Load Calculation, System Design, and Energy Code

Use ACCA Manual J to calculate sensible and latent heating and cooling loads from construction, insulation, glazing, orientation, and infiltration.

Account for major gains such as west-facing solar load rather than relying on square-foot rules of thumb.

Distinguish sensible load (temperature) from latent load (moisture removal) when sizing for comfort.

Select equipment with ACCA Manual S using expanded performance data at local design conditions to match the calculated loads.

Avoid oversizing, which causes short cycling and poor humidity control.

Design ducts with ACCA Manual D using available static pressure and friction rate to deliver each room's design CFM.

Use approximately 400 CFM per ton for typical residential cooling airflow.

Convert tonnage using 12,000 BTU/hr per ton when sizing equipment.

Apply the sensible heat formula, BTU/hr = 1.08 x CFM x delta-T, to verify delivered capacity.

Calculate duct velocity as CFM divided by cross-sectional area to control noise and friction.

Obtain a mechanical permit for installing, altering, or replacing regulated equipment and ductwork.

Demonstrate compliance with Title 24, Part 6 energy efficiency standards on new and altered systems.

Verify duct leakage and refrigerant charge as required, often confirmed by a HERS rater.