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Why all the fuss about LED light bulbs? 

Just when we had all become used to using CFL* low energy bulbs wherever possible, we start hearing more and more about LED* lamps as a further alternative.  (* CFL – compact fluorescent lamp, LED – light emitting diode)  So what's it all about?  

Firstly it's helpful to understand that the big manufacturers have recently been devoting a lot of their development efforts to LED lighting, and as a result technical details, performance and prices are all changing rapidly.  By comparison CFL technology has largely stabilised.  One aspect of LED lamps that has improved a great deal is that, instead of the cold blue light of earlier lamps, they now produce light that is much closer to conventional lighting, with a choice of 'warm white' or 'cool white' often available.    

At the current stage of development the efficiency of LED lamps is generally similar to that of CFL lamps, although there is the prospect of LED efficiencies improving considerably in the future.  This leads to a first conclusion that, where CFL lamps are giving good performance, then currently there is little or no incentive to change to LED lamps, especially as LED lamps still cost a lot more than CFL.  

However if you have downlights or spotlights with conventional halogen bulbs (either 240V or 12V type) then LED lamps are well worth considering as they are much more efficient, with bulbs of 7 to 8.5 Watts giving light outputs that are equivalent to a 50 Watt halogen bulb (ie  energy cost is around 15% of halogen bulb).  CFL lamps are not well-suited to this application as they tend to be too bulky, so that when miniaturised to fit into standard downlight fittings they generally give poor performance and are slow to reach full brightness.   By comparison LED bulbs reach full brightness immediately, operate at low temperatures and have a much longer life span than halogen bulbs.  Also many newly developed LED bulbs are dimmable.  But one point to watch out for is that there is a tendency for the bulbs to give a relatively narrow concentrated beam. 

The main downside is the cost.  High performance LED bulbs such as those described above cost around £25 to £30.  However for applications where lower power is acceptable, bulbs of about 3 Watts are now available for around £10 to £12.  

In many applications the high purchase cost can be fully justified by the energy savings and the long life of the bulbs.    

A worked example is helpful in showing the benefits that can be achieved.  Our small lobby & bookcase area was originally lit with two GU10 35 Watt halogen downlights.  Our first try at low energy bulbs was to use 11 Watt CFL bulbs (Megaman), but these were woefully slow to reach full brightness which was a big problem in this location.  We now have two 4.5 Watt LED bulbs (Maxilux) and these have proved to be an excellent solution and should last for many years. So overall we've managed to reduce from 70 Watts down to 9 Watts. 

To learn more, there is a great deal of information on the internet, however a supplier that both Chris Handel and I have found to be good for both information and for buying LED bulbs is YourWelcome.co.uk (Moat Farm Trading Ltd.) - see www.yourwelcome.co.uk . 

A final note of caution, based on recent experience, there can be a problem with radio reception interference from some LED bulbs.  Initial feedback suggests that this is associated with some brands of MR16 (12 Volt) LED bulbs when in proximity to a DAB radio.  One supplier has advised that this happens in a few cases (because the electronic circuit in the bulb uses the same frequency as the radio).  As it is infrequent their policy is to acknowledge the incompatibility and offer a refund for the bulbs; they say it does not affect all customers, LEDs or locations.  We'll give more details on this problem in future newsletters.  (Do let us know if you have experienced this or other problems with LED bulbs.)  

The pictures are of:

Toshiba high performance LED downlight bulb (GU10, 240 V, 8.5 Watt, 300+ lumens)  which performs well as a direct replacement for 240 Volt 50 Watt halogen bulbs.

Osram Parathom LED downlight bulb (MR16, 12 V, 4.5 Watt, 185 lumens), sold as a direct replacement for 12V halogen lamps, with same dimensions as normal MR16.