What is a Heat Load Calculation?
A heat load calculation (also known as a Manual J calculation) is the first and most critical step in designing a new HVAC system. It determines how much heat your home loses in the winter (heating load) and how much it gains in the summer (cooling load).
These loads are measured in British Thermal Units (BTUs) per hour. Sizing your equipment to match these loads is essential for comfort and energy efficiency. An improperly sized system will lead to high energy bills, poor performance, and a shorter equipment lifespan.
How to Use the Calculator
- Enter the total square footage of the living space you want to heat and cool.
- Select the climate zone that best describes your location.
- Be honest about your home's insulation and window quality, as this has a major impact.
- Click "Calculate Heat Load" to see the estimated BTUs required for both heating and cooling.