Designing a new home

A well designed house can give you good comfort and service, yet use a surprisingly small amount of energy. It shouldn't cost much more to design and build than a house that isn't designed with efficiency in mind. It's important to consider things like insulation, double glazing, and heating.

On this page:

Design for your needs

Insulation, airtightness, ventillation

Windows and heating strategies

Saving money up front when designing and building your house can be false economy. It can lead to higher energy bills for years or decades after that.

Here are the key strategies in designing an energy-efficient house:

Size your house to suit your needs

Think about how much space you use on a day-to-day basis. Designing a house big enough to cope with all your relatives once a year is generous but impractical. Smaller houses are cheaper to build, easier to heat and use a lot less energy.

Position your house to make the most of the sun

Place living areas and rooms you use a lot on the north-facing side of the house so they make the most of the heat and light from the sun. Locate less used rooms like the bathroom, laundry and garage on the south-facing side. This will act as buffer against heat loss. Also consider passive cooling if you are designing for a hot region. You can find more information and advice in the manual Design for the Sun.

Use thermal mass

A concrete floor exposed to the sun will soak up heat during the day and release it at night. The concrete slab needs to be well insulated both underneath and around its perimeter. It shouldn't be covered with insulating floor coverings such as carpet.

Install plenty of insulation

Good insulation is the key to a warm and comfortable house that doesn't cost a fortune to heat. And the best time to do it is when you are building so you can access all areas as you go.

Under the Building Code all new houses are required to be insulated to a certain level. All external ceilings, floors and walls need to be insulated. Check the Building Code to see the minimum requirements.

If you really want to improve your home's comfort and lower power bills, consider exceeding these minimum requirements. This is particularly important in colder areas of the country. How well the insulation is installed is just as critical as the level of insulation. Make sure your insulation is installed according to the New Zealand Standard 4246:2005.

Garages are often uninsulated. If your garage is attached to your house, insulate the wall between the house and the garage.

Find out more about insulation in the Department of Building and Housing's Your Guide to Smarter Insulation.

Make your house as airtight as possible

Even well-insulated houses are hard to heat if hot air is constantly replaced with cold air. Good airtightness requires joinery and wall, floor and ceiling construction to be well sealed. Often this is done with membrane systems. These are high-tech versions of building paper. They get installed in the floors, walls and ceiling of houses while they are being built.

Consider how the house will be ventilated

There are requirements in the Building Code for adequate ventilation in houses.  You may feel natural ventilation through opening windows is sufficient, but a good ventilation system will keep your house warm, even on a cold, winter's day. True heat exchange ventilation systems are ‘balanced', pumping even amounts of air into and out of the house. They also have a heat exchanger where the heat from the stale air pumped out of the house is used to pre-heat the cold outside air coming in.

Think about direction when choosing window sizes

A lot of heat can be lost through windows if not sized properly for the direction they're facing. This is true even of windows with double-glazing. Ideally, windows should be fairly large on the north-facing side of the house, moderately sized on the east and west sides, and small on the south side.

Use good double-glazing with insulated frames

Double-glazing is the easiest way to meet the new Building Code requirements for insulation levels of windows. It pays to be aware of the following.

  • Choose thermally broken frames or frames made from an insulating material such as PVC or wood. These will perform better than standard aluminium frames without thermal breaks
  • The performance of double glazing can be enhanced by including an inert gas filling (such as argon) between the glass layers. This acts as insulation and slows down the rate at which heat is lost. This gas filling is an option with most good double glazing
  • Or you can install low-emisivity glass. This allows light and heat in, but prevents heat from escaping. Again this is an option that your glazing supplier should be able to offer you.

Try to create zones

Think about the heating requirements for different spaces around your home. Group rooms with similar uses. By blocking off unheated and heated rooms, you can reduce your overall heating needs and energy use.

Consider whole of house heating

Once your house can be heated cheaply and efficiently, it makes sense to look at good heating options. There are many types of central heating available. Or you can plan a system of individual heaters to heat areas of your house as required. There are now lots of efficient heat pumps, pellet fires and log burners on the market. Find out more about household options for heating and cooling.

Get a you new house energy rated

You can get your new house rated while it is still in the planning and design phase through the Home Energy Rating Scheme (HERS). Getting a HERS assesment done on your house before it is built lets you modify the design to maximise the energy efficiency and comfort of your new home.

More information

From the Resource Centre

Related documents and additional information: