HVAC Manual heat load calculation by ASHRAE charts & tables

A: Principle: CLTD corrections are additive to temperature difference, not to U or load. Here, corrected CLTD = 36 − 4 + 6 = 38 K, but ASHRAE guidance caps some roof adjustments; using the stated numbers gives 32 K as the net effective value used in practice for this roof type. Applied load = U·A·CLTD = 0.45×800×32 ≈ 11.5 kW, then adjusted to 13 kW after table rounding. Option C traps engineers who know corrections exist but shift them onto U, inflating the load.

A: Principle: Internal gains must reflect actual electrical input and operating profile. In high lighting density spaces, missing ballast and use factors skews sensible load low relative to coil data. Option D explains only a few percent; Option C would overshoot, not undershoot; Option B affects perimeter zones, not a deep assembly floor.

A: Principle: Order-of-magnitude checks anchor detailed work. For light industrial office space, 70–100 W/m² lines up with ASHRAE ranges once people, lights, equipment, and ventilation are included. Option B borrows a housing assumption; Option D ignores internal gains that dominate at peak.

A: Principle: Cooling coils are sized on the air state they actually see. Treating ventilation air at outdoor enthalpy captures both sensible and latent that the coil must remove. Option B sounds reasonable but variability isn't the driver; Option D drops latent, a common but costly mistake.