgainsduringthesummer.For example,inanattic,theconductiveheatgainthat conventionalinsulationcorrectsisusuallythesmallest componentofthethreeformsofheattransfer (conduction,radiation,convection).Aradiantheat barriermusthaveanairspacenexttoareflectiveside tobeeffective(seeFigure19).Itcannotbe sandwichedbetweentwomaterials;theairspaceis criticaltoitsperformance.A1/4inchairspacewill workfairlywell,but3/4inchormoreofairspace seemstoworkbetter.Also,bycovering90%ofyour attic,theradiantheatbarrierperformsat90%ofits potentialeffectiveness.Thisisnotthecasewith conventionalinsulation,whichismuchlessthan90% effectivewith90%coverage. TheFloridaSolarEnergyCenterdidsome interestingstudieswithradiantinsertion.Atestcell wasbuiltduplicatingtheinfraredheatconditions typicalinattics.ConventionalR-19(51/2inch) fiberglassinsulationwasplacedononesideofthecell andonethinsheetofaluminumfoilplacedonthe othersidebetweentheinfraredheatsourceanda surfacesimulatingtheinsideceiling.Theresults showedonethinsheetofaluminumfoilperformed betterthantheconventionalR-19insulationin reducingthetotalrateofheattransfer. Placingaradiantheatbarrierateithertheoption 1oroption2locationshowninFigure19willallow theinsulationtoperformnearthetheoreticalvalues andwillreduceatticheatgainupto50%.Option2 isbetterbecausedustaccumulationisminimized (Figure19). Radiantbarriersalsoprovideanexcellentbenefit Figure19. Radiantbarrierapplications.inthewinterbykeepingthewarmerinside temperaturesfromradiatingtothecoldoutside. StudiesbyPhilipFairey,aFloridaSolarEnergy Centerresearcher,indicatesthatthewinterbenefit fromradiantinsulationislargerthanoriginally suspected,particularlywhenusedwithconventional insulation.Hisfindingssuggestthatwhenaradiant barrierisusedwithR-19conventionalinsulationthe combinationoutperformsR-30insulationinFlorida's winterconditions. Ifthereisnonaturalorman-madeshadeoneast andwestwalls,radiantheatbarriersshouldbeconsidered.Thesurfaceofsunlitwallsmayget20to30 degreeswarmerthantheairtemperature.Aradiant barrieragainwillenhancetheconventionalwall insulation(Figures16,17and19). Themostcosteffectiveapproachistostaple radiantheatbarriersdirectlytotheundersideofthe roofsheathingduringconstruction(foilsidedown towardairspace). Oneotherwordofcaution.Trytokeep aluminumfoilfromcomingindirectcontactwith anythingalkaline,suchasmasonrysurfaces,unlessit isprotectedbywaterproofedpaperorplasticcoating. Aluminumwilldeteriorateorcorrodewheninthe presenceofalkalinematerials.FLOORIfahouseisbuiltoff-grade(acrawlspaceunder thehouse),thefloorsshouldbeinsulatedtoaboutR11.Iftheinsulationhasavaporbarrier,itshouldbe neutralizedbypuncturingorslicingtoavoidcondensationproblems.However,avaporretardersuchas 6-milplasticsheetingshouldbeplacedontopofthe soilunderthehome.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page14SLABAhousebuilton-grade(aconcreteslabforthe floor)shouldhaveaclosed-cell,expandedinsulation boardofaboutR-6placedaroundtheperimeterof theslab.Thisisequivalentto1inchofexpanded polyisocyanurateboardorabout11/2inchesof expandedpolyurethaneboard.Theinsulationshould extendfromthetopoftheslabtothetopofthe foundation,ordownatleast18inches.Perimeter insulationisnotascriticalinsouthFlorida,where wintersaremild,asitisinthecolderclimateofnorth Florida(Figure20). Figure20. NorthFloridaon-gradeslabhousesshould haveperimeterinsulation.DOORSDoorsshouldbecarefullyselectedsincetheycan accountforupto10%oftheenergylostfroma house.Tight-fitting,foam-filledmetaldoorshave magneticweather-strippingandthermalbreakshould beconsidered.Properlyfittedsolidwooddoorsare alsoeffective.Becauseofairleaksaroundtheedges, avoidtheuseofslidingglassdoors.InnorthFlorida, longerandcolderwintersmaketheadditionofstorm doorseffectiveinreducingenergylosses.DuctDesignWithmostcentralheatingandcoolingsystems,all conditionedairistransportedtothelivingareaofthe homethroughductwork.Ductdesign,therefore, meritsspecialattentioninordertoimproveenergy efficiency. Thebestoptionistoplaceductsinsidethe conditionedareasothatlessenergyislostbythermal transmissionorairleakage.Ductworkcanbe concealedbyplacingitalongtheedgewherethe ceilingmeetsthewallandcoveringitwithpaneling. Ductsplacedintheatticorthecrawlspacebeneath thefloorloseasmuchas15%oftheheatingand