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In hot water - turn it down and save energy

published, Jun 24, 2009 2:11am
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So how much power does my electric hot water system actually use?

You may not realise it, but your hot water is a significant component of your homes total energy usage. I didn't know just how much, until I started measuring.

You see, my two little boys, and starting to become mighty curious. Hot! Hot! Hot! water has the potential to cause nasty burns and all the good parenting manuals tell you to turn the temperature down.

Effergy energy meter

As part of the energy manager project I've been building, I've acquired an effergy energy meter, a neat little device that clips onto the the power cables and counts all those electrons moving back and forth - the perfect little unit for my wee experiment.

I started as was, a scalding hot 80C (176F) degrees, logged data for a week, then wound it back to a toasty 55C (131F) and logged for another week.

At the warm temperature, my boys are safe and my shower is still great. The kicker is this - it takes 47% more energy to scald my ass! That is a remarkable fact.

At the end of this little hot water experiment, I was surprised, and the the data doesn't lie, on average per day each was:

  • Hot: 9.9 kWh
  • Warm: 6.7 kWh

Now, considering this energy is coming from stinky brown coal - this represents a saving of:

  • 3.18 kWh
  • 6.5 kg of CO2
  • 15 cents per day

So go save some energy today, and turn your hot water service down. You will be surprised!




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That's great information.

Do you know why hot water is so hot by default?

The nudge people have told us about the enormous impact of setting defaults. It sounds like they could hot water temperature to their list.

I noticed a significant drop in my electric bill after turning the temperature on my hot water down from just under 200 degrees to 110 degrees.  I could not believe how high my apartment's water temperature was set at when I moved in.

A few weeks later I started to turn off my hot water tank until I needed it.  I only use hot water once a day for about 10 minutes; when I take a shower.  My circuit breaker is located in my main hallway so it's really easy to just flip off the hot water when I'm not using it.  After I started doing this, I noticed another big drop in the power bill.

These two simple steps save me about $15 a month.

That was a good read.


What can be done about  about apartment building with central hotwater? I'd estimate that the hot water temperature is around 80'C!!! As you say, not very children friendly and I find myself warning vistors who are staying overnight.


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