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How well does your home keep the cold at bay? Are you warm, dry and comfortable within its four walls on cold days or do you huddle over the heater for relief?

An energy-efficient home is a building which provides a high level of thermal comfort without an over-reliance on artificial heating and cooling.

Passive design features make the difference

Passive design is energy-efficient design which makes the most of local conditions to make your home more comfortable while reducing your bills. Did you know every two square metres of north-facing window can bring in as much warmth as a one kilowatt heater? Good passive design uses natural heat from the sun and natural night-time cooling to keep your home at a comfortable temperature year round. It can significantly reduce the need for expensive mechanical heating and cooling. Passive design incorporates:

  • Orientation and solar access
  • North-facing shaded glass
  • Sealing and ventilation
  • Insulation
  • Thermal Mass

Thermal mass

The measure of the ability of a material to store or retain heat energy is called thermal mass.  A lot of heat energy is required to change the temperature of high density materials such as concrete, bricks and tiles; they are therefore said to have high thermal mass. Lightweight materials such as timber and metal have low thermal mass.

Buildings with high thermal mass iron out temperature variations naturally, allowing temperature ranges more consistent with the ideal human comfort zone. This can save you money as the building has improved thermal comfort, meaning there is a reduced need for artificial heating and cooling, resulting in less energy use.


Aside from ensuring that your new home is well oriented to capture the sun’s rays and makes use of the principles of thermal mass, insulating your home is the single most effective thing you can do to keep your home warm and to save energy and money. A well-insulated home provides year-round comfort; it is cooler in summer, warmer in winter. And a warmer home is a drier, healthier home.

How much is enough?

New Zealand has a bad record as far as insulation is concerned. Before 1978 there was no requirement in the Building Code for homes to have wall insulation, so most didn’t. Additionally, an estimated 60% of New Zealand households have insufficient ceiling and underfloor insulation, so it’s worth checking if your home is one of them.

Why insulate?

Research proves that many homeowners put up with a lower temperature than is healthy, get sick more often and waste money on large heating bills. World Health Organisation research shows that if a home’s temperature is constantly below 18 degrees, people in it are much more at risk of colds and respiratory illness such as bronchitis and asthma.

Which insulation?

According to the Ministry of Economic Development, in the last 5 years power bills have increased by up to 46% – a scary figure to say the least. Depending on your geographical location and your lifestyle, Pink® Batts® Ultra insulation can provide efficiencies leading to savings of up to 30%* every year for the life of your home.

100% New Zealand made, Pink® Batts® is this country’s most popular and proven form of home insulation. Pink® Batts® insulation is bio-soluble and has M1 indoor air quality certification, is made up from up to 80% recycled glass and the higher R-value products also get the tick from Environmental Choice New Zealand for sustainable manufacturing processes.

A gap as small as 5mm in the fitting of insulation can reduce its effectiveness by up to 50%. PinkFit® installers will guarantee that Pink® Batts® insulation has been properly installed.

What about windows?

Insulation isn’t only to do with what’s behind your walls, floors and ceiling. Standard windows are huge holes in a home’s thermal envelope where heat can simply flood out in winter. By now, we have all heard of the benefits of double glazing, but what about window frames?

A high proportion of window frames in New Zealand are made of aluminium. While aluminium is a strong, high-quality metal, it conducts heat and cold easily. In cold climates – even with double glazing – the aluminium frame can be cold enough to cause moisture to condense on the inside surface of the glass. This spurred the development of better insulating aluminium window and door frames.

Aluminium Systems Ltd (ASL) is one company who produces such a product which significantly enhances the insulating qualities of a home by utilising thermal break technology – that is to say, the inside and the outside of the metal frame is separated using a non-heat-conducting material.

A smaller slice of the pie

According to the Ministry for the Environment, 33% of energy in the typical kiwi household is used to heat and cool the home.

A well-insulated home which captures the heat of the sun in the thermal mass of its exposed concrete, brick or tiles in living areas framed by north-facing windows will need much less heating in winter.

Extra measures like thermal curtains to keep the heat in and deciduous trees to shade your home in summer will reduce that percentage to a smaller slice of the pie, saving you money and making your home a warmer, healthier place to live.

*Department of Building and Housing, Your guide to a smarter home, 2008, p. 28

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