Manual J prepared for you.
ACCA-approved residential heat load calculations. Overnight service available. Made in the USA.
What is Manual J?
A Manual J is a standardized residential load calculation method developed by the Air Conditioning Contractors of America. HVAC contractors use it to determine the correct heating and cooling capacity (size) needed for a home.
Instead of sizing an air conditioner or furnace based only on square footage, a Manual J calculation considers factors such as:
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Home size and layout
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Insulation levels
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Window size, type, and orientation
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Local climate
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Air leakage and ventilation
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Number of occupants
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Appliances and lighting that generate heat
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Ceiling heights and room-by-room conditions
​A correct Manual J is the foundation of right-sized equipment, lower utility bills and happier homeowners. It's also required by most building departments before a permit is issued.
Why it Matters
A proper Manual J helps prevent installing equipment that is:
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Too large: short-cycles, wastes energy, and may not remove humidity effectively.
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Too small: struggles to maintain comfortable temperatures during extreme weather.
What you get
The calculation typically provides:
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Total cooling load (BTU/hr)
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Total heating load (BTU/hr)
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Room-by-room load requirements
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Those results are then used with Manual S (equipment selection) and Manual D (duct design) to design the HVAC system correctly.​
Example
A 2,000 sq. ft. home might need:
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24,000 BTU/hr (2 tons)
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36,000 BTU/hr (3 tons)
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Or more/less depending on insulation, windows, and climate.
That's why square footage alone is not a reliable sizing method.
If you're replacing or installing HVAC equipment, asking your contractor for the Manual J report is generally considered a best practice.
What we need to prepare your Manual J
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Floor plans for every level (including basement, if applicable)
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Address of the property
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Measurement of each room and outside walls
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Measurement of all windows and doors
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Known insulation R-values of walls
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Location of equipment and ductwork — basement, conditioned space, attic, garage, etc. If we have to assume, we'll assume worst case
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Email all these to Info@HeatLoadUSA.com
Why HeatLoad USA?
Since 2008, we've prepared thousands of Manual J reports for HVAC contractors and builders across all 50 states. Our reports are accurate, code-compliant and accepted by building departments nationwide.
Certified by ACCA we are one of the few firms qualified to prepare both residential (Manual J) and commercial (Manual N) load calculations.