Manual J software
Manual J software that gives you room-by-room loads without a designer
Manual J software calculates the heating and cooling load of a home, room by room, using the ACCA Manual J method: design temperatures, wall, window and ceiling areas, insulation, air leakage and internal gains. Tradewright runs the Manual J calculation from a LiDAR scan or plan, so your salesperson gets engineered loads during the visit.
Heating design load
38,400
BTU/h at 2°F outdoor, 70°F indoor
Cooling
24,500
BTU/h · 2.0 tons
How a Manual J calculation works in Tradewright
The calculation is deterministic: the same inputs always give the same loads, and you can see every one of them.
Step 1: Capture the house
Scan with LiDAR or upload a plan. Rooms, wall lengths, windows, doors and ceiling heights come into the model, and you can correct any of them.
Step 2: Confirm the envelope
Set insulation levels, window types and air tightness for the house. Defaults are shown, never hidden, so you know what was assumed.
Step 3: Apply design conditions
Outdoor design temperatures for the location and your indoor setpoints are applied to every room.
Step 4: Get room-by-room loads
Heating and cooling loads are calculated for each room and the whole house, in BTU/h, with sensible and latent cooling split out.
Step 5: Share the report
Export a Manual J report that lists the assumptions behind each number, for your designer, a rebate program or an inspector.
Who uses Tradewright for Manual J
Comfort advisors
Run an engineered load during the visit, without design training and without waiting on the office.
Designers and technical leads
Review every input and result instead of redoing the calculation from scratch.
Heat pump contractors
Size cold-climate heat pumps on the real design-day load, not on the old nameplate.
Rebate-driven jobs
Produce the load documentation that programs such as NYS Clean Heat and Mass Save ask for.
Boiler and radiator homes
Calculate room heat loss for hydronic and steam homes, not just ducted systems.
Manual J in Tradewright vs the alternatives
| Rules of thumb | Load-calc-only tools | Tradewright | |
|---|---|---|---|
| Room-by-room loads | No | Yes | Yes |
| Geometry from a LiDAR scan or plan | No | Some | Yes |
| Every input visible and editable | No | Yes | Yes |
| Done during the sales visit | Yes | Some | Yes |
| Feeds equipment selection and the proposal directly | No | Some | Yes |
| On ACCA's approved Manual J software listSee the FAQ below | No | Some | Not yet |
Columns describe software categories and common practice, not specific vendors. See our dated comparison of named load calculation products for details.
Questions
What is a Manual J calculation?
Manual J is the ACCA method for calculating a home's heating and cooling loads. It uses the outdoor design temperatures for the location, the size and construction of walls, windows, ceilings and floors, air leakage, and internal gains to find how many BTU/h each room needs on a design day.
Is Tradewright ACCA-approved?
Not yet. Tradewright is not on ACCA's list of approved Manual J software. Our load calculations follow the ACCA Manual J (8th edition) and Manual S methods, every input is visible, and reports show the assumptions behind each number. We plan to apply for ACCA approval in 2028 and will update this answer when that status changes.
Does Tradewright calculate loads room by room or for the whole house?
Both. Tradewright calculates heating and cooling loads for every room and totals them for the whole house. Room loads matter for duct and radiator sizing and for placing mini-split heads.
Where do the inputs come from?
Geometry comes from a LiDAR scan on an iPhone Pro or iPad Pro, or from an uploaded plan. Construction details such as insulation and window type are set by your team, with visible defaults you can change.
Can I check or change the numbers?
Yes. Every input is visible and editable, and the report shows the assumptions behind each load. The calculation is deterministic, so the same inputs always give the same result.
How is this different from a free online Manual J calculator?
Free calculators, including ours, give a whole-house estimate from a few inputs. They are useful for a first look but are not a substitute for a room-by-room Manual J. Tradewright calculates each room from measured geometry.
Can I use the Manual J report for rebates?
Tradewright generates a Manual J report from the design that you can include with rebate documentation. Check each program's current requirements; our NYS Clean Heat and Mass Save guides summarize them.
Related tools and guides
See a room-by-room Manual J run on a real home.
A 20-minute demo on a house in your territory.