# More on LEDs: some numbers

Late last summer I went around the house replacing halogen lamps with LEDs, which resulted in such things as 430W of kitchen lighting being replaced with 32W of LEDs. At the same time in the hall and landing the total of 4 20W MR11 lamps were replaced with 4W LEDs. Many other lamps throughout the house were replaced.
Last month's electricity consumption was our lowest ever, at 192 kWh. However, it's not possible to put this down to any one cause, as SWMBO has taken to such things as making curry, etc, by the gallon and freezing the portions, saving on cooking time.
However, the usage of the hall and landing lights remains fairly constant; in winter (which lasted 4 months here this year) they are on 16 hours a day, and for the other 4 months they have been fitted, 5 hours a day.
4 months x 30 days x 16 hours x (4 x 20 - 4 x 4) = 123 kWh
4 months x 30 days x 5 hours x (4 x 20 - 4 x 4) = 38 kWh
Total 161 kWh of electricity saved @ 12.5 p/kWh = £20 saved.
However, in that 2500-hour period, probably most of the halogens would have blown at 2000 hour life, for a good-make lamp at £1:50 that's another £6 saved, for a total of £26.
That's nearly half the cost of the LEDs saved in 8 months. By the end of next winter the LEDs will have paid for themselves, and if the manufacturer's claims of a 25000-hour life are correct, still have another 20,000 hours of life left.
In 25,000 hours 1 x 4W LED will consume 100 kWh for a cost of £12:50. plus initial cost of the LED at £14:50, totalling £27:00
For 25,000 hours operation in one position 13 2000-hour-life halogens will be needed, at a cost of £20, plus energy consumption of 500 kWh or £62:50, for a total cost of £82:50.
Each LED over its life saves £82:50 - £27:00, or £55.50, and I have a total of 4 in this application, therefore saving £222:00 over the claimed LED lifetime.
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Terry Fields

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I can think of an easy way to reduce your energy usage. Called a switch.
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*Not all men are annoying. Some are dead.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Thu, 11 Jul 2013 10:24:41 +0100, Dave Plowman (News) wrote:

Would it be cheaper to fall down the stairs in the dark?
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Terry Fields

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Every house I've lived in has had a switch at the top and bottom of the stairs.
Tim
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On Thu, 11 Jul 2013 12:05:53 +0100, Tim+ wrote:

But you have to get to the switch in the dark...
Once upon a time I lived in a semi, where the party wall supported the staircases of the two properties. Before the kids were old enough to go out socially, it was click-click-click-bloody-click seventy times an evening. And this in a family that ran a 500W security light during the day and left all the house lights on at night. Sheesh...can't people see what's under their noses? Why didn't they just leave the landing light on?
As for the LEDs, it's a no-brainer on long-term cost, but they are more difficult to buy to to the greater range of choices, such as colour temp. It's no good saying 'it's hideously white' if you bought a 6000K lamp, or balme the LED.
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Terry Fields

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We have nightlights at the top and bottom of the stairs ...
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Today is Boomtime, the 46th day of Confusion in the YOLD 3179
RIP Douglas Carl Engelbart (January 30, 1925 – July 2, 2013)
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No such thing as hideously white. White is white, why settle for yellow?
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A chicken crossing the road is poultry in motion.

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On Thursday, July 11, 2013 12:05:53 PM UTC+1, Tim+ wrote: <snip>

That's been the case for me, too - unfortunately, though, whoever wired my current house (most likely the electrician I bought it from) didn't seem to believe in two way switching, so the two switches switch two different lights... In addition, the only switch for the hall light is 4 metres from the front door and round a corner, so the hall light tends to get left on near permanently.
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On 11/07/2013 12:05, Tim+ wrote:

+1
But here, this is adequately compensated for by the presence of SWMBO and assorted offspring.
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David

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I have switches where needed. 5, for the ground floor hall. Lot cheaper than fitting low energy lamps and leaving them on just in case.
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*Sticks and stones may break my bones but whips and chains excite me*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Thu, 11 Jul 2013 14:55:15 +0100, Dave Plowman (News) wrote:

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Cheers
Dave.
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On Thu, 11 Jul 2013 14:55:15 +0100, Dave Plowman (News) wrote:

Ah but I don't think you have a SWMBO'd and/or children living with you. I switch off far more lights in a day than I switch on...
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Cheers
Dave.
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You don't beat them nearly enough.
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*Where there's a will, I want to be in it.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Dave Plowman (News) wrote:

Chris
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Chris J Dixon Nottingham UK
snipped-for-privacy@cdixon.me.uk
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Not sure they were around when I wired this house - and you'd need several to cover the area properly. Two of the switches are on the first floor. So why make things complicated for the sake of it?
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*Growing old is inevitable, growing up is optional *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Terry Fields wrote:

It depends on how much you charge to fall down the stairs in the dark:-)
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Fit automatic lights. You can buy the sensors to directly replace lightswitches. The good ones need a neutral (or an earth will do if you don't have those pesky circuit breakers). But some are a lot better than others, get one with a relay in it as the transistor ones often require a decent load on them of about 60 watts, which doesn't happen with LEDs. This one is good: http://www.ebay.co.uk/itm/190615620954
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English > German
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On 11/07/2013 10:24, Dave Plowman (News) wrote:

But there is comfort, security and convenience.
Although even I wouldn't go to the lengths of the OP - in my case it's a 2W undercounter kitchen LED array from Lidl, which is on most of the time. Hideous white light though - I will change it in the fullness of time.
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Cheers, Rob

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On Thursday, 11 July 2013 12:22:39 UTC+1, RJH wrote:

I ahve one of these in the bathroom http://www.diy.com/nav/decor/lighting/lightbulbs/led_bulbs/Motion-Detector-LED-Night-Light-2-Pack-9279717
which means I don;t have to put on the light when goiong to the toilet day or night. But when having a bath there's 3X40W incandescent candles. I don't see the need for replacing them with LEDs.
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On Thu, 11 Jul 2013 06:53:14 -0700 (PDT), whisky-dave

13 outlet in the bathroom. Is that a good idea?
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