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LED lights

posted 24 Apr 2014, 05:37 by Martyn Goss

One of my personal actions at home during this year’s Lent Carbon Fast was to replace existing low-energy light bulbs with the new generation of LEDs (Light Emitting Diodes).  The challenge was to reduce our Wattage consumption from about 500, from 21 fittings. It now seems we will achieve this by dropping to about 145W, although LEDs are also measured in Lumens so it is a more complex comparison than it seems.

This required initial investigation and I was helpfully encouraged and guided by an article by John Adams in Permaculture Magazine (No. 79, Spring 2014).  Like him I quickly discovered that if you can afford the initial outlay (I was helped by a recent long service gift from my employer), it makes every sense to refit as many lights as possible – environmentally and economically.  LEDs can make power savings of 80%-90% over the old incandescent lights; they are much longer lasting (up to 25 years); they produce very little heat; are cheaper to run; and also less polluting - containing no mercury and producing neither UV or IR radiation nor visual flicker.

However, there are many makes, various sizes and diverse fittings, so it is worth trying out a few in different rooms.  In my experience those rated between 5 and 8 watts are adequate for smaller spaces – and the larger ones are available in a warm (yellowish) or a cool (bluish) light.

Prices vary between £5 for a small spotlight to £12, and it is worth buying a quality brand rather than some very cheap options which seem not to last.  My estimate is that financial costs will be repaid in 8 - 12 years at current prices.

LED bulbs are manufactured in old style standard-size bulbs, but also as spotlights, globes and candles (both clear and cloudy glass).  Fluorescent tube replacements are available at a higher price but may require a slight rewiring.  Because most of the energy is converted into light there is little heat, which means LED strips can be placed in locations such as on cupboard doors or integrated into worktops.

I conclude by reproducing John Adams’ Cost Table below:

Costs per annum to produce 800 lumens for 5 hours a day,

averaged over 10 years
















Includes replacement costs of bulbs over 10 years.  The life of the LED bulb

May well exceed 10 years and may be as long as 30 years, which would greatly

increase the saving.  Electricity calculated at 12.5p. per KWh.   All costs are approximate.

Martyn Goss, April 2014