Opaque-Envelope Conduction Cooling Load (Sol-Air CLTD)

U x area x the sol-air CLTD, which for a dark roof in summer can run 70 F or more against a 95 F design day because the sun heats the surface well above the air. Dropping the surface's solar absorptance with a reflective cool-roof membrane cuts the load far more than the air temperature would suggest - the entire case for a cool roof in one comparison. The U-factor is the whole-assembly value; the CLTD is from the ASHRAE/ACCA table. One Manual J component, not the stamped load sheet.

q_cond = u_factor x area_ft2 x cltd_f.

ASHRAE / ACCA Manual J opaque-envelope cooling load (Q = U x A x CLTD, the CLTD being the sol-air cooling-load temperature difference), by name; the relation is public.

The opaque-envelope conduction cooling-load relation is a public ASHRAE / ACCA Manual J equation; the U-factor is the whole-assembly value.

Estimate. AHJ and licensed professional govern.

Field names used by the API: area_ft2, u_factor, cltd_f, q_cond

• Conduction Q = U x area x the sol-air CLTD; the sol-air CLTD, not the air temperature, conducts through a sunlit surfaceASHRAE / ACCA Manual J
• Cool roof cutting the surface's solar absorptance drops the CLTD and the load far more than the air temperature would suggestfirst principles
• Component only one envelope line of a cooling load, not the whole Manual Jfirst principles