How do I keep a caravan or motorhome cool?

Caravans and motorhomes combine several of the worst features for summer heat: minimal insulation, a very large glazed area relative to the volume, a roof presented flat to the sun, and no thermal mass at all. They also have one feature nothing else has — permanent ventilation openings that exist for gas safety and are not optional. Getting the cooling right means working with those rather than around them.

Safety

Step by step

1. Pitch for shade and orientation together.Shade from the afternoon sun matters most for a caravan, because the interior is still hot at bedtime. Where full shade is not available, orient so that the large side windows and the door face away from the strongest sun, and the smaller windows take it instead.
2. Never block the fixed ventilation.Caravans have permanent low-level and high-level ventilators sized for the gas appliances. They are a combustion safety requirement, not draughts to be sealed. Blocking them to keep heat out — or to stop draughts in winter — risks carbon monoxide accumulation. Work around them.
3. Create a through-draught end to end.Open a window or the door at one end and a roof vent or window at the other, so air moves along the length of the van rather than swirling. Roof vents are particularly effective because hot air collects at the ceiling, and a vent open at the high point with a low opening elsewhere gives a genuine stack effect.
4. Use the roof vents properly.Most vans have two or more roof lights. Opening one at the front and one at the rear, with their flaps set so one scoops air in and one lets it out, moves considerably more air than opening both the same way. Many vents can be set at different angles for exactly this.
5. Shade the windows from outside.External silvered screens on the windscreen and cab windows of a motorhome are far more effective than internal blinds, and the difference is dramatic in the cab area, which is the hottest part of any motorhome. For caravan side windows, an awning or a simple shade cloth on the sunny side does the same job.
6. Use the awning as shade, not as an extra room.A full awning zipped up in a heatwave becomes a hot enclosure attached to the van, radiating heat inwards. Roll the sides up, or use only the roof panel, so it shades the side of the caravan while air flows through. In that configuration it is one of the most effective things you have.
7. Reflect the roof if you are staying put.For a long stay in real heat, a light-coloured tarp or shade sail rigged above the roof with an air gap is very effective, because the roof is the largest sunlit surface and it is directly above your head. It needs proper guying and it must not chafe on the van.
8. Manage the fridge separately.Absorption fridges, which many caravans use, cool relative to the outside temperature and struggle badly in heat. Shade the fridge vents on the outside wall, make sure they are clear of debris, run it on mains rather than gas where possible, keep it full and open it as little as you can. A caravan fridge in a heatwave is often the first thing to fail.
9. Move the heat-producing activity outside.Cooking inside a caravan in a heatwave heats the whole van and adds a great deal of moisture. Cook outside under the awning wherever you can — it is also better for the gas ventilation situation and the smell.
10. Use 12V fans and consider air conditioning honestly.Small 12V fans are cheap, quiet and effective for moving air where the breeze does not reach. Fitted or portable air conditioning genuinely works but is heavy, expensive, and needs either a mains hook-up or serious battery capacity — realistic for a long stay on a serviced pitch, not for wild camping.

Tips

• The cab of a motorhome is the hottest part by a wide margin, because of the large windscreen. External silvered screens make more difference there than anything else you can buy.
• Damp towels hung in an open doorway cool incoming air a little by evaporation, and work best where there is a genuine breeze.
• A windbreak positioned to shade rather than to enclose can be surprisingly effective on a pitch with no natural shade.
• Check the roof vent seals at the start of the season. They perish in ultraviolet light and a leaking vent found in August is a miserable discovery.
• If the van is stored through the summer, leave a roof vent open on its rain-proof setting so it ventilates rather than cooking and going musty inside.

Common mistakes

• Blocking the fixed low-level vents to keep heat out — They are a gas-safety requirement sized for the appliances fitted. Blocking them risks carbon monoxide accumulating, which is a far greater danger than the heat.
• Zipping the awning up in a heatwave — It becomes a hot enclosure attached to the van and radiates inwards. Roll the sides up so it shades while air flows through.
• Opening both roof vents facing the same way — One should scoop air in and the other let it out. Set the same way, they work against each other and much less air moves.
• Expecting an absorption fridge to cope in a heatwave — It cools relative to the ambient temperature and is at its weakest exactly when you need it. Shade the external vents, keep it full, run it on mains, and open it sparingly.

Questions people ask