Air conditioning vs passive design

Air conditioning is a summer staple. Unless you’re willing to sign up for one long sweat session, you’d be crazy to go without it, wouldn’t you?

As more people switch to a “greener” style of living (centred around sustainable practices), passively designed homes are becoming increasingly popular, and many are thinking twice about installing air conditioning.

With zero running costs (anecdotal evidence suggests air conditioning can be up to $100 per month to run or fractionally less for energy efficient models) but all the cool factor, passively designed homes seem to be the way of the future.

If you’re going to explore this option, however, you’ll have to do it properly to ensure you reap the full rewards (especially with all the upfront costs involved).

There are two crucial elements that make up a successful passively designed home:

Site orientation
Site orientation (the positioning of the home on the land to maximise solar access and prevent unwanted sun) is key to smart passive design. The first step in orientation is maximising the northern aspect, where exposure to the sun is best controlled. Eaves and pergolas can be precisely designed to block the summer sun and still allow the desirable winter sunshine to penetrate. North-side deciduous trees that shade the house during summer allow the sun prime access once they have lost their leaves in winter. Reducing your exposure to the west will also minimise heat gain via the horizontal rays of the hot summer sun.

Cross ventilation
Cross ventilation is an important design factor and significantly reduces the need for air conditioning. The process entails providing at least two carefully placed and treated openings in every room. Tips for effective ventilation include the inclusion of louvres to direct airflow, high-level windows to allow hot air to escape, reversible fans and door and window seals to prevent cold air from whistling under doors and windows.

Smart passive design should not be an afterthought and must be carefully planned out. Otherwise, you might end up being stuck in a “hot house”, reaching for a remote to air conditioning that’s not there!

Even if you’ve opted for a passively designed home with a good aspects and natural ventilation, at some point, as the weather gets warmer or cooler, some artificial assistance might be required.

If this is the case, you can still be content knowing that thanks to your smartly designed home, your air conditioning (and heating) won’t have to work as hard – which means a significant reduction in your energy usage and savings for your hip pocket.