By Stuart Graham

Most people have a poor perception of energy saving “light bulbs” (more accurately known as lamps) due to cheap compact fluorescent lamps, which provided poor light quality and sometimes took several minutes to achieve full output. This has not been helped by the early LED lamps being too dim when replacing tungsten halogen, too glare-y as they extended out of the spotlight housing or too white, as white LEDs are more efficient than warm white tungsten replicas.

However, in the last two to three years LED lamps have matured such that there are warm white, bright and energy-efficient lamps available for most types of domestic “light bulbs”. In most instances these are as good as conventional lamps, but with significantly lower running costs and much less waste heat. They also provide instant light, as they do not suffer from the warm-up periods and have much longer life expectancies –  typically 15-20 times that of conventional lamps.

While these are currently more expensive to buy than conventional lamps, the energy savings result in much lower life cycle costs.  Take the example of a 60W conventional lamp.Running costs over 15,000 hours(the typical life expectancy for domestic LED lamps) are:

15 bulbs @ £1.50 = £22.50

15,000 hours x 0.06kW x 10p per kW hour  = £90.

Total cost = £112.50

An LED equivalent is now available which uses 6.2W of energy to provide the same light output and has estimated life expectancy of 15,000 hours:

1 LED @ £5.48 =     £5.48

15,000 hours x 0.0062kW x 10p per kW hour  = £9.30.

Total cost = £14.78 (saving £97.72 ).

(based on a typical price of electricity at 10p per unit, but greater savings will be obtained with higher electricity costs).

Another way of thinking about this is that the 6.2W LED lamp saves around 0.5p per hour of operation. The payback period is around 740 hours, which is 5% of the overall life expectancy of the LED. For the remaining 95% of the life of the LED, you are saving on energy and replacement of lamps.

A frequent complaint about compact fluorescent lamps was that the quality of light was poor compared to conventional lamps, particularly as they were often cooler in colour. LED lamps are now available with warm and cool options, with warm lamps being very similar to conventional lamps at around 2700K colour temperature.

Dimmable LED lamps are also readily available, some of which are configured to change to a warmer colour as they dim, replicating conventional lamps.

In addition, options are available for replicating a conventional filament.

Things to consider before buying are:

  1. Cheapest isn’t always best. Better quality manufacturers generally have better manufacturing tolerances, so have better life expectancy. Also, lamps from higher quality manufacturers are more likely to be closely matching colours. Also beware of using auction sites.
  1. LED lamps can be larger than conventional lamps. If you’re installing the lamp into a light fitting which is already a close fit, it’s best to check the dimensions first.
  1. Avoid lamps with lots of visible LED microchips / elements
  1. In domestic use, “warm” lamps are generally best. If colour temperature is indicated on the packaging, 2700K is close to GLS bulbs.
  1. Dimmable lamps are available, but the dimmer unit needs to be compatible with the lamp. Some manufacturers now provide dimmers specifically for LED lights, which are similar in appearance to ordinary dimmers.
  1. Where 12V lamps are installed, the transformer needs to be suitable for use with LED lamps. Most transformers have an upper and lower power range – you need to ensure the transformer is not under-loaded as well as overloaded (or the life expectancy of the LED lamps may suffer).
  1. LEDs do not contain mercury (unlike some compact fluorescent lamps) and some councils accept these within ordinary domestic refuse, with recycling programmes being developed to accommodate LED lamps. However, you should check with your council whether they accept and / or recycle before disposing with household waste.

There shouldn’t be any reason why you can’t try at least one in your home.

For more information on lighting services, please contact Stuart Graham, s.graham@cundall.com

 

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Electrical Engineering, Lighting Design, Stuart Graham

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