# Halving My Gas and Electricity Bills

I want an energy efficient house. However I don’t want to move or build from scratch. So I have decided to see what I can do with my 80 year old double-brick house here in Suburban Adelaide, South Australia. This post talks about the steps I have taken over the last 3 months to roughly halve my gas and electricity bills.

Electricity Audit

I once worked with a guy whose mantra was “If you can’t measure it, you can’t manage it”. So the first step was to audit my electricity use with this \$40 power meter from Jaycar:

You plug this puppy in line with an appliance to get voltage, current, and most importantly the power in Watts. It can also add up the power used over time to give you the total energy used in kWh. This is really useful when the power used by the appliance varies. For example a fridge motor starts and stops over the course of a day.

So I wandered around the house for a few days, irritating my family while I plugged the power meter into various appliances and working up the results in a power audit spreadsheet (here is the power audit spreadsheet in Excel format).

Some appliances (like the air conditioner and stove) were directly wired in and couldn’t be tested using the power meter. So I worked out how to measure power from the household electricity meter. I have a really ancient one like this:

The more electricity used, the faster the ring spins. On my meter is says that every 400 revolutions is 1 kWh. So if it rotates 400 times in one hour, then I must be using an average power of 1kW. A little maths and I worked out that the instantaneous power in Watts is given by P=9000/T where T is the number of seconds it takes for the ring to revolve once. For example as I write this the ring is taking about 18 seconds to turn which means the house is using 500W. With two TVs and a few PCs running, that is about right.

To measure stuff like the air conditioner I would first make sure loads like the fridge/pool were switched off (I didn’t want them switching on by themselves half way through my measurement). It also helps to have no one in the house, as the electricity jumps up and down all the when people (especially kids) are in the house. Then I would look at the power before and after the appliance was switched on, and subtract the two measurements.

One interesting test was to switch off everything. You see I wanted to make sure there were no “phantom” load sucking power that I didn’t know about, like a suspect alarm system or IR sensor light. Switching everything off (i.e. using no electricity) was really hard – just try it! I had to chase all the kids out of the house (to avoid TVs, lights being switched on and off), and run around the house switching off the fridge, my server etc. All that was left was a few clocks (too much effort to reset) plus stuff that was permanently wired in (like IR sensor lights). The minimum was about 70W. Not zero, but about what I expected.

Electricity Audit Results

Anyway, back to the power audit results. There were some shockers. For example my sons desktop PC uses more energy off (20 hours off at 28 Watts/hr) than on (4 hours on at 91 Watts/hr). It uses more power off than my laptop does on!

Standby power was also a big problem for the older appliances like TVs and VCRs. Some of the newer DVD players were much better, drawing 0W when off.

The effect of 24 hours is interesting. Just wasting 20 W/hr adds up to nearly 500Whr/day (180 kWh/year)! Add that up across several appliances and it really starts to stack up.

There were also some pleasant surprises. Before starting the audit I was sure that my server would be the main power culprit, however combined with my DSL modem and a hub it only uses about 20W. This I totally have Linux to thank, it runs a powerful server on a 10 year old P133 PC. It’s a file server (SAMBA/NFS for both Windows and Linux machines), print server, DHCP server, firewall, SSH server for remote login, runs a small web server. All on an ancient P133 with 64M of RAM.

Reducing Electricity

OK, so here are the steps I took to increase electrical energy efficiency:

• Conduct an Energy Audit to sniff out the culprits. Many surprises here, both good and bad.
• Used a Floatron to dramatically lower pool energy requirements.
• Switching off at the wall standby power loads at night, like TVs and PCs. Grumble. I wish there was a box that could do this for me, or that beeped in my kids ears when they forget.
• Swapped out nasty incandescent light bulbs for compact fluorescent (CFLs).
• Swapped out nasty halogen downlights for LED downlights.
• Encouraged the use of laptops (20W) rather than desktops (90W).
• Where possible use my laptop on mains rather than battery power, as I have read the charging/discharge cycle is only about 50% efficient
• Placed my home office equipment on a separate power board than can be switched off at night, while leaving my server running. Previously I just left everything on.
• Promised my 9 year old son an extra \$1/week if he remembers to switch his PC off at the wall every day. Good training, teaches him “the value of energy”. I figure that energy efficiency is going to be a much bigger issue in his life than mine.

