Lighting - Cost of ownership


24 Oct
24Oct

When buying an electrical item, it is very easy to fall into the trap of only thinking about the up front ticket price!

Did it ever cross your mind that buying an item such as a light bulb that the ticket price may represent only a tiny fraction of its lifetime cost of ownership.

Suppose we compare an halogen spotlights, Fluorescent tubes, and LED panels for lighting a shop.


Halogen spotlights 

Light output about 12 lumens per watt so for 500 lux, you need around 42 watts per m2

Electricity cost per m2 per year at 15 p/kWh running 50 hours a week

0.15 x 0.042 x 50 x 52 = £16.38 

Estimated Electricity Cost £16.38 per m2 per year for 500 lux lighting


Fluorescent tubes in suspended ceiling fittings 

Useful Light output about 33 lumens per watt so around 15 watts per m2

(Fluorescent tubes generate light fairly efficiently but are not directional and a lot of light is lost in the fitting)

0.15 x 0.015 x 50 x 52 = £5.85

Estimated Electricity Cost £5.85 per m2 per year for 500 lux lighting


Back lit LED panels (high efficiency)

Useful light output about 150 lumens per watt so around 3.33 watts per m2 

(LED lights are inherently directional so virtually all their output is useful)

0.15 x 0.00333 x 50 x 52 = £1.30 

Estimated Electricity Cost £1.30 per m2 per year for 500 lux lighting


LED lights are also substantially more reliable and last far longer so needing far less maintenance than fluorescent or halogen lights so delivering significant additional savings.


If you have old halogen of fluorescent lights, can you afford not to change them for LED?


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