Heartland: energy calcs & Manual J.
Six rural counties, one zone-1A outlier, and Florida’s highest mobile-home share.
These six inland counties share 90–91°F cooling design limits and 41–44°F heating limits, so sizing is a cooling and moisture problem everywhere here. Hendry is the exception on paper: it sits in climate zone 1A while its five neighbours are 2A, which changes the prescriptive baselines on an R402 or R405.
- Counties
- 6 countiesDeSoto, Hardee, Highlands, Glades, Hendry and Okeechobee
- Departments
- Each county’s ownSeveral cities run their own · what we publish
- Code edition
- FBC Energy Conservation, 8th Ed. (2023)9th Ed. (2026) scheduled for Dec 31, 2026 · what changes
- 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
DeSoto, Hardee, Highlands, Glades, Hendry and Okeechobee
Per-county table6 counties · zone, design °F, permits, housing
| County · stations | Zone | Design °F | Permits | Median built | Single-family | Mobile | Electric heat |
|---|---|---|---|---|---|---|---|
| HighlandsCharlotte County (ASHRAE) | 2A | 91° / 41° | 706 #35 | 1987 | 59.8% | 24.2% | 93.1% |
| HendryBelle Glade (Manual J) | 1A | 91° / 44° | 464 #39 | 1991 | 57.9% | 32.5% | 90.2% |
| DeSotoCharlotte County (ASHRAE) | 2A | 91° / 41° | 159 #46 | 1990 | 48.7% | 31.8% | 89.0% |
| GladesBelle Glade (Manual J) | 2A | 91° / 44° | 98 #50 | 1990 | 40.9% | 54.0% | 91.1% |
| HardeeLakeland City Office (Manual J) | 2A | 91° / 41° | 86 #54 | 1987 | 57.7% | 27.1% | 89.6% |
| OkeechobeeSt Lucie County Intl. (ASHRAE) | 2A | 90° / 41° | 68 #55 | 1988 | 51.0% | 38.9% | 92.4% |
What it means for sizing
2 paragraphs · design temperatures, housing stock, equipment
Hendry is the only county in this group in zone 1A; DeSoto, Hardee, Highlands, Glades and Okeechobee are all 2A.1 Glades and Hendry both take their limits from the Belle Glade station, 91°F and 44°F, while DeSoto and Highlands borrow the Charlotte County airport and Hardee uses Lakeland's record.2 Our reading: a plan that crosses from LaBelle into Moore Haven keeps the same design temperatures but not the same climate zone, so the energy form has to change even when the Manual J barely does.
Mobile homes are a large share of the housing everywhere here, from 24.2% in Highlands to 54.0% in Glades.4 New single-family construction is thin by Florida standards: Highlands led the group with 706 one-unit permits in 2025, and Okeechobee issued 68.3 That scarcity, not a lack of rules, is why these counties share a page; each still has its own building department and checklist.
Worked example
1,700 sq ft house in Highlands County → 23,200 Btu/h, 1.93 tons · illustrative
Illustrative · not a Manual J
We ran a 1,700 sq ft three-bedroom in Highlands, the group's busiest county, because new houses here run modest; the rooms median is 5.2.4 Inland humidity drove our 50-grain assumption.
| House | new single-storey block home, Sebring area |
|---|---|
| Conditioned area | 1,700 sq ft, 1 storey, 9 ft ceilings |
| Bedrooms / occupants | 3 / 4 |
| Glazing | 13% of floor area (221 sq ft), U 0.32, SHGC 0.25 |
| Walls / ceiling | R-7.8 walls, R-38 ceiling under a vented attic |
| Air leakage | 5 ACH50 |
| Ducts | in the attic, 8% gain allowance |
| Outdoor design | 91°F cooling / 41°F heating (Highlands County, sourced) |
| Indoor design | 75°F cooling / 70°F heating |
| Design grains difference | 50 gr/lb (assumption) |
Illustrative only. A simplified block-load estimate with the inputs shown, not an ACCA Manual J, and not for permitting. A real calc goes room by room with your plans, orientation and equipment data.
Building departments
How we publish department checklists
Every county here has its own building department, and several cities run their own. We publish a department's checklist, contacts and quirks only after reading them on its official page, and each county here gets its own page once that's done. Until then, check with the county building department before you submit. Ordering works statewide today.
Heartland questions
3 answers · Is Hendry County climate zone 1 or 2?
Is Hendry County climate zone 1 or 2?
Climate zone 1A. Table R301.1 of the 8th Edition energy code puts Hendry in 1A with Lee, Collier, Palm Beach, Broward, Miami-Dade and Monroe, while neighbouring Glades, Highlands and Okeechobee are 2A. The zone sets the prescriptive baseline your R402 or R405 is measured against, so use the right one.
What design temperatures apply in Glades and Okeechobee counties?
Glades uses Belle Glade's limits, 91°F cooling and 44°F heating. Okeechobee takes the St. Lucie County airport values, 90°F and 41°F. Those are RESNET's county design-temperature limits drawn from ASHRAE and Manual J data; a Manual J for either county shouldn't exceed them.
Do you do energy calcs for manufactured homes in the Heartland?
We prepare energy calcs and Manual J, S and D for site-built homes and additions permitted by Florida building departments. If your project is a manufactured or mobile home, ask the building department which documents it needs before you order, then send us that list and we'll quote it.
Nearby and related
Price
One statewide price in all 67 counties. Building departments decide what they accept; we don’t guarantee approval. Revisions for plan-review comments on the same design are free.
Sources
4 primary references · numbered to match the citations
- 012023 Florida Building Code, Energy Conservation (8th Ed.), Table R301.1, climate zones by countyup.codes
- 02RESNET / ENERGY STAR, Appendix A: HVAC Design Temperature Limits by State and County (v4, 2019)resnet.us
- 03U.S. Census Bureau, Building Permits Survey, 2025 annual county data (new privately-owned 1-unit housing units)www2.census.gov
- 04U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates (B25001, B25003, B25018, B25024, B25034, B25035, B25040), via Census Reportercensusreporter.org