Most of these changes cost me very little, they mostly paid for themselves by the next power bill.

When you start to look around it’s amazing what you find. In my family room I have two light fittings which had 5 60W lights each. That’s 600W total for one room! The funny thing was that with the dark walls in that room the light still wasn’t any good for reading. Now I have a pedestal lamp with a single 11W CFL – it’s direct lighting actually makes reading easier than the previous 600W of indirect light.

In the kitchen I replaced 4 nasty 60W Halogen downlights with 3W(!) LED downlights:

The LED versions aren’t quite as bright, and my wife Rosemary wasn’t very happy with them at first. However we are now quite used to them. Compared to CFLs they were expensive at \$30 each, but I figure the payback is a little over 1 year. Thats one good thing about working out the numbers with something like a power audit, you can make educated decisions on where it is a good idea to spend money.

Also, I have to admit there is just a good feeling about being efficient. Not everything in life reduces to economic, dollar based decisions like payback period. Sometimes it just has to feel right. That’s enough.

Hacking my House – Insulation and Air Conditioning

To attack the gas consumption we had a hard look at our insulation and air conditioning options.

In August 2006 my wife Rosemary was shivering through our vicious Australian winter and suggested we get a reverse cycle (heat pump) type air conditioner. Actually in Australia we are blessed with fairly mild winters (it rarely gets to freezing). However as a result building codes are lax, and most houses have single glazed windows and poor insulation. During a winters day when it’s 15C outside, it’s often 15C inside. I have several Norwegian and Canadian friends say that their coldest winters have been in Australia!

The current, socially accepted solution, is to bolt a massive reverse cycle ducted air conditioner onto the energy sieves we call houses. In winter they heat, in summer they cool. These air conditioners can draw up to 8kW and often require a 3 phase power connection to the house. When I step outside on a summers day I can hear them roaring all over the neighborhood. Our electricity companies are creaking under the load, especially in summer, as more and more are being retrofitted to older homes like mine.

Our house (which is gas heated) was unpleasantly cold in winter. In summer it was too hot, our old evaporative air conditioner just wasn’t cutting it. So we asked for a few quotes on reverse cycle air conditioning. About \$15,000 plus the cost of a three phase connection. Plus I figured significant ongoing electricity bills. Running 8kW means \$1.20/hour and rising each year as electricity costs go up. Ouch.

So I decided as a first step to look at our insulation. No point pumping all that heat into/out of the house if the insulation was just going to let it all leak out again. Sure enough, our insulation was shot, so I arranged to have new insulation put in.

The more I thought about it, the more I felt bad about a big reverse cycle air conditioner. So I decided to upgrade our evaporative unit, by getting new ducting (the ducting was ripped) with a high insulation standard. We have mainly dry heat here in Adelaide, so evaporative is fine most of the time, and it draws between 500 and 1000W, a fraction of a heat pump.

After reading about household heat loss, I realised that my standard, single glazed windows were a big problem. Swapping to double glazed windows would be a big job (new frames in all windows) so after some research I decided to install some special laminated glass called Pilkington Comfort Glass that has insulation properties almost as good as double glazing.

Curiously, a few people I discussed this with thought I was wasting my money. Why not, they suggested, install some nice looking new window frames for the same money? I figure this is evolution at work, these people will be naturally selected out of the population if we ever face energy shortages.

Results – House 2.0

We installed our new insulation and windows in August (end of our winter). That day we switched off our gas heating and it wasn’t needed again. Normally we would still be using it (off and on) until October. So we are far more comfortable and using less energy. Nice.

