How to Save Power at Home, Part 1

Dear Reader,

A great many apologies for not posting last week; I'll try to be a bit more on-the-ball.

Now I'm sure you've noticed that I've been telling you quite a bit about new technologies that might hit our shores... a long time from now. Which is interesting and all, but not overly practical. So, I'd like to give you a bit more down-to-earth information, particularly on ways to save power.

Now, some of things I'm going to cover in the next few weeks you're probably already doing; but you probably don't have much of an indication of exactly how much you could save if you were doing them, and whether it was worth making the changes to get the savings (if changes needed to be made).

But, before I can get into all that, I need to show you what assumptions I'm making:

1. The power bill is $250 (if your bill is smaller, find out how much smaller by percentage, and apply that percentage to the amounts I work out).

2. You're being charged a flat-rate of 20 cents per kilowatt-hour (kWh); I'll write cent amounts in dollars from now one, i.e., 20 cents is $0.20.

3. The bill spans for 30 days.

4. Water flows out of the tap at 10 litres per minute (don't worry: this'll be relevant later).

5. Water flows out of the shower-head at 14.5 litres per minute (also relevant, but later).

6. Hot water heating accounts for 30% of the bill (based on what the EECA Energywise website says).

7. Space heating (heating done to heat rooms) accounts for 29% of the bill (see the Energywise website).

8. Lighting accounts for 8% of the bill (Energywise again).

OK, now that we have a groundwork done, let's have a look at lights.

I'm pretty sure you've guessed that I'm going to tell you to change to those cork-screw compact fluorescent lights - and I am.

But you might not know why, in the first place, the old incandescent light bulbs use so much power; well, around 98% of the power they use is actually converted into heat!

This is because they have to run electricity through a very thin bit of wire that has to heat up until it's white hot. And, it takes a lot of power to become white hot (go figure, eh?).

So, how much would you save?

75% on the lighting costs, and about 6% on the overall bill.

The reason for this is because the fluorescent light bulbs use about a quarter of the power used by the incandescent light bulbs.

Here are the sums:

15 x 60W incandescent light bulbs x 4 hours on a day x 0.2 x 30 = $21.60 every month

15 x 15W fluorescent light bulbs x 4 hours a day x 0.2 x 30 = $5.40 every month

And to work out the savings we go: 21.6 - 5.4 = $16.20

And to work out the difference it makes to the overall bill: (16.20 / 250) x 100 = 6%

OK, 6% isn't huge, but they'd pay for themselves in 4 months, since:

(15 x 8.99 (the cost of a 2 pack)) / 2 (since they come in a 2 pack) = $67.43

And to work out how long it'd take, we divide the cost by the savings: 67.43 / 16.20 = 4.14 months.

4 months for it to pay for itself? I'd say that's pretty good.

Next time, I'll have a look at why the fluorescents give off a funny light, and what you can do about that. And I'll have a look dangers they could pose with the mercury they use.

Yours sincerely,

Andrew Greaves

How Optical Illusions Can Help You Save Power

Dear Reader,

From the scientists over in America, a way has been suggested that would allow us lowly power users to save power through optical illusion.
The way? Create a length of tape with numbers on them that fits neatly over the meter, so that the meter reader's optics are illusioned...

Just joking - don't go reporting me, thanks. No, the real way is far more interesting. It goes something like this:

All your light bulbs are run on AC electricity, which means that they 'flicker' (sort of). The reason for this is because the current goes one way, stops, goes the other way, then repeats - meaning that the light, at some point, turns off. Sort of.
I don't want to get too technical, but the point is that it 'flickers' at such a high rate (60 times a second) that we don't even notice it.

Now, what they want to try and do is keep it on for 70 milliseconds, turn it off for 10, then turn it back on. Basically, this alters the 'flickering' so that it stays off for a bit longer than normal - about 12.5% longer - and you wouldn't even notice it.

And this 12.5% translates into 12.5% savings. Sort of.

Why all the sort ofs? Well, it's difficult to get reliable testing out of optical illusions because people's brains respond differently.

Anyway, onto the figures: the EnergyWise website reckons that 8% of the bill goes on lighting. So, in a bill of $200, you'd be spending $16 on lighting.
If you were to save 12.5% on that, you'd have saved yourself a great big $2 a month!

Well, it's a bit underwhelming, I suppose; but now you can go and give an interesting little tid-bit to your mates.

Yours sincerely,

Andrew Greaves