Calculate the home’s heating and cooling load
Measure the square footage of the space
Account for ceiling height and room volume
Consider insulation levels in walls, attic, and floors
Evaluate window size, type, and orientation
Check air leakage and home tightness
Factor in local climate and design temperatures
Include occupancy, appliances, and internal heat gains
Assess ductwork size, condition, and layout
Determine required BTU capacity for heating
Determine required tonnage for cooling
Use Manual J load calculation for accuracy
Use Manual S to match equipment to the load
Use Manual D for duct sizing if needed
Compare multiple system options and efficiencies
Have a licensed HVAC professional verify the sizing