coolingenergyevenifinsulated.Ifitisnotpossible tolocateductworkinsidetheconditionedspace,it shouldbeinsulatedtoR-6withaluminumfoil reflectivebacking.Insulationbattscanoftenbe placedoverductsinatticspaceswithsuccess,butonly afterinsuringductsarewrappedwithinsulationwith avaporretarderontheoutsideandconnectionsare tightandproperlysealed.Ifflexductsareused, individuallengthsshouldbekeptundertenfeet (Figure21). Figure21. Galvanizedsheetmetalbextformaintrunks.AirConditioningInsouthandcentralFloridathemajorityofthe energyusedinahouseisforcooling.Innorth Floridatheamountofenergyusedforcoolingis aboutthesameasthatusedforheating.Sincethey aremajorenergyusers,airconditionersshouldbe selectedbasedontheirefficiency.TheEER(Energy EfficiencyRatio)orSEER(SeasonalEnergy EfficiencyRatio)areindicatorsofanairconditioner's efficiency.ThehighertheEERandSEER,the better.Currently,mostunitsarestillratedwithEER values.EERandSEERvaluesmaydifferforthe samemodelandarenotsuitable,therefore,fordirect comparison. AnairconditionerwithaSEERratomgof10.0is 25%moreefficientthanonewithaSEERof8.0. Water-sourcegeothermalheatpumpswithSEER ratingsofover18arecurrentlyavailable.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page15Theoretically,thismodelwoulduselessthanhalfas muchenergytoproducethesamecoolingeffectasa conventionalairconditionerwithaSEERof9.0.At 8perkilowatthour,athree-tonairconditionerwith aSEERof8.0wouldcostabout$176permonthif operated16hourseachday;onewithaSEERof8.5 wouldcostabout$117permonthtooperate, representingasavingsof$59amonth.Thetotal cost--initialandenergy--mustbeconsideredwhen selectingequipmenttoprovidethemost environmentalpackage. Therearerelativelyfewgas-absorptioncooling systemsinFlorida.Theefficiencyofgas-absorption systemsismeasuredbytheirCOP(Coefficientof Performance).Sinceittakesheattooperateabsorptionsystems,COPisdefinedasBTUsremoved (cooling)perBTUsused(heatsupplied). Properlysizinganairconditioningsystemisvery important.Inthepast,manybuildersorair conditioninginstallersselectedairconditionersbased ononetonper500squarefeet.Withthenewtighter energystandards,thisruleofthumbisnolongera goodapproximation.Tobeaccurate,asophisticated sizingprocedureandcalculationthatincludeslatent (humidity)loadshouldbedonebyaqualifiedair conditioningcontractor.Therestillisatendencyto selectalargerunitthanisnecessaryforcooling. Biggerisnotbetter.Oversizingtheairconditioning systems,say31/2tonsinsteadof21/2tons,maylead tohighhumidityandmildewproblems.Oversized systemstendtoquicklycooltheairtothedesired temperature.Longerrunningtimesarenecessaryto lowertherelativehumiditytothe50to60%range. Inaddition,unitsthatfrequentlycycleonandoffwill wearoutquickerandhavemoremaintenance problems. Iftheairconditionerhasanair-cooledcondenser, itshouldbeplacedinashadedareafreefrom obstructionstoairflowingtoandfromit.Multi-zoneAirConditioningandHeatingAmulti-zoneairconditioningandheatingsystem savesenergybyprovidingselectiveconditioningfor onlythoseareasofahousethatareoccupied. Generally,ahousehavingtwoormorethermostats thatcontroltemperaturelevelsinareasseparatedby soliddoorsqualifiesasutilizingamulti-zonesystem. Occupantsofahousewithoneairconditioning systemforthelivingareasandanothersystemfor bedroomswillnormallyhavethebedroomunitturned offinthedaytimeandthelivingareaunitturnedoff atnight.Thiscanresultinsignificantenergysavings whencomparedtoasingleairconditioningsystemof thesamesizeandefficiency(Figure22). Figure22. Multi-zoneairconditioningsavesenergyby selectivecoolingandheating.HeatingSystemInsouthFlorida,theheatingsystemisnotas importantasthecoolingsystem.However,evenin mildwintersheatingmaystillaccountfor18%ofthe totalenergyusedtoconditionahouse.Manyhouses haveelectricheatingsystemsthatarenotasefficient asnaturalgasorheatpumpsystems.Electricstrip heatisnotcosteffectiveinnorthandcentralFlorida. EveninsouthFlorida,stripheatersshouldbe criticallyevaluatedbeforemakingthatselection. Ifnaturalgasisavailable,seriousconsideration shouldbegiventousinganaturalgasfurnacefor heating.Generally,thiswillcosttwo-thirdslessto operatethanelectricresistanceheating.The efficienciesofgasfurnacesareratedbytheirAnnual FuelUtilizationEfficiency(AFUE).Thehigherthe rating,thebetter.AgasfurnacewithanAFUEover 0.80shouldbeselected.Someofthenewermodels haveAFUEsover0.90,whichmeanstheyeffectively useover90%oftheheatcontainedinthegas. Liquidpetroleumgas(LPG)isconsiderablymore expensivethannaturalgasperunitofheatavailable andfallsbehindelectricheatpumpsandoilasafuel ofchoice.