We experienced the first warm weather in November; a week of 30C plus. I only needed to switch on the (evaporative) air conditioner at the end of this week, and then only right at the end of the day for a few hours. This is amazing – last year we had the air con running all day in weeks like that. When I walk outside I can hear the roar of air conditioners (big nasty reverse cycle heat pumps) all over the neighborhood. At night we open up the house to capture the “cool” night air inside. Then in the morning we shut the doors. The only problem we noticed is that the air inside gets a little stuffy. So we have started using a couple of fans, just to give the cool air some movement. Ceiling fans would be perfect I think.

Since then we have had several weeks of 40C weather. The inside temperature hasn’t been above 25C, although on the hotter days we run the evaporative air conditioner most of the day, on a moderate power setting. Last year, before the house 2.0 upgrade, even at full power the air con just wasn’t up to it.

We just received our latest electricity and gas bills. Electricity dropped from \$509 to \$272, and gas from \$413 to \$168. Gas usually drops this time of year, so the true test will be next winter. However it’s still the lowest gas bill we have had in years.

Negawatts

Energy efficiency, or Negawatts can be considered a really cheap, easily available new power source equivalent to at least halve our current energy consumption. Low hanging fruit. Much smarter than building new power stations, and lowers the bar for converting across to renewables.

Next Steps

I am working on some related projects:

• We have just had a solar hot water system installed. This should drop the gas bill even further, as we get almost all of our water heated by the sun now. Totally makes sense in a country like Australia.
• We are getting a 2 kW grid-connect solar electric PV system installed.
• I am recycling a small car into a Electric Vehicle (EV)! Totally out of my depth on this one (it’s very mechanical) but slowly making progress.

## 46 thoughts on “Halving My Gas and Electricity Bills”

1. Right on. We installed an 18 kW solar system in our house last year and after a year we were net negative 160kWh. The biggest difference in our gas usage was getting a tankless water heater, so now it only heats water as we use it. Cut gas usage to about 30%.

This year we bought a US\$50 electric space heater to change some of the extra electricity into less gas usage. (PG&E resets our account every october and any spare electricity we have just disappears, no compensation of any kind)

2. david says:

Wow – 18kW is really big. Is that the continuous output? Mine is about 2kW continuous, or average of 9 kWh per day. That a pity with PG&E. Our State government will hopefully bring into law a new buy-back rate this year so I am hoping to sell a little electricty!

The instant hot water system (as well call them here) is a good idea – I was told that the regular systems were like having “a pot on the stove” 24 hours a day.

3. You can definitely count me among the Canadians who think they’ve never been as cold as in Australia (Sydney). In winter, there’s no way to get our (double?)-brick house above 15-17 degrees, even with heaters costing us as much power as it did in Canada by -20 degrees (and that would heat our house to 22 degrees!). This is even after we made a few quick fix (this is a rental house), like plugging the 2cm gap at the bottom of the front door! By way of comparison, in the last place we lived in Canada (which I considered to be badly insulated by canadian standards), we wouldn’t even have to heat until temperatures dropped below around 5-10 degrees (it would still be >20 degrees inside). It should be a crime to build such poorly insulated houses, especially considering the costs could be recouped in only a few years! I’ve hears some Australians tell me it’s because Australian houses are built for the summer, but even then I disagree. Most hot places tend to at least have white houses with window shutters, something I rarely see here. OK, done complaining

4. Fascinating discussion – thanks David. I will certainly start looking at our money and energy sucking property in a new light now (pun intended)…

What struck me a quite strange was the idea of what is cold… Living in the southern part of UK we rarely get snow, but during the cold months (Nov-Feb) we get frequent frosts and sub-zero temperatures but nothing too harsh.

In our summer, if it gets to much over 28′ it’s a total disaster. People faint and industry stops (everyone takes a sicky and heads for the coast where it is cooler). Our house’s thermostat is never set above 18′. That is a comfortable temperature where just a T-Shirt is fine.

