Key points
- Insulating your home is an excellent first step to reducing energy consumption and electricity costs.
- Investing in ceiling insulation, then wall and floor if possible in your home, will help maximise energy efficiency.
- Michael Ambrose says installing insulation in your home could reduce your heating and cooling costs by 45 per cent.
Many of us are making big decisions about rooftop solar and energy efficiency as we transition our homes to address the climate challenge. But have you considered the energy and cost saving benefits of having good insulation in your home?
Michael Ambrose is our senior experimental scientist. He says before installing solar panels on your old home, you need to first consider ceiling insulation.
Insulating to reduce electricity costs
Insulation is the most effective way to keep our homes warm in winter and cool in summer. It works by restricting the transfer of heat from one space to another.
"In winter, when we are warming our homes, we want to keep the heat in our homes and not lose it to the outside," Michael says.
"In summer, we want to stop the heat from outside getting in. Insulation greatly helps in achieving both those objectives, effectively reducing both our heating and cooling costs."
New homes and older homes
New homes, built in the last 20 years, should be well insulated. Building regulations require all new homes to meet minimum energy efficiency standards. This is referred to as the energy star rating of your home.
"Most new homes in Australia were required to achieve a minimum of six stars. But in many places, including Victoria, NSW and the ACT, this has now increased to seven stars," Michael says.
"So, our new homes are now even more energy efficient!"
Older homes, built before 2001, were typically not subject to any energy efficiency regulations. This means they are often far less energy efficient. There are lots of easy ways you can improve the efficiency of your older home.
Installing ceiling insulation is a great start to making your old home more energy efficient long term. Installing insulation will lower your heating and cooling energy costs.
Value of insulation
Insulation acts as a barrier to heat flow from one space to another. We install insulation around the exterior envelope of our houses – in ceilings, external walls and even floors – to help keep our interior spaces cool in summer and warm in winter.
Insulation materials come in many different forms. The most common material is insulation batts, but there is also foil, cellulose fibres, rigid panels, and more. All have an R value.
The R stands for 'Resistive'. The higher the R value, the better the thermal resistance of that material and, consequently, the better its insulative properties. It is usually best to aim for the highest R value that is practically possible.
Start with ceiling insulation
Ceilings are the most critical part of homes to be well insulated. To be effective, ceiling insulation needs to well installed, continuous over the entire ceiling area, and have a high R value.
"Although you might be able to check whether your ceiling has insulation or not by having a look through your ceiling access hatch, to get a full assessment often requires a professional," Michael says.
To determine whether you have complete coverage, a professional will usually do a physical inspection of your ceiling space. They may also use a thermal imaging camera to identify gaps in the insulation layer. They will check for quality of the insulation material and that it has been properly installed.
"You’ll need to get a professional to do this because ceiling spaces often contain lots of other items, not just insulation," Michael says.
"Hot flues, exhaust fans, heating and cooling duct work, and light fittings may all be there, and it is important to allow insulation clearance around many of these to ensure heat does not build up and cause a fire."
Some modern LED downlights do allow insulation to be installed over them. You should always check the manufacturer's instructions to verify if this is possible.
Installing insulation to save
Heating and cooling our homes contribute our single biggest energy use.
Michael says reducing your need for heating and cooling through good insulation will lower your energy bills year-on-year.
“Insulation, especially ceiling, provides excellent bang for buck," Michael says.
"Exact costs to install ceiling insulation will vary from house to house, but expect to pay between $1800 to $2800.
"Going from no insulation to a well-insulated home could reduce your heating and cooling costs by 45 per cent or even more.
"Combined with other energy efficiency measures, like appliances, an energy efficient home will deliver significant savings on your energy bills."
Working in wall insulation
Installing wall insulation when building a house is easy. But once the house is constructed it can be challenging to install insulation in your walls.
Silicon-treated Rockwool or glass fibre insulation is used to insulate existing wall cavities.
"Wall insulation can reduce heating and cooling costs by 15 per cent, so it is worth considering," Michael says.
"Particularly if you’re renovating, there may be an opportunity for a professional to add insulation to an entire wall."
Getting down with floor insulation
Many old homes have suspended floors, rather than a concrete slab. Like ceilings, a non-insulated suspended floor will allow heat to escape to the space below. However, it is possible to install insulation on the underside of the floor.
"Different types of insulation options are possible for floors, including expanding foams, rigid boards and concertina foils," Michael says.
"Speak with a professional about the best options for your home."