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Energy Efficiency Blog

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Archive for August, 2008

Aug 28

Today the energy audit continues to the most important appliance next to the coffee machine. The kettle. As a pommie, I need my tea, so let’s hope this baby isn’t a planet killer…

If you think about it, the traditional kettle sums up our approach to energy for the last 100 years. i.e we waste energy every day because we are too damn lazy to come up with a better way to get a cup full of boiling water. We use resistive heat to boil much more water that we need in a jug with almost zero insulation, and if you are like me you usually end up boiling it twice because between switching the kettle on and it boiling you’ve got distracted so much that the water’s tepid by the time you realize.

That’s the theory what doe s the power meter tell us over 24 hours? Well here’s the plot of Watts vs. time over 24 hours:

The energy consumption of my kettle over 24 hours

The energy consumption of my kettle over 24 hours

Well it looks like my household has 6 cups of tea in a typical 24 hours (click on the image to enlarge and you’ll see six spikes). And 2 of those spikes are thicker because that’s where I boiled it twice as described above.

The accumulator on the power meter tells me that the kettle used 0.52kWh which extrapolates to 190kWh ($30) per year to feed my family’s tea habit.

So what’s the potential for energy efficiency here?

Well the kettle uses no power in stand-by thanks to the switch breaking the circuit when it switches off, so no savings to be made there. But I know that I always boil more water than I need.

My exhaustive research (i.e. 10 minutes on Google) reveals only 2 alternatives:

Tefal Quick Cup - Is a crap cup of tea worth it treehuggers?

Tefal Quick Cup - Is a crap cup of tea worth it fellow treehuggers?

[caption id="attachment_43" align="alignright" width="300" caption="The ecokettle"]The ecokettle[/caption]

The eco-kettle and the Tefal Quick Cup both claim energy savings – 31% and 65% respectively. The ecokettle is a neat design where you have 2 chambers – one to store the water – which dispenses a measured amount into a second chamber. The idea being you only boil the water you need. The quick-cup boils the water on demand, a bit like an electric shower. The feedback on Amazon is that the quick cup makes a crap cuppa because the water only comes out at 93 degC. Plus it costs $15 in filters every six weeks! Hmmm, what’s the embodied energy in those?

So I think I’ll invest in an ecokettle. They aren’t available in Australia – so it’s off to ebay.co.uk where I can pick one up for 20 quid. If it saves me 30% then that’s a further 60kWh per year lopped off the bill for a total cost of $100 (20 pounds plus shipping from the UK is another 20 pounds = 40 pounds = $100). I’ll stick the power meter on there when I get it and see if the numbers stack up with Australian water ;-)

Stop press: more efficient kettles on the way says the hippy shopper

Aug 26

The sign on the door says ‘ecological consultants’.

energy efficient vehicle?

Aug 22

The next appliance to get the DIY energy audit is my Foxtel IQ. For those of you outside of Australia, it is a pay TV DVR (a rebadged Sky+ box if your are from the UK).

foxtel iq - how much power?

foxtel iq - how much power?

This box is essentially a PC with a 60GB hard drive. The sad thing about it for energy misers like me is that you aren’t meant to switch it off. Ever. Thats because it needs to be on to receive its software updates and to record your favorite telly programmes when you aren’t there.

Bearing in mind that it’s on 24×365, it’s really important that boxes like these have a low standby consumption. Which is a bummer because as you can see this planet killing piece of junk doesn’t have a standby mode!. That’s right – look at the power draw over 24 hours below – it is always between 21.5 and 23 Watts over 24 hours. So I religiously switch the power button to standby every night, and the little light on the front goes from green to red pretending to be ‘in standby’ whilst all along the lazy ass of an engineer that programmed the firmware couldn’t be bothered to implement any power saving features at all. Which begs the question “why does it have a power switch at all?”.

X axis is minutes, Y axis is Watts

X axis is minutes, Y axis is Watts

Here’s a design for a foxtel IQ that can safely power down to < 1 Watt

Most PC’s can go into standby and only consume less than 1W. The foxtel IQ is just a PC in a box. The manufacturers claim that it can’t go to proper standby because it has to update software and record programmes unattended. Well why not use “Wake-over-LAN” technology to wake the box up when it needs to do these things? Wake-over-LAN is a way to switch PC’s on over the network. This means that as long as foxtel’s central server is switched on the foxtel boxes can all go to sleep safe in the knowledge that if they need to do something they will be politely woken up over their network connection. Hey – this company can even sell them the software to make it happen!

There are about 300,000 foxtel iq boxes in Australia, so if they all powered down for just 10 hours per day they would save 20W x 10 x 365 x 300,000 = 22,000,000kWh per year. Enough to power 6000 homes for a year. Just by changing some software.

As for my bill – the foxtel box is consuming 20W x 24h x365 = 175kWh per year and there is nothing I can do about it except get rid of it – which is a big ask because it is the only way I get to see the Sydney Roosters since I moved away from Sydney. I think I’ll have to upgrade to an IQ2 ;-) and hope that it’s a bit better designed when it comes to standby power use.

In the meantime I’m gonna write to Foxtel and ask them why they don’t try harder to keep my power bill down. I’ll post their response when/if I get it.

Aug 14

The nearest appliance to my fridge is the espresso machine – now this is absolutely an appliance that I could not live without. I don’t care if the sea has risen and is lapping at my ankles – I still need my hit every morning – so I really hope that it isn’t going to blow my kWh budget of less than 1000kwh per year per person.

(The machine is a Sunbeam EM5600 and it makes awesome coffee for a $300 machine!)

the trusty EM5600 coffee machine

the trusty EM5600 coffee machine


Before I got my funky new wireless power meter that interfaces to my PC, I was worried about how much power this thing uses in stand-by. So I bought one of those cheapo energy-meters with an LCD display and tried to measure it. It told me that it was drawing zero Watts – so I decided it wasn’t worth diligently turning it off all the time.

I never quite believed that crappy little power meter though, so I kinda looked forward to sticking an accurate meter on the thing for 24 hours to see exactly how much power it drew.

Here’s the Watts consumed over 24 hours after I downloaded the data and graphed it on M$ Excel:

Power profile for the espresso machine

Power profile for the espresso machine

I only have one coffee a day – that’s where the concentrated power spikes are on the RHS. The rest of the time the machine was in standby. You can see that it normally draws less than 3 Watts, but every so often there’s a huge spike as it blasts the cup warmer with a jolt of resistive heat.

These spikes actually add up to a hell of a lot of power being used for one cup of coffee – the accumulator on the power meter measures it at 0.62kWh per day. That’s 230kWh per year! Nearly 25% of one person’s power budget!

Just goes to show that you can miss some sneaky power guzzlers if you don’t have the right tools.

The solution of course is to switch the machine off after the coffee is made – that will save 200kwh per year, and my coffee habit will only be costing me 30 kWh per year (3% of my budget) which I can easily live with.

The score so far in my DIY energy audit:

Fridge maintenance: saved 200kWh ($30) per year
Coffee Machine switching off: 200kWh ($30) per year

next: the dishwasher