Design Criteria for Manual J Calculations

Elevation Below 7,400 Feet Above 7,400 Feet
Latitude  39 degrees North  39 degrees North
Winter Heating 99% Dry Bulb   -7°  -11°
Summer Cooling 1% Dry Bulb 95°   90°
Coincident Wet Bulb 59° 59°
Design Grains difference at 50% Relative Humidity  -39° to -45°  -39° to -45°
Daily Range High (H) High (H)
Relative Humidity 50% winter and summer 50% winter and summer
Indoor Design Temperature Heating 72° 72°
Indoor Design Temperature Cooling 75° 75°
Heating Temperature Difference  79° 83°
Cooling Temperature Difference 20° 15°

Solar Heat Gain Coefficient (SHGC): While not required for windows in Climate Zone 7, the SHGC is still required data for Manual J calculations. SHGC should be taken directly from the sticker on the glass. If not known, either use default as per Table 102.1.3(3) of the 2009 IECC or equation SHGC equals 0.87 multiplied by the Shading Coefficient under19-23 of Manual J.

Altitude Correction Factor (ACF): Site-specific to elevation

Wind Velocity Values: 15 miles per hour for Heating and 7.5 miles per hour for Cooling