“During a winters day when itâ€™s 15C outside, itâ€™s often 15C inside. I have several Norwegian and Canadian friends say that their coldest winters have been in Australia!” 15’C is quite comfortable for us Limeys… Just a pullover is all that is needed to stop a chill.

Maybe we (the human race) is getting too soft in our over insulated and protected-from-the-outside-environment world?

5. The Open Sourcerer, keep in mind that temperature isn’t the only thing, you have to factor in humidity. Australia is very dry compared to other places (even Sydney, despite what some Australians say), so 35 degrees in Sydney is no worse than 30 in Montreal. I’ve seen days where the effect could be as much as 8-10 degrees on the perceived temperature.

6. Yeah, we don’t get much trouble with humidty here – the air never gets warm enough for long enough to hold all that much water. Having been in places like Singapore where the air is basically saturated I know what you mean…

But I was more interested in cool temperatures rather than warm and how perception of what is “cold” is so different. 15’C is fairly ambient for me 😉

7. david says:

It’s interesting what people adapt to and consider normal. I have visited a few countries (e.g. Canada and Norway) in winter and really struggled with 22C inside, for example I couldn’t sleep or work properly. It was just too hot and stuffy. So I found myself opening a window a little to let some -20C air in!

Sounds like .au has similar heating norms to the UK, e.g. we might heat our house to 18C or so and be comfortable wearing an extra layer inside.

As to why .au houses evolved to be built with poor insulation – I am guessing its’ because we can get away with it here. In a country like Canada heating is essential (to maintain life), and heating energy costs are significant, so good insulation has a fast payback. In Australia historically heating/cooling was an option (although fairly standard these days).

I agree with Jean-Marc on humidity. Adelaide is dry – a 35C Sydney day is like 40C in Adelaide in terms of comfort (or 30C in Montreal I guess). Except for the sun – a 40C Adelaide sun will burn you very quickly, lot’s of tourists get caught by that!

8. Open Sourcerer, actually the humidity plays a role at almost every temperature. Even at 15-20 degrees, it makes the air feel warmer. Then when it gets to 5 or so degrees, it makes the air feel cooler. About your comment that “the air never gets warm enough for long enough to hold all that much water”, it’s actually the “relative humidity” that counts, i.e. how much water there compared to what the air can hold at that temperature. The higher the relative humidity is, the less effective sweating is.

David, one other thing about hot water. I’m not sure how common that is in Australia, but in Canada, I remember from a “saving energy” initiative a couple years ago that one of the first things they were doing is insulating the hot water. That meant insulating the hot water tank, but also insulating the pipes as well. Another shock I has in the house we live in is how fast the water cools down in the pipes after we’re done using the hot water. Don’t know how other Australian houses are, but I’m pretty sure decent insulation there would not only save energy, but would actually save a lot of water that people waste buy letting the hot water run until it’s actually hot.

9. I’ve been going to do the windows for ages… it’s almost the last thing I haven’t done.

One thing you may not realise is that the transformers on the downlights use more power than the downlights or almost as much (depending on which lights you are using). Plus they are a fire hazard. Simply convert a few of your lights to full lenght fluoro’s and you’ll get more light for the same amount of power about 40W (including the ballast). If you want flicker free and the lights to come on instantly get an electronic ballast. This also uses even less power and allows fluoro’s to be dimmed.

You can also add fulls spectrum tubes… so the light is similar to sunlight. This is all good for reading and also for colour matching.

BTW: Full length fluoro’s last about 10 years and the tubes range from \$1.50 each to \$20 (full spectrum).

The breezaire site says my household evaporative air conditioner uses 500W of power. It cools the whole house… and a few years of the year when humidity is very high it still brings the temperature down significantly (enough to sleep).

I run gas hot water with no tank… so as much as you want/need… and never runs cold.

I’ve considered solar hot water but decided it’s a bit complicated for the benefit.

Our power bills are usually under \$200 in any 3 month period.

Thanks for taking the time to detail your investigations.

BTW: Am considering a low power fridge… but it’s expensive. However the fridge is the highest usage device in most homes (other than air con).