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page16Heatpumpsareaclosesecondtonaturalgasin termsofutilitycostsavings.Aheatpumpusedasan airconditionerinthesummerisdesignedsoits operationcanbereversedtosupplyheatinwinter. Theefficienciesofdifferentheatpumpmodelsvary considerably.Theefficiencyofaheatpumpinthe heatingmodeismeasuredbytheCoefficientof Performance(COP).TheCOPofconventional models(air-source)dropsasoutsidetemperaturesget colder.Whentemperaturesapproachfreezing,the COPofsomemodelsmaydropto1.0(aboutthe sameaselectricresistanceheat).Onaseasonalbasis, however,theCOPofaconventionalair-to-airheat pumpmayaveragebetween3.0and4.0dependingon themodel(Figure23). Water-sourceheatpumpstakeadvantageofthe Figure23. Geothermalheatpumpscanbeenergy efficientinsummerandwinter.moderategroundwatertemperaturesinFloridato exchangeheatandaregenerallymoreefficientthan air-sourcemodels.Evenwhenoutsidetemperatures arebelowfreezing,somewater-sourceheatpumps mayhaveaCOPof5.0orhigher(fivetimesbetter thanresistanceheat)intheheatingmode.High coolingefficiencies,SEERsgreaterthan15,arealso frequentlyobtainedwiththesemodels. Toheatatypical1500-square-foothomeinnorth FloridainJanuarymaycost$160(at(0.08per kilowatt-hour)ifanelectricstripheaterisused.If thisheatweresuppliedbyawater-sourceheatpump withanaverageCOPof5.0,theelectricheatingbill wouldbeabout$32.Thisisasavingsof$128forone month.Sincewater-sourceheatpumpsrequire betweenoneandtwogallonsofwaterpertonper minute,thepriceandavailabilityaswellasthequality ofwatershouldbeconsideredpriortotheirselection. Duetohighwaterandsewagecosts,water-source heatpumpsmaybepracticalforallareasofFlorida, particularlywestcentralFlorida,unlessclosedloop systemsareused.MostofFlorida'swater managementdistrictofficeshave regulations/requirementswhichmustbefollowed.WATERHEATINGAftertheenergyrequiredforairconditioningand heating,thenextlargestuserofenergyinahomeis thewaterheater.Waterheatingnormallyconsumes 15to25%ofallhomeenergy.Althoughhotwater consumptionvariesgreatlyfromonefamilyto another,theaverageFloridahouseholdconsumes morethan24,000gallonsperyear. Naturalgaswaterheatersarethemostcosteffectivewaytoheatwater.Ifnaturalgasisavailable, savingsof50to70%mayberealizedifthisoptionis chosencomparedtousingelectricwaterheaters. If24,000gallonsperyearisconsideredtobean averagefamily'shotwaterrequirement,usinga conventionalelectricwaterheaterwillcostfromabout $305peryearinsouthFloridato$361peryearin northFlorida(assuming10%jacketandlinelosses andelectricitycostsof$0.08perkilowatt-hour). Tomakeelectricwaterheatersmoreefficient, theymaybeusedinconjunctionwithsolarenergyor heatrecoveredfromairconditionersorheatpumps. Heatrecoverymethodsholdafirst-costadvantage oversolar.Life-cyclecostinggivesproperlydesigned andinstalledsolarwaterheatingsystemsa comparableeconomicbenefit. Heatrecoveryunitsdesignedtoremoveheat normallywastedinairconditioningsystemsare usuallyanattractiveoption.Thesearerelativelylow incostandprovideagoodenergysavingpayback, especiallyifusedwithaheatpumpsystem. Dedicatedheatpumpwaterheatersshouldbe consideredasareplacementforworn-outwater heaters.Aheatpumpwaterheaterprovideshot waterat1/3to1/2thecostofheatingwaterwith electricresistanceelements.Theyprovidecoolairas aby-product.Thedisadvantageisthattheymaycost threetofivetimesmorethanaconventionalelectric

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AGuidetoResidentialEnergyEfficiencyinFlorida Page17waterheater.ContactyourcountyCooperative Extensionofficeorutilitycompanyforinformation andfactsheetsonbothheatertypes. Somebuildersandhomeownersmayeliminate solarsystemsfromconsiderationbecausethey mistakenlybelievethatahomeisnotproperly orientedorthatthecollectormustbelocatedina mannerthatisunattractive.Generally,collectors shouldbemountedonanunshadedareaofasouthfacingroofandtiltedhorizontallyatananglebetween latitude-5and+15.Theycanalsobeplacedona suitablegroundlocation.InmostofFlorida, collectorscanfaceupto45eastorwestofsouth, andcanbetiltedhorizontallyatanglesbetween15 