Heat LossHeating Load ComponentsDesign TemperaturesDesign Weather DataConduction Heat LossesRates of Heat TransferAir SpacesDetermining RatesHeat Loss CalculationDegree DayFloors – Slab on GradeBasementsPier & Beam (crawl space)Other Heat LossesSample Heat Load FormAssignmentNext TimeHeat LossHVACCNST 305 Environmental Systems 1Dr. BerrymanHeating Load ComponentsroofroofexteriorexteriorwallwallglassglassconductionconductionfloorfloorInfiltration Infiltration and and VentilationVentilationpartitionpartitionwallwallDesign TemperaturesInside   OutsideDesign Weather DataSt. Louis,MissouriSt. Louis,MissouriDBDBDBDB99.6%99.6%99%99%2°F[-16.7°C]2°F[-16.7°C]8°F[-13.4°C]8°F[-13.4°C]1997 ASHRAE Handbook–Fundamentals, Chapter 26St. Louis,MissouriSt. Louis,MissouriDB WBDB WBDB WBDB WBDB WBDB WB0.4%0.4%1%1%2%2%95°F[35°C]95°F[35°C]76°F[25°C]76°F[25°C]93°F[34°C]93°F[34°C]75°F[24°C]75°F[24°C]90°F[32°C]90°F[32°C]74°F[23°C]74°F[23°C]SummerWinterConduction Heat LossesBH = U  A  TRates of Heat TransferAir SpacesDetermining Ratesthermal resistance (R)outdoor-air filmAL siding (hollow back)8” LW concrete blockR13 insulation board½”gypsum boardindoor-air filmTable 2-2 (Toa)Table 2-3Table 2-4Heat Loss CalculationEXAMPLEUsing wall section:Winter Design: 10oF DBIndoor Design: 75oF100’ long; 10’ highDetermine Heat LossDegree DayHeating load is proportional to the temperature difference between 65oF and the average daily winter outdoor temperature.•Example: Omaha, NE65oF - -8oF = 73 degree daysWinter Design = -8oF w/ 6612 degree days**From ASHRAE Handbook of Fundamentals6612/73 = 90.6 heating days90.6 x 24hrs = 2174 heating hours/yearFloors – Slab on GradeMild ColdClimatic ConditionsBasementsHeated basements:Unheated basements•Use 50oF for OA design temperature•Calculate R-values through floorNote: Any exposed wall above grade has to be calculated a different wall sectionPier & Beam (crawl space)Same as wall/roofUse Design OA temperaturesCalculate R-values through floorUse OA Design TemperatureOther Heat LossesWallRoofFloorWindowsDoorsInfiltrationVentilationBTUH TotalSample Heat Load FormAssignmentWall SectionSketch (on graph paper)•Show in one section: roof, wall, floor•Provide dimensions, material call-outsDetermine rates of heat transfer•R values of each construction•R Total•U valueDetermine indoor/outdoor design temperaturesNext TimeHeat TransmissionCondensationVapor