10. BTW: Also added some spinning roof ventilators a long time ago.

This helps pump out the heat and humidity on a hot day.

Also added shutters… they improved window insulation dramatically while improving security and decreasing noise.

11. david says:

Thanks for your comments and the tip on the spinning roof ventilators – I was not sure if they were effective or not.

Some people suggested the shutters to me but I really like sunlight, especially in the winter so didn’t want to couple my thermal insulation to having less natural light.

BTW the comfort glass we had installed also made a big difference to noise – an unexpected bonus. Unfortunately most of our noise pollution is “internal” to the house

Re downlights yes some of the transformers can chew 50W or so however I understand that the newer ones use switch-mode designs and much more efficient. I need to work out what sort I have one day! Also keeping the existing transformer and down-light fittings is easier from an installation point of view. Thanks for the tips on the fluros, I wasn’t aware of the newer options (e.g. colours available).

Re solar gas hot water I ran a few numbers and the pay-back period is actually pretty good (e.g. better than current PV solar electricity). After having it for a few months my wife and I are very happy – we haven’t used the gas booster at all and have the “feel” of endless free hot water, as we never seem to draw down the hot water supply much.

12. Klaus Leiss says:

If you would use shutters for the time that there is no sunlight you would have less energy loss for at least 12 hours in winter.

A web site with good tips regarding energy conversation can be found at:

http://www.builditsolar.com/

13. niall says:

loved the piece you wrote, i’m online researching how to heat my house so i don’t freeze in winter! and how to reduce energy consumption.
moved over from ireland 6 months ago, don’t understand why they don’t have heating/insulation/double glazing in homes over here, they clearly need it for 4/5 months of the year!
first thing i must do is insulate properly, was thinking of reverse cycle but dont really want to go there.
was just reading about solectair system which fits to existing evaporative system, sounds interesting and is a much cheaper alternative.

thanks for all the tips and info, very useful

14. david says:

Hi Niall,

Thanks you for you kind comments on the post. That’s interesting about the Irish houses – I would have thought is such a climate insulation and glazing would be better.

The solectair system looks like a great idea. I have actually been researching solar air heaters (our winter is coming up), there are quite a few designs around on the web, some passive, some using small fans.

Cheers,

David

15. Well done for making all those changes to your house and lifestyle. Simple changes can make such a difference. Using LED downlights can certainly make a significant difference. For those of you looking to do the same, look out for some LED products that are too cheap because they will be very low in quality.

16. robert probin says:

rental properties are a problem . owners are usually reluctant to do anything .
I’ve put a spinner on the roof for summer and sealed doors also after fitting an exhaust fan in toilet and sealing window have noticed a big difference in warmth to kitchen area and laundry they are connected thru to toilet.
have also cut right back on gas heater use. have an oil column heater in bedroom that is on minimum o/night.
so far this winter my last gas bill was about \$100 less and elec bill was about 60 less than same period last year
also the other night i went for a three hour bike ride it took me 2 hours to cool down “Thinks maybe i could rig a trainer with a generator to run a led tv keep warm and watch telly or a laptop lol”

17. Peter Blyth says:

Hi David
Enjoyed your energy audit article in Renew. I am installing a pool shortly and was curious about the ‘Floatron’ you mentioned in your article. I Googled and found some impressive information. How have you found this product and is it as good as the manufactures claim ?

18. david says:

Hi Peter – yes the Floatron has worked out very well. I have posted a full Floatron review.

19. Maryann Syer says:

Hi David,
I was reading about your house in Renew and was very impressed with all the results that you have achieved. We have a double brick house in Melbourne and so was interested in how you insulated yours. What sort of insulation did you use. Did you just insulate the roof or did you insulate the walls as well?

20. david says:

Hi Maryann,

The insulation we chose was a recycled newspaper (mixed with some chemicals to reduce fire and rodents). I forget the exact name, they blow it in with a big pump. Its performance was about the same as good fibreglass batts, but it was a little more expensive. It cost about \$5,000 including removal and disposal of the old batts. We just insulated the roof.