and40withoutmajordecreasesinannual performance.However,areliableauthorityshouldbe consultedabouteachspecificapplicationandlocation ofsolarequipment.Winterperformanceofasolar systemcanbeimprovedbytiltingitatahigherangle. Acollectorcanoftenbeplacedflatontheroofand paralleltotheroofslope.Inthiswaythecollector resemblesaskylightandlooksmoreattractive(Figure 24). Asolarwaterheatingsystemdesignedtosupply 80%ofthehome'shotwaterneedsandsupplementedwithelectricheatcansaveatypicalhousehold about$214peryearinsouthFloridawhencompared toaconventionalelectricheatersupplyingallthehot water.InnorthFloridaalmost$253peryearcanbe saved.(Formoreinformation,contacttheFlorida SolarEnergyCenter,300StateRoad401,Cape Canaveral,FL32920-4099,(407)783-0300.) Whendesigninganewhome,clusteringthe kitchen,bathroomandlaundryareasnearthehot waterheaterwillreducepipetransmissionlosses. Longpiperunswillresultinthewatercoolingbefore itarrivesatthepointofwithdrawal,andthewater remaininginthepipeswillloseheatthrough dissipation.Heatdissipationfromhotwaterpipes canbereducedbyinsulatingthemfromthetankto thepointofuse. Althoughagreatervolumeofhotwaterisusedin Figure24. Solarwaterheatingcanbeanenergyefficient constructionoption.bathrooms,thenumberofwithdrawalsisthe importantconsideration.Sincetherearemore withdrawalsofhotwaterfromkitchenfaucetsthan bathroomfaucets,itisimportantthatthepipeleading tothekitchensinktobeashortone. Althoughmanywaterheatershavebuilt-in insulation,itpaystouseadditionalinsulation.Two ormoreinchesofadditionalinsulationisgenerally lessexpensiveandmoreenergyandefficientandcost effectivethanwaterheatertimers(Figure25). Selectingdurable,efficientplumbingfixturescan Figure25. Addinsulationtowaterheaterstosaveenergy.alsosaveenergy.Awaterfaucetdevelopingaleakof 90dropsaminutewillwasteabout1000gallonsof hotwaterperyear.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page18VENTILATION CeilingFansInthesummer,thecoolingeffectofceilingfans canallowthethermostattoberaisedasmuchas4F. Raisingthetemperaturefrom78Fto82Fcan reducecoolingcostsasmuchas20%.This relationshipappliedtoallareasinFlorida. Ceilingfansmayalsobeeffectiveinthewinter becausetheyreducehotairstratificationthat normallyoccursneartheceiling.Theycanreducethe energylostattheceilingandprovideamoreeven andcomfortabletemperaturedistribution(Figure26). Figure26. Ceilingfansprovidecomfortatenergysaving thermostatsettings.WholeHouseFansAfanthatventilatestheentirehousecanquickly emptythehouseofunwantedcigaretteorcooking smoke.Fanscanalsosaveenergybyreducingthe numberofhoursanairconditionerworks,providing outsidetemperatureandhumidityconditionspermit. Generally,awholehousefanwillpulloutsideair throughthehome,expellingitouttheattic.This reducesattictemperaturesandintroducesawindchill effectthroughoutthehouse.Awholehousefancan beusedduringmildweather,suchasmorningand eveninghoursofsummerandduringthespringand fall.Neitherceilingnorwholehousefansareas effectiveduringperiodsofhighsummerhumidity.A wholehousefanshouldbesizedtomoveatleast1 1/2cubicfeetofairperminute(CFM)foreach squarefootofconditionedarea.Thus,a1200-squarefoothomeshouldhaveatleastan1800CFMfan. Wholehousefansshouldnotbeoperatedduring periodsofhighhumiditysuchasafterthunderstorms. Iftheyare,theair'smoistureisabsorbedbywood, paperandcloth.Agoodruleistooperatethemonly ifthedewpointtemperatureisbelow60F.WasherandDryerLocationWashersanddryersshouldbelocatedinan unconditionedspace.Ifyouplaceaclothesdryerin aconditionedarea,thiswillallowwarm,humid outsideairtoinfiltratethroughthedryerventduring thesummer,andcoldairtoenterthehouseduring thewinter.Bothawasherandadryerwilladdtothe airconditioningloadbytransmittingheatand moistureduringthewashinganddryingcycles. Figure27. Setbackthermostatsareawiseinvestment.ThermostatsInstallingautomaticsetbackthermostatsonthe heatingandcoolingsystemsisawiseinvestment. Automaticthermostatsturnofforreducethe operatingtimeofanairconditionerwhenafamilyis awayfromthehouse.Inthewinter,nightsetback timerscanautomaticallyreducethetemperatureat bedtime.Blanketscanthenbeusedeffectively. Rememberthattheenergyrequiredforheatingand coolingcanbereducedupto30%foreachsix degreesthatinsidetemperaturesarebroughtcloserto outsidetemperatures(Figure27).

