Nature Coast: energy calcs & Manual J.
Heating design down to 30°F, and mobile homes from one in seven units to two in five.
Citrus, Hernando and Levy counties sit in climate zone 2A with 91–92°F cooling limits and some of the peninsula's coldest heating limits: 34°F in Citrus and Hernando, 30°F in Levy. Marion, Lake and Sumter, once part of this hub, now have full pages built from their own permit checklists.
- Counties
- 3 countiesCitrus, Hernando and Levy
- 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
Citrus, Hernando and Levy
Per-county table3 counties · zone, design °F, permits, housing
| County · stations | Zone | Design °F | Permits | Median built | Single-family | Mobile | Electric heat |
|---|---|---|---|---|---|---|---|
| CitrusHernando County (ASHRAE) | 2A | 91° / 34° | 2,082 #19 | 1990 | 69.8% | 21.1% | 94.4% |
| HernandoHernando County (ASHRAE) | 2A | 91° / 34° | 1,734 #24 | 1991 | 76.6% | 14.4% | 94.8% |
| LevyCross City (ASHRAE) | 2A | 92° / 30° | 240 #41 | 1993 | 50.3% | 42.8% | 92.5% |
What it means for sizing
2 paragraphs · design temperatures, housing stock, equipment
Citrus and Hernando share the Hernando County airport's limits, 91°F cooling and 34°F heating, while Levy borrows Cross City's 92°F and 30°F.2 All three are zone 2A.1 At 30°F, in our view, a heat pump's output at design temperature and the size of the strip heat behind it decide comfort on the coldest mornings, so the Manual S check matters as much as the cooling total.
Citrus issued 2,082 one-unit permits in 2025 and Hernando 1,734, ranking 19th and 24th in Florida; Levy issued 240.3 Mobile homes are 42.8% of Levy's housing, against 21.1% in Citrus and 14.4% in Hernando.4 Electric heat is near-universal in Citrus and Hernando, at 94.4% and 94.8% of occupied homes.4
Worked example
1,800 sq ft house in Citrus County → 24,300 Btu/h, 2.03 tons · illustrative
Illustrative · not a Manual J
An 1,800 sq ft block home at Citrus's 91°F and 34°F limits; the county's median home has 5.5 rooms.4 Read the heating figure against the cooling total; that ratio is what separates this region from the Gulf coast to the south.
| House | new single-storey block home, Inverness area |
|---|---|
| Conditioned area | 1,800 sq ft, 1 storey, 9.33 ft ceilings |
| Bedrooms / occupants | 3 / 4 |
| Glazing | 13% of floor area (234 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 / 34°F heating (Citrus County, sourced) |
| Indoor design | 75°F cooling / 70°F heating |
| Design grains difference | 48 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.
Nature Coast questions
3 answers · What heating design temperature should a Manual J use in Levy County?
What heating design temperature should a Manual J use in Levy County?
30°F at 99% heating, from the Cross City station, which RESNET assigns to Levy along with a 92°F cooling limit. That is colder than any county page we publish on the peninsula, so size heat-pump backup heat from capacity at 30°F rather than from rated output.
Do Citrus and Hernando use the same design temperatures?
Yes. Both take the Hernando County airport values in RESNET's county table: 91°F at 1% cooling and 34°F at 99% heating. Pasco County uses the same station, so a builder working across all three counties can expect identical outdoor design conditions on the Manual J.
Where did the Marion, Lake and Sumter pages go?
They moved out of this hub on October 10, 2026, once we had read each county's own permit checklist and confirmed its building office. Each now has a full page with its submittal rules, design temperatures, housing data and a worked example. Citrus, Hernando and Levy remain here.
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