The other key change was replacing all of the windows with Pilkingtons Comfort Glass, also around \$5,000. This was a radical step from a typical Australian point of view.

At this time of year (September, early spring in AU) we now get a temperature change of about 2C overnight, e.g. from 19C at 6pm to 17C at 6am with no heating at all, with an outside min temp of about 7C.

Over this winter (coldest in Adelaide for 35 years) we found that we still needed to run the gas heater, but hardly at all in Autumn and Spring. As soon as the daytime temp hits 17-18C we seem to be able to capture the heat of the day and hold it overnight.

Combined with our solar water and electricity systems our yearly gas/electricity costs have dropped from around \$3,500 to \$500 per year. The insulation, windows & solar water heating have reduced the gas bill from \$1,800 to \$500, per annum at a capital cost of \$15,000. Thats an 8.6% return, but tax free and the benefit will increase every year as energy costs rise. Better than shares or bank interest. Plus nice side effects like zero carbon emissions and better sound insulation from the new glass.

Hmmm, enough material for a new blog post in all that!

Cheers,

David

21. John says:

Hi David,

Do you think there is any demand for home energy auditing services in Australia?
Do you think such services plus implementing the solutions would be a good and progressive business?

Sincerely,
John
Sydney

22. david says:

Hi John,

Saving a customer significant money is a strong business model, so yes I think there may be a business there. The idea of extending that to say coordinating energy efficiency upgrades is also a good idea as some people don’t have the time and energy to research and manage the process.

Cheers,

David

23. John says:

Hi David,

Thanks for your response. May I know about the maximum current or power capacity of your measuring device: power meter from Jaycar?
Is it suitable for power measuring over 2KW?

Regards,
John

24. david says:

Hi John,

The meter is a MS6115 from Jaycar (only \$29.95 now), however I can’t seem to find the specs for it now. I have seen it measure up to 2kW continuous and over 3kW peak (like when switching on a high power device).

Both Renew and Choice has reported that this meter is not particularly accurate, however I figure for the price it’s a great start.

Cheers,

David

25. Robert Mcewin says:

Your article in Renew speaks of your evaporative cooler being fitted with ducting of ‘a high insulation standard.’

26. david says:

Hi Robert,

I can’t seem to find the receipt so sorry I don’t have the exact model number of the material. However I understand that it was pretty standard ducting used for todays modern evaporative air conditioner installations. It was to ‘a high insulation standard’ compared to the original 20 year old ducting that was in the roof. The entire house cost around \$1,800 (including removal of the old ducting) however I suspect it could have been performed cheaper than that (e.g. closer to \$1000), so get a few quotes.

It was well worth it – combined with the insulation and new windows it turned an anemic air con into one that could handle the 3-week above 38C heatwave we had in March, at a modest power consumption.

Cheers,

David

27. Thalass says:

You can get house window tinting nowdays, much like car tinting, which I’m looking into for my house when it gets built. Also you can use old-style window awnings to shade the windows and reduce the heat coming in in summer.

I’ll definitely be investing in extra insulation, too!

28. excellent work.. Its great to see you made the time available to do all this in only 3 months AND get the results, very impressive.. I’m wondering how old you son’s pc is. the findings do not suprise me. And you’ve so right about the effect of 24 hr/ day consumption of appliances (like yours son’s). Standby power is said to be 5% of your power cost but can easily be more. KEEP IT UP!

