Heat TransmissionTemperature GradientsDevelop Thermal Resistant ValuesDetermine Design Temperatures (winter)Calculate GradientsSurface TemperaturesSurface Temps (cont.)PowerPoint PresentationSlide 9Application?At inspection, you see…You see…Slide 13Wall inspectionBlower Door TestYou discover…Your Notes after InspectionSlide 18Check for condensation w/in wallsCheck WindowsNext TimeHeat TransmissionHVACCNST 305 Environmental Systems 1Dr. BerrymanTemperature GradientsThe temperature differential between two separate surfaces as heat transmits across them.A Proportional calculationUses IA OA TemperaturesR values PurposeDetermine surface temperatures•MRT•Dew PointDevelop Thermal Resistant ValuesAL Siding¼” USBR19 Batt3/8” Gyp BoardIA Air FilmOA Air Film21.37RTOTAL = 0.17 0.61 0.6619.00 0.32 0.61R valuesWall SectionNote: This is an actual construction in Grand IslandDetermine Design Temperatures (winter)AL Siding¼” USBR19 Batt3/8” Gyp BoardIA Air FilmOA Air Film 0.17 0.61 0.6619.00 0.3221.37 0.61RTOTAL =R valuesLincoln, NEOA –5oFIA 75oFt = 80oFCalculate GradientsLincoln, NEOA –5oFIA 75oFt = 80oFOA Air film:80oF x0.1721.37=0.6 oF 0.6121.37=AL Siding:80oF x 2.3 oF 19.021.37=80oF x71.1 oF R19 Batt:AL Siding¼” OSBR19 Batt3/8” Gyp BdIA Air FilmOA Air Film 0.17 0.61 0.6619.00 0.3221.37 0.61RTOTAL =R valuesAnd so forth…[ t x RRTOTAL]Surface TemperaturesLincoln, NEOA –5oFt = 80oFIA 75oFAL Siding¼” OSBR19 Batt3/8” Gyp BdIA Air FilmOA Air Film 0.17 0.6oF 0.61 2.3oF 0.66 2.5oF19.00 71.1oF 0.32 1.2oF21.37 80oF 0.61 2.3oFRTOTAL =R values GradientsHCGypsum Board Room Side Surface:75oF – 2.3 =72.7oF[ t x RSUM RTOTAL]IA -Surface Temps (cont.)Lincoln, NEOA –5oFt = 80oFAL Siding¼” OSBR19 Batt3/8” Gyp BdIA Air FilmOA Air Film 0.17 0.6oF 0.61 2.3oF 0.66 2.5oF19.00 71.1oF 0.32 1.2oF21.37 80oF 0.61 2.3oFRTOTAL =R values GradientsHCGypsum Board Wall Cavity Surface:75oF – (2.3+1.2) =71.5oFIA 75oFSurface Temps (cont.)Lincoln, NEOA –5oFt = 80oFAL Siding¼” OSBR19 Batt3/8” Gyp BdIA Air FilmOA Air Film 0.17 0.6oF 0.61 2.3oF 0.66 2.5oF19.00 71.1oF 0.32 1.2oF21.37 80oF 0.61 2.3oFRTOTAL =R values GradientsOSB Board Cavity Surface:75oF–(2.3+1.2+71.1)=0.4oFIA 75oFHeat Transmission-20o 10o 0o-10o 20o 30o 40o 50o 60o 70o 80oF TemperatureLincoln, NEOA –5oFIA 75oFAL Siding¼” OSBR19 Batt3/8” Gyp BdIA Air FilmOA Air Film 0.17 0.6oF 0.61 2.3oF 0.66 2.5oF19.00 71.1oF 0.32 1.2oF21.37 80oF 0.61 2.3oFRTOTAL =R values GradientsHCOSB Cav Side 0.4oFGyp Cav Side71.5oFOSB OA Side-2.1oFSiding Surface-4.4oFGyp Rm Side72.7oFApplication?Case StudyScenario:You have been called in as a consultant to find out why a certain building is having the following problems:•On the south side of the building, the sheathing is warping between studs•Same side…AL siding is popping loose•During the winter they occupants cannot keep the building any warmer than 65oF (in fact, some liquid items near the north facing wall have froze)•Also, at different point of time in the winter, all of the insulated double pane glass has frosted over on the inside•Snow has accumulated on the inside during heavy blustery snow storms•High electric bills for heating and coolingAt inspection, you see…North SideSiding warpsSiding pulled awayYou see…South SideSiding warps in and out every 16”You see…North Side WindowsYou note that the snow extends into the closetWall inspectionNothing behind AL siding but bare OSB sheathingR19 batt insulation not properly installedmmhhh…..Request Blower Door TestBlower Door TestA blower door is a large calibrated fan that is temporarily mounted in a house door to measure the "leakiness" of the houseSmoke pufferInfrared cameraCalculate room air changeA recreation of a 20 mph windYou discover…Air leaksAround doors and windowsBehind plumbing fixturesBetween sill plate and floorInfrared Shows air infiltrating around each insulation batt and at sill plateCalculations from pressure differentials133 CFM infiltration (ASHRAE recommends 10 cfm for residential)35 CFM ventilationYour Notes after InspectionHeating/Cooling sized correctlyYou sketch the wall constructionDetermine R valuesWallWindowIA conditions: DB=75oF WB = 56oFCalculation winter surface wall tempsWhat next?Check for condensation w/in walls-20o 10o 0o-10o 20o 30o 40o 50o 60o 70o 80oF TemperatureHeat Transmission and Exfiltration (ventilation)InfiltrationIA: DB=75oF WB = 56oFOA: DB=-5oFDP: 39oFDS GlassAir SpaceDS GlassIA Air FilmOA Air Film 0.17 0.01 1.00 0.01 0.611.8RTOTAL =R valuesLincoln, NEOA: –5oFt = 80oFIA:DB=75oF WB = 56oFCheck WindowsInside Surface Temperature?48oFW/30% RH DP=39oFWhat about 40% or 50% RHNext TimeHeat GainsChapter 2.6 – 2.8 (Toa)roofrooflightslightsequipmeequipmentntfloorfloorexteriorexteriorwallwallglass solarglass