The energy efficient house – Canberra retrofit

We have just sold our first house, a little brick house in Canberra’s inner north, typically called a “Govie” by the locals. We were there for 4-years and during that time we changed the Energy Efficiency Rating (EER) from 0 to 4. I’ve been promising for a while to write this up, so here it is. What we did, and what we should have done.

The House

The front wall, winter sun behind the camera.

Three bedroom (more like 2.4) brick-veneer house. Single brick on the outside with timber stud walls and plasterboard. Suspended timber floor without carpet. Timber framed gable roof with concrete roof tiles. Windows are all single pane in timber frames. The front of the house has the most glass and faces about NNW. The house was built in the late 60s

We didn’t get seriously into the energy efficiency modifications until about 2 years in. We had bigger fish to fry before that, like re-doing the bathroom, which had some excellent examples of early 70s asbestos.

Ceiling Insulation

We received Pink Batts money from Kevin Rudd and got what we could for free and felt pretty good about it. There was essentially nothing in there before then and we added R4 batts, which cost about $800 in 2010.

We should have spent a little bit more and gone for R5 or even R6. Canberra is a properly cold climate, so it’s worth significantly insulating the ceiling. Much of the cost of paying someone to install insulation is just showing up, so spending more on the materials is better value than upgrading it later. This guide from the Victorian Government gives the range of values for the different climates in Australia.

Draft Sealing

This was really worth doing in this house, as the main form of heating was ducted gas. This has vents in each room which blow hot air, and a large central vent that sucks air out of the house. Because the friction in the room vents is higher than the central vent the pressure inside the house is lowered slightly and cold air from outside comes in through every single little hole and crack.

The range-hood was the worst. It had a pipe straight through the wall and a broken flapped exhaust port. I cut a piece of neoprene foam (an old hiking mat) that fit the hole exactly, stuffed newspaper in from outside, then put the cap on. We just decided not to use the range-hood in winter.

I sealed the external door frames with these special squishy tapes you get in hardware stores, and put weather strips on the bottom. This can be a bit of a fiddly job and makes your doors work badly if you’re not careful. Buy a range of thicknesses and have a good look at where the door sits (or more importantly doesn’t sit) against the door jamb. It will probably take some fiddling to get the latch-tongue to go into the strike plate when you’re done too. I used a little file to open the strike plate on a few doors.

I did the same to all the internal doors as well. This means that you can use the room to insulate the hall against the outside of the house, and again because of the gas heater suck it was another way of slowing air movement.

Window Treatments

We didn’t have a lot of money for this step, and were terrified by the idea of making curtains. So we bought blockout roller blinds, which were really good at keeping the heat out, and moderately good at keeping it in. We also used semi-opaque honeycomb blinds in the big window in the front room, which we loved. They have noticeable thermal affect, and the good ones will supply a tested R-value. The slight transparency meant it let light in while they were closed, which was nice, but mostly for privacy.

Outside we put roller blinds on most of the windows. The kitchen window got hot early sun in summer at an awkward angle, then the front of the house baked in the afternoon. These blinds were great actually, and made the house much cooler in summer.

If I had my time again I would have put the external blinds on for the first summer.

Inside, I would get high-quality honeycomb blinds made to fit snuggly inside the window frame (actually called the “reveal”, the wooden frame that engages the window with the house frame). This would probably be a bit expensive, in which case I’d buy a good sewing machine and go for it. But honeycombs would be my first choice.

Wall insulation

This is another thing I wish I had known about earlier; until we’d done almost everything else I didn’t think this was possible. Turns out I was very wrong.

The brick veneer of a typical Govie creates a great pocket of air between the plaster board and the bricks. There are now machines and insulation products designed to exploit this and they can pump insulation in. It cost us about $2k and after the first round of draft sealing probably made the single most noticeable difference. Strongly recommend this step, particularly if you have the same construction technique.

Windows

I probably should have put this at the top of the page as many readers will be interested in it, but it should not be your first priority when looking for the most effective projects.

We spent at least $15k on ours, replacing every single piece of glass in the house, in 21 separate apertures. The cost affect is actually hard to judge for an individual, as it looks like we might have added that much to the value of the house at sale. But for the house, the payback period is in the order of 30 years.

However, in terms of niceness, the windows were hard to beat. The originals were very tired, push-out awning windows, that leaked in a way I couldn’t fix without gluing them shut, which I did in a few cases. Rather than hinging at the top they hinged off a brass bar in the middle, and the top slid down. Then where the bar folds into the frame there it a gap that you can actually see through. They were awful to use, which involved opening the flyscreen like a door, then diving out the window to push it far enough to sit still. Terrible things.

For all 5 of those we went for aluminium framed “sash” windows; two panes that slide up and down past each other. The first thought behind this was to open top-down in the afternoons to eject heat, which worked really well. Every day once the outside temp was less than the inside temp we opened all the blinds and all the windows, which made a difference quickly. The aluminium frames are not ideal for thermal performance, but at that time we didn’t have much choice in suppliers. This guy got the job because he was the only one who would show up and quote. UPVC and timber are becoming more commonly available now and they work much better than aluminium.

On the north wall we used a laminated and coated glass called ComfortPlus, made by CSR. It’s not quite as good thermally as double-glazing, but we used it for a number of other reasons. First it’s a toughened glass, which we wanted for the front room which has glass at ground level, and we had a toddler whose favourite toy was a hammer. It also blocks UV light, which means your furniture and floor doesn’t fade and your baby doesn’t get sunburnt lying nude in the sun. Lastly it blocks IR light as well, which slows the heat transfer into the house in summer.