29. Hi David
Have just read your article in Renew and am most impressed. We’ve gone down the same road over the years with our house, to the point where our power use averages out at around 4 kWh per day now – less the 3 in summer. With a 1700W pv array fitted, we only have to buy power from the grid in winter.
I have a few suggestions to do, if you haven’t already. First, fit a couple of whirlybirds to the roof to pull heat out of the ceiling cavity – this made a huge difference in summer (we live in Sydney). Then get hold of some flat vents with a sliding cover that fit to your ceilings – they cost \$10 or \$12 each depending on the size. These allow heat to rise out of your rooms into the ceiling cavity, to be pulled out by the whirlybirds. They make a massive difference in summer – and can be closed off in winter.
If your house is built on piers, cut a hole in the kitchen floor behind the fridge and cover it with a screened vent ( to prevent mice etc getting in) – your fridge will work much more efficiently with cool air being pulled up over the coil. You can also wire in small computer fans to blow air up over the back of the fridge when the motor is running – I got an electrician friend to do this for me – the motors cost \$16 each from Jaycar.
Could you give me an idea what it cost to get the Pilkington windows fitted? I’ve considered double glazing, but it’s too expensive. I’ve fitted “Clear comfort” plastic double glazing to the wooden french doors in our living area, which have made an enormous difference to that part of our house. I’d love to be able to replace our crappy aluminium windows with something affordable that is also efficient.
Cheers, Graeme

30. david says:

Hi Graeme,

I am very happy that you enjoyed the Renew article. Wow – I am totally impressed with you running your house on just 4 kWh/day! Despite my efforts to date, I still use around 14 kWh. Actually it’s going up a little for a good reason – charging my electric car!

I was wondering about the effectiveness of whirlybirds so thanks for the tip, I will fit some soon. I figure that insulation just slows the flow of heat from the roof cavity to our house, so removing the heat source by cooling the cavity is a good idea. I do have some vents at either end of the roof, not sure if these are as effective as whirlybirds.

The sliding vents are an interesting idea. Tell me, when the hot air escapes, what replaces it? Is the idea to replace the hot air with external air, or air from the air conditioner? We actually already have some spring loaded vents in the ceiling, they open under the pressure of the evap air con, letting air out into the roof.

Thanks also for the fridge tips, our fridge is pretty dodgy from an energy perspective so I might look into that.

The Pilkington Comfort Glass cost \$5,400 for the glass to be replaced in every window in the house (including labour). We have a large house and many windows (including many fiddly colonial windows with many small panes), so I would guess most houses would be cheaper. We kept all the frames, including some crappy aluminium ones of our own. We are very happy with the glass – combined with the insulation (also around \$5k) it is very effective, e.g. just a 2C temp drop over night with no heating in Spring/August.

Cheers,

David

31. Peter Osman says:

Hi David,

My attempts at analysis suggest that for retrofitting its best to focus on ceiling insulation and take it to the maximum available. Likewise focusing on double glazing taking especial care of the window frames to make sure they are PVC or wood or at least aluminium with an inslating break.

Retrofitting wall insulation can be very difficult and expensive. While it can be effective in double brick or wood/fibro houses it loses the advantage of thermal mass in brick veneer where it would be better to go for reverse brick veneer i.e the insulation on the outside of the house. But this is still tricky and expensive.

I’d be keen to here more about how you insulated and if possible how effective the different stages of insulation were.

All the best, Peter

32. david says:

Hi Peter,

To upgrade our insulation we had the old ceiling insulation removed and new insulation installed. We used the “blow in” type insulation that is made of recycled and treated newspaper mix. This was perhaps 20% more expensive than fibreglass batts that would have done about the same job (my wifes choice). We only insulated the ceiling.

My gut feel is that after the ceiling, the windows are the most important item, but this is anecdotal. I feel windows are a big energy “blind spot” in most Australian houses – we install massive, power hungry air conditioners instead!

We did the windows and ceiling within a few weeks of each other at the end of last winter, so it was difficult to seperate the effect of the two. The combined effect is excellent. At this time of year (October) we get a mix of weather. It was hot (30C) for a few days recently and I could hear air cons firing up around the neighborhood. Not us. Over a typical day for this time of year (20C down to 8C at night) the house temperature only changes about 2C with zero heating or cooling.

Cheers,

David

33. Peter Osman says:

Thanks for the description David, It certainly ties in with what I was trying to analyse for my own house. So I’ll be following in your footsteps shortly.

