Reduce your home’s carbon footprint with passive design

How to design your home to reduce its carbon footprint

Passive design may sound like it can’t stand up for itself – yet, it’s the easiest way to stomp down a home’s energy-guzzling carbon footprint.

Designing a building according to passive – also called passive solar – principles is ancient: when cave men chose a north-facing cave rather than the cold, dark south-facing cave, it was passive design. It’s all about letting nature do the hard work to create a great living space, rather than relying on expensive fittings and fixtures.

Passively designed buildings harness solar heat and light in winter to keep a house warm while cutting out hot sun and encouraging natural breezes in summer to keep a house cool.

It may sound as contradictory as scoffing ice cream and losing weight at the same time, but a passively designed house is warmer in winter and cooler in summer, leading to lower energy bills and less greenhouse gas emissions.

“Orientation of the building and designing for the local climate are two of the most important techniques,” says University of NSW Interior Architecture head Kirsty Mate. There are a range of complex design techniques to harness the winter sun – which is lower in the sky – and cut out the harsh, west-facing sun in summer to ensure a house remains comfortable all year round. “Another thing you can do with large living rooms is choose a dark stone like a slate, instead of carpet – the dark stone absorbs the sun during the day and let’s off the heat at night,” Mate says.

Other passive design principles include:

  • shading west-facing windows and walls;
  • planning a home’s rooms according to their orientation – north for living, south for sleeping, and east and west for service rooms like laundries or bathrooms;
  • having high windows that open, with low-opening windows on an opposite wall to create cross-flow ventilation;
  • maximising sunlight to minimise artificial lighting and heating;
  • choosing insulated lightweight materials rather than brick for second storey additions to keep upstairs rooms cool;
  • designing to the local climate – small brick houses work best in the cool climates like Tasmania while open, lightweight shaded buildings work best in the tropics.

“If you have a house or apartment with good cross-flow ventilation then it’s possible to keep your home comfortable with ceiling fans. You could run an air conditioner on really hot days rather than every day, which is what you have to do in badly designed homes,” says Energy Australia’s efficiency guru Paul Myors, who estimates that heating and cooling make up around 30 per cent of an average household’s energy bill.

“Living in a passively designed house doesn’t mean you can let the house do all the work – you have to be a competent user of the house,” says RMIT adjunct professor Alan Pears, one of Australia’s best energy efficient building experts. “You can have the best passively designed house in the world, but if someone likes to leave all the windows open in winter, then it won’t be much good.” Oh.


This article was originally published in House & Garden magazine as The Green House column.