ManualJ Lite

ManualJ Lite is a fast, offline heating and cooling load estimator for houses. Enter the building, pick the climate zone, and read the cooling load, the heating load and the equipment size in seconds.

WHAT IT CALCULATES

Cooling load (BTU/h), itemised:
- Walls, ceiling, window conduction and window solar gain
- Internal gains, ventilation and infiltration
- Tons, and the next nominal size at or above the load

Heating load (BTU/h), itemised:
- Walls, ceiling and windows
- Ventilation and infiltration

INPUTS

- 8 IECC climate zones and 16 California Title 24 climate zones, with outdoor design temperatures you can edit for your location
- Separate indoor setpoints for cooling and heating
- Floor area, ceiling height, window area and occupants
- Wall and ceiling insulation, selected separately
- Window type, or the U-factor and SHGC from the NFRC label

DOCUMENTED SIZING REPORT (IN-APP PURCHASE, PER REPORT)

A clean, signable PDF of the estimate for proposals, customer files and job folders: every input, each load component, the formulas with your numbers substituted, where the design temperatures come from, and signature lines. Preview the whole report before you buy. A purchased report can be exported again for the same house at no extra charge.

GOOD TO KNOW

- This is a simplified whole-house block load on a single-storey, square footprint. It is not ACCA Manual J and the report is not a permit document. Where a permit, rebate programme or certification requires ACCA Manual J, use ACCA-approved software.
- Not calculated: basement, slab and floor losses; duct gains and losses.
- Works completely offline. No account or login required.