25 January, 2007

Smart Energy Stars

As many of you are seeing when you visit the site, I'm adding other focii to the site. I have a swag of tips and ideas on how to reduce your energy use, grow healthy food, use smarter energy rather than costly polluting energy, and save and recycle water and other things. I mentioned on the Zencookbook Dot Com website that there is an advantage to thinking smarter - we get to live on the Earth longer...

Because if we use smarter energy, do smarter things with our water, and change our thinking about some very outmoded models, then we will beat global warming and weather, energy, fuel, and water crises. If we don't, then we may as well hold the farewell party now because none of our kids will survive that.

So here's a relatively simple couple of tips that could see you save a few hundred kilos of emissions going into the atmosphere every year - directly as a result of you doing a few things to use what you already have in a smarter way...

If you're like 85% of Perth's houses then you have some form of airconditioning. What is an airconditioner? (Not evaporative systems, they are a different kettle of fish.) It's a heat pump. It pumps heat from inside your house, to the outside. Don't believe me? Go stand near the outside part of your air conditioner when it's operating - that heat belting out of it is what it extracted from your house. Plus a BIG chunk of waste energy from all the inefficiencies in air conditioners - compressor and motor losses, running a fairly hefty fan to pump the air over the heat pump, and general losses because nothing in the world is perfect.

Evaporative systems use water to extract heat from outside air, then pump that into your house to replace the hot air. They use less electricity to achieve the result, but they are also not as efficient - you have to leave doors and windows open, if there is a breeze then hot air will enter at the upwind side of the house and mix with the cooled air, making the house hotter. Evap systems work best on bone dry ( < 20% RH ) windstill days. Which we don't get a lot of here.

So how can we improve the efficiency of these two pretty appaling wasters of energy? Well, if you can manage it, close upwind windows and doors if you have evap air. Make sure you have good solid doors and some heavy curtains to keep heat out. Have roof insulation. Have a roof air extractor to take hot air out of the ceiling cavity.

Those things cost little to do, and can reduce your air conditioning bill by 10% to 25% - more if you put good insulation and a whirlybird in the roof. But there are a few other things you can watch for and fix.

We've established that an air conditioner is a heat pump that pumps heat from where we don't want it to a place where we don't care. Your fridge is in essence a very airconditioned room for your food. It happily pumps heat from the inside to the outside, adding its compressor, motor, and general losses to the heat load. If you open the fridge door in a hot house, the fridge fills up with hot air which then has to be shifted back outside the fridge, with all that wasted energy being used to do it. And it's probably the same heat that the fridge pumped out when Billy got his cold drink out of it 20 minutes earlier.

Because, what do we do with the heat which has been laboriously extracted from your fridge? That's right, we DUMP IT BACK into the house so that the airconditioning can laboriously extract it a second time from your house and add a second set of energy losses to that!

Get that straight in your head for a moment. We put warm food in the fridge and it gets extracted, with quite bit of energy wastage, then we extract that heat from the house with a second set of energy wastage. That half kilo of butter you just put in has probably cost you an extra 25c to pump the heat twice.

Secondly, a fridge works best if it is insulated or in a cool environment to start with. That's the second big improvement we can all make. Make sure the fridge door stays sealed well, and that the insulation is up to the job. If you can, put the fridge in its own insulated alcove.

And now the biggest energy saver of all. You've got the fridge in an insulated alcove, you're running air conditioning to keep the surroundings cool, what's missing? Right! The hot air from the fridge is going to fill up the alcove and heat up your airconditioned house. So make sure the alcove has a vent to the ceiling space (where the whirlybird will soon dissipate it) and - this is important - that there is a low volume continuous extraction fan there. The kind that computer power supplies use are fine, and consume an almost negligible amount of energy to run. But the difference to your fridge, not having to pump heat uphill as it were, is immeasurable.

Can you immediately see the other appliance in your house that needs venting? Oh yes - the stove may have a range hood but most rangehoods just return the air (minus grease and some smells) back into the room. If you have a range hood, make sure it's a generous size, has a powerful fan, and is vented OUTSIDE or into the ceiling space. (where the whirlybird will... you know the rest...)

Do these things and you might find that your power bills reduce to almost half of what they were before. I'm not kidding. It's smart...

2 comments:

Darren said...

Airconditioner filters should also be replaced regularly.

Using Compact Fluorescent Lighting is a great energy saver, particularly in rooms where lighting is used all the time.
CFLs use 60% less energy than conventional bulb. True they do cost more but the power the save will make them pay for themselves in 3-6 months.


If you reduce you water usage you are effectively saving power too.
All water to your home is pumped from a reservoir.
Using less water in turn produces less greenhouse gases.
Even filling a balloon with 1 litre of water and placing it in your cistern tank can save water.
(also try reusing water from the rinse cycle of your washing machine for watering or putting it back in the machine for the wash cycle of the next load.)

Conservation of our resources is our best hope to preserve our planet.

teddlesruss dat who! said...

Yep so right - one or two small things make a very large change to the energy budget.

The water pumping is an angle I hadn't thought of yet but very true, it takes a lot of energy to move the water to a height or pressure where it's useable.

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