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Energy Efficiency Blog

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Aug 07

It’s been a bit quiet on the sokitt blog for the last coupla months…

That’s because we’ve been busy launching our new site, SolarQuotes:


Once you have gotten your home as energy efficient as possible, the next step is to start generating what little energy you do need yourself.

SolarQuotes lets you fill in one quick form and quickly get 3 quotes for solar power from 3 local installers.

Now all we have got to do is wait for the pollies to pass the Emissions Trading Scheme legislation so that the new solar rebate becomes law… C’mon Fielding and Xenophon stop blaming global warming on solar flares, pull your fingers out of your arses and pass the legislation!

Apr 09

Today we launch our 7 day course: “7 days to an energy efficient home”.

Follow the advice here, and slash your bills…

Here are the lessons

Day 1: An Introduction to Energy Efficiency

Day 2: We’ll find out where the biggest savings can be made for a typical Aussie house like yours.

Day 3: We’ll discover how to massively tame your biggest energy guzzler: Space heating and cooling.

Day 4: We’ll decide if you should upgrade your water heater.

Day 5: We’ll look at all the appliances in your home that run 24/7, and find out how to cheaply and easily measure which ones suck the most electricity.

Day 6: We’ll look at all your ‘single use’ appliances and figure out which ones need your urgent attention.

Day 7: We’ll set an energy use target for your home, and find out how to cheaply monitor your whole home’s electricity use to try and stay under that target.

Feb 12

Good News! The Feds have mandated that all TVs must have an Energy Label by October 2009.

The first TV on the block with a rating is the Sharp LC-37D85X (three stars).

The energy use is calculated as 10 hours per day – 365 days a year! Seems like a lot to me.

This is a really good move by the Department of Water, Environment, Heritage and the Arts, as the new, bigger TVs can be a shocker in terms of energy use. Have you felt the heat that comes off a big plasma?!

As soon as the data becomes available we’ll start a sokitt for TVs so that you guys can quickly and easily track down the most efficient TV in your price range!

Watch this space.

Jan 12

We’ve finished the sneaky new scraper to pull water ratings from waterrating.gov.au and it works a treat. So washing machines and dishwashers are back up and you can compare water ratings, energy ratings and price all on one page. Hurrah!

Dec 22

One of the reasons I put sokitt together was the irritation that, although the Aussie Government do a great job collecting energy and water ratings for appliances – for some bizarre reason, they fail to provide a interface that lets you compare the water rating AND energy rating of a specific washing machine or dishwasher.

That made it really frickin’ difficult to compare appliances if you care about water and electricity consumption. You have to check in energyrating.gov.au for the electrickery data and waterrating.gov.au for the water numbers.

I guess the reason is that water and electricity are covered by separate government departments and they each do their own thing and co-operating ain’t one of those things! The joys of bureaucracy – reminds me of my days at CSIRO….

So one of the things that sokitt does is scrape water ratings and water usage info from waterrating.gov.au and merge that with the data provided by energyrating.gov.au.

Last week I noticed that the IT dudes over at the water rating site have decided to scrap their HTML tables and go with JavaScript? Not sure why – but it broke our scraper.

So we’re working on a bot to get the data from the new tables (it is a lot more tricky than before from a technical point of view – but a piece of cake compared with navigating the Canberra corridors of power to actually get our water rating friends to provide the data in a nice user friendly format like the energy rating dudes do)

Anyway my point is that sorry, the dishwasher and clothes washer comparisons will be down until after xmas – but like Arnie says ‘they’ll be back!’

Oct 17

(with a big-up to Pete Dormand of Newcastle City Council first made this point…)

Efficiency is not sexy. Having a 6 star fridge does not get you any green street-cred compared with having a big shiny solar panel on your roof for the neighbors to ooh and aah at. But efficiency is by far the cheapest way to reduce emissions, which means that before spending thousands on solar panels, households should do everything they can to see if they could spend that money on efficiency improvements that would make a much bigger difference to reducing emissions per dollar.

example: cost of 1kw solar panel installed = $12,000, energy produced in one year = 1500kwh, cost per kwh saved per year = $8

But spend an extra $220 on a more efficient washing machine and save 548kwh per year, cost per kwh saved per year = $0.40

Energy efficiency here is 20 times cheaper!

Justification of the efficiency numbers using sokitt’s clothes washer efficiency comparison tool.

