We all love a home that’s refreshingly cool in summer and wonderfully warm in winter, but with the average electricity bill in Queensland now amounting to over $1,500 per year, finding ways to reduce your energy consumption is becoming more and more critical to many households.
Many of us probably underestimate the impact the design and construction of your roof can actually have on both maintaining a comfortable temperature in your home and your power usage. Here are some of the factors that can affect energy efficient roofing.
Heat retention
Because hot air rises and roofs are exposed to a lot of solar energy from the sun, the air in your roof cavity tends to be a lot warmer than the air in the rest of your home. That’s why how you manage the area under your roof is so vital in terms of your home’s heating efficiency.
Roofing materials can vary in terms of their natural insulation properties, and those with a high ‘thermal mass’ are slow to absorb and release thermal energy, which can help maintain a constant, comfortable temperature inside your home. Energy efficient roof materials like ceramic, slate, concrete or stone tiles will absorb and trap heat and continue to emit warmth into your ceiling cavity. On the other side of the coin, metal roofing is a good heat conductor but a poor insulator, so metal roofs can be ideal for homes that are located in hot climates.
Ventilation
A building’s ‘envelope’ or skin is one aspect of a home that can assist with ventilation. A tightly sealed building envelope won’t allow much air in from the outside, whereas a loose envelope allows a more free-flowing exchange between the air that’s inside and the air that’s outside. That’s why homes in cooler climates often favour a more tightly sealed envelope.
In terms of ventilation and energy efficient roofing, heating and cooling costs can be reduced in your home by controlling the heat trapped in your roofing cavity. Lowering the temperature of your house is often as simple as encouraging warm air to exit the apex of your roof. Vents in the soffits of your eaves can help draw cool air into the roof, which pushes the hot air upwards and out of the ridge vents at the top of your roof.
Using warm air to heat your home is a little more complicated, however the addition of a mechanical ventilation system can help ensure that effective circulation occurs. Heat recovery ventilation (HRV) systems for example, will collect the warm air trapped in your roof and blow it back into your house, and in warmer months, a HRV system can also be used to mechanically ventilate your roofing cavity.
Insulation
We live in a country that experiences a range of climates, which can sometimes make regulating your home’s temperature a challenge. In cold weather, up to 35% of the heat in your home can be lost through the ceiling, and a similar amount of heat can be gained in summer.
When you are heating your home in winter, the internal heat conducts outwards through the roof and walls and hot air can escape through gaps around doors and windows. Because hot air rises, most of the heat escapes through the ceiling however, so installing roof insulation like ceiling batts can help minimise this process.
Homes in tropical and subtropical climates often have no need for bulk insulation so ‘cool’ roofs are often an option. ‘Cool roofs’ are roofs that are painted or clad with materials that both release and reflect solar energy.
Investing in insulation will not only help you gain a more energy efficient roof, it will ensure a more pleasant living environment, and can save you significant amounts of money on heating and cooling costs.
Eaves
Eaves are the parts of a roof that hang out over walls in order to provide shade to your home’s exterior, and they can play a crucial role in regulating the sunlight that enters your home at different times of the year. If they are correctly designed, they’ll block summer sun, while still admitting winter sun.
However, the inclusion of eaves normally needs to be accounted for at the design stage of a home, so if your home doesn’t have them, there are a number of alternatives that can still assist you with obtaining an energy efficient roof. These include shading your home with plants, opting for low emissivity (or double glazed) windows or using alternative fixed shading options like awnings or pergolas.
Colour
When it comes to roof colour and efficiency, about a third of the unwanted heat that builds up in a home comes in through the roof. So traditionally, it made sense that if you live in a hot climate, you should opt for a light to medium coloured steel roof. The reverse is obviously the case for cooler climates – darker colours tend to absorb heat, and combined with a construction material that also stores warmth, can help with the passive heating of your home.
However, with the advancement of roofing technology and construction, these days peak thermal performance can be guaranteed regardless of the colour palette you choose. Companies like BlueScope Steel, for example, offer a range of COLORBOND® steel roofing products that include unique THERMATECH® technology. In summer, this technology reflects more of the sun’s heat so it can help your air conditioner work more efficiently. In winter, the ‘cooling’ effect is greatly reduced because the days are shorter, it’s often overcast and the sun sits lower in the sky.
Need some advice on how to achieve the most energy efficient roofing? Contact us on (07) 3623 4422 for a quote!