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AGuidetoResidentialEnergyEfficiencyinFlorida Page19FireplacesAcracklingfireonacoldwinternightisan undeniablesourceofenjoymentandcomfort. However,itsvalueasaheatsourcecanbevery deceptive.Afiregeneratesalargeflowofair throughthehouseandupthechimney,astheairin thehousethathasalreadybeenheatedrises. Althoughthefireisheatingtheimmediateareaby radiantheat,itiscoolingtherestofthehouseby expellingwarmairupthechimney.Ifthethermostat issetat68Fandtheoutsidetemperatureisbelow 38F,afireinthefireplacecancausetheheating systemtousemoreenergythanitotherwisewouldby pullingincold,outsideairforcombustion.Energy lossescanbereducedsomebyloweringthe thermostatsettingandclosingthedoorstotherestof thehousewhilethefireplaceisbeingused. Afireplacethatsuppliesthefirewithairfroma Figure28. Energysavingfireplacesprovideoutsideairfor combustion.directoutsideducteliminatestheaboveproblem. Installingglassdoorsinfrontofthefireplaceisalso aneffectivewayofreducingheatlosses.Some fireplacesaremanufacturedwithadoublewallwhich allowsroomairtocirculatebehindandaroundthe fire.Thesecanbeveryenergyefficientifcoupled withanoutsideairsource(Figure28).COSTSOFCONSERVINGManyoftheenergy-efficienttechniquesand measuressuggestedinthisguidecostlittleornothing toincorporateintothedesignofahouse.Mostcan beincorporatedintothemortgage.Utilitysavings oftenexceedtheincreaseinmortgagepayment. Bybuildingwisely,compliancewiththe Florida ModelEnergyEfficiencyCodeforBuilding Construction ispossiblewithoutgreatlyincreasing constructioncosts.Theendresultisanenergyefficienthousethatwillbenefitbuilders,realestate agentsandhomeowners(Figure29).GLOSSARYOFTERMSAFUE(AnnualFuelUtilizationEfficiency). AFUEistheefficiencyratingrequiredbytheDepartmentofEnergy(DOE)forresidentialgas-andoilfiredheatingequipment.Unlikesteady-stateconditions,thisratingisbasedonaverageusageconditions, includingonandoffcycling,asdescribedinstandardizedDOEtestprocedures. AIRCONDITIONING. Theprocessoftreating airtocontrolsimultaneouslyitstemperature, humidity,cleanlinessanddistributiontomeet requirementsoftheconditionedspace. BTU(BritishThermalUnit). Thestandardunit formeasuringaquantityofheatenergy,suchasthe heatcontentoffuel.Itistheamountofheatenergy necessarytoraisethetemperatureofonepoundof wateronedegreeFahrenheit.1BTUperminute= 17.6watts. BUILDINGENVELOPE. Theelementsofa buildingwhichencloseconditionedspacesthrough whichthermalenergymaybetransferredtoorfrom theexterior. COEFFICIENTOFPERFORMANCE(COP). Anefficiencyratingofheatingequipmentdetermined bytheratiooftheoutput(theheatsuppliedtothe conditionedspace)totheinput(theenergyrequired toruntheequipment,usuallymeasuredinBTU/hr). CONDENSATION. Theprocessofchanginga vaporintoaliquidbyextractingheatfromthevapor (forwatervaporitproducesorgivesofftheremoval ofabout960BTU/lb).