If you are looking to buy a top loading washing machine, you can pay $704 for a cheap 1.5 star one (just sort by energy rating and top-loading style and scroll to the bottom of the page)

But if you pay an extra $220 for the top rated top loader (3.5 stars) you will save $955 in electricity over 10 years. (look at the clothes washer at the top of the sokitt comparison grid when sorting by energy rating)

My opinion: the government (or a forward thinking retailer) should provide an interest free loan to cover the extra $220, so no-one has to buy the cheap, inefficient one.

Oct 13

Next to get the power meter shoved up its jacksy is the goggle box.

Last night we had a baby sitter round (we went to a Michael Franti concert :-) ) and she watched TV solidly from 8pm to midnight. So the profile might be a bit atypical, but here goes anyway.

The power meter tells me that over the last 24hrs my 28 inch CRT TV used 0.576kWh of juice.

Here’s the power profile:

My TV\'s power use over 24 hours

My TV's power use over 24 hours

You can see the big chunk of viewing when the babysitter was here. The TV uses about 80 Watts when it is on. You’ll also see that it uses zero watts when we are not watching, because we are in the habit of switching it off at the wall.

There’s not a lot of scope to reduce our energy use except watch less TV (which isn’t a bad idea).

At least we’ve got an efficient TV. A similar sized plasma would use at least double the power.

P.S. The government announced earlier this year that they are gonna put energy rating stickers on new TV’s. Great news.

Oct 08

Here’s the energy profile over 24hrs for my Whirlpool AWM6100 clothes washer:

The Watts sucked by my clothes washer

The Watts sucked by my clothes washer

This shows that it uses 2W (about $2 per year) in stand by which is pretty good. And you can also see that we used the clothes washer twice that day, which is pretty typical for us with 2 kids.

In one day we used 1.092 kWh of electricity washing clothes – or 398kWh per year. That’s 40% of 1 person’s budget 0f 1000kWh per year or 10% of our 4-person budget.

The really interesting thing about the profile is that almost all the energy is used to heat the water in the washing machine, as can be seen from the big spikes at the beginning of each cycle. Let’s zoom in on one wash:

Zooming in on one wash

Zooming in on one wash

So almost all the energy is in the heating of the water at the beginning of the cycle – and this was for the coldest wash setting on the machine – 30 degrees!

With the water heating – each wash uses uses 0.47 kWh. If we remove the heating this drops to 0.15kwh, less than one third of the energy, and remember this is for a cool wash.

So if we wash twice per day, we could save 290kWh per year by washing cold. Is this practical?

Well here in sunny Australia there’s a detergent called Cold Power and a quick call to the manufacturer’s helpline found out that they recommend 20 degrees Celsius as the optimum temperature.

Unfortunately my washing machine only goes down to 30 degrees. So if I want a cold wash then I will have to buy a new machine!

One other question that I need to find the answer to. Is a a cold wash done with zero heating, or is the water heated to a minimum temperature? I’ll get on to the manufacturers and find out.

I’ve just added a feature to sokitt that allows you to filter washing machines to only show those that are cold wash compatible. I think you’d be crazy to buy a new machine that doesn’t let you take advantage of cold wash detergents. If you are looking for a new machine this feature can save you hours of research.

Another feature I’ve added is a filter to only show washing machines with dual connections. That is: a hot an cold water connection. If you have solar hot water, then this is essential, as it means you can use solar thermal energy to directly displace 80% of the electricity that your washing machine would use on a hot cycle.

Sadly if you ask sokitt to show all clothes washers with a dual connection AND cold wash compatibility with an energy rating over 4 stars… there aren’t any!

But if you reduce the energy rating required to 3 stars and do another search about 20 washers are available. For some reason they are all top loaders.

The counter intuitive thing is – if your hot water is solar, then dual connections are more important that the energy rating! If this is you – then I would use sokitt to choose a machine with a low “Cold Wash kwh per year” and a high water rating, and a dual connection and not worry about the energy rating. The “cold wash kwh/year” is the energy the machine will use without heating the water. As long as this is low, you will use very little energy to wash your clothes thanks to the heating from the sun.

As for me, sokitt tells me I can get a 4 star water and energy efficient front loading washer with a cold wash program for $599. This uses 200 kwh/year on a cold wash if am using it twice per day. I reckon I can get $100 for my old washer, so the opportunity to save electricity with the washer is:

$499 to save 200kwh/year

Again, I’ll wait until I’ve audited every appliance and then work out where my limited funds will best be spent to save the most electricity with minimum dollars.

Sep 09

The next appliance to get the wireless power meter treatment is my 3 month old dishwasher.

