If your home is oriented to take advantage of warm sun and cooling breezes, you'll achieve greater comfort at lower cost.
In general, ideal orientation means:
- you get the right amount of sun - plenty in winter and in cooler climates, not too much in summer and in warmer climates
- you're protected from strong/cold winds but can take advantage of breezes to cool your home when it is too warm.
When you're designing a home or planning renovations, there'll also be other considerations such as local climate, view, terrain, vegetation, street access and noise. You'll need to balance these against the benefits you can achieve through harnessing the sun's energy for heating and breezes for cooling.
When should you think about orientation?
It's important to consider orientation if you're buying a property (including an apartment or townhouse), or designing a new home or renovation.
It's also worth considering orientation for your existing home. There may be simple ways to improve orientation - for example, increasing the size of north-facing windows, or swapping rooms around so you're using the sunniest rooms as living areas.
Positioning for sun
To make the most of the sun for warmth and natural light, your home's main living areas (or any rooms you use a lot) should face north. The main glazing in the house, such as windows, skylights and glass doors, should also face north. Anywhere between 20ºW - 30ºE of true north is fine.
You'll want less glazing facing west because of the potential for glare and overheating from late afternoon sun. This is an increasing problem in New Zealand houses.
East-facing glazing captures morning sun and can be sized according to your preference for light, heat control and ventilation in summer. South-facing windows receive minimal sun and should be relatively small to avoid heat loss but allow for light and ventilation.
The exact amounts and proportions of glazing will vary depending on other considerations such as climate, how well insulated your home is and how energy-efficient your glazing is. You may, for example, want less north-facing glass in a warmer, sunnier climate. It is also worth considering the type of glazing alongside the placing and number of windows – for example, if you want larger south-facing windows to capture the view, you might want to have these double glazed, or you might consider tinted glass for west-facing windows.
The exact amount of heat your home gets from the sun will depend on the season, time of day, weather, local climate and rate of air pollution. Heat is greatest when the sun is at a high angle relative to the horizon (i.e. it's higher at noon than at dawn or dusk). Heat is also greater in summer than winter.
Buildings, trees and terrain that block the sun
To make the most of the sun, your home should ideally be positioned as far as possible from neighbouring buildings, terrain or vegetation that might block north sun:
- A site that slopes north will get more sun than a south-facing slope. A south-facing slope will be more shady, which may be useful in summer but restrict your ability to make the most of the sun's warmth in winter.
- A site that runs north-south should get sun throughout most of the day. Neighbouring homes won't generally block the sun during the middle of the day, but they may provide shade in early mornings or late afternoons if they're close to the boundary.
- A site that runs east-west is more likely to have its north sun blocked by neighbouring houses. However, this depends on how wide the site is and how close neighbouring homes are to the boundary.
If a north-facing site is too narrow, you'll have limited ability to place your living areas along a large north wall. Try making the most of morning or afternoon sun in a number of rooms.
Note that in winter, objects cast shadows two to three times their height, so if possible your home should be sited well back from anything that might block the sun. Building along the southern boundary is a good idea if your local council permits it.
Even if your site isn't ideal for catching the sun (for example because it slopes south), it may be possible to maximise the sun's warmth using north-facing clerestory windows or other glazing.
Shade when you need it
If you orient your home to make the most of the sun, you can use shading and ventilation to keep your home cool in summer.
Because the sun travels higher in the sky in summer and lower in winter, you can use features such as overhanging eaves and vegetation to ensure you get don't get too much sun in summer. You can also position your home to get shade from neighbouring homes, terrain or trees when the sun is at its hottest, such as late afternoons in summer. For more information see Passive cooling.
Letting in breezes, keeping out wind
From southerly gales to northwesterly blasts, wind is an issue in many parts of New Zealand. Ideally, you'll orient your home in a way that avoids the strongest and coldest winds - but still allows you to harness mild breezes to keep you cool in summer.
Vegetation can be used to filter harsh winds, and landscape and building structure can be used to deflect cooling breezes into the interior but exclude harsh winds. Other features such as well-designed windows will also help.
When you're thinking about orienting your home to catch breezes and avoid wind, consider:
- whether there is a prevailing wind direction (vegetation patterns can sometimes indicate this, or you can ask the neighbours; coastal breezes are usually from an onshore direction)
- whether the wind changes with season - in terms of direction and strength
- whether the wind strength or direction changes at different times of day - for example, in hilly areas cool breezes often flow down valleys in late evening and early morning
- how exposed the site is to wind - winds are stronger near coastal areas and ridgetops
- whether the strength is affected by nearby buildings, hills and vegetation - buildings and valleys can funnel winds (which makes them stronger), and hills and vegetation can provide shelter.
See Passive cooling for more information.
As well as sun and breezes, you'll also need to consider orientation to:
- take advantage of views
- avoid noise
- achieve privacy
- achieve the appearance you want for your home
- ensure you have clear street access (see Safety and security).
Beware of west-facing views. If you orient your house west, your home will get the full glare of late afternoon sun and it may also be exposed to strong winds (see Passive cooling).
Striking a balance
Achieving the ideal orientation is about striking a balance between sun, breeze and these other factors. If you compromise on orientation in order to take advantage of views, you may still be able to make your home energy-efficient by using features such as good insulation and well-placed, well-sized windows.
From Smarter Homes
From other sites
The Energywise website has a web page on designing for the sun. And you can download the Energy Efficiency and Conservation Authority publication Design for the Sun, which provides comprehensive and conceptual information and guidance for designing energy-efficient and passive solar houses in New Zealand.
Designing Comfortable Homes is a guide to energy-efficient design using glass, thermal mass and insulation, produced by EECA and the Cement and Concrete Association of New Zealand (CCANZ). The booklet can be downloaded for free from the Energywise website.
Maps, aerial photographs and topographical information can be found at the Land Information NZ website.
The National Institute of Water and Atmospheric Research’s website has information about New Zealand’s climate and climate data for various parts of the country.
Your local council may have information about the local climate. Visit the Local Government Online website to find contact details for New Zealand local authorities.
If you're really keen to see whether an object will shade the house, you can work it out using a sun path diagram from Victoria University's Centre for Building Performance Research.