The Great Kilowatt Challenge – Final Confession

I took my final reading tonight.  It worked out that my daily average for week 4 was 16.8 kWh, which was similar to my baseline reading.  Now that the weather is heating up, the airconditioning is being used sparingly, but still it uses so much of our daily consumption.  I estimate that on hot days, our demand goes up by at least 40%.  You can tell just by a quick glance at the graph below which 4 days were the ones over 30 degrees C!  They stick out like a sore thumb.

Here are a few statistics from my end of the challenge.

Highest electricity generated by Solar PV in one day: 19 kWh (5th December)
Highest electricity drawn from the grid in one day: 17.6 kWh (18th December)
Most exported to the grid in one day: 13.6 kWh (5th December)

Lowest electricity generated by Solar PV in one day: 2 kWh (26th November)
Lowest electricity drawn from the grid in one day: 6.4 kWh (6th December)
Least exported to the grid in one day: 0 kWh (26th November)

Highest daily total consumption in the home: 28.4 kWh (9th December)
Lowest daily total consumption in the home: 11.1 kWh (6th December)

Biggest cost in one day: $2.31
Biggest profit in one day: $7.46

Total profit: $64.16 for the month!

Our electricity consumption was variable, however we had more days under 15 kWh than we had above it, which is quite pleasing.

So what have I personally learnt.  My first point of action will be to replace a very old air-conditioner in the living area, which is the box type that fits into a hole in the wall.  I estimate that it uses about 3000 watts per hour, and has the biggest impact on our daily consumption.  Over the next few months I will be saving up for a replacement.  The old one is about 15 years old and on its last legs, so I will not feel guilty replacing it.  Once it is replaced with a more energy efficient one, we should be able to keep our consumption below 15 kWh, even on a hot day!

As we come to the end of the challenge, I would just like to thank everyone for participating.  I hope that everyone gained a bit more insight into their electricity usage, and what events and appliances are the culprits for high energy utilisation.  

From the initial response that I had via comment and on my Facebook page for the blog, there were about 30 to 40 people who gave the challenge a go.  I don’t know how many made it to the end, but if you did, well done and please leave a comment with either your week 4 confession, or just a friendly note.  I would really appreciate it as well as any feedback you may have.

Cheers, Gav


  1. says

    Hi Gavin,

    I fell down with posting about our ongoing efforts with this challenge. But will do a final update. I fell behind in filling out the spreadsheet but we just got our first bill with solar and are using 4.3kWh a day. So am very impressed considering Granny B’s solar isnt in the sun all day long.

    Cant wait for our new house’s solar. It should go up sometime in the next 6 weeks!!

  2. Dawn says

    Hi Gavin: My baseline was 34, and we hovered around that for most of the challenge, but finished out with an average for the final week of 52. Yup, not a typo, 52 kWh. It’s called having major reconstruction done on an exterior wall in your basement in WINTER, in the fortnight before Christmas. It was a bit of a crisis, otherwise we would have put it off till Spring. I think the thing that surprised me the most over the course of the challenge was that we were consistently 20kWh more than everyone else posting. The most obvious difference would be that we are in winter here, while most of you are in summer, but some of you are running air conditioning and fans and swimming pool pumps – surely that should even up the score to our extra useage of light and heat? Maybe I’ll try the challenge in the summer for a couple of weeks and see how the numbers compare – apples to apples as it were.
    Thanks for running the challenge, Gavin – I know how to read my meter now!

  3. says

    The climate smart people are well worth organising. You can book an appointment online. We have the meter, and it’s made a big difference to our power consumption, we’re able to see what we’re using at any one point.

    We just got our latest bill, and we’re down well over $200 from the last one, and we only started power saving about half way through the period. Looking forward to the next one being even less!

    I’m really impressed at the 4kw a day! I think we’d use that much even when we’re not home between the fridges and other small things we can’t turn off (like the pump for the solar hot water). Will have to look into combining to one fridge when budget allows (we have a seperate fridge and freezer), as that would probably make a big reduction over time.

  4. says

    I have to admit that I didn’t read the meter at all (it is at the top of our driveway, so not convenient), but I did feel guilty and manage to turn off some fridges and freezers. Thanks Michael for sharing his secrets as I have been very impressed at the 4 kWh usage he has been reporting. I’m sure there is more I can do to reduce standby power, that was really good idea to borrow a power meter – you can get them in QLD with the “climate smart homes” program, I think its only $50 and you get lots of good stuff (just its really hard to organise for them to come to country areas, so we haven’t had an assessment yet, grr)

  5. Steph says

    Hi Gavin,
    We started at 11 and ended at 10.5kWh, which, though not much of a reduction, we were pretty happy with, given the increasing use of the aircon as summer hits Perth. Unfortunately, none of our usage reduction strategies seemed to make any discernable difference.

    More importantly to us, we were thrilled to find that not once did we import more than we exported, or use more than we generated. I plan to continue to monitor weekly, which I think will average out the higher use days with washer and oven. Now to learn enough of Excel to build a spreadsheet for that…

  6. says

    Our consumption has remained nice and low 8kW / day over the last week. It has been a nice cool summer so far. we have only had the air con on one day and have left a second frig off. There is only 2 of us. We produced 9.25kW/day. So all good. not perfect but good.

  7. Michael from Canberra says

    Hi All,

    Overall our average daily usage was 3.9kWh per day. Along the way some of you have asked about how I am achieving such low results and I have written up how we’ve done it as part of a larger article I am putting together for the environmental group I’m involved with. The extract on electricity is written up here ->

    Thanks Gavin for running the challenge! My sister is also taking part and in the last 4 weeks she has reduced her usage from 8.6kWh/day to 4.1kWh per day! – More than half!

  8. says

    Hi Gavin, I was very happy with our results on the challenge but found if I forgot to record (which I did on two days) it mucked up the spread sheet and I didn’t know what to do about that. Then I received my bill telling me I was using heaps more than I KNOW we were using and I got so despondent about that, that I stopped recording about a week ago. Thank you so much for doing this challenge. I am going to try and take up the recording again, simply so that I have facts to show the damned electricity company!

  9. Prue says

    Thank you for organising us. I learnt that little changes can add up, and that despite this lovely mild summer so far in Brisbane, some scorching sun would increase my exports. We were using less power than what I had thought, which was encouraging. I liked the spreadsheet that would tell me my cost for the day. Cheers

  10. says

    Hi All, well we made it all the way with some really mixed results. Like Gaving our average ended up a little under our baseline which was a bit disappointing. But the spikes co-incided with using the dryer, oven or washing maching were on together. The constant rain has had me use the dryer maybe 3 or 4 times but even with that I think we may get under the $400 mark for our quarterly bill!!! Thanks so much Gavin!

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