I have scraped 'alot' of great ideas off this thread. Nobody's as smart as all of us. Metal truss building -> wood in the dirt here = termite snacks. Engineered for 165mph windload. There's a highrise amount of concrete in the dirt below it.
Take a look, LMK with any markups for changes to the Barn electrical?
Estimated Cooling/Heating Load
Using a conservative approximation for a well-insulated metal building (8-10 ft ceilings, minimal windows, commercial/light residential use like a workshop/garage):
- Cooling Load: ~5-6 tons (60,000-72,000 BTU/h) total. (Rule of thumb: 25-30 BTU/sq ft in FL's climate zone 1A; higher if poor insulation or high internal heat gains.)
- Heating Load: Minimal, ~2-3 tons (24,000-36,000 BTU/h) for shoulder seasons—heat pumps handle this efficiently.
- Key FL Factors: High latent load (humidity) means systems must dehumidify effectively (aim for 50-60% RH indoors). Energy code requires SEER2 15+ efficiency.
This load supports either option, but ductwork adds complexity in a prefab metal build.
Mini-Split Systems (Ductless)
Mini-splits (wall- or ceiling-mounted indoor units connected to outdoor condensers) are ideal for open-span metal buildings. You'd use a
multi-zone system (one outdoor unit serving multiple indoor heads) or
multiple single-zone units.
- How Many Units?For even coverage in 2,520 sq ft:
- 3-4 indoor units recommended (e.g., two 18,000 BTU heads for main areas, one 12,000 BTU for ends/corners). This zones the space (cool zones independently) without overworking one unit.
- Total: 5-6 tons split across units. Example config: Mitsubishi or Daikin multi-zone outdoor unit (48,000-60,000 BTU) + 3 heads.
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LED Lighting Layout Blueprint – 40'x72' × 4/12 Pitch Metal Building
Goal: Zero-shadow, dimmable, tunable-white (2700K–4500K) illumination in
two independently dimmable zones using high-bay LED fixtures.
Fixture Specs (Recommended)
| Parameter | Value |
|---|
| Type | 150W UFO-style high-bay LED (20,000 lm @ 4000K) |
| CRI | 80+ |
| Tunable CCT | 2700K → 4500K (via 0–10V or app) |
| Dimming | 0–10V (smooth 1–100%) |
| Beam Angle | 120° (wide flood) |
| Mount Height | 16'–18' AFF (above finished floor) |
| Lifespan | 100,000 hrs |
| Cost | ~$180/ea (e.g., Lithonia CPX or WareLight) |
Lighting Zones
text
Code:
ZONE A (Front 36')
ZONE B (Rear 36')