Residential heating and cooling loads
Manual J load calculations, room by room.
The Manual J is the number every other decision rests on. We calculate the heating and cooling load of every room from your plans, your orientation and your climate, so the equipment and ducts that follow are sized to the house, not to a rule of thumb.
What it is
ACCA Manual J, 8th edition, is the residential load calculation standard referenced by the International Residential Code. It adds up heat gain and heat loss through every wall, window, ceiling, floor and duct run, plus people, appliances, infiltration and humidity.
Because it is room by room, the result is more than a tonnage. It tells your installer how much air each room needs, which is what Manual D uses to size the ducts.
When you need it
Most building departments that follow the IRC ask for it. Section M1401.3 requires heating and cooling equipment to be sized with Manual S, based on loads calculated with Manual J or another approved method. Many jurisdictions will not issue a mechanical permit without it.
What we need from you
- A dimensioned floor plan
- Elevations and wall sections, if you have them
- Window schedule or sizes and types
- Insulation values for walls, ceiling and floor
- Project address, so we use the right design weather
- Our short project questionnaire (we send it)
What you receive
- Room-by-room heating and cooling loads
- Whole-house sensible and latent totals
- Design conditions and assumptions, stated plainly
- A report formatted for plan review
“We had a new residential build about 3900 sq’. We called several places and nobody got back to us. Our first call to them they picked up, I explained the situation, they sent me the questionnaire and were quick to help us walk through the entire form patiently. Once we had all the info filled out they had the Manual J back to us within a day.”
Questions
Is a Manual J required for my permit?
In most places that adopt the IRC, yes, for new systems and new construction. Requirements for equipment replacement vary. Tell us the jurisdiction and we will tell you what they typically ask for, then confirm it with the building department if needed.
What if I do not know every insulation value?
Send what you have. If something is unknown we use documented code-minimum defaults and note them, so the job keeps moving and the assumptions are visible to the plan reviewer.
Can you do a Manual J for an existing home or a replacement?
Yes. Replacements are where rule-of-thumb sizing does the most damage. We work from a sketch, photos and measurements when there are no plans.
Same-day quotes
Drop the plans. Get a quote today.
Drop in the plan set and pick your services. A designer replies with price and turnaround, usually within 30 minutes during business hours.