Home/Systems/Heat and Humidity
Bunker Systems
Heat and humidity: comfortable, dry and safe to breathe.
A sealed bunker full of people rarely gets too cold. It gets warm and damp. Every person gives off about 400 BTU an hour, a third of it as moisture, against walls the earth keeps cool all year. Climate control keeps the space dry, the temperature steady and the air free of combustion gases.
Three tiers
Priced,
installed.
Every Builder bunker includes at least the Basic tier. Prices are installed in Utah, including equipment, labor and commissioning, and are confirmed in writing after the site visit.
Basic
$3,500installed
Dry air and electric heat.
- Santa Fe Compact70 dehumidifier, rated down to 49°F
- Electric radiant heaters
- Condensate pump to drain or holding tank
- Temperature, humidity and CO sensors
Standard
$6,900installed
Year-round heat pump comfort plus dehumidification.
- 12,000 BTU mini-split heat pump (22 SEER)
- Santa Fe Compact70 dehumidifier
- Line set, electrical and condensate drain
- Protected outdoor condenser placement
Premium
$14,500installed
Two zones plus fuel-fired backup heat.
- Two-zone mini-split heat pump
- Dehumidification sized for full occupancy
- Sealed-combustion backup heat (Rinnai direct-vent or Webasto diesel)
- Hard-wired CO alarms and a protected condenser enclosure
How we size it
The numbers
behind it.
Body heat
A person at rest gives off about 100 watts, roughly 340 to 410 BTU an hour, and 30 to 40 percent of it as moisture. Ten people add about 4,000 BTU an hour.
Condensation
Warm, moist air meeting cool walls is the most common failure below ground. Dehumidification is sized for full occupancy, not an empty room.
Combustion safety
Only sealed-combustion, direct-vent heaters belong below grade. Unvented propane heaters do not, and propane is heavier than air, so we confirm local code before installing any fuel-fired unit.
The exposed condenser
A mini-split's outdoor unit sits above ground. We protect it in an enclosure or a well, and the dehumidifier and electric heat carry on if it is lost.
Questions
About
heat and humidity.
Does a bunker need heating or cooling?
Mostly drying and cooling. The earth keeps the walls cool, and a full household produces more heat and moisture than most people expect.
Can we heat with a propane heater?
Only a sealed-combustion, direct-vent model, with carbon monoxide alarms, and only where your county's code allows propane below grade. Never an unvented space heater.
What if the heat pump fails?
The Basic electric heat and the dehumidifier work without it, and the Premium tier adds fuel-fired backup heat.
Prices set 2026-10-28 from published retail equipment prices plus installation. Brand names describe the class of equipment; we may substitute equal or better equipment based on availability. Subscriptions, well drilling and septic systems are quoted separately.
Build it your way.
Pick a bunker, choose each system and see the installed price, then reserve with a deposit.