Infiltration Heating / Cooling Load (Sensible + Latent)

Sensible Qs = 1.08 x cfm x delta-T and latent Ql = 0.68 x cfm x delta-grains, from the natural infiltration cfm a blower-door test produces. In cooling the latent half (the moisture the leaking air drags in) is nearly as large as the sensible, which is why air-sealing pays back on both design days. The 1.08 and 0.68 are sea-level standard-air constants. The infiltration component only, not a stamped Manual J.

q_sensible = 1.08 x cfm x delta_t_f; q_latent = 0.68 x cfm x delta_gr; q_total = q_sensible + q_latent.

ASHRAE Handbook of Fundamentals air-side sensible (q_s = 1.08 x Q x dT) and latent (q_l = 0.68 x Q x dW_gr) equations, by name; the 1.08 and 0.68 are the sea-level standard-air constants.

The air-side sensible and latent equations are public ASHRAE Fundamentals relations; the 1.08 and 0.68 are standard-air constants.

Estimate. AHJ and licensed professional govern.

Field names used by the API: cfm, delta_t_f, q_sensible, q_latent, q_total

• Sensible q_sensible = 1.08 x cfm x design dry-bulb delta-T (the 1.08 = 60 x rho x cp at sea-level standard air)ASHRAE Fundamentals
• Latent q_latent = 0.68 x cfm x humidity-ratio difference in grains/lb (zero for heating, so the term drops out)ASHRAE Fundamentals
• Component only the infiltration line of the design load, not the whole Manual Jfirst principles