Think of your perfect house, and chances are that sunlit rooms, cool breezes, shady verandas and cosy rooms figure prominently.

These are the elements that inspire the principles behind passive design – homes designed perfectly to suit their environment.

Whether your house is a traditional Queenslander or a modern inner-city townhouse in Sydney, you can incorporate some of the principles behind passive design to ensure that your house functions perfectly, whatever the weather.

With steadily rising energy costs an issue for every household, passive design is an excellent way to reduce energy consumption in our homes. Coupled with the sustainable building trend, passive design principles are becoming increasingly important in all new buildings and renovations.

What is passive design, and how can you incorporate its principles into your home?

Basically, passive design is a building design philosophy that takes advantage of the climate to maintain a comfortable temperature range in the home. Passive solar heating and cooling can reduce or even eliminate the need for extra heating or cooling, which, when you consider that it counts for about 40% of our energy usage, is very significant indeed.

Architects and designers incorporate passive design philosophy into the design of a house. While it is easiest to incorporate passive design when you are starting a building from scratch, it is also possible to incorporate elements of passive design in a renovation, and even when retrofitting an existing house. This article looks at various passive design strategies, but to get more information, you should use the internet to research the latest information, or talk to an expert.

Passive solar heating

This is the easiest and cheapest way to heat your home. Basically, a passive solar heating design will keep out summer sun while letting in winter sun. At the same time, the building is constructed in such a way that the heat is kept inside the house in winter and is allowed to escape in summer. Orientation, insulation, sealing and thermal mass (a heavy building element such as a concrete floor or brick wall that stores the heat) help to achieve maximum comfort levels all year round.

Passive cooling

An easy and cheap way to cool your home (and yourself!) passive cooling reduces the need for air conditioners in summer. Factors taken into account include shading, air flow, evaporative cooling and thermal mass.

Orientation

Perhaps the most critical element of a well-designed house is its orientation. This refers to the way your house is placed on the land. Ideally, the house will be orientated so that the living areas can be warmed by the winter sun, with cross breezes from south-facing windows cooling it in the summer months. In all areas of Australia except the tropics, a north facing living area that takes advantage of the sun is the ideal. While the high angle of the summer sun allows for easy summer shading, the warmth will warm the rooms in winter. Bedrooms are ideally placed along the darker parts of the house facing east and south, while small rooms such as laundries and bathrooms can be placed along the west, to insulate against the summer heat.

Shading

Shading is a core principle for cooling. Direct sun on a window is the greatest source of heat gain in a house – it can generate the same heat as a radiator over a square metre of a surface. So shading can help cool the house. Consider using eaves, window awnings, shutters, pergolas and even deciduous trees – you could block up to 90% of summer heat! This will reduce the need for air conditioning, so you’ll save on energy costs too.

However, it is important to get the shading right – poorly designed shading can block the winter sun. Online calculators can determine the angle of the winter sun for your part of Australia, allowing you to design shading that will protect your house in summer while allowing winter sun to warm your rooms.

Sealing

You can lose about 15-25% of your winter heat due to draughts and air leakages around your home, and you can also lose your cool air-conditioned air the same way. To seal your home from leaks and draughts use runners under doors, sealing strips around windows and doors and close your chimney flue.

Insulation

Correctly installed insulation is essential to keep your home warm in winter and cool in summer. Walls, floors and roofs need correct insulation to protect against heat loss in winter and heat gain in summer.

Thermal mass

Thermal mass is the ability of a material to absorb and store heat energy, which creates a heat sink to store energy during the day. For example, a concrete floor that absorbs the warmth of the winter sun all day will release that heat in the evening – in this way thermal mass moderates indoor temperatures. Concrete, bricks and tiles have a high heat storage capacity and thermal mass. It is important to use passive design techniques, such as shading, to avoid the material heating up in the summer months.

Glazing

Up to 40% of a home’s heating energy can be lost and up to 87% of its heat gained through windows. To avoid this, choose the right-sized windows for the orientation of the room, as well as the right air flow capacity. Choose small windows for cold south-facing windows and hot west-facing windows, and instead install large north facing windows to capture the maximum amount of sunlight. In addition, use double glazing where possible to avoid heat loss in winter, and consider using casement or louvre windows to maximise the airflow.

More information on passive design in Australian homes can be found at www.yourhome.gov.au/passive-design.

To discuss your house or building project, talk to an architect who specialises in sustainable design. There are nearly 1500 of them listed on Yellow Pages. Call one today.