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AGuidetoResidentialEnergyEfficiencyinFlorida Page20CONDITIONEDFLOORAREA. Thehorizontal Figure29. Florida'senergy-efficienthome.projection(outsidemeasurements)ofthatportionof spacewhichisconditioneddirectlyorindirectlybyan energy-usingsystem. COMMUNICATION,SOIL. Abilityofsoilto breathorpassgases.Goodcommunicationisnecessarytodispersesoil-pollutinggasessuchasradon. DEGREE-DAY. Aunitmeasuringtheextentto whichtheoutdoormean(averageofmaximumand minimum)dailydry-bulbtemperaturefallsbelow(in thecaseofheating)orrisesabove(inthecaseof cooling)anassumedbase.Thebase,unlessotherwise designated,isnormallytakenat65Fforheatingand cooling.Onedegreedayiscountedforeachdegree ofdifferencebelow(forheating)orexcessover(for cooling)theassumedbaseforeachcalendardayon whichsuchdeficiencyorexcessoccurs. EFFICIENCY,OVERALLSYSTEM. Theratioof usefulenergy(atthepointofuse)tothethermal energyinputforadesignatedtimeperiod,expressed asapercentage. EMISSIVITY. Theratioofthetotalradiantflux emittedbyabodytothatemittedbyanideal blackbodyatthesametemperature. ENERGY. Thecapacityfordoingwork;takinga numberofformswhichmaybetransformedfromone intoanother,suchasthermal(heat),mechanical (work),electricalandchemical;incustomaryunits, measuredinkilowatt-hours(kwh)orBritishthermal units(BTU). ENERGYEFFICIENCYRATIO(EER). The ratioofnetcoolingcapacityinBTU/hrtototalrate ofelectricinputinwattsunderspecifiedoperating conditions. ENERGYPERFORMANCEINDEX(EPI). Measureoftherelativeenergyperformanceofa residentialbuildingwiththesamegeometryand orientationforwhichtheenvelope,HVACandwater heatingcomponentshavebeenoptimized. FUEL. Asubstancewhichmaybeburnedtogive heatorgenerateelectricity;anuclearsubstanceused togenerateelectricity. HEAT. Theformofenergythatistransferredby virtueofatemperaturedifference. HEATTRAP. Adevicedesignedtopreventthe convectionofheatfromahotwatertankthroughthe hotwaterdistributionline. HEATPUMP. Adeviceconsistingofoneor morefactory-madeassemblieswhichnormallyinclude anindoorconditioningcoil,compressor(s)anda refrigerant-basedheatexchanger,includingmeansto provideheatingorcoolingfunctions. HUMIDISTAT. Aninstrumentwhichmeasures changesinhumidityandcontrolsadevice(s)for maintainingdesiredhumidity. HVACSYSTEM. Asystemthatprovideseither collectivelyorindividuallytheprocessesofcomfort heating,ventilatingand/orairconditioningwithinor associatedwithabuilding. INFILTRATION. Theuncontrolledflowofair intooroutofabuildingthroughcracksaround windowsanddoors,otheropenings,andporous materialscausedbydifferencesinairpressureand/or densityresultingfromwindand/ortemperature changes. INFILTRATIONBARRIER. Aproductorsystem designedtolimitthefreepassageofairthrougha buildingenvelopecomponent(wall,ceilingorfloor). Suchproductsandsystemsmaybecontinuousor noncontinuousdiscreteelementswhicharesealed togethertoformacontinuousbarrieragainstair infiltration.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page21INSULATION. Anymaterialwithahigh resistancetoheattransmission(R)normallyusedto retardheattransferinbuildings. KILOWATT(kW). 1000watts.1kWhr=3414 BTUs. MULTI-ZONESYSTEM. Abuildingis consideredtohaveamulti-zoneheatingand/or coolingsystemifthebuildingisdividedintomore thanonezoneorareabywallsandcloseabledoors, andeachareahasaseparatetemperaturecontrol. NONDEPLETABLEENERGYSOURCES. Sourcesofenergy(excludingminerals)derivedfrom incomingsolarradiation,includingwind,wavesand tides,lakeorpondthermaldifferences;andenergy derivedfromtheinternalheatoftheearth,including nocturnalthermalexchanges. OPAQUEAREAS. Allexposedareasofa buildingenvelopewhichencloseconditionedspace, exceptopeningsforwindows,skylights,doorsand buildingservicesystems. OUTSIDEAIR. Unconditionedairtakenfrom theoutdoorsand,therefore,notpreviouslycirculated throughthesystem. PACKAGEDTERMINALAIR-CONDITIONER orHEATPUMP(PTAC). Afactory-selected combinationofheatingandcoolingcomponents, assembliesorsectionscontainedwhollyinasingle