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A paler shade of light?

An incandescent and energy efficient light bulb
More or Less
Friday, 11 December 2009
BBC Radio 4, 1330 GMT

In our last series, we briefly touched on the subject of compact fluorescent lamps (CFLs) - also known as energy-saving light bulbs.

Our email inbox was rapidly filled by listeners who believe the benefits of CFL bulbs to be exaggerated.

Are they really as bright, long-lasting and energy efficient as is often claimed?

Clearly, we had to investigate. So we put Ruth Alexander on the case - and it seems our email correspondents are onto something.

WATTAGE VS LIGHT OUTPUT
100W - 1500 lumens
60W - 800 lumens
40W - 500 lumens
25W - 200 lumens
(Figures are approximate)
Source: The Society of Light and Lighting

Shrinking the Budget

In the case of the Budget, a simple way of understanding "is that a big number?" is to divide everything by sixty million, roughly the population of the UK.

The GDP of the UK is £1400 billion, about £23,500 per person.

UK government debt is £780 billion, about £13,000 per person.

Alistair Darling, the Chancellor of the Exchequer leaves the Treasury to give his Pre-Budget report
Dividing the huge figures in the PBR by 60 million breaks it into manageable chunks.

The public sector net borrowing - that's how much money the government needs to borrow from investors in the UK or overseas - is about £3000 per person this year and much the same next year.

It will be £2300 per person the year after that, and £1900 per person in the fiscal year 2012-2013, by which time the total UK government debt will be £20,500 per person.

Of course, per taxpayer, all these numbers will be a lot bigger.

The cut in tax on Bingo means a fall in tax takings of between 8 pence per person and 17 pence per person - it's hard to know because the figure is so small it falls within the Treasury's rounding error.

The Treasury estimates that the one-off tax on Bank bonus pools will raise £9 per person, although nobody really knows because it's an unusual tax.

The 50p income tax band will raise £19 per person, although of course a few people will pay a lot and most people will pay nothing.

And the additional increase in national insurance by half a percentage point will raise less than £15 per person, after allowing for an increase in allowances, too.

Race and crime

A storm in the blogosphere spilled into the newspapers this week.

The Spectator columnist Rod Liddle wrote that "the overwhelming majority of street crime, knife crime, gun crime, robbery and crimes of sexual violence in London is carried out by young men from the African-Caribbean community".

Is he right?

Winning by a nose

Pouring wine
Reports suggest the likelihood of a wine being awarded a gold medal is the same as chance.

How do you know if a wine is any good before you have even tasted it?

You might look at how it has fared in wine competitions.

But statistical analysis suggests wine judges (in California, at least) are wildly inconsistent.

Tim looks for answers in the data. Then he looks for answers in the bottom of a decent Côtes du Rhône.

Count von Count

The Count von Count from Sesame Street. Image supplied courtesy of Sesame Street
The Count first appeared on Sesame Street in 1972. He lives in a castle in Transylvania.

He likes to count.

And so do we.

Marking forty years of Sesame Street, Tim talks to the mathematical Muppet who has been introducing children to numbers for the last four decades.

Altogether now: Ha, ha, ha, ha.

YOUR COMMENTS

The views expressed on these pages are not necessarily the views of the BBC. The comments published will reflect the balance of views we receive.

A paler shade of light?

You missed out two very important points: 1. The different amount of energy used in the manufacture of the CFL when compared to traditional bulbs. The ballast is made up of many electronic components, each of which takes energy to manufacture and ship. And the assembly of the ballast.

2. Disposal. CFLs need to go be recycled ( more energy used here ) whereas the traditional bulb can go straight into the bin.
Paul Caston

On fluorescent light bulbs, there is at least one more factor to be considered in terms of their overall energy saving: disposal. My LEA will not accept them unless they are taken to a specialised waste disposal depot several miles away. I guess that is because of the mercury they contain. Recovering it must also be a costly and energy demanding business.
Tom Gilchrist

Our main complaint [about low energy light bulbs] is that they take so long to get going.

This means if my wife is in a hurry she turns the hob light (two 40W bulbs) on as well and/or the worktop light (three 40W bulbs). So we end up with anything up to 200W in addition to the still warming-up CFL bulb. If there's any risk we'll go back into the kitchen in the next 10 minutes we leave it on.
John Collins

I got involved in an argument with DEFRA over mercury in CFLs and asked them to send me some reading material that supported their case that mercury in CFLs was not an environmental problem. I read the paper and wondered why they had sent it in support of their argument as the paper said that the mercury in the fly ash of coal fired power stations was more environmentally locked in than the mercury in a CFL.
Rex Waygood

Race and crime

You neatly exposed the exaggeration of black crime but failed to answer the key underlying suspicion of many that the crime figures for say the young black ethnic minority are higher than the proportion of that minority in the general population, i.e. they may not be a net majority of the criminals but is their group over represented?
Paul J. Weighell

Count von Count

The square root of 34969 is 187 which is:
a) American code for murder
b) 94sq - 93sq
c) 187th street is in Manhattan, as I believe was Sesame Street
Simon Phillips


BBC Radio 4's More or Less is broadcast on Friday, 11 December at 1330 BST and repeated on Sunday, 13 December at 2000 BST.

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