Archive for the ‘environment’ Category

Making Sense of your Gas Bill

Saturday, January 30th, 2010

This is how to interpret a British Gas gas bill.

Your gas meter measures cubic metres of gas flowing through it. (The old ones used to measure cubic feet; but the gas companies switched to proper measurements longer ago than the lifetime of a gas meter, so they should all be cubic metres by now.) But your bill is calculated on the number of kilowatt-hours of energy liberated from the gas.

On your bill, there will be a calculation such as this:

metric units used 239 * calorific value 39.3572 * volume correction 1.0226400 / convert to kWh 3.6 = gas used in kWh 2448.43

So what do the figures mean?

  • metric units used is the number of cubic metres of gas measured by your meter.
  • calorific value is the number of megajoules of energy in a cubic metre of gas, at some specified combination of temperature and pressure.
  • volume correction is a “fiddle factor” to account for seasonal variations in air pressure and temperature. When it’s cold, the molecules are more densely packed, so you get more energy in the same space. When the atmospheric pressure is low, the gas molecules are free to jiggle about more, so you get less energy in the same space. Each molecule contains a certain amount of potential energy stored in the bonds between atoms. So the calorific value depends on pressure and temperature, which is why this calculation is required.
  • conversion to kWh is because there are 3.6 megajoules in a kilowatt-hour. (A watt is one joule per second; there are 3600 seconds in an hour. Kilo means * 1 000 and mega means * 1 000 000.)

Given these figures, you can work out how many kWh are in one cubic metre of gas, simply by doing the same calculation for 1 metric unit used. According to the above, it is 11.23 kWh per m; but this figure may well be different for you, as the volume correction is seasonally-dependent.

But that’s not the whole story. The price per kWh depends on how many units you have used, with the first few kWh each day being more expensive. There will be a section like this:

2448.43 kWh used over 103 days
First 756.00 kWh @ 6.846p = £51.76
Next 1692.43 kWh @ 3.275p = £55.43
Total cost of gas used = £107.19

The higher rate applies to 756.00 kWh over 103 days, and adds an extra cost of 3.571p per kWh. As long as we actually use up all the “expensive” kWh, we will end up paying a fixed extra amount each week. If we are allowed 756.00 kWh in 103 days, then that is equivalent to 756.00 * 7 / 103 = 51.38 kWh in 7 days; which will cost us an extra 51.38 * 3.571p = £1.83 on top of what they would have cost if we had only been paying 3.275p for them.

Meanwhile, one cubic metre of gas on the meter gives us 11.23 kWh and so costs us 36.78p. So, our weekly bill will be equal to £1.83 plus 37p for each m of gas used.

Simples! :)

If you ask your gas supplier nicely they will send you a payment card, which can be used at local shops to make payments towards your gas bill. All you need to do is to work out the cost of the gas you have used each week (basing it on the figures from your last bill, which probably won’t be the same as mine), and round it up or down to the nearest whole pound.

The Embargo is Lifted

Tuesday, September 15th, 2009

Now that the person who was not to know about it is safely home, I can finally reveal the home improvement I recently had carried out:

Esse 100 SE

Esse 100 SE


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An Idea Whose Time has Been and Gone

Friday, September 4th, 2009

Filament light bulbs — at least the 100W flavour — have been banned. The only question that needs to be asked is, what took the government so long?

Anyone who has ever tried generating their own electricity will know that these bulbs are stupidly wasteful. A 100W bulb kicks out some 95W of heat. It’s surprising really, what with the distinction that has to be drawn between (for example) strawberry flavour, strawberry flavoured and strawberry lest the consumer be unaware how little fruit the product contains, that they’re even allowed to call them “light” bulbs at all! Heat bulb would be a much more accurate description!

Every person who has bought a 100 watt filament bulb to use for general illumination instead of a 20 watt compact fluorescent bulb is needlessly pissing 80 joules of energy up the wall every second the thing is on, using up fossil fuels that won’t ever be available again. Add up all those 80s and you could probably take a whole coal- or gas-fired power station out of service.

