Manual J, S and D, explained for Florida permits.
Florida's energy code requires heating and cooling equipment to be sized with ACCA Manual S, based on loads from ACCA Manual J or another approved method, for the building's actual orientation. Manual D designs the ducts. Cooling equipment can't exceed 1.15 times the calculated total load, and designer safety factors aren't allowed.
- Code basis
- FBC Energy Conservation, 8th Ed. (2023)9th Ed. (2026) scheduled for Dec 31, 2026 · what changes1
- In this guide
- 4 sections + what each manual answersManual J: the load · Manual S: the equipment · Manual D: the ducts · What is different about Florida
- Reviewed by
- Designda Inc.Florida engineering firm license PE 39202 · verify
- Price
- $195 · $445 · $595Energy calc from · full package · sealed. Same in all 67 counties · price list
- Ready by
- 2–3 business daysExpedited: within 24 business hours, +$150. Clock starts when complete plans pass intake (3:00 PM ET cutoff) · how it works
- Evidence
- 7 primary sourcesCode sections and county checklists, numbered · references
Manual J: the load
Manual J calculates how much heat a house gains in summer and loses in winter, room by room. The code ties it to specific conditions: indoor design temperatures of no more than 72°F for heating and at least 75°F for cooling, outdoor conditions for the location, and the building's directional orientation.21 County outdoor design limits come from RESNET's Appendix A, based on ASHRAE and Manual J data; they range from 86°F cooling in Gulf County to 94°F in Duval, and from 27°F heating in Okaloosa to 55°F in Monroe.3
Keep reading1 more paragraph
The code is blunt about padding: it does not allow designer safety factors, provisions for future expansion or other factors that affect sizing, and the load may not include intermittent kitchen and bath exhaust.1
Manual S: the equipment
Manual S picks equipment against the Manual J loads using the manufacturer's expanded…
Manual S picks equipment against the Manual J loads using the manufacturer's expanded performance data at the design conditions, not the AHRI nominal rating, which the code says shall not be used for sizing.1 Cooling equipment's total capacity must be at least the calculated total load and no more than 1.15 times it, or the closest available size; latent capacity can't fall below the latent load.1 For heat pumps, the 1.15 ceiling on cooling capacity holds even when the heating load is larger.1
The permit submittal has to show the outdoor and indoor model numbers and the sensible and total capacities at design conditions.1 Pasco County, for one, asks for Manual J and Manual S data on every new A/C installation.4
Manual D: the ducts
Florida's residential code says duct systems shall be installed according to ACCA Manual D,…
Florida's residential code says duct systems shall be installed according to ACCA Manual D, the appliance manufacturer's instructions or other approved methods.5 Some counties ask for it by name: St. Johns County's checklist lists Manual J and D with the energy forms.6 Ducts outside the envelope must also be tested; on a rough-in test the prescriptive limit is 4 cubic feet per minute per 100 square feet of conditioned floor area.1
What is different about Florida
In our experience, the latent load is what separates a Florida Manual J from a generic one.…
In our experience, the latent load is what separates a Florida Manual J from a generic one. Every county is warm-humid in Table R301.1, so a system that meets the sensible load but not the latent load leaves a cold, clammy house.7 North of Ocala the opposite problem appears: heating design temperatures in the 20s and low 30s make heat-pump capacity at design a real check, not a footnote.3
What each manual answers
3 rows · Question vs Code hook vs What the reviewer looks for
| Question | Code hook | What the reviewer looks for | |
|---|---|---|---|
| Manual J | How much heating and cooling does the house need? | R403.7.1 | Orientation, design temps within county limits, no safety factors |
| Manual S | Which equipment meets those loads? | R403.7.1, R403.7.1.1 | Model numbers, capacities at design, ≤ 1.15× total cooling load |
| Manual D | How should ducts deliver the air? | FBC-R M1601.1 | Duct sizes and layout; duct leakage test result at rough-in or final |
Questions
3 answers · Is a Manual J required for an A/C change-out in Florida?
Is a Manual J required for an A/C change-out in Florida?
The energy code requires new or replacement equipment to be sized per Manual S based on Manual J or an approved method, but what each county asks to see differs. Pasco, for example, wants only an AHRI certificate for a change-out and Manual J and S for a new installation.
Can I size A/C by square feet per ton in Florida?
No. The code requires sizing by ACCA Manual S based on Manual J or another approved calculation for the house's orientation, and it rules out safety factors. Rules of thumb like 500 square feet per ton routinely oversize Florida homes, which hurts dehumidification.
What is the 1.15 rule for Florida A/C sizing?
Cooling equipment's total capacity must be at least the calculated total cooling load and no more than 1.15 times it, or the closest size the manufacturer makes. Latent capacity can't be below the latent load. The 1.15 cap also applies to a heat pump's cooling capacity when heating loads are larger.
County requirements and related guides
Sources
7 primary references · numbered to match the citations
- 012023 Florida Building Code, Energy Conservation (8th Ed.), Chapter 4 [RE]: R401–R406up.codes
- 022023 Florida Building Code, Energy Conservation (8th Ed.), Chapter 3 [RE]: R302.1 interior design conditionsup.codes
- 03RESNET / ENERGY STAR, Appendix A: HVAC Design Temperature Limits by State and County (v4, 2019). 1% cooling and 99% heating values drawn from the ASHRAE 2013 Handbook of Fundamentals and ACCA Manual J 8th Ed.resnet.us
- 04Pasco County, Permit Submittal Requirements: Residential Air Conditioning Units (PDF)cms1files.revize.com
- 052023 Florida Building Code, Residential (8th Ed.), Chapter 16: M1601.1 Duct Designup.codes
- 06St. Johns County Building Department, Residential Sufficiency Checklist (PDF, 2026)sjcfl.us
- 072023 Florida Building Code, Energy Conservation (8th Ed.), Table R301.1, climate zones by countyup.codes