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Energy Efficiency Blog

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Posts Tagged ‘energy rating’

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!

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.

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.


Jul 27

The cliffhanger in the last post was… How does my fridge’s performance compare with when it was brand spanking new?

This is a really important question if you are going to make an informed decision about reducing your electric bill, so we’ve been busy developing a database backend for sokitt that pulls historic energy performance figures for appliances from the energyrating.gov.au site. Yes that’s right, pick yourself off the floor, there is a government website out there that actually contains really valuable data! Data input by men in white suits who spend their Canberra days torture testing fridges, dishwashers, dryers and clothes washers to decide how many stars to put on their energy rating sticker.

So I can put my fridges make and model: Fisher & Paykel E249T into sokitt and it shows me the ‘as new’ performance of my fridge:

1.5 Stars - Oh Dear!

1.5 Stars - Oh Dear!

So, when new, my fridge was guzzling 691kWh per year costing $1300 bucks over 10 years in Energy (sokitt assumes electricity will go up by 5% a year – but this can be changed in Advanced Options) and was Rated at 1.5 stars. How embarrassing!

My bluetooth power meter told me that it is currently using 891kWh per year: that’s 200kWh per year I’m piddling down the drain.

I kinda knew that my fridge should be maintained – but this has shocked me into getting off my ass and doing something about it. So I defrosted my fridge (there was a lot of ice in the freezer) and re-seated the door seals that had come off in places and re-measured my fridges performance with my wireless energy meter. The graph of Watts vs. time over 24 hrs looks like this:

save energy - defrost your fridge!

save energy - defrost your fridge!

That’s better – at least now the compressor switches off regularly (although it is still swutched on more than it is off – but hey it’s a crappy 1.5 star fridge whattdya expect?).

(by the way I think the really high spike is the auto-defrost where little heaters suck heaps of juice in an attempt to melt the ice off the coils)

Extrapoloating the kwhs measured over 365 days tells me that my fridge now uses 722kWh per year which is within 5% of it’s new performance and is as good as I can expect from a fridge this old.

So by defrosting my fridge overnight and pushing some door seals into place I’ve saved nearly 200 kWh per year. Not bad, but get this: If I’m typical for an Aussie household – multiply that by 10 million Australian homes and you’ve saved 2 million MWh (a MWh is 1000 x kWh). To put that in perspective that is 20 times the total amount of electricity generated by every solar panel in Australia in 2006. Oh yeah – the power of energy efficiency.

But before I get too smug – my fridge is still pretty crappy on the energy front at 1.5 stars. Hell you can buy 6 star fridges these days.

Before sokitt the place to go for appliance comparisons was www.energyrating.gov.au . This has some amazingly useful data except for one fatal flaw – it doesn’t display the prices of the appliances. It drives me freakin’ mad because you see your dream 6* fridge, then have to spend 10 minutes on Google looking for the price and you find out it costs $4,000 dollars and the freezer is another 2 grand on top!

Anyway, we’ve developed an appliance energy comparison tool that mashes up price and energy data and lets you compare current appliances with your old ones. When I put my fridge model in I find out (in about 5 seconds flat) some interesting things (to a tight-ass efficiency geek like me anyway):

See the comparison with my crappy fridge here

  • The best payback for a similar size fridge is 10 years (assuming 5% increase per year in elec prices) and that is actually a 3.5 star fridge. (pay back is how long it would take for my savings in my bill to pay for the fridge)

  • If I sort the list by Energy Rating, I see that the highest rated fridge on the market a similar size is a 4.5 star whirlpool for $879. (can someone tell me why you can’t get a 6* fridge that’s not the size of a house?)
  • The cheapest 4 star fridge is $642. I can’t begin to tell you how hard it is to answer that question without this tool!
  • So should I buy a new fridge? You think it would be a no-brainer with a 1.5 star guzzler…

    But I can’t answer that question until I have measured every electricity using device in my house and I have worked out the cheapest way to get my electricity down. There may well be much bigger wins to be had in terms of dollars per kWh saved where I should focus my limited funds first. We’ll see what the wireless power meter says over the next few weeks…

    Jul 23

    Over the next few weeks I’m going to post every day as I go through every appliance in my house with a prototype version of the sokitt toolkit and take action to get my electricity bill down.

    The point of all this is to show you a real life example of how a typical family can painlessly and cheaply get their electricity below a target usage of 1000kWh per person per year. If “kWh” means nothing to you think of 1kWh of electricity as 15 cents, so 100kWh of electricity is $150 worth.

    Why get your per person use down to under 1000kWh?

    Well the average per-person use of electricity in Oz is 3,000 kWh. So the average person should be able to reduce their bill by 2,000 kWh. That’s $300 per year per person. $1200 bucks per year for a 4 person household. And bear in mind that electricity is probably gonna double in price over the next few years…

    The other reason is that we could shut down 2 or 3 of Australia’s biggest dirtiest power stations if we all did this. Which would be nice.

    Anyway back to my fridge. 24 hours ago I plugged it into my sokitt compatible power meter. This wireless power meter logs the power that the fridge is using every minute and beams it to my computer (using Bluetooth).

    Here’s a graph showing how many Watts my fridge sucks every minute for 24 hours:

    fridge power

    fridge power

    The y-axis on this graph is Watts. The high black areas are when the compressor is running, you can see that the compressor is on a lot more than it is off. This is bad news – fridges are designed to have the compressor switched on for less time that they are off. It looks like my fridge has become a bit of an energy guzzler and has to keep the compressor on for ages to keep the temperature down.

    sokitt takes this data and can tell me the following:

    1) my fridge is using 2.44kWh per day
    2) this is 891kWh per year
    3) it’s costing me $131 per year to run
    4) it is the equivalent of a zero star rated fridge in 2008 terms! (it’s only 5 years old!)

    Remember my budget is only 1000kWh per year per person, so my fridge is using 90% of 1 person’s allowance!

    Now what I really want to know is: how does my fridges performance compare with what it was when it was brand new? And what are my options for buying a much more efficient fridge? Should I buy a new one or get this one fixed up?

    sokitt can answer all those questions too. I’ll show you how in the next post.