Of course, the 20 watt fluorescent is still putting out 15 watts of heat, so there’s room for improvement, and there does need to be a recycling scheme set up — but since compact fluorescent lamps contain enough valuable materials to be well worth recycling if you can get enough of them together, this is pretty much inevitable.

I’m looking forward to seeing the next generation of LED-based lamps.

Thing done

Friday, August 28th, 2009

I have had a home improvement carried out.

Unfortunately, it’s meant to be a surprise for someone, so I can’t mention what it is until that person returns from where they are. I can’t even mention who that person is, or where they might be coming back from, in case they are reading this and work out who I mean and what I’ve had done. In fact, I think I’d better stop now.

Better Late than Never

Tuesday, February 24th, 2009

Well, my local council have finally got around to including my street in the door-to-door recycling collection scheme. Which they have been promising for about 4 years. Better late than never. I should save a fortune in shoe-l**th*r from not having to make a special trek to the recycling centre every so often.

I have had my blue bin (for cans and bottles) delivered yesterday, along with bags for paper and textiles. The brown bin (for organic matter: kitchen and garden waste and cardboard) should be arriving today.

First recycling collection will be next week, then alternating week-to-week with rubbish collections. It takes me a lot longer than two weeks to fill a rubbish bin, though …..

*** UPDATE *** The brown bin has indeed arrived. Can’t help noticing that it and the blue bin are rather slimmer than my black bin!

A New Addition to the Blogroll

Tuesday, August 5th, 2008

BBC reporter Chris Jeavans is embarking on an ambitious project: to see if she can spend a month without buying any disposable plastic items, including packaging — that’s right, she isn’t even going to buy anything with a plastic over-wrap. Re-usable plastic (e.g. food containers) is O.K. though.

Most of the negative response has been from smart-arses trying to point out that computer keyboards &c. are made of plastic — yes, but you don’t throw a keyboard away after typing one document, do you? (I bet I am going to hear from somebody who does exactly that now.)

I say good luck to her. She’s linked on my Blogroll. You can read the initial story here and the blog here.

For once, I agree with the Prime Minister

Monday, July 7th, 2008

Stop the presses! For once in my life, I actually agree with something Gordon Brown has said: we need to reduce the amount of food that goes to waste.

Unfortunately, I can predict exactly the way that his message is going to go down with the public: people are going to talk as though they had some sort of “right” to waste food.
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Pay-as-you-throw for the win!

Tuesday, October 30th, 2007

Someone who uses energy-saving light bulbs and switches off appliances at the wall when not in use pays less for their electricity than someone who leaves filament light bulbs and electric heaters blazing away in unoccupied rooms.

Someone who has a high-efficiency combination boiler and TRVs on all radiators pays less for their gas than someone who leaves pans uncovered and has an inefficient, permanent-pilot boiler with a poorly-insulated, gravity-fed hot water cylinder.

So why the hell should I pay the same amount to have a two-thirds-full wheelie-bin removed every six weeks, as somebody who puts out an overflowing wheelie bin every single week?

Bring it on, I say. It’s about time.

“Dumped” – an interesting parallel

Sunday, September 9th, 2007

Dumped” was a reality TV show and eco-experiment which was broadcast on Channel 4 from 2-5 September 2007. If you didn’t see the programme, you can find more about it here.

One of the things I noticed from the Dumped experiment was that some people seemed to take the attitude that suffering the hardship of living in a s#!thole, in the knowledge that they were going to be taken back home at the end of it all anyway was preferable to making the effort do something about that ‘hole right now.

There’s an interesting parallel, I think, with religions that promise an afterlife in heaven if you just put up with life on Earth for long enough and don’t do anything positive for the here-and-now.

Of course, what we saw on the dump was that the “death-cultists” were actually suffering noticeably (to us; I’m not sure they noticed it). Everyone’s mood was lifted when the new shelter was built, even the ones who didn’t think it was worth making the effort at first.

What could we achieve if instead of bickering about whose “fantasy theme park for dead people” was the nicest, we actually worked together at making a difference in the real world just for awhile?