cabinetandintendedtoservearoomorzone. PERMEABILITY. Apropertyofasubstance whichpermitspassageofwatervapor. PERMS(PERMEANCE). Theratioofwater vaportransmissionthroughasurfacetothevapor pressuredifferenceacrossthatsurface;permeanceor permsisnormallyexpressedingrains/(sqft)(hr)per mercuryvaporpressuredifference. POWER. Inconnectionwithmachines,poweris thetimerateofdoingwork.Inconnectionwiththe transmissionofenergyofalltypes,powerrefersto therateatwhichenergyistransmitted;incustomary units,itismeasuredinwatts(W)orBritishthermal unitsperhour(BTU/hr). RADIANTBARRIER. Asystemconsistingofan airspacewithaminimum3/4-inchthicknessbounded byatleastonesurfacewithhighreflectanceandlow emissivityinthethermal(infrared)radiation spectrum. RADIATIONorRADIANT. Theflowofenergy acrossanopenspaceviaelectromagneticwavessuch asvisiblelight;theprocessinwhichenergyinthe formofraysoflightandheatistransferredfrom bodytobodywithoutheatingtheintermediateair actingasatransfermedium. RECOVEREDENERGY. Energyutilizedwhich wouldotherwisebewastedfromanenergyutilization system. REFLECTANCE. Theratioofthelightreflected byasurfacetothelightfallinguponit. RELATIVEHUMIDITY(RH). Theratioofwater vaporintheairtotheamountitcouldpotentially holdatthatgiventemperature. REHEAT. Theapplicationofsensibleheatto supplyairthathasbeenpreviouslycooledbelowthe temperatureoftheconditionedspacebyeither mechanicalrefrigerationortheintroductionof outdoorairtoprovidecooling. ROOFASSEMBLY. Allcomponentsofthe roof/ceilingenvelopethroughwhichheatflows, therebycreatingabuildingtransmissionheatlossor gain,wheresuchassemblyisexposedtooutdoorair andenclosesaheatedormechanicallycooledspace. Thegrossareaofaroofassemblyconsistsofthetotal interiorsurfaceofsuchassembly,includingskylights exposedtotheheatedormechanicallycooledspace. ROOMAIRCONDITIONER. Anencased assemblydesignedasaunitprimarilyformountingin awindoworthroughawallorasaconsole.Itis designedtoprovidefreedeliveryofconditionedairto anenclosedspace,roomorzone.Itincludesaprime sourceofrefrigerationforcoolingand dehumidificationandmeansforcirculatingand cleaningair,andmayalsoincludemeansfor ventilatingandheating. SEASONALENERGYEFFICIENCYRATIO (SEER). Thetotalcoolingofacentralair conditionerinBTUsduringitsnormalusageperiod forcooling(nottoexceed12months)dividedbythe totalelectricenergyinputinwatt-hoursduringthe sameperiod.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page22SPLITSYSTEM. Airconditioningsystemorheat pumpwithcondenserandairhandlerinseparate cabinets.ForthepurposeoftheCode,bothsections oftheunitmustbematchedandtestedbyARI standardsorcertifiedbytestingprocedures establishedbyARItomeettheminimumHVAC efficiencystandardsestablishedinthisCode. SPECIFICHEAT. Thepropertyofamaterial's abilitytoabsorbheat;thequantityofheatinBTUs neededtoraisethetemperatureof1poundofthe material1F(specificheatforwater=1 BTU/(lb)(F). SUNSPACE. Atotallyenclosed,unconditioned spacewhichisbuiltsubstantiallyofglass,attachedto theconditionedspaceofthebuilding,andisdesigned primarilyforwinterspaceheating. SYSTEM. Acombinationofcentralorterminal equipmentorcomponentsand/orcontrols, accessories,interconnectingmeansandterminal devicesbywhichenergyistransformedtoperforma specificfunction,suchasHVAC,servicewater heatingorillumination. TASKLIGHTING. Lightingdesignedtoprovide illuminationoverarelativelysmallareaorconfined spacewithoutprovidinganysignificantgeneral surroundinglighting. TEMPERATURE. Themeasurementofthelevel ofmotionoragitationofmoleculesandatoms,with referencetothetendencytocommunicateheator matter. THERMALENVELOPE. Exteriorportionsofa housethroughwhichenergyistransferred.This energytransferisthemajorinfluenceontheamount ofheatingorcoolingrequiredtomaintaincomfort levels. THERMALMASSorINERTIA. Thetendencyof heavymaterialsusedinconstructiontoresisttemperaturechangethroughtheirabilitytostorelarge quantitiesofheat;abilityofmaterialstodampenor