The south is all double-glazed.

Southern wall of the house, halfway through deck construction, with new windows.

If I had my time again I would try pretty hard to get double glazed windows, with toughened and coated glass, in UPVC frames. A bit of a scout around suggests there are more suppliers operating now than when we were shopping, and a lot more choice.

Hot Water

We didn’t touch, but should have tried harder. We had a gas storage hot water system, which doesn’t lend itself well to solar addition. The problem might have been that I just didn’t speak to anyone imaginative enough, as I have since found solutions to that problem. Evacuated tubes work really well in Canberra and have been cost effective for years.

The idea

As I’ve mentioned elsewhere, I would rather you don’t just make energy efficiency decisions on cost. If possible, consider niceness. You are pursuing comfort, rather than spending the least amount possible on energy. Just pursuing costs can lead to some perverse and unpleasant outcomes, like living in a north facing, perfectly sealed Esky.

Hold in your thoughts a house that keeps the heat where you want it, but is also well ventilated when you want it, with easy to operate equipment made of durable materials.

I’ve written at The Conversation about the fundamentals to consider when launching into something like this, followed by a period of thinking and observing. Where does the sun fall in summer and winter? Any big deciduous trees that will block sun in summer and allow it in winter? Where does the air go that I don’t want it to? Which rooms do we use and when?

And this is the fun part. Making a house run efficiently is a dynamic and complex problem. As the seasons and usage patterns change, so do the most efficient choices. But I encourage you to give it a go, it’s surprising how much difference a few simple changes can make to your comfort.

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About evcricket

Extreme gardener, engineer and bird nerd.
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3 Responses to The energy efficient house – Canberra retrofit

  1. Russell says:

    Thanks for the write-up! Handy info.

    One question I have – I’m about to re-paint mine and am considering spacking over the wall-vents which are present from the ?early 70s brick-veneer ex-Govvie build (sounds similar to yours – although my window frames are the sideways-sliding aluminium type – am in Waramanga).

    I suspect that these vents are not actually very good at ventilating the wall-spaces and are just heat-sinks – but wasn’t sure if maybe you had any knowledge of that?

    Cheers!

    • evcricket says:

      Woah, sorry it’s taken me a while to get back.

      I doubt the wall vents contribute anything at all, possibly even make insulating worse. Air flow means energy transfer and i reckon the wall vents make energy transfer through the wall cavity greater. I’d cover them over I think.

  2. Aidan says:

    Great writeup. Thanks.

    Our place is oriented with the long side facing NNW with properly sized eaves. I recall the EER report when we purchased marked the house down because the northern glazing didn’t have external blinds. No sun comes in during summer! Consequently I lost a little faith in the EER system. Your external roller blinds are the metal jobs? A colleague installed them on his place at Bundanoon and reckons they were brilliant at keeping heat in and out. Expensive though? I would have thought it was an either/or double glazing/external shutters equation. Is both overkill?

    Our place is also a brick veneer. We also have gas ducted heating. I like the heat, I don’t like the noisy blowing, and I’m also concerned that the inlet is in the coldest, least well sealed room in the house (kitchen). Hydronic would be a big improvement, but the cost is astronomical.

    We got the blow-in rockwool wall insulation pretty early on. This seemed to have the desired effect of slowing down the cycling of the heater. Later we increased the ceiling insulation (also courtesy of Mr Rudd), but from the sounds of it we could go more. My Mum’s house (in NZ) got some Gov funded insulation installed. In the ceiling they just rolled out great long strips of insulation over the crappy exisiting stuff and over the ceiling joists. They said it was a better solution as there was no heat leakage round the sides of the batts. I was thinking this might be the best solution if I wanted to improve the insulation.

    I’ve also been a draft-Nazi, but it is a little dispiriting that the stuff was so expensive (seems to be coming down in price now) and needed replacing every few years. Our place is on horrid clay that moves A LOT. Consequently it was difficult getting a decent seal around the kitchen door. In the end I fitted a bead of quad around the frame that the door sealed up against. That worked pretty well, but it is fiddly as hell to get it right.

    The most expensive change we made to our place was reorganising the internal space when we extended and put on a fourth bedroom. We moved the living area from the south side to the north, and simultaneously got rid of the gabled roof (with horrid bubble plastic heat-leaky skylight). I don’t know if we saved a lot of money, but the comfort levels are out of sight improved.

    The renovated bits of the house now have under-floor insulation. I’ve been thinking about extending that to the rest of the house, but it is a bugger of a job and I’m not certain it will make as much difference as other measures, particularly as we mostly have carpeted floors.

    As for keeping cool in summer, we installed evaporative cooling. The positives are that it works really really well. The electricity usage is seriously low (we didn’t notice it on the bill). The water usage is also low. We used to shut everything up and then only open up when the humidity and temperature got unbearably. Nasty. More than 50% of the time we use the system we aren’t actually cooling, just pushing cool night and morning air into the house and then closing up until the temperature hits 24/25. The only major downside (apart from cost – $6k or so) is we now have large holes in the ceiling. I stuff them up with insulation in winter, but they definitely a source of heat loss as they are difficult to air seal.

    I’m also planning on retrofitting some RFL to the undersides of the rafters. As well as helping to keep cool in summer I was hoping to slow down the rate of heat loss in winter as the wind fairly rips through the roof space. As it is difficult to properly draft proof the ceiling from the inside, it seems logical to slow down the heat loss by making the roof space less drafty.

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