Manual J Load Calculation
An HVAC engineering calculation sizing equipment to a home's heating and cooling needs.
Definition
A Manual J load calculation is the ACCA-standard methodology for determining the exact BTU heating and cooling load of a home based on square footage, insulation, windows, orientation, and climate.
In plain English
Required by most modern codes before installing new HVAC equipment. Rule-of-thumb sizing produces oversized, inefficient systems.
Example
Before installing a new heat pump, the HVAC contractor runs a Manual J that shows the home needs 2.5 tons of cooling, not the 4 tons currently installed.
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