A guide to buying LEDs

Although statistics vary, somewhere between 16% and 19% of global power consumed is used for lighting.   It therefore makes sense to look at how efficiencies can be made.

Incandescent lightbulbs need to be replaced – in an incandescent lightbulb (for the purposes of this blog halogens work in a similar way), electricity runs through a very thin tungsten filament, which heats up to about 2,500°C and then glows, thereby emitting light.  However, whilst the light emitted is good quality light, approximately, 90% of the energy consumed by such lightbulbs is given out as heat, only 10% is converted into light.  This means that much energy is wasted, which is why they can’t be used.

..by another type of lighting There are two types of more energy efficient lighting.  Compact Fluorescent Lights (CFLs) or Light Emitting Diodes (LEDs).

A CFL is like a strip light you would find in an office.  It contains a combination of argon and mercury vapour which produces ultraviolet light when electrified and the lamp’s coating converts the ultraviolet light into visible light.  Less of the energy is used in producing heat and less is wasted. However, the trouble with CFLS is that as they contain mercury, they are difficult to dispose of.

LEDs have been used since in 1960s in a number of applications, such as the figures on digital clocks, backlights on watches, in remote controls and a collection of LEDs has been used to form images on TV screens.  A very simple explanation of how they work is that they are illuminated by the movement of electrons in a semiconductor material.  A much lower proportion of the electricity used in LEDs is used in generating wasted heat and as they don’t have a filament that is prone to burning out, they last much longer. They contain lots of different components and are therefore more expensive than incandescent bulbs, halogens and also CFLs.  Your existing bulbs can be replaced with LEDs directly or you can replace the whole fitting.

..which requires a bit more careful choosing


–         a 40W incandescent bulb around 390 – 460 lumens

–         a 60W incandescent bulb is equivalent to around 750 – 850 lumens

–         a 100W incandescent bulb is equivalent to around 1,700 – 1,800 lumens.