It's getting stinking hot outside and in. Is your house a hotbox? A sauna without the Scandinavian scent? Mine is. But what can we do about it?
How hot your house gets in summer, and how much it retains heat, largely depends on the orientation of your house and the building materials it's made from. These are big things to change without some serious reconstruction or a bulldozer.
Another factor, and a much simpler one to tackle in the hot-box equation, is how much sun hits the glass? When sun hits the glass and shines into the room it provides loads of free heat. In winter it's like having a heater on in the room and in summer it's like... having a heater in the room.
Controlling the amount of sunshine that enters your house in summer and winter is the basic principle behind solar passive design. Once the sun hits the glass the house will heat up*. To really stop that heat in summer, you have to stop the sun hitting the glass any way you can.
Curtains and blinds on the inside don't work nearly as well as tackling it from the outside. So do a wander around your house, at various times of the day, taking note of sun hitting windows - especially pesky skylights - and investigate ways to stop it. There are some cheap quick fixes and others that need a savings plan or years of preparation. All are basically effective but the better the block-out, the better the result. That said, you have windows for a reason so it's about finding a compromise that can still give you a bit of light, a bit of the view and a bit of ventilation while stopping that sun hitting the glass.
Cheap (occasionally nasty) quick fixesBamboo blinds or shade-cloth. I think Coolaroo, available in hardware shops by the metre, is a great product for this - it still lets in some light and air but blocks out most of the sun's heat. You can attach it to a frame or just 'drape' it over the window. It's not a really cheap fix but a great one.
Foil laminated cardboard (Renshade) - velcros up on the inside of your windows and reflects almost 90% of the heat back outside. This is great for apartments and rentals as you can take it with you. It's a very cheap and effective solution for skylights as well... although it does look a bit space-age with all that silver around. Holland blinds with reflective backing (works in a similar way to Renshade) on the inside of the window. Trap: Make sure that the reflected sunlight from your brilliant reflective blinds doesn't reflect into someone else's windows - it might reflect badly on you!
Not-so quick fixesGrow deciduous vines on a pergola or plant deciduous trees/shrubs to block summer sun - they're full of leafy green-ness in summer to shade windows and bare in winter allowing the sun's warmth inside.
Awnings and exterior blinds - need to be professionally fitted and can cost more. They need to be adjusted so you can still open windows for ventilation while doing their job of stopping the sun hitting the glass. The down-side of blockout awnings is that they also block out the light and views.
I overheard someone recommending cardboard on windows the other day. To me this really is very ugly even through perhaps highly effective. I suppose it depends on your style and if you like living inside a box rather than a hot-box. I have a modicum of style that remains; the decision is yours...
So park your windows in the shade this summer and notice the difference. As soon as the heat is over, let the sun shine in again.
*What's in a little ray of sunshine? The following may contain traces of science. If you want to know a bit more about the science behind this sunshine stuff read on. Hopefully, it makes sense...
The scientific name for sunshine is solar radiation. Solar radiation is made up of a few types of electromagnetic radiation: 2% ultraviolet (UV) light, 47% visible light, and 51% infrared (IR) radiation (the heat we feel from the sun). Most of the other types of radiation, such as gamma rays and microwaves, don't make it through Earth's atmosphere.
Why can infrared radiation (IR) get through glass but not out again? There are 3 main types of infrared radiation, differing in their wavelength - long, mid and near. Solar IR, shining directly from the sun, is near-wavelength and can easily pass through glass. Thermal radiation, like that from a hot object, a human or machine, is long-wavelength and cannot pass through glass, it just doesn't have what it takes. This is why some rooms in your house get really hot. The solar IR shines through the glass and heats up the furniture, floor, cat, etc. These radiate thermal IR which heats up the air. Due to its longer wavelength this radiation can't pass through the glass again and the room gets hotter and hotter.