The past few years have seen a huge upheaval in how we light our homes and offices. The traditional incandescent lightbulb is no longer on the shelves of shops. They were very inefficient. 90% of the electricity used to light incandescents was lost in the form of heat. Halogen light bulbs – a much smaller version of incandescents – also generate a lot of heat. They use less electricity than incandescents, but tend to be used in greater numbers, which cancels out the savings.
Introduction
Changes to regulations have triggered a step change in developments in the lighting industry. Incandescent and halogen light bulbs both generate a lot of heat and are not very energy efficient. A great variety of Compact Fluorescent Lamps (CFL) and Light Emitting Diodes (LEDs) are now available instead.
LEDs are the most energy efficient, turn on instantly at full brightness, and are available to fit pretty much any light fitting in the home. LEDs produce light from the electricity flowing through them. Within a bulb, you will find many LEDs to create sufficient brightness.
LEDs also cost about the same as other bulbs but last longer so you will need to replace them less. One LED bulb could last over 10 years.
Lighting makes up 15% – 20% of the average UK household electricity bill. If you replace all the bulbs in your home with LED lights, you could reduce your carbon dioxide emissions by up to 65kg a year, and save up to £40 a year, plus the extra for not having to replace light bulbs so often. Turning off lights when you leave a room, considering the number of lights you have in one room, installing timers and cleaning lampshades and light fittings can all help make the lighting in your home more efficient and reduce your energy bills as well.
How to choose the right lamp
Traditionally we’ve measured the strength of our lightbulbs (lamps) in watts. A 40-watt incandescent light bulb was dim, a 100–watt one was bright. However, that measure was misleading. Watts are a measure of power consumption, not of light.
Brightness:
Lumens are a measure of the light given out by a lamp. The higher the lumens, the brighter the lamp.
A traditional 40-watt bulb is equivalent to a 470 lumen LED bulb. And a traditional 100-watt bulb is equivalent to a 1,520 lumen LED bulb.
Colour temperature:
The colour of light is measured in degrees Kelvin. The colour is what results in us perceiving light as warm or cold; harsh or soft. Cold light will have more blue in it and warm white has more yellow.
Daylight is 5,000 Kelvin
Cool white is 4,200k
Warm white is 2,700k
We suggest you test one bulb to make sure you’re happy with the light it gives before investing in larger quantities.
There is also another colour measurement, the colour rendering index or CRI. This measures the quality of a light source compared with sunlight. Sunlight is given the maximum CRI value of 100. The closer a lamp is to that, the better its ability to show true colours. This is important in art galleries and shops, but is not critical for optimal light levels in homes. A CRI of 80 or more is appropriate for most household tasks. The bulb’s packaging will indicate the CRI alongside the lumen value.
