

Simon Hobson linux at thehobsons.co.uk
Fri Mar 20 15:54:26 UTC 2009

Johnny wrote:

>  > But if a study starts by noting that a CFL uses only 20% of the 
>energy of an
>>  incandescent, and therefore there is an 80% saving, then in many markets any
>>  further analysis is (almost) totally invalid.
>>  Over here in the UK, few properties won't be without heating - certainly for
>>  the winter months when the lights are used the most. So there will certainly
>>  be a balancing between lower thermal input from the lighting, and increased
>>  thermal input from the heating. In our house the heating is gas, so it'll be
>>  more efficient than electric, quite a few homes have electric heating of
>>  some sort.
>Again this claim that CFL aren't efficient because you have to use
>your heat more are anecdotal at best. This stems from a statement made
>by a Canadian energy administrator, and has been debunked many times.
>You are using energy to heat your home either way. So essentially this
>claim is that incandescent bulbs are more efficient at heating your
>home than whatever system you use which is designed for that purpose.

I never made that claim, but you seem to be sticking to the "it makes 
no difference" argument.

Note that I did say "in many markets". Over here, A/C is the 
exception, we have long days in summer, and long nights in winter. So 
the time when lighting is used the most, is when the heating is also 
being used.

>Since this isn't the case, you would actually be saving total energy
>on heat by heating your home with your more efficient heating system
>than the heat that was produced by incandescent bulbs. So while energy
>used to heat your home will increase it will be less than the energy
>gained by the more efficient lighting.

That's the crux of it. If the heating is electric then there is ZERO 
difference in efficiency - both the electric heating and light bulb 
are 100% efficient at turning incoming electricity into heat. For 
other forms of heating there will be some saving - but I don't know 
what it will be other than "nothing like 80%".

Even one of our quangos*, the Energy Savings Trust, has admitted that 
in our climate they make little difference.

Read the footnote on this article :

>Eventually, the Trust admitted, the low energy bulbs make little 
>difference to the householder because the lower heat output in cool 
>climates - like ours - means people spend more on heating

CFLs probably do give savings - the amount will be heavily dependant 
on a whole host of factors, but in most cases it will be nothing like 
80%. So when someone does a study and works out what that "anything 
between zero and 80%" actually is in different situations, and THEN 
goes on to work out if there is an overall saving - only then will 
the results be worth the effort to read.

As I said before, any study that concludes "CFLs save 80%, therefore 
<some conclusion>" is not worth the paper it's written on.

You have to even take some of the energy usage statistics with a 
pinch of salt. Eg, there are various figures bandied about along the 
lines of "x% of our energy goes into lighting". When talking about 
swapping bulbs for CFLs in a domestic environment, such a statistic 
is meaningless unless it actually breaks out what amount is used by 
lighting in domestic environments - and leaving out industrial, 
commercial, street lighting etc which already uses various forms of 
efficient lighting.

Don't get me wrong. What I am NOT saying is that CFLs don't save 
energy overall. What I AM saying is that it's not 80% (even leaving 
out all production and shipping costs) in a great many cases.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
Christmas stocking fillers. Some available as e-books.

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