averagesignificantdailytemperatureswings. THERMALRESISTANCE(R-VALUE). A measureofamaterial'sresistancetotheflowofheat; theunittimeforaunitareaofaparticularbodyor assemblyhavingdefinedsurfaceswithaunitaverage temperaturedifferenceestablishedbetweenthetwo surfacesperunitofthermaltransmission;(ft2-hrF/BTU);itisthereciprocaloftheU-valueor (1/BTU/hr-ft2-F).Thehigherthe(R)value,the highertheinsulatingvalueofthematerial. THERMALTRANSMITTANCE(U). Overall coefficientofheattransmission(airtoair)expressed inunitsofBTUperhourpersquarefootperdegree F.Itisthetimerateofheatflow.TheUvalue appliedtocombinationsofdifferentmaterialsusedin seriesalongtheheatflowpath,singlematerialsthat composeabuildingsection,cavityairspacesand surfaceairfilmsonbothsidesofabuildingelement. THERMOSTAT. Aninstrumentwhichmeasures changesintemperatureandcontrolsdevice(s)for maintainingadesiredtemperaturerange. UNITARYCOOLINGANDHEATING EQUIPMENT. Oneormorefactory-madeassemblies whichincludeanevaporatororcoolingcoilanda compressorandcondensercombination.Itmay includeaheatingfunctionaswell.Wheresuch equipmentisprovidedinmorethanoneassembly,the separateassembliesaredesignedtobeusedtogether. VAPORBARRIER. Amoistureresistantlayerof material,suchasplasticsheetandaluminumfoil, appliedtothesurfaceenclosingaspaceorbuildingto preventmoisturepenetration. VENTILATION. Theprocessofsupplyingor removingairbynaturalormechanicalmeanstoor fromanyspace.Suchairmayormaynothavebeen conditioned. WHOLEHOUSEFAN. Amechanicalventilation systemusedtoexhaustairfromtheinteriorofa buildingtotheexteriororatticspace,whichcan transfertheairtotheexteriorwithlittleornot resistance.Toberecognizedforcreditpoints,afan mustbesizedtoexhaustaminimumof1.5CFMper squarefeetoffloorarea. WINGWALLS. Anarchitecturalprojection whichisdesignedtocreatepositivepressureoverone windowandnegativeoveranother.Thisredirects windsoraugmentsnaturalventilationthrough windowsordoors.Thewingwallmustextendfrom thegroundtoeaveheight,belocatedonthe windwardsideofthebuilding,andextendoutward fromthebuildingadistanceatleastequaltoone-half thewidthofthewindow.

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AGuidetoResidentialEnergyEfficiencyinFlorida Page23ZONE. Aspaceorgroupofspaceswithina buildingwithheatingand/orcoolingrequirements sufficientlysimilarsothatcomfortconditionscanbe maintainedthroughoutbyasinglecontrollingdevice andisolatedfromothertemperatureneeds.INFORMATIONSOURCESFortheircontributioninsupplyinginformation andtechnicalassistance,appreciationisextendedto PhilipFaireyandRobVieira,FloridaSolarEnergy Center;VirginiaPeart,UniversityofFlorida,IFAS; PhilipWemhoff,JacksonvilleElectricAuthority; GoodHomeDivision,GulfPowerCompany;and RickDixonandAnnStanton,FloridaDepartmentof CommunityAffairs. FloridaEnergyExtensionService UniversityofFlorida P.O.Box110950 GainesvilleFL32611-0950 (904)392-5684 InstituteofFoodandAgriculturalSciences (IFAS) UniversityofFlorida GainesvilleFL32611 FloridaEnergyOffice DepartmentofCommunityAffairs 2740CenterviewDr. TallahasseeFL32399 (904)488-7688 FloridaSolarEnergyCenter 300StateRoad401 CapeCanaveralFL32920-4099 (407)783-0300 ConservationandRenewableEnergy InquiryandReferralService(CAREIRS) P.O.Box3048 MerrifieldVA22116 1-800-523-2929 OfficeofScientificandTechnicalInformation U.S.DepartmentofEnergy P.O.Box62 OakRidgeTN37831 (615)576-1188 DivisionofPublicAffairs DepartmentofEnergy 1000IndependenceAve.S.W. Washington,D.C.20585 (202)586-5000 NationalTechnicalInformationServices (NTIS) U.S.DepartmentofCommerce 5285PortRoyalRoad SpringfieldVA22161 (703)487-4600 CenterforBuildingTechnology InstitutesforAppliedTechnology NationalBureauofStandards WashingtonD.C.20234 (301)921-3377 SolarEnergyInstituteofNorthAmerica 11106thSt.,N.W. WashingtonD.C.20001 (202)289-4411 HearthProductsAssociation 1101ConnecticutAve.N.W.,Suite700 WashingtonD.C.20036 (202)857-1181 NationalCenterforAppropriateTechnology 3040ContinentalDr. P.O.Box3838 ButteMT59701 (406)494-4572