It’s a Fisher & Paykel DW60CDX2. It is actually the thing that inspired me to make the sokitt appliance comparison tool because it was inordinately difficult to work out which dishwasher under $1000 gave me the best water and energy efficiency.

Anyway, here’s the 24hr energy profile of the beast:

DW60CDX2 Dishwasher

DW60CDX2 Dishwasher

As you can see, we only used it once, and it spiked up to over 2000W (2kW) on 2 occasions. The first spike must be the initial water heating and the second spike the heater for drying the freshly washed dishes. It’s interesting to see that apart from the heating actions, the dishwasher uses very little power for the rest of its cycle.

Zooming in:

DW60CDX2 Dishwasher wash cycle detail

DW60CDX2 Dishwasher wash cycle detail

This wash cycle was the eco-cycle (of course!). The cycle lasts about 90 minutes and if there was no heating, then the dishwasher would use about 130W for the 90 minutes, that would be a power use of 0.130kW x 1.5hours = 0.195kWh which in cash terms = 0.195 x $0.15 = 3 cents.

However because the dishwasher is connected to cold water only, inefficient resistive heating has to take place causing these spikes, this brings the power use for one wash up to 0.714kWh (as calculated for me by the power meter’s internal accumulator). That means that each cycle costs me 11 cents in electricity. In terms of annual electricity use, the dishwasher uses 365 x 0.714 = 260kWh per year.

[ The energy rating by the Aussie government benchmarks this dishwasher as using 233kWh per year (3.5 stars), so my DIY calculations are pretty close to their test lab's results :-) . ]

One other thing from the charts above – this dishwasher is pretty good in standby. It only sucks 0.7W when not washing, that’s about the same as a mobile phone charger and costs me about 70 cents a year in electricity. I can live with that.

So what’s the scope for reducing the energy use here. I have 3 options.

1) use the dishwasher less
2) buy a more efficient dishwasher
3) heat the water more efficienctly

1′s a no no because we generate too many dirty dishes.

As for 2? Lets use the sokitt advanced comparison tool and see what my options are.

If I go to the advanced page then choose my dishwasher, sokitt shows me all the dishwashers that i can buy that use less energy, and calculates the payback. Let’s give it a go:

Step 1 go to www.sokitt.com.
Step 2 click on the advanced link under the main selection box.

Advanced Appliance Energy Comparison

Advanced Appliance Energy Comparison

Step 3. Choose Dishwasher, click Go

Step 4 – Choose your dishwasher make and model

should you upgrade your dishwasher?

should you upgrade your dishwasher?

Step 5 – look at the results here

This screen is showing me all the dishwashers I can get in Australia which have a better energy rating than mine, and details of how much energy they use, plus how much they cost, and how long it would take me for any savings in electricity to pay for the new appliance.

Interestingly all the appliances that have a better energy rating actually use more electricity (look at the kwh/yr column). They get a better energy rating because they have a bigger capacity (i.e number of place settings), and the energy rating is based on electricity use per setting.

This means that the payback for each of these is “never” because they will cost more to run than my current dishwasher. At least that puts my conscience at ease!

So that leaves option 3. Heat the water with a more efficient source, e.g gas or solar. This means either putting hot water into the cold inlet on my washing machine, or finding a new washing machine that has a dual connection – e.g hot and cold water. Putting hot-water in the cold connection is a bad idea because then you are using hot water for everything, including the parts of the cycle that only need cold water. That would waste more energy than we save.

Dishwashers in Australia with 2 water (hot and cold) connections are rarer than rocking horse poo. I can only find 2 for sale, both Bosch. The SGS55E42AUW and the SGU55E55AUSS.

(on the to do list – add a filter to show dual connection dishwashers on sokitt)

If I got one of these and piped solar heated water into the hot water connection, my use could potentially drop from 260kwh per year to (0.195kWh x 365) 71kWh per year – saving 190kWh per year. However, the reality is that because dishwashers use so little water these days, it would draw mostly the cold water in the pipe and very little hot water, and have to heat it anyway. So I would need very short pipes between the hot water tank and the dishwasher.

Or I could get a device like the Chilli Pepper Hot Water System for about $200. This nifty little thing recirculates the cold water in your pipes until hot water comes thru. Neat eh? This would guarantee that your dishwasher filled with hot water and didn’t have to use the dishwasher’s crappy resistive heater.

So cost for saving energy with my dishwasher:

New dishwasher with dual water connection $999
Chilli pepper hot water thingy $200

Possible savings (assuming water is heated by non electric means) 190kwh/year = $28.50 per year.


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