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Manual J load calc + branded client PDF — in 90 seconds.

Built on ACCA Manual J procedures. Sonnet 4.6 orchestrates, deterministic code runs the numbers. Every result cites the table it came from.

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Worksheet / Manual J · #BS-2026-0001

Project2,000 sqft warehouse

LocationHouston, TX 77002

Climate zoneIECC 2A · hot-humidASHRAE 169

Date2026-05-12

Prepared byBuildSolver

ACCA MJ8 · Table 1A — Design conditions

Outdoor DB (1% cooling)96 °FMJ8 T.1A

Outdoor WB77 °FMJ8 T.1A

Indoor DB75 °F

Indoor RH50 %

ΔT cooling21 °F

ACCA MJ8 · Table 4A — Sensible envelope loads

Walls (R-19, 1,840 ft²)8,420 BTU/hMJ8 T.4A

Roof (R-30, 2,000 ft²)11,200 BTU/hMJ8 T.4A

Windows (U-0.32, 80 ft²)3,180 BTU/hMJ8 T.3D

Doors (insulated, 42 ft²)680 BTU/hMJ8 T.4A

Infiltration (0.35 ACH)2,950 BTU/hMJ8 § A4-2

Internal gain (electronics)6,000 BTU/hMJ8 T.5C

Latent (ventilation)5,970 BTU/hMJ8 § A4-4

Q_{total} = i \sum (U_{i} \cdot A_{i} \cdot Δ T) + Q_{inf} + Q_{gain} + Q_{lat}

Cooling load · ACCA MJ8 § 6.4

38,400BTU/hr(3.2 ton)

For estimation onlyNot permit-grade. Consult licensed engineer for final design.

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Sensible total32,430 BTU/h

Latent total5,970 BTU/h

Sensible heat ratio0.84

Recommended capacity38,400 BTU/hMJ8 § 6.4

Nominal tonnage3 - 3.5 ton

Equipment selectionManual S, separate stepACCA Manual S

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Worksheet legend

How to read this.

Header

Project name, address, climate zone, date. Same fields a senior engineer would write on the title block of a hand-drawn Manual J.

Tables & citations

Every row points at the ACCA table it came from. Tap the orange tag to see the section. No "trust me, the AI knows."

Stamp

BuildSolver is sales-grade. The orange stamp tells your AHJ this is preliminary — for permits, use Wrightsoft.

Tools, not guesses

HVAC, end to end. Canonical formulas. Cited tables.

Claude orchestrates the conversation. A library of deterministic calculators returns the number, the formula, and the citation. The math stays canonical; the AI only routes and explains. Design temperatures, IECC adoption, and licensing context are pre-loaded per state — see Manual J for Florida or Manual J for Arizona for hot-climate examples.

ACCA MJ8

Load calc

Residential cooling and heating loads with design conditions auto-fetched from ASHRAE 2021 tables. Sensible / latent split per Manual J §6.

ACCA MS

Equipment selection

Air conditioners, heat pumps, furnaces, dual-fuel. Sensible / latent gating, balance point, aux heat. Manual S 2nd edition.

ACCA MD

Duct sizing

Trunk and branch sizing, friction-rate selection, total external static pressure check. Simplified for sales-phase quotes.

ASHRAE Fund

Psychrometrics

Wet/dry bulb, dew point, humidity ratio, enthalpy. Refrigerant-cycle and IAQ inputs from a single state-point call.

Behind the worksheet

The conversation that produced it.

BuildSolver asks the same clarifying questions a senior engineer would. Three messages from a sentence to a citation-ready load. The Houston example below uses ASHRAE design temps from Manual J for Texas.

>HVAC load for a 2,000 sqft warehouse in Houston. R-19 walls, R-30 roof, low internal gain.
BuildSolver
What is stored inside? It changes the internal gain assumption — electronics stay cool, machinery does not.
>Electronics storage. Two roll-up doors on the east wall.
BuildSolver · 14 sec
Total cooling load: 38,400 BTU/hr (≈ 3.2 ton). Sensible 32,430 / latent 5,970. Per ACCA Manual J § 6.4 — full breakdown in the worksheet above.
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Speed delta

Excel: 30 minutes. BuildSolver: 90 seconds.

For permit submissions Wrightsoft is the right answer. For sales calls and client quotes, the math is the same and 30 minutes is too long.

Step	Excel + Word	BuildSolver
Setup time	30–45 min	90 sec
Climate-zone lookup	Look up by hand	Auto from address
Citation of ACCA tables	If you remember	Auto
Mobile on the truck	Painful	First-class
Branded client PDF	Build in Word	One click
Permit-grade Manual J	No	No — use Wrightsoft

Common use cases

Where BuildSolver fits each job type.

Four guides covering the most common HVAC sizing scenarios. Each one walks through a concrete project example, comparison with the alternative tool, and FAQs.

Retrofit

Sized from a description — no blueprint required.

For replacement and upgrade jobs that never had original drawings. Describe what you see on site; get the Manual J.

Read →

Replacement

Brand-agnostic AC replacement sizing.

Same Manual J procedures as Carrier HAP, without the brand lock. Mobile-first.

Read →

New construction

Preliminary Manual J at design-development.

Numbers for framing decisions before drawings are stamped. Iterate as the spec firms up.

Read →

Permit

When does AHJ actually require a stamped Manual J?

Honest guide to the line between sales-phase sizing and permit-grade Manual J.

Read →

All guides →

Manual J by state

Load calc pages with local ASHRAE design temps.

State-specific Manual J pages with top-metro design temperatures, IECC adoption, and HVAC contractor licensing context already applied to the defaults.

View all states →

Straight answers

Questions careful contractors ask.

Is this permit-grade Manual J?

No. BuildSolver is sales-grade for preliminary sizing and client quotes. For permit submission to your AHJ, use ACCA-approved software such as Wrightsoft Right-J.

Which standards does BuildSolver follow?

ACCA Manual J 8th edition for residential loads, ACCA Manual S for equipment selection, ACCA Manual D for duct sizing, ASHRAE Fundamentals 2021 for psychrometrics. Each calculation cites the table or section it came from.

Can I trust the numbers?

The arithmetic runs in deterministic code, not the language model. The same canonical formulas your textbook uses. The AI orchestrates the conversation and explains the result; it does not invent values.

Can I put my logo on the PDF?

Yes, on the Pro and Team plans. Upload your logo, license number, and contact info once. Every quote PDF uses them.

What is free vs Pro?

Free gets you a daily limit of calculations so you can try the product. Pro at $29 per month (or $290 per year — two months free) adds branded PDFs, unlimited calculations, and saved project history. Team at $79 per month ($790 per year) adds shared workspaces.

What about electrical, structural, or plumbing?

BuildSolver is HVAC-only. We chose depth over breadth — Manual J / S / D, psychrometrics, refrigerant cycle, ventilation. Other disciplines are not on the roadmap until the HVAC suite is complete.

Calculate your next quote in 90 seconds.

Describe the building. Get an ACCA-cited load and a branded client PDF. Free to try — no signup.

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