- A bare steel container in the sun gets far hotter than the air outside, so insulate it before using it as a room
- The common insulation options are PU foam, isowall panels and fibreglass, differing in price and thickness
- An insulated 20ft container needs roughly 12,000 to 18,000 BTU of air conditioning
How hot: a bare container in the sun versus an insulated one
The steel walls of a container absorb heat from the sun and pass it inside quickly, so a bare container in the afternoon sun is noticeably hotter than the air outside. From measurements on our own jobs, the inside of a bare container in full sun reaches about <<FILL>> °C, while an insulated, air-conditioned unit sits at about <<FILL>> °C. The good news is that it can be fixed, and a container done properly is as comfortable as any ordinary room.
Three insulation options: PU foam, isowall, fibreglass
| Insulation | Typical thickness | Approx. price | Strengths |
|---|---|---|---|
| Spray PU foam | <<FILL>> mm | <<FILL>> THB/m² | Sprays into every corrugation with no joints |
| Isowall (sandwich) panels | 50 mm walls / 75 mm roof | <<FILL>> THB/m² | Smooth, clean finish, quick to install |
| Fibreglass + lightweight panel | <<FILL>> mm | <<FILL>> THB/m² | Budget option with good sound insulation |
Our isowall office cabins use 50 mm walls and a 75 mm roof, as listed on the specifications page.
How many BTU for a 20ft container, and the running cost
A 20ft container has about 13-14 m² of floor space. Once insulated, a 12,000 BTU unit is enough for an office of 2-3 people. If the container is in full sun all day or holds more people, go up to 18,000 BTU. A 40ft unit split into rooms should have a separate air conditioner in each room. Running a 12,000 BTU unit 8 hours a day costs roughly <<FILL>> THB a month, depending on the model and electricity tariff.
Orientation, shade roof and paint colour: how many degrees they save
- Orientation: point the long sides north-south so the afternoon sun hits a short end
- Shade roof: a raised metal-sheet roof above the container with an air gap does the most to cut heat through the roof
- Paint colour: white or light colours reflect far more sun than dark ones
- Shade: trees or an awning on the west side make a big difference
From past jobs, a shade roof lowers the temperature inside by about <<FILL>> °C.
Example: an air-conditioned office container we delivered
See two 20ft air-conditioned office containers that were insulated and fitted with air-con before delivery, and see designs and prices on office containers or container homes.
Want a real price today?
Message us on LINE with the container size and your site location. We reply within 30 minutes during business hours.