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Which is the best light bulb?


Which is the best light bulb?

Renew Wales mentor, Peter Draper, wrote this blog on which lightbulbs we should choose

 http://ecohomecentre.blogspot.co.uk/2014/04/which-is-best-light-bulb.html

Choosing a bulb would appear to be a straight forward choice. Incandescent bulbs are slowly being withdrawn as they are better at making heat than light! However, we are very used to the light that they give and the way that they do it. The change over from incandescent to better efficiency bulbs has been a focus of the energy saving movement, but it has hit upon a degree of resistance from the great British public. So what are the choices now that the market has matured a bit?
 
Incandescent and halogen bulbs are high energy users, but they do give a instant light that has a high CRI value. A what? CRI is Colour Rendering Index. So this tells us how much of the visible spectrum is given off by a bulb. CFL bulbs have poor CRI, hence the light that they produce makes colours appear different. LED bulbs give off a better CRI than CFL bulbs.

Another common complaint about energy saving bulbs is that they are duller than the incandescents and halogens. This can be true, if you don't get a powerful, or efficient enough one. We are used to looking at the wattage of the bulb and also believing what companies tell us are equivalents, whereas we should be looking at Lumen output. Lumens are a measure of the quantity of light. So if you want an equivalent to a 60w bulb you will need to match its light output which is around 600 Lumen. This means that you will need a modern CFL bulb of around 11w and a LED bulb of around 6w. But check the box as there is a wide variety of outputs for different types, shapes and colours of bulbs. Colours??

Well now, a whole different area. White light comes in a variety of colours! This is measured in K (Kelvin). Warm whites (incandescent and halogens produce warm white) is around 2700 to 3000K. LED and CFL bulbs are available at this colour temperature. But they produce more light at higher K, but this means that they produce a whiter / slightly bluer light and this is commonly called Cool White. Cool White is around 5000K. You can also get Daylight bulbs at around 6500K. The different light that these bulbs give off is very different and so make sure that you are getting the right Lumen with the Colour Temperature (K).

So what with size varying, the amount of time required to get to full brightness (CFL's have to warm up, whilst LED is instant), cost, length of time a bulb is on for (no point investing loads of money on a new bulb if it is only on once a week for a few minutes!), guarantee periods (these tend to come with LED bulbs), estimated lifespan (LED bulbs have the longest span, but CFL's also have a good lifetime), location of bulb (is it hard to get to? If so you might wish to go for the longest projected life), is it on a dimmer? etc etc.

Get the idea? There is a huge variety of factors that can influence what bulbs you might put where. So, it is worth thinking a little about the lights that would suit you best.

If you need instant light that will be on a lot - LED
If you need background light - CFL
If you need a high quality light - LED
If you only use the light ever now and again - keep what you have!

You get the idea.

Just be aware that there is a wide variety of choices and that not all bulbs are the same.

Check Lumen, not Watts.
Check Guarantee as well as Lifespan.
Check Colour Temperature to ensure who have the right type of light.
Check size to ensure that it will fit in your fittings (especially important for some halogen replacements). Check to ensure that your bulbs are compatible with your dimmer system (if you have one).




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