20 January, 2009

Your Electric Bill - part 1

How to understand it, what to do to make it smaller.
So (in this time of increasing energy costs) you've just received your electricity bill, and done a double take at the final number in the bottom right hand corner.  Problem is, the rest of the bill looks like gibberish, and even if you're one of the people to whom the bill makes sense, it still doesn't help you because, like, umm - what can you do about it?

I'll try and explain the bill, and also give a few tips about what you can do to perhaps make it significantly smaller next time.  That way, you're not only doing something nice for your wallet, but also something good for the environment.  And quite possibly, for your health, too.

First, let's take a look at an electricity bill that left its recipient floored.  (No, it wasn't me, it was a friend who had just moved to a new house, with all sorts of new gotchas.  After we discussed it, they now have a strategy in place and expect to have a bill that's only half this amount, next time.)


The bit that the electric company charges you for, I've outlined that in yellow.  The difference between the previous meter reading and the current meter reading, that's the amount of energy you've used during the billing period.  I've outlined that in red in the picture, you can do the maths yourself if you like, but generally, electric companies are pretty good at doing basic math.  The next bit, which I've outlined in green, is the price per unit of energy.  For this person, that rate changed on Dec 31 to a new, and much higher, rate, hence the bill is split into two sections.  And lastly, there's the dollar amount that this energy has cost you.

There is also a "service to property" charge, that's pretty much profit to the energy company as once the power line is supplied, it ceases to need much in the way of service.  But this money is often put towards repairs to street power lines etc.

What is a "unit" of electricity?
In general, (and you might want to check this with your electric company as they generally don't put this information on the bill) a unit of electricity is a kilowatt/hour. (kWh.)  That is, it's how much electricity a 1000watt device will consume in an hour.  A 100watt device will take 10 hours to consume a kWh, a 2000watt device will consume that kWh in half an hour.  It's pretty simple maths.  If all your gadgets and appliances draw 10,000W between them, and are turned on all together for six minutes (one tenth of an hour) they will chew up one kWh, which is generally one unit.

Your aim is to examine all your appliances and work out how much energy they use, and for how long each day they are drawing that amount of energy.

So what should I do next? 
Start by looking at the devices and appliances you have sitting around the house.  They generally have a ratings plate somewhere on them which will give you the energy consumption of the device.  Ignore "energy star" ratings stickers which give you the total energy consumption of the appliance over a full year of average use for the moment - we'll use those energy star ratings a bit later to check our work.

For now, you need a notepad and patience and a few days to write things down and work them out.  Start by writing down all your major appliances, (give them a few lines each, you'll be adding details to each one as we go) and then check the ratings plate and write down the rating of each device.  For an electric kettle or jug, for example, you'll generally find a small plate on the jug or it's power base saying something like "240VAC, 2200W" - it's the "W" part you want, so write down "Jug/kettle, 2,200W" in your notebook.

Do that for all the major appliances in your household, fridge, A/C, hot water system, etc.  Don't panic at this stage if you add them all together - this is their rated energy draw, most of these devices aren't using this much power continuously.  Phew!  Don't forget to add TVs, home theatre systems, plasma and LCD, portable heaters or coolers.

For air conditioning (A/C) systems and units, the rating is often given in horsepower (HP) and for a reverse cycle system (which is on that both cools and heats) there will usually be two ratings on the plate, one for normal cycle one for reverse cycle, you'll need to use whichever one is relevant at the time you're recording it.  If your A/C's rating is in HP, work on the rough basis of 900W = 1HP. It's close enough for this purpose.

Now for some less obvious ones.  How many PCs and laptops, LCD and old style screens, DVD players, phone chargers, PDA and iPod bases, old style filament bulb security lights, and so forth?  Even if you don't know exactly what they draw (many don't explicitly state it on the plate) write each of them down.

Here's a rough guide: (I emphasise - it is a rough guide only!)
  • A PC running or with screensaver will draw about 100W.
  • In hibernate mode it will still draw 25W or more.
  • A normal 19" LCD monitor will be around the same.
  • A laptop will run 90W operating or charging, about half that when hibernating.
  • Leaving a laptop or ipod or phone charger plugged in but not connected to a device, count about 5W - 15W per device.
  • Each TV, DVD player, or other device plugged in and on standby will draw between 5W and some TVs go as high as 50W in standby mode.
  • Each ADSL router, WiFi router, or printer will draw about 40W when running.  
  • Each old style filament light bulb will have its wattage printed on it.  The average is 70W.
  • Larger outdoor security and flood lights will draw 150W to 300W apiece.  Ratings on each bulb.
  • Each CFL energy saving bulb will also have its wattage written on it, average is 11W.
And now, you watch and wait.  For the next week, watch each of the things on your list, and estimate how many hours a day they are working and drawing power.  (Also, in the case of chargers, TVs, and other devices, whether they get unplugged when not in use or are on "standby" power - i.e. plugged in and ready to be switched on by a remote or by just plugging the phone or iPod in.)

I'll continue this article in a few days - for the moment, keep your notebook and start to get a feel for how often the major appliances operate each day, record notes and times and anything else you think of next to each item in your notebook.

(to be continued)

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1 comment:

Lynne Dawe said...

Wow I am impressed....Very well written..although I wouldn't expect any less from you and thanks for explaining it so well:)

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