Keeping cool

Keeping cool in summer.

Hot weather is lovely, but the windows that allow the sun to warm us in winter, can overheat us in summer. And UK summers are getting hotter due to climate change. Here are some tips on keeping cool. There’s more from our architects, too.

Look at how this is done in hot countries. Shades, and ventilation are key. If you allow direct sun through our large windows, the house will heat very quickly. Close fitting blinds or curtains will help a lot. Venetian blinds can allow you to get a balance between light and shade.

Ventilation can keep you cool, as a breeze passes over your skin, evaporation of sweat helps you feel cool. But if the air temperature (in the shade) is high then ventilating your house will make it hotter, not cooler. Similarly fans won’t cool a room, even though they might cool you. Actually, that’s not strictly true: if you had lots of damp washing in a room, a fan might help to cool the room. So ventilating a room with hot air won’t help if there’s nobody in the room, unless it’s cool outside.

If the outside temperature is above about 21°C, then keeping your windows closed might be a good idea. And keep the blinds closed on the sunny side of the house. If your house or flat gets too hot, then cool it down with lots of ventilation in the evening: when it gets cooler, throw the windows right open. As long as the outside temperature is below the indoor temperature: ventilate! The cooler you get the house overnight, the longer it will take to heat up the next day.

If you want the best ventilation in a house, to create a draft open windows upstairs and downstairs. If you have a window at the top of the stairs, open that. Then open downstairs windows on the shady side of your house to create a chimney effect: hot air rises through your house to draw in cold air from below. You can get a draft even on a still day.

In a flat, open windows front and back to get a through draft.

Our upstairs windows have wedges in the frame (on the left side) that allow you to prop open the window about 10 centimetres, without releasing the safety catch. The safety catch is there to prevent kids falling out, but if that’s not a concern, you can open the window wider.

On a ground floor window, you might want to consider fitting a lockable casement window stay, or even two, if you’re concerned about security. Screwfix do some, but B&Q don’t seem to. I can’t recommend any particular make or type, but they should be reasonably easy to fit. Careful not to damage the window! Tenants should seek permission from JRHT (just email with the details of what you want to fit, and why). I don’t think these stays will stop a determined burglar (but what would?), but they should give you peace of mind while sleeping.

Less concrete: keep your garden lush, and it will help to keep you cool. Evaporation of water from leaves helps cool the area around your house, so it helps to keep your house cool. Pave over the lawn, and that won’t happen any more (it’s called the urban heat island effect).

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