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The heating factor for the surfaces in the zone shall be calculated using Equation C-16.
(C-15)
where
HLU = Areaopaque × Uow × [HU1 × HDD50 + HU2 × (VS × HDD65)2]
HLUO = Areagrosswall × UO × [HUO1 × HDD50 + HUO2 × HDD65 + HUO3 × EAH × VS × HDD65]
HLXUO = Areagrosswall × {(1/UO) × [HXUO1 × EAH × (VS × HDD50)2 + HXUO2 × EAH × (VS × HDD65)2] + (1/UO2) × [HXUO3 × EAH2 × VS × HDD65]}
HLM = Areaopaque × SHMC × [HM1 + HM2 × G × UO × HDD65 + HM3 × G2 × EAH2 × VS × HDD50 + HM4 × UO × EAH × VS × HDD65 + HM5 × UO × HDD50 + HM6 × EAH × (VS × HDD65)2 + HM7 × EAH2 × VS × HDD65/UO]
HLG = Areagrosswall × {G × [HG1 × HDD65 + HG2 × UO × HDD65 + HG3 × EAH × VS × HDD65 + HG4 × EAH2 × VS × HDD50] × G2 × [HG5 × HDD65 + HG6 × EAH2 × VS × HDD65]}
HLS = Areagrosswall × {EAH × [HS1 × VS × HDD65 + HS2 × (VS × HDD50)2] + EAH2 × [HS3 × VS × HDD50 + HS4 × VS × HDD65]}
HLC = Areagrosswall × [HC1 + HC2 × HDD65 + HC3 × HDD652 + HC4 × VS2 + HC5 × VS × HDD50 + HC6 × VS × HDD65 + HC7 × (VS × HDD50)2]

where
VS = annual average daily incident solar energy on surface
SHMC = sum of the HMC from Equation C-12 for each mass wall in the zone
EAH = effective solar aperture fraction for zone calculated using Equation C-17.
(C-17)
ΣSAh = the sum of SAh from Equation C-7 for all vertical fenestration in the zone.
The coefficients used in the above equations depend on the orientation of the surface and shall be found in Table C6.8.3. Terms not defined for Equation C-16 are found under Equation C-14.

TABLE C6.8.3
Heating Coefficients for the Exterior Wall Equation
Variable Orientation of Surface
North East South West
 
HU1 0.006203 0.007691 0.006044 0.006672
HU2 —1.3587E-12 —5.7162E-13 —2.69E-13 —4.3566E-13
HM1 0.531005 0.545732 0.837901 0.616936
HM2 0.000152 0.000107 0.000208 0.00015
HM3 —5.3183E-07 —1.0619E-07 —6.8253E-07 —2.6457E-07
HM4 —7.7381E-07 —1.4787E-06 2.11938E-06 —4.5783E-07
HM5 —0.000712 —0.000484 —0.001042 —0.000625
HM6 3.34859E-13 4.95762E-14 7.7019E-14 7.37105E-14
HM7 2.39071E-07 2.75045E-07 —3.8989E-07 0
HUO1 0.004943 0.008683 0.009028 0.008566
HUO2 0.013686 0.011055 0.010156 0.01146
HUO3 —1.1018E-05 —8.6896E-06 —7.3232E-06 —8.9867E-06
HXUO1 1.2694E-12 7.85644E-14 —2.8202E-13 3.04904E-14
HXUO2 —7.3058E-13 —8.109E-14 7.45599E-14 —7.4718E-14
HXUO3 1.9709E-07 1.94026E-07 9.87587E-08 1.95776E-07
HG1 —0.001051 —0.000983 —0.000981 —0.000948
HG2 —0.001063 —0.00093 —0.000815 —0.000975
HG3 2.99013E-06 2.62269E-06 2.4188E-06 2.49976E-06
HG4 7.49049E-07 —1.1106E-06 —2.1669E-06 —8.5605E-07
HG5 0.000109 0.000093431 9.75523E-05 8.62389E-05
HG6 —5.5591E-07 —3.158E-07 —2.61E-07 —2.9133E-07
HS1 —2.1825E-05 —2.0922E-05 —2.1089E-05 —2.0205E-05
HS2 3.39179E-12 1.905E-12 1.48388E-12 2.18215E-12
HS3 —6.5325E-06 —2.2341E-05 —1.8473E-05 —2.4049E-05
HS4 2.23087E-05 2.41331E-05 2.45412E-05 2.30538E-05
HC1 —0.106468 —5.19297 —3.66743 —5.29681
HC2 0.00729 0.007684 0.007175 0.007672
HC3 —2.976E-07 —3.0784E-07 —2.6419E-07 —3.0713E-07
HC4 2.01569E-06 6.3035E-06 3.32112E-06 6.43491E-06
HC5 1.29061E-05 4.77552E-06 3.25089E-06 4.83233E-06
HC6 —1.2859E-05 —6.1854E-06 —4.6309E-06 —6.251E-06
HC7 2.75861E-12 8.20051E-13 4.38148E-13 8.09106E-13

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