Seb Crangle-1 My name is Seb Crangle, I'm the Head Energy Coach at Enova Community.

My personal journey with energy efficiency started in our own home, looking for ways to use less energy and reduce our carbon footprint.

My goal was to reduce our emissions, lower our energy bills, whilst staying comfortable.

Getting my hands dirty

When we had solar installed a few years ago, I was spurred on to be even more energy conscious. I was determined to use as much of the solar energy we were producing as possible.

The house was built in 1984, with very little thought for passive design. In more modern homes, ‘passive design’ is design that takes advantage of the climate to maintain a comfortable temperature range in the home.

My house was poorly insulated. It had a very hot roof cavity, lots of direct sunlight through windows in summer and some terrible heat traps. It was too hot inside in summer and too cold in winter, so we were using a lot of electricity to cool and heat the house to be comfortable.

Most homes built in Australia before 2010 are badly insulated, so putting the effort into creating better energy efficiency through retrospectively improving the ‘thermal barrier’ is a worthwhile endeavour.

I embarked upon a process to improve the energy efficiency and comfort levels (internal temperatures) of the house.

I got stuck in, “getting my hands dirty”, insulating various cavities, finding and plugging draughts and installing blinds and shade sails to reduce heat traps.

Using a sealant to plug a cavity in the old wooden floor boards:

A cavity in the old wooden floor boards Using a sealant to plug a cavity in the old wooden floor boards

Over a two-year period, I adjusted and improved our home and added solar panels on the roof.

The energy bills are now down from $2,000 per year to around $800.

Thermal performance

The term 'thermal performance' generally relates to the efficiency with which something retains or prevents the passage of heat.

Improving the thermal performance of a house in summer can be achieved with things like insulation, creating shade, preventing ‘heat loading’ with curtains or blinds and outdoor awnings, and ventilation in the evening.

Ventilation can significantly improve the indoor thermal comfort, reducing the need for air conditioning and thereby provide good energy savings in summer.

Most homes have a ceiling cavity, which can be a big heat trap in summer. Like a lot of people our first step was to insulate the roof space to stop the heat getting in. But even with insulation, the extremely hot roof space still makes the house hot, as the thermal load builds up during the day and sinks down through the insulation and ceiling.

To reduce this load, I found a solar powered heat extractor, which unlike a standard ‘whirligig’, actively draws out heat from the roof space. And because it is powered it does not need to wait for wind (or a high temperature differential) to operate effectively.

Efficient AC use

During last year’s hot summer we relented and got reverse cycle air conditioning. Aircon

To mitigate the additional energy used, I run the aircon only when the solar system is generating excess energy. I keep an eye on the outside temperature compared to inside with an indoor/outdoor thermometer. As the outside temperature starts to drop, I turn the air conditioner off. With the house still closed up it stays cool for about half an hour, and then I open doors and windows to let the evening air ventilation in and through the house.

Thermometer helping me keep track of cooling temperatures:

Air conditioners get a bad wrap because of high energy consumption. However, they can be a very energy efficient way to keep a house comfortable, especially once you’ve done everything you can to improve the house’s thermal performance. However if they aren’t used well they can use a lot of energy unnecessarily. For example, if the temperature is set much lower than needed, or by being over-eager to quickly change the temperature in a room or house, by “blasting” it down to 16 degrees.

It’s better to turn aircon on low during the day before the house gets too hot, to prevent the heat load of the house building up. Heat load is when the materials in a house, including its walls, floors, furniture and so on, heat up from exposure to sunlight and ambient air, retaining that heat. It’s because of heat load that a home can continue to stay hot even once the temperature has fallen to comfortable levels outside. This is why we want to keep direct sunlight out of our houses, and try to shade external walls, decks and rooves.

If you have an air conditioner, by closing up the house and keeping the inside at a reasonable temperature (say 25°), you prevent internal heat load building up without using excessive amounts of cooling (energy) to do so. And if you have solar and are generating excess power this may well be a cost-effective way of using that power.

'Leaky' house no more

Some people advise against this approach because Australian houses tend to be so poorly insulated and ‘leaky’.

That is, in summer they let the coolness generated by air conditioning to leak out; and in winter they let cold air in by way of draughts.

It is important to identify these leaks and plug them up. There are a range of draught-stopping products available.

I plugged the leaks that I found in my house by using draught stopper products around door frames and under doors, filling gaps between floorboards with coloured gap filler, and insulating under the floorboards with fiberglass batts with wind resistant fabric on one side.

I use a special technique to find draughts and ‘leaks’ in my house. I light a candle or stick of incense, moving it slowly past door and window frames when the house is closed up, looking for the candle to flicker as it passes a draught.

Importance of external shade

I suggest households look for heat traps in patios and try to create shade externally, using shade sails or outside blinds which can be taken down or rolled up in winter. These stop the heat getting into the house in the first place, as opposed to internal blinds which block sun but still allow the heat in.

A shade sail over my patio prevents that space from becoming a source of heat that would seep into the house in summer.

Heat traps

You can borrow from the library an ‘energy saving kit’ which includes a digital infrared temperature gauge. This device tells you the temperature wherever you point the laser, so can identify places where there are changes in temperature, such as gaps in insulation or hotter air leaking in through draughts.

By paying attention to where my house was trapping heat and leaking energy, over time I was able to remedy these areas and dramatically reduce my household carbon emissions as well as my energy bills.

We can help you!

If you’re interested in learning more about the areas where you can improve the energy efficiency in your home, we can help.

Enova Community’s team of volunteer energy coaches will be available to households again this year to give you guidance on improving your home’s energy efficiency. We’re passionate about this because finding ways to use less energy allows everyone to take immediate action on reducing their carbon emissions.

You can book a session with us here.