Building or renovating a home the GreenSmart way starts with the appropriate site selection to ensure that you can maximise passive solar design principles in your home. Getting the orientation right is the first step.
Orientation refers to the correct placement of the building on the block to allow sun to penetrate in winter and to minimise this in summer. The best site is one which provides enough room to place a house with the living areas facing north. Renovation projects can consider this by the relocation of rooms to improve passive solar access.
The efficient design of eaves on the northern side lets the sun into the home in winter, warming it naturally and reducing heating bills. It also prevents the hotter summer sun – which is at a higher angle – from entering the home, reducing the need to artificially cool the home in summer.
Insulation should be seen as the first line of defence against the external elements after incorporating passive solar design as it reduces heat loss and heat gain through walls, roofs, floors and flooring systems. Ceilings can account for 25 – 35 per cent of heat loss in winter so it is important to place insulation close to the ceiling to help reduce this. Floors can account for 10 – 20 per cent of heat loss in winter, so timber floors and suspended concrete slabs used in cooler climates should be insulated. Walls can account for 15 – 25 per cent of heat loss in winter. However, in cooler climates selecting suitable thickness of insulation can reduce the heat loss. The correct selection and installation of insulation in the ceilings, floors and walls in conjunction with using thermal mass can achieve significant reductions in heating and cooling costs.
Thermal mass refers to the ability of a material to absorb heat energy. High density materials such as concrete, rammed earth, bricks and tiles have a high thermal mass, which allows them to absorb heat, unlike timber which has a low thermal mass.
In winter, the correct positioning and treatment of thermal mass has the ability to absorb free heat from the sun during the day and re-radiate the heat through the house at night. In summer, the thermal mass absorbs any heat that has entered the house during the day and cools it at night, which can help reduce internal temperature fluctuations between day and night. To achieve the benefits from materials with a high thermal mass, these should be placed on the inside of the building.
Ventilation is the movement of air through and around the home. Ventilation can be achieved using both mechanical and natural methods. Mechanical methods include ceiling fans and externally ducted exhaust fans. Natural methods include the location and orientation of openings (doors and windows) to allow the flow of air across the rooms, externally ducted air vents to allow air to be pulled through the home or roof-mounted systems to extract hot air from the roof cavity. It is also important to minimise draughts throughout the home by sealing gaps in doors, windows and exhaust fans. This can reduce heat loss by 15-25 per cent.
Your choice of flooring can contribute to your home’s thermal performance, i.e. how thermal mass is utilised in the home. Carpets can minimise the benefits of thermal mass by covering and ultimately insulating the thermal mass, i.e. preventing useful accumulated heat from entering via the floor, unlike tiles and concrete floors, which will assist in heat gain through conduction. The colour of flooring can also influence heat absorption, with darker colours absorbing more heat which can re-radiate into the house.
The Housing Industry Association (HIA) has developed these information sheets as a source of general information and guidance for consumers when building or renovating a home. HIA does not make any representation as to the suitability of these information sheets for any particular project. This information is not legal or professional technical advice and should not be relied on as being suitable or appropriate for any particular task or project. Always consult a licensed HIA builder Member or other professional adviser in relation your own circumstances.
Real Estate Advisor
0421 274 996
Specialising in real estate in Cheltenham, Mentone and surrounds.