Good stewardship and LED’s

DSC_2159I have recently bought some more LED’s. With the EU’s incandescent bulb phaseout complete (at least for 240V – a low voltage bulb efficiency mandate is mooted) the manufacturers have really worked on technical improvements to alternatives and prices have also fallen. Compact fluorescents and LED’s have improved with better light and in the case of compact fluorescents faster start-up times. In addition LED’s are being produced at higher power outputs and are able to replace higher wattage bulbs. I’ve noticed all this over the last few years. I bought some very low power  240V candle LED’s and the light was still slightly blue.  When mixed with other light types this was not noticeable, but you certainly would not want to use them solely to light a room (in any case the light output was too low).   The power output of LED’s has been rising and is now up to 100W equivalent.

In terms of light quality the manufacturer (a very well known multinational) has got it right.  The light on all new LED’s is indistinguishable from an incandescent bulb. This is a remarkable technological feat. Also with LED’s there is no warm-up time. The cost is still high however. I paid £12. What I was wondering was how do the economics stack up?

There are two alternatives to LED’s; compact fluorescents and GLS halogens which use about 30% less electricity than a classic halogen bulb, but a lot more than a compact fluorescent.

LED versus GLS. Cost of “25W” LED £12 (5W consumption) cost of GLS “35W” £2.95 (28W consumption). They are not quite “like for like” but this is near as can get and these are the bulbs I’ve actually bought for lighting my daughters room via spots (gradually using more LED’s and compact fluorescents). The crude economics are better than I thought. GLS bulbs are (like normal halogen ones) not incredibly reliable. I reckon they last 6 months at the use they get, so it looks like a payback of 4 years (not taking electricity savings into account).

The other alternative is a “51W” compact fluorescent that uses 12W of power and costs £5.95. Again the comparisons are not exact, but this is one I have bought in the past for this use. Compact fluorescent bulbs last a lot longer than halogens, so if you are considering which one of the two to buy on cost grounds you should buy the compact fluorescent. Compact fluorescent bulbs longevity makes them in theory a economic challenge to LED’s. They can work for many years, we had an outside one that lasted 15 years at least. However, we have also had some fail and I’m going to stick my neck out and suggest that a compact fluorescent will have half the lifetime of an LED, making the economics merely on bulb replacement even stevens.

Of course for a full analysis we need to take into account the relative amounts of electricity used. For this I’m going to have to make some assumptions about usage. Assumption one is we import the electricity used rather than produce it ourself on-site. The second assumption is that the usage by my daughter for each bulb is 5 hours per day. This is on the low side, but I’m being conservative. Third that electricity prices won’t rise (or fall – although this seems less likely). Lastly the economics will be calculated for one bulb at a cost of electricity of 16.4p/KWh (which in two weeks time is what I will be paying). So per year I calculated the running costs as the following;

GLS 5 hours x 365 days a year x 28W/1000 is 51.1KWh a year @ 16.4p/unit making the cost £8.38.

Compact fluorescent 5 hours x 365 days a year x 12W/1000 is 21.9KWh a year making the cost £3.59.

LED 5 hours x 365 days a year x 5W/1000 is 9.125KWh a year making the cost £1.49.

Since I’ve only partly bought energy efficient bulbs for monetary reasons and never considered the economics before I have to say I’m stunned by the results. The LED compared with a GLS bulb pays for itself in less than a year taking into account both projected failure rates and the cost of running them. Comparing the LED to a compact fluorescent isn’t as good with just over £2 a year difference in the price of running them its going to take 6 years of running costs to close the gap. However, remember that compact fluorescent will need replacing over the lifetime of the LED and a simple calculation suggests if you use it more the payback is faster. If the usage was double the payback would be three years. Of course the opposite is true if you use a light very little then the economics of the extra cost looks terrible.

My parents church has replaced a failed outside light with an LED cutting the power consumption from 500 to 50W. Since its on a lot the economics almost certainly stack up. My church has bought some LED stage lights and intends buying more. However, the remainder of the lighting is either 12V fed by transformers that are incompatible with 12V LEDs or compact fluorescents (we have some LED’s in our entrance). Is it good stewardship to replace our compact fluorescents with LED’s? In my view it is and we should replace them gradually as they fail. Please let me know your views and experiences.

This is a repost with mild updating.  The cost of electricity is now higher than quoted above so I’m saving even more money as well as the environment.


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