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Wall insulation

Improving my house’s heating and cooling and energy efficiency is an ongoing project.

This week it was wall insulation.

Obviously this is best fitted when the house is built, but in a house built circa 1930, the only way is to retrofit it.

They do this by drilling small holes in the walls all the way around the house, then spraying in filler stuff into the wall cavity.

Insulation installation

They’ve filled the holes, but they’ll need sanding and painting, which leaves me somewhat regretting I didn’t do this before I got the house painted in 2015. Not to worry, but for now the house looks like it has measles.

Last year’s winter gas bill (covering 15th June to 15th August) was a whopper, at $489 ($7.87 / 354 MJ of gas per day) – similar to 2016. (In 2017 we were away on holiday for some of winter.)

I’m hoping that by getting the new insulation in time for winter, the gas bill for winter this year can be reduced quite a bit – hopefully daytime warmth can be better retained into the evening and overnight.

It might be a while before the investment (not insubstantial) pays off, but already there’s a noticeable difference, which is good.

Future options around the house include:

  • double-glazing on the windows
  • under-floor insulation
  • PV panels for the roof
  • replacing gas cooking with electric
  • replacing gas central heating with more reverse cycle units
  • and one I learnt about recently which seems like an easy no-brainer: a balloon in the fireplace.

By Daniel Bowen

Transport blogger / campaigner and spokesperson for the Public Transport Users Association / professional geek.
Bunurong land, Melbourne, Australia.
Opinions on this blog are all mine.

10 replies on “Wall insulation”

Do you still have a gas oven? Then yes, an electric one will be more efficient and stop you breathing in gas fumes. Same with the cook top, there is something nice about a gas burner, but its not as efficient as a induction electric cook top which can be had very cheap nowadays, I believe Ikea has one for around $500. They can be a little troublesome however, if the pan inst just in the correct spot etc.

Agree that reverse cycle air conditioning is the future of heating and cooling, as it can run of renewable electricity and PV panels.

“Last year’s winter gas bill … was a whopper, at $489.”
Yikes! We have gas central heating and our 2-monthly bill is less than half that. And we have crappy home insulation.
I think there’s an issue with your appliances. In summer our gas bill is tiny, indicating that our hot water service and stove use stuff all gas compared to the heating.

Those chimney balloons are apparently hard to get to fit right. I was going to get a couple (we have two fireplaces), but after doing some research I got a couple of pieces of foam rubber instead. It works great. You could try or get a piece cut to exactly the right size at Just remember to remove it before lighting the fire!

I got a $524 bill for 354 MJ/day over the same period last year, but we have gas hot water during winter (when the sun doesn’t shine enough to heat the water much at all). We were also getting ripped off for our gas, so this year we should be better off. And our walls are already insulated with R2.0 batts!

@Roger, in contrast, the gas bill covering 2 months of summer (12th December to 13th February) was $131 (46 MJ/$2.04 per day). So it’s certainly it’s much higher in winter when the heating is used.

That said, it was about double the usage of the same time the previous year… for reasons unknown.

@David, thanks – that looks like a good option!

Hi Daniel. We’ve been thinking the same for our weatherboard. Can you share approximate cost? Is ‘not insubstantial’ $5k, $10k or ?? Thanks.

@Donna, it’ll obviously vary widely according to the size of the house. For my smallish weatherboard house, it came in at about $4500, and it took about 5 hours.

Now we’re a couple of weeks into having the insulation, I’m wishing I’d done it years ago. It’s made a huge difference to heat retention, especially when it’s cold overnight – though we haven’t seen the coldest part of winter yet.

I’m happy to recommend this mob:

(I haven’t yet worked out when I’m going to address the drill marks, eg sand and paint. Eventually.)

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