Here at the SW fortress of solitude, we usually concern ourselves more with keeping warm in winter than cool in summer: our thermal imaging project, for example, is targeted at reducing heating costs more than anything else.
In theory, if you properly insulate your house, then you proof it against both extremes (and so should have a cooler home in summer); in practice, keeping cool in a heatwave is always harder than you’d expect for us British, isn’t it?
With that in mind, here (hopefully still with a few days of heatwave ahead of us) are three simple ways to keep your house cool, without having to invest in expensive and climate-harming technology like air conditioning.
1. Close your windows
It might seem counterintuitive, but in hot, still weather, you should close your windows. Only if the air is cooler than in your house, or is moving quite fast, will it actually cool you down to any extent. And it certainly won’t cool the building down unless it’s a lot colder than that: brick retains an awful lot of heat.
2. Put shutters up, or reflective material
Heat should be deflected from south-facing windows during the hottest parts of the day. If your house is unusually Tuscan in appearance, you might have shutters on those windows; if not, you can put up temporary internal shutters using a reflective material.
You can buy solar-reflecting film for windows, and have it installed permanently, although you might not want something in place all year round, especially in the depths of winter. A more DIY and temporary option – if you don’t need it outside July and August – is to put a reflective sheet up, outdoors if possible, but close to the panes indoors if necessary.
You can attach a tanning blanket or car windscreen sunshade to a couple of hooks in the window frame; or even more cheaply (and as a first experiment, to see if it makes a difference), strengthen sheets of tinfoil with a “frame” of double-sided silver gaffa tape, and stick it up with Blu-tac or similar. Shiny side out, and try not to worry about what the neighbours think.
(Curtains won’t work anywhere near as well: mirrored surfaces are best; and even if the curtain material is a pale colour, it still warms up considerably in the sun, and then re-transmits the heat into the room’s air as much it does as back through the window.)
3. If you do decide to open the windows, cool the draughts with water
Any draughts you do have, you can cool even further through the evaporation of water. You need to work out which way through the house the draughts are blowing first, and then turn your attention to the window(s) through which the draught enters.
If you’ve got net curtains or fabric blinds against these windows, mist them with a water spray. You can also hang towels or other damp cloths near the draught, although try to keep them out of the sun as that will just dry them on its own! When the water evaporates into the draught, it will take heat out of the air. So as the draughts blow through or over the wet fabrics, they will cool slightly. This is how zeer pot fridges work, or terracotta wine coolers.
Dampening the air does have the effect of spreading a little bit of dampness through your house; but then if you’ve persevered this far with this article, sweat pouring off your brow, thoughts turning sluggish in the sun, then damp is probably the least of your worries: for at least the next month or so!