Keeping Cool in Summer

  • 13 October 2011
  • Home Energy Centre

What are the options for staying cool in summer?

Well-designed homes in most parts of New Zealand should need little or no mechanical cooling in summer.

Photograph of eaves extending the roof to shade a windowOverhanging eaves help keep the sun out during summer

Passive cooling

Passive cooling includes shade to keep the summer sun out, good insulation and good ventilation.

Passive cooling isn't just for new homes. Passive cooling features can be added to existing homes - it may be as easy as planting trees to provide shade or leaving windows open to get breeze circulating inside.

In most parts of New Zealand, even in summer, this should be enough to keep your home cool.

Other cooling options


If natural ventilation doesn't keep you cool enough, a fan may make you feel several degrees cooler. Fans are cheap to buy, easy to install and comparatively cheap to run.

Portable floor and desktop fans are widely available, and can be stored away when not in use.

Ceiling fans

A ceiling fan circulates air in summer and helps to keep you cooler. In winter it can re-circulate warm air that collects near the ceiling.

A ceiling fan uses very little energy compared to an air conditioning unit. It needs a reasonable ceiling height to give good clearance and an electrical connection.

Evaporative coolers

Evaporative coolers are a form of air conditioner.

They cool air by evaporating water, so work best in dry climates. If humidity is high, as in Auckland, these coolers will not work well.

A meteorology service may advise you on what humidity levels to expect in summer - tell them why you want the information.

The only energy used is for the fan, so evaporative coolers are reasonably energy-efficient. They use water and portable units must be topped up regularly.

To keep the humidity low, let outside air into your house.

Heat pumps

Heat pumps provide heating in winter, but most models can be switched to reverse - which means they can be used to cool your home in summer.

However, using a heat pump isn't an energy-efficient way of cooling. If you run it in summer to keep your home cool, you'll wipe out any savings you made on your heating bill in winter.

More information

From Smarter Homes

Share this post