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Finally seeing the light over compact fluorescent lamps

Further to the recent discussion regarding the benefits of using a 'smart meter' (NCE 17 January), the use of CFLs (compact fluorescent lamps) has been suggested as a means of reducing energy consumption and therefore being the greener option.

The smart meter will confirm the reduction in 'energy' consumed, which I understand is measured in KW as opposed to VA. Not being an electrical engineer, I carried out some brief research on the internet:

A normal incandescent filament bulb is an almost entirely resistive load, and the voltage and current will be in phase (hence a power factor of 1). But a CFL – with a significant proportion of capacitive load due to the ballast – will have a much lower power factor, perhaps only 0.5.
This means that a 15W CFL actually requires 30VA from the power station – which the private customer will not pay for directly, since home electricity meters only measure watts, but it is still equivalent to needing to supply double the power. That increase in necessary generation can't be ignored: the consumer will pay for it one way or another.

The EU has ruled that ordinary 40W/60W/100W incandescent lamps will be banned from 2012. Is this truly a 'green' measure?


Editor's note: I contacted Ray Molony, the editor of Lighting magazine, one of NCE's sister titles, for an expert comment. Here is his reply:

Mr Ogden raises a valid issue with CFLs. The fact is that the picture is more complex than initially appears.

The power factor of CFLs is indeed an issue for the power generation sector who must take measures to manage the reactive element of its load. Additionally, there is, certainly in northern Europe, a heat replacement effect whereby consumers turn up their (usually wet system) central heating to compensate for the heat removed from the household when incandescents are removed in favour of CFLs.
So bald energy reduction figures should be treated with caution.

-Ray Molony, editor, Lighting magazine,

With reference to recent articles and letters on the subject, efforts at domestic energy conservation are to be applauded.
The population hasn't quite twigged yet that energy prices in this country are not particularly high and if monthly energy bills are excessive then it means consumption is too high – it's as simple as that.

As a tip to save a bit more, aside from the usual switching off unneeded lights, I gleaned from a website sometime back that one only need a hot water boiler switched on for about 19 minutes a day for two persons.

We do this in the evening, it provides sufficient hot water for washing at night and will still be warm come the morning. Should one require hot water during the day (for washing up for example), it is far cheaper to boil up a kettle. Our monthly energy bill varies between £30-£40 which I think is reasonable for two persons, especially as neither of us bother about work too much these days and therefore spend a lot of time at home.

We're also economical on appliance usage, nothing is left on standby. Fortunately, with TV schedules in this country so appalling, the set is rarely on compounding the savings even further – TV companies are to be commended for contributing to this economy!

-BEN ZABULIS (M), 31 Redhill Lodge Drive, Redhill, Nottingham NG5 8JH

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