Staying cool naturally

Nick Hollo


It’s another stinking hot day, you feel sticky and tired. What can you do to keep cool inside your home?

Well, let’s start with keeping the sun out. Shade all the glazing. Light-coloured shading is better because it is reflective. Dark colours absorb heat. It is much better to shade outside your windows than rely solely on curtains inside. Once the sun shines through the glass, the warmth inside has different radiant properties and won’t go back out through the glass as easily as it came in. Paved, glary areas are hotter and more reflective. So, shading the whole surrounding garden area of your home is a good idea.

If you are renovating or building new, it is better to minimise glazing on the west and east, as the prolonged, low-angle summer sun in the morning and afternoon is hard to keep out. The north side can be simply shaded from summer sun by an overhanging roof or pergola. This will still allow the lower, winter sun to shine in.

You can greatly reduce the heat coming through the roof, ceiling and walls with insulation. A combination of reflective foil and bulk insulation is a good idea in the roof space. But remember that if you insulate your home without shading your windows, it’ll be hotter because the heat coming through the windows will be trapped inside.

Would it help to open the windows during the day for ventilation?

In humid conditions, you need air flow to cool down by evaporative cooling.  However, if it is hotter outside than inside, it is smarter not to open the windows and wait till it cools down at night to flush the hot air from the house.

You can help capture the breeze by the way the window opens or by using screen walls or hedges outside the house to deflect the air flow to where you want it. Insect-screening a whole veranda provides an outdoor area free of insects and does not impede air flow as much as screening each window.

Finally, you can make your home stay cooler longer if the inside is made up of heavier materials, such as brick, earth or concrete. These heavy building materials need more heat to warm up, so they warm up or cool down slowly. They have thermal mass. Having solid masonry walls and concrete floors inside the house and shading them from the sun in summer will help to keep the inside cooler.

Nick Hollo is the author of Warm House Cool House: Inspirational designs for low-energy housing, second edition out now from Choice Books.