Reducing the Energy Consumption of Light
Making Lighting Installation More Energy Efficient
CFLs use up to 80% less energy for the same light output as a conventional incandescent lamp. Over a 15–year period this will save one megawatt hour (1MWh) of electricity and half a tonne of CO² emissions.
Lighting accounts for 20% of all electrical energy usage. It is therefore not surprising that in the drive to reduce energy consumption, lighting has attracted a lot of attention.
The need to reduce energy consumption has affected both domestic and commercial buildings, with the lighting industry bringing out more efficient lamps, better fittings to focus the light where it is most needed, more efficient control gear and control systems to better manage its switching and/or dimming.
Lamps
Starting with lamps, there has been a huge increase in demand for energy efficient Compact Fluorescent Lamps (CFL) to replace the inefficient incandescent lamp. Not only is demand from the public bringing the price of these down, but also the technology and aesthetics are improving.
Indeed to meet Part L(1) of the Building Regulations all new house builds must install a low energy pendant set. Only four–pin compact fluorescent 10/13W lamps can be used with these pendants, which are typically installed where lighting is left on for long periods, such as in the hall or landing.
These lampholders contain high frequency electronic control gear for operating the four–pin compact fluorescents ensuring quick flicker–free starting.
Whether installed in the home or in a commercial build, CFLs use up to 80% less energy for the same light output as a conventional incandescent lamp. Over a 15–year period this will save one megawatt hour (1MWh) of electricity and half a tonne of CO² emissions.
And CFLs are only the beginning of the lighting revolution. While they will not dominate the interior lighting market for some years, low–energy LEDs are already proving their usefulness for exterior and decorative lighting.
…LEDs have much to offer. Their potential lifespan is 5 times that of a fluorescent lamp and up 100 times that of an incandescent bulb.
Unfortunately they are not suitable for lighting up a room, as they have a very small light source. It is possible to make LED lights that are comparable in brightness to a 25–watt bulb, but they are very expensive to manufacture, and need a power controller. Manufacturers such as Philips and Osram believe it will take another five years before they are suitable for lighting a room and probably a decade before they become commercially viable for such an application.
For those seeking energy efficiency however, LEDs have much to offer. Their potential lifespan is five times that of a fluorescent lamp and up 100 times that of an incandescent bulb. They are also more efficient than both, so watch this space.
Energy efficient halogen lamps offer another light source. These will often retrofit into existing lamp holders and offer energy savings of up to 65% compared to incandescents and 30% over existing halogen lamps. They produce a dimmable bright white light, which many people prefer to the light output from CFLs.
Commercial Opportunities
While much can be done in the home to save energy from lighting, even more opportunities are available in the commercial environment. Here lighting can account for a staggering 50% or more of all energy consumption. Better lamp selection, better fittings, more efficient control gear and lighting control solutions can make a real impact.
Again legislation proves to be a major driving force. Part L(2) of the Building Regulations for nondomestic premises in England and Wales plus the new Scottish Building Standards, both demand action to reduce the wattage output for lighting per square metre of building.
Also many large corporates are taking their energy consumption very seriously. For instance, both Tesco and Marks & Spencer have pledged to reduce their carbon footprint or even eliminate it entirely. For the contractor there are real opportunities in understanding energy efficient lighting installations for commercial build.
Changing from conventional switch start control gear to high frequency can save a further 20% in energy or even more, if it is combined with lighting control.
Fluorescents dominate most commercial premises, certainly for general ambient lighting. They produce up to 70% of artificial light throughout the world and are used because they combine high luminous output with low power consumption.
Simply replacing 12 and T8 halophosphor tubes with triphosphor fluorescents could save up to 30% energy consumption. They also have a longer life, higher lumen maintenance over time and better colour rendering.
Well–designed light fittings will boost this efficiency further. By focussing the light where it is needed, less fittings and, therefore, less lamps are needed to achieve the same desktop illuminance. When the lighting system is being designed, the use of ceilings, walls and floors to reflect light can further reduce the number of luminaires needed, thus cutting down both energy and installation costs.
But this is only the start of what is possible. Changing from conventional switch start control gear to high frequency can save a further 20% in energy or even more, if it is combined with lighting control.
It also has benefits for the end user, with a flickerfree start, automatic shutdown of failed lamps, flicker–free lighting and silent operation. High frequency control gear also needs less Maintenance since it is all in one unit compared to the separate starter, ballast and capacitor used for switch start circuits.
Lighting Control
So there is much that you can do to improve lighting efficiency just by changing lamps, control gear and the fittings; but for really big savings consider lighting control.
After all, how many times are the lights left on when there is nobody left in the office?
The most obvious form of lighting control is the light switch or a manual dimmer. To be relevant, and indeed to meet the Building Regulations, this needs to be close to the lights that it controls and not stuck at the other end of a long open plan office.
An alternative, which many argue is better, is to switch the lights automatically in response to presence detection. PIR occupancy sensors can be hard wired into either the luminaires or the marshalling box that provides power for a group of luminaires. Solutions exist for both switch start and high frequency fittings.
Maximum savings are realised by using daylight linking to dim the lights up and down in response to the natural light levels.
Some people might groan at such a solution. They associate it with having to wave madly at the sensor every twenty minutes or so to turn the lights back on. Like anything the technology has moved on, so PIR sensors are now sensitive to even the smallest of movements. They also have a far greater range and a good design will ensure that neighbouring sensors overlap so that there are no “dead” areas.
Even greater savings can be realised when such occupancy sensing is combined with daylight linking. Systems exist for both switch start and high frequency lighting. With switch start systems, the lights are simply turned on or off in response to occupancy and natural light levels. These systems have a delayed off to avoid constant switching in response to the sun going behind a cloud.
Maximum savings are realised by using daylight linking to dim the lights up and down in response to the natural light levels. This needs a digital lighting control solution and high frequency lighting for fluorescents.
Such systems also maximise lamp life, since typically they do not turn off in response to bright light, but dim down to say 10%. They can also have a delayed off setting, so for instance if no occupancy is detected for 20 minutes they dim down to a set level, 15% for example, and then after a further hour they turn off.
So there is much that can be done to make a lighting installation more energy efficient. If you are worried about the extra cost of installing high frequency control gear or lighting control, then take a look at what funding is available.
The Enhanced Capital Allowance scheme (ECA) allows businesses to claim 100% of their capital tax allowances on selected energy efficiency products in the first year. In addition the Action Energy Programme provides interest free loans of up to £100,000 for small and medium sized businesses.
So in conclusion it is time to take a closer look at energy efficient lighting and control. The demand is there and it means more profitable business for installers. If they don’t meet the need then, a competitor down the road will.
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