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How to keep your house cool in a heatwave (UK): what works and what doesn’t

UK houses are designed to trap heat. Here is what genuinely helps, roughly in order of effort and effect.

British homes are built to keep warmth in — thick walls, small windows, loft insulation. Brilliant in February, miserable in a 32°C July. Here's the honest, ordered list of what actually keeps a UK house cool, from free habits up to the thing that truly works.

Free, do these first

• Close curtains and blinds on the sunny side during the day. Most heat comes in through glass. Blocking direct sun is the single biggest free win — blackout or light-coloured blinds are best.
• Open up at night, shut up in the morning. Throw windows open once it's cooler outside than in (usually after ~9–10pm), then close everything before the morning sun hits to trap the cool air.
• Create a through-draught. Open windows on opposite sides of the home to pull air through. A fan placed to push air out of a warm window helps.
• Turn off heat sources. Old halogen bulbs, the oven, and devices on standby all add heat. Cook cold meals or use the microwave on the hottest days.

Cheap kit that helps a bit

• A fan — won't lower the temperature but makes warm air feel cooler. Point it across your skin, not just around the room. Putting a bowl of ice in front of it is a mild, short-lived trick, not magic.
• Reflective window film — bounces sun off south/west-facing glass; helps for the season, fiddly to fit.
• Draught-excluding / thermal blinds — better than thin curtains at blocking radiant heat.

The thing that actually works

Habits and fans take the edge off, but in a genuine heatwave they don't make a hot bedroom comfortable. The only kit that reliably lowers the temperature is a portable air conditioner — it removes heat from the room rather than moving it around, and drops a room by 8–10°C regardless of humidity. It's the most expensive option and needs a window to vent, but it's the difference between coping and actually sleeping. (See the best UK models and how to size one.)

The honest order of operations

Start with the free habits — they genuinely help and cost nothing. Add a fan if you don't have one. And if you've decided the heat is bad enough to warrant a real fix, get a portable AC — but buy it before the next hot spell, because they sell out within hours once a heat warning lands. The whole point of this site is to tell you the moment your chosen model is back: set a free alert and you'll beat the rush.

Figures are approximate and change with energy prices, stock and season. This guide contains affiliate links — we may earn a small commission at no cost to you, and it never affects what we recommend.