All the best, Peter

34. Bernard Kobier says:

Hi David,
Just read the article in renew and then reading through the comments has been very educational. The solectair looks like a fantastic idea.
Im just purchased a house due to move the day before Christmas and will be conducting an energy audit as soon as I get in and implementing some of your findings.

Thanks for taking the time to share your experiences.

All the best

Bernie

35. david says:

Hi Bernie,

Good to see the article was useful for you.

We installed a Solectair in April, but we are not happy with it. In our case it didn’t generate enough heat to be effective. I think this was partially due to the long axis of our roof facing north, and that our roof is half covered with solar panels. These factors limit the amount of heat the roof cavity can collect. So I think the effectiveness of the Solectair is very dependent on the house it is installed in.

Cheers,

David

36. Awesome article, David!

I’ve just started down the same track with our house, and am pondering over all the same things as you. I’ve got 30 halogen downlights throughout the house, and I think they’re drawing over 5 kWh/day! So converting them to 240v CFL downlights (in the same fittings) is high on my list.

I’ve also looked at solar hot water and solar power. Both are made affordable by the current rebates, and NSW will be announcing details of their new solar feed-in tariffs in January, so hopefully that will give the solar industry a boost too.

My second fridge is an energy hog (the MS6115 really pointed that out!), so I want to investigate what we can do better there too.

I look forward to reading more of your site tonight! Oh, and also visiting the library to track down your Renew article.

Keep up the great work!

37. It’s funny how differently houses are built in other parts of the world. I had some Australian friends over for lunch last month and we talked for a bit about house construction. He asked why pretty well every house in the northern US is built with a basement. I told him it’s because the ground freezes and unfreezes during the winter months, so you have to dig deep to lay a foundation that won’t shift.
One consequence of digging a foundation and having a basement is that it moderates the temperature a great deal during the winter AND summer.
That is to say, it can be -20 outside in the winter but the basement actually helps to make the house warmer because the outside (ground) temperature is above freezing.
In summer, needless to say, the coolest place in the house is the basement.
I really don’t understand why Australian homes don’t have basements, if only to escape the heat.

38. david says:

Hi John,

Thanks – I didn’t know the reason for basements in North America. As to basements here, well I bet it’s a (false) cost issue. All that excavation means extra \$, and it’s cheaper (in the short term) to bolt a massive heat pump onto the house and burn electricity to heat and cool it. Dumb move both financially and environmentally when viewed over the long term, however.

Cheers,

David

39. Peter Dawborn says:

Hi David
I saw your article in ReNew magazine and found it all very inspiring, your EV project particularly, but I don’t have the knowledge/skills you obviously have but would love to convert our inherited 1981 trusty and rusty toyota corolla sometime! I’m particularly curious though about what sort of PV panels are pictured in ReNew and are you happy with them, if they’re the thin film ones I think they are? Thanks
Peter

40. david says:

Hi Peter,

I think my PV Panels are the amorphous type, which I had installed by the Solar Shop here in Adelaide. We are happy with them.

Cheers,

David

41. This is so depressing, my old 42″ LCD tv draws nearly 290W while in use. Sadly its one of the most used items in my house. A Great excuse to buy one of those new Samsung LED TV’s they draw only around 100W.

42. david says:

We recently bought a new 42inch TV plus blu-ray DVD. About 150W while on however I am very pleased that the pair are < 1W off. Big improvement on standby power over my older analog TVs. I will soon by purchasing a new fridge, old one is 15 years old and a big part of my Flukso graphs!

43. Quick question about your evap unit, does power consumption vary with fan speed or does it draw 900w regardless of fan speed.

44. david says:

I would guess it varies with fan speed, but I haven’t measured it.

45. Hey I am in the same process with a 45 year old house. We live in montana and it gets cold. The house is poorly insulated so that is on my list. I will also be building some solar air heaters from soda cans and I also want to build my own windmills to add to the roof. so that I can run an electric heater generated by the wind and also solar panels. I need to watch the use of my laptop like you have stated.

Good going… keep us informed.