Cooling your home without overheating your budget

New Zealanders are increasingly using the cooling buttons on their heat pumps to beat the summer heat but this comes with the risk of high power bills. EECA ENERGYWISE technical specialist Allen Davison has simple tips to keep cool without blowing the budget.

Heat pump companies are reporting a boost in summer sales from people buying heat pumps for their cooling, as well as their heating, properties. And some power companies are reporting spikes in electricity use on swelteringly hot days.

Before resorting to the cooling button on your heat pump, try to create a cross draft by opening windows throughout the house, allowing the breeze to waft through. Closing curtains will also keep the sun out.

Ceiling and floor standing fans are relatively cheap to buy and install, and are cheaper to run than air conditioning. They're especially good if you only get a few weeks of extremely hot weather each year.

Other options to think about are deciduous trees planted on the north and west of the house to provide shade in summer. If you don’t have trees, eves or roof overhangs stop sun entering the house in summer; alternatively external shades or awnings will do the job.

If you are considering a heat pump to use for air conditioning, make sure the appliance does cool effectively. The Energy Rating Label, found on all appliances, also has a blue cooling star rating. Energy rating labels all have a simple star rating - the more stars on the label, the more energy efficient the appliance is but also look for the specific cooling information on the label.

Make sure the appliance is the right size so it will cool your house properly without having to work too hard. The same sizing rules apply for cooling as for heating.

There are a number of ways to make sure your air conditioner or heat pump will cool as effectively and as cheaply as possible.

  • Try using just the fan - most heat pumps or air conditioners have a fan only setting which can help create cross-draughts in your home. Keep your windows open while using the fan only mode.
  • Use the dehumidifying mode - if it’s the humidity rather than the temperature that’s the problem. This mode uses less electricity than the full cooling mode. Shut your doors and windows in the rooms you're dehumidifying.
  • Only use cooling mode on really hot days - when the other methods aren't enough. Shut all your doors and windows in the rooms you're cooling. It's best to just cool one room as this is what most heat pumps/air conditioners are sized for. Set the thermostat to around 22˚C. The room won't cool down any quicker if you set it lower, but you are likely to use more electricity by overcooling.
  • Avoid using auto settings - if you forget to switch the unit off it will start heating if the temperature drops below the thermostat setting.


Heating and cooling - ENERGYWISE website


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