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Energy Efficient Lighting – Costs and Benefits

In commercial premises, the opportunities for savings are generally higher than domestic properties. Fluorescent luminaires account for 80% of lighting on commercial premises and are generally used because they combine high luminous output with low power consumption. Simply replacing T12 and T8 halophosphor tubes with triphosphor fluorescents could save up to 30% in energy terms. They also have a longer life, higher lumen maintenance over time and better colour rendering.

Self-finance calculation

Well designed light fittings can boost energy savings further. By focussing the light where it is needed you need fewer lamps and, when designing a lighting system, using ceilings, walls and floors to reflect light can further reduce the number of luminaires needed. More savings — up to 20% — can be achieved by changing from conventional switch start control gear to high frequency. This gives a flicker–free start and lighting, automatic shutdown of failed lamps and silent operation. High frequency control gear also needs less maintenance as it is all in one unit.

Other simple steps that can cut down on the energy consumed by lighting include fitting dimmers or time lag switches but, for real savings, we should look at more sophisticated types of lighting control. As with most systems, human habits are the weakest link, people forget to turn lights off and in work areas in particular, it seems to be taken for granted that lights will be on all day, every day, regardless of occupancy. If people forget to turn lights off, then install a system that does it for them. PIR occupancy sensors switch lighting on or off and can be hard wired into either the luminaires or the marshalling box that supplies power to a group of luminaires.

This alone can save energy but by going one step further and you have an occupancy system that incorporates a photocell that switches the lighting off if there is enough natural light ’ or, with a digital lighting control system, one that enables luminaires to dim up and down in response to changing light levels. Digital control systems can achieve energy savings of up to 70% and they maximise lamp life because rather than turning off in response to bright daylight, they just dim down to about 10%.

For domestic properties, Lighting accounts for up to 20% of a typical household’s energy bills: cutting your lighting bill is one of the easiest ways to save energy and money in the home. Whether you rent or own your property, or live in a house, flat or bungalow, you can save money today by changing the way you use your lights and by fitting new energy-saving lights.

If you replace a traditional light bulb with a compact fluorescent bulb of the same brightness you will typically save around £3 per year, or £55 over the life of the bulb, if you replace a 50W halogen downlighter with a 6W LED you will typically save around £4 per year, or £70 by the time you have to replace the bulb.

Many homes today use a mixture of standard light fittings and halogen downlighters or spotlights (mainly in kitchens and bathrooms). There are low-energy alternatives for both these types of light:

  • Compact fluorescents (CFLs) – these are what most people think of as an energy-efficient light bulb. A cost-effective option for most general lighting purposes, and now widely available.
  • LEDs – even more efficient, and the ideal replacement for halogen downlighters. More expensive than CFLs but save even more money in the long term.

Of course, the easiest way to save on your lighting bill is simply to turn off the light when you’re not using it. You will ALWAYS save energy if you turn the light out when you leave the room, even if it’s only for a minute or two.

We all need light to do the things we want to do, but sometimes we leave lights switched on when we don’t need to, or we use more lights than we need. The basic message is simple – turn it off if you don’t need it.


Most types of light bulb will last longer if you don’t switch them on and off repeatedly throughout the day. But you won’t save money by leaving any type of light on for a few minutes just to try and make it last longer. Just turn it off when you don’t need it and turn it back on again when you do. Simple.

Use the right light for the job in hand. If you’re watching television you probably only want low level background lighting, but if you’re reading a book you will want something bright but local.

Having a range of lights in a room, all with separate switches, will make it easier to achieve the lighting you want and need, whenever and wherever you want it. And you’ll save more energy than you would by using a single dimmer switch for the whole lot.

CTS Renewables are able to provide a full on site lighting survey, followed by design, installation and savings calculations for commercial customers. Domestic customers can access a telephone advice service

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