How Insulation Works
Insulation is essential to keep your home warm in winter and cool in summer. A well insulated home is up to 10 degrees warmer in winter and up to 7 degrees cooler in summer and can save as much as $300 per year in reduced energy costs.
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If your house is too cold in winter or too hot in summer, or both, installing insulation may well be the answer.
In winter, you could make your home warmer using a larger heater, but this will cost you more money to run. In summer, you could make your home cooler by using an air conditioner. Again this will cost money to buy and money to run. A better choice might be to install insulation first.
Using insulation in the ceiling and walls of your home, and in some cases under the floor, will provide a number of benefits:
Beware of the 'Hot Box' Syndrome
- Correctly installed insulation will make your home warmer in winter and
cooler in summer. This will make your home more comfortable to live in.
- Insulation can save money on your heating and cooling bills. When
compared to an uninsulated home, an insulated home will require less
energy for heating and cooling, to maintain the same comfort conditions
- Insulating your home helps the environment. By reducing the amount of
energy required to heat and cool your home, you will reduce the amount of
carbon dioxide and other pollutants which are released into the
Care needs to be taken when insulating a home that is too hot in summer.
The radiant heat from the sun which shines on east and west facing windows in summer can be as high as 1,000 watts per square metre, equivalent to the heat output of a small bar radiator. If a house has a lot of unshaded east and west facing glass, and unshaded north facing glass, there can be a lot of heat coming into the home through the windows.
If this is the case, the best thing to do in summer is to provide adequate shading for these windows first. If insulation is installed but there is no shading, heat will build up inside the home until inside temperatures are higher than outside temperatures. In this case, the insulation will help to keep the heat inside, creating an oven effect.
Heat always moves from a hotter region to a colder region. The greater the temperature difference, the faster will be the rate of heat flow. In winter, it is warmer inside than it is outside, and so heat flows through the building structure to the outside air. In summer, it is generally hotter outside than it is inside, and so the heat flows into the home.
Heat flows in three ways:
It flows through the external structure of a house by all three methods.
Conduction is the process by which heat travels through solid materials including the ceiling roof, walls, and floor of a house.
Radiation is the way in which heat is transferred from a hot body to a colder body by infra-red radiation, without warming the air in between. Some of the radiation is absorbed by the cold body, some is reflected, and some is re-radiated to colder surfaces. On a sunny winter's day, for example, your body is warmed by the radiant heat from the sun even though the air is cold.
Convection is the process by which heated air rises and transfers its heat to colder objects above.
Heat gains or heat losses from a home through the building structure occur due to conduction, radiation and convection.
Insulation reduces the rate of heat transfer through building structures, those being ceilings, roofs, walls or floors. In winter it reduces the rate that heat is lost from the home, and in summer it reduces the rate of heat entry into the home.