Lighting is something that most of us take for granted. How often do we question how much
it costs to run and maintain? Is the amount and quality of the light appropriate for your workspace?
Good lighting is essential for creating a healthy and effective working environment. Providing a bright and comfortably lit workplace can help improve mood and moral amongst staff. Lighting is also a significant energy cost, directly affecting an organisation’s bottom line.
It is estimated that lighting uses 20 per cent of the electricity generated in the UK. Energy savings can be achieved by improving equipment, maintenance processes and staff habits. Up to 75 per cent of lighting installations are thought to be below current design standards for efficiency. However, there are many simple and inexpensive ways to reduce the energy consumption and costs associated with lighting without compromising health, safety or comfort levels.
This guide sets out to explain the basics of LED lighting; the equipment, design principles, and how to go about installing and financing LEDs in your workplace.
What are LEDs?
A light emitting diode (LED) is an electronic device that can easily replace your existing lighting system. LEDs have been commonly used as a light source for over 40 years, most traditionally as the ’standby’ indicator on televisions. The range of LED lighting has developed rapidly over the past few decades, making them viable for commercial lighting.
What are the benefits?
The long lamp life and high efficiency of LEDs can significantly reduce maintenance (lamp changes) and running costs. LEDs typically have a life of up to 50,000 hours and currently use up to 80 per cent less electricity than an equivalent traditional tungsten lamp.
As LEDs are very compact, point sources of light they are good for directional or spotlighting applications, which is often important in retail environments. However, the range in LED technology now available means that they can be used for a variety of general lighting applications.
LEDs can be turned on instantly, without delay or flicker, and can be switched on and off frequently without reducing their life. This allows them to be controlled very easily which can further reduce running costs (read more in the Controls section).
Whatever the application, though, the use of LEDs should not compromise good lighting design principles and criteria.
The importance of light
The quality of artificial lighting is one of the most important influences on performance in the work place. Some 80 per cent of our sensory input at work comes through our eyes; compromising our vision is, therefore, not an option when considering energy efficiency measures. It is vital to provide good quality lighting that is designed to match the tasks being undertaken and to respect the needs of the occupants. And it is not only the visual effects of lighting that need to be born in mind; recent research has revealed that lighting has a clear impact on our health and wellbeing in the work place. The right levels and the quality of light have been shown to affect alertness and accuracy at work. The need to reduce carbon emissions presents an opportunity to make lighting more efficient and more effective; so long as the right decisions are made when selecting new lighting.
Daylight is the only freely available light source and yet all too often it is overlooked; well controlled daylight can provide a space with the best possible lighting effect, superb colour rendering, and great user comfort. Best of all there is zero cost or carbon dioxide emissions.
Traditionally, coloured lighting has been produced by using gels or filters applied to white light sources. These filters can reduce light output by as much as 80 per cent. LEDs are available in a range of saturated colours – red, blue and green being the most commonly used. As a result large improvements in efficacy can be achieved where coloured lighting is required. Some fixtures contain red, green and blue LEDs in order to allow colour changing. Such a fixture can also produce white light when all three colours are used.
What are the implementation options?
LEDs can readily replace most display and directional lighting, as well as down lighting. However, some consideration needs to be given to the existing fixture. Some LED replacements claim compatibility with existing control gear and fittings but a trial should always be carried out. Suppliers may offer their lamps with new control gear or may suggest changing the fixture from low voltage to mains operation based on the application.
It is important to check how your existing lighting is controlled. Many display lighting schemes are operated by dimmers and the change in the load from traditional incandescent to electronic LEDs may be incompatible. The marked reduction in the load (Watts) can also upset some dimmers.
Full lighting refurbishments are well worth considering if your existing lighting is more than 5 - 10 years old. In addition to energy savings, there may be other good reasons to choose new LED luminaires in some applications, for example in hard to access areas where it is difficult to change failed lamps.
Lighting renewal may be carried out as a direct one-to-one replacement or a complete re-design. In either case it is worth consulting a qualified, or experienced, person to check that the solution meets your needs. Renewal also offers an excellent opportunity to either introduce or to improve your lighting controls.
Lighting controls help to save time, money and energy with automated switch off. As an example, offices with meeting rooms, or where staff or cleaners work late may benefit from occupancy sensors. These help to ensure that lights only operate when necessary. Sensors can achieve savings of up to 30 per cent on lighting costs and are especially useful in areas with relatively low foot fall such as storerooms, toilets, and meeting rooms.
Light sensors or ‘photocells’ can be used to control artificial lighting when there is sufficient natural daylight. As daylight hours vary throughout the year, sensors help to provide closer control and thus substantial savings can be achieved. They can be particularly useful externally for lighting car parks or signage and can often pay back their costs in less than a year. Occupancy and light sensors can be combined with timer controls.
How to install LEDs
It is recommended that you consult a qualified electrician or engineer before replacing existing lighting with LEDs. Ask your supplier to create a proposal that details:
- the number of lights being replaced
- whether it is like-for-like or changes (for example more or fewer fittings, switching luminaires)
- power use of existing and new lighting, with an estimate of the saving, the cost and the payback versus current system
- expected performance in terms of light levels versus existing lighting
- whether any new controls are desirable or required
- commissioning or operational details
Involving staff affected by the new lighting, by seeking their opinions in the early stages of the lighting design process, is likely to lead to better working conditions and a smoother transition process.
The business case
Making the business case for low energy lighting is quite straightforward in terms of electricity saved compared to the investment required.
Calculating the potential savings is based on identifying:
- the current lighting load (watts or kilowatts)
- the hours of use per year
- the new LED lighting load (watts or kilowatts)
- the unit rate you pay for each kilowatt-hour (kWh) of electricity
- first multiply the existing lighting load (watts or kilowatts) by the hours of use. This will give you the annual electricity use, in kilowatt hours (kWh). If you have calculated the lighting load in watts (rather than kilowatts), remember to divide this figure by 1000
- multiply the annual use (kWh) by the cost of electricity (pence per kWh). Divide by 100 to give the annual cost in pounds
- do the same calculation (steps 1 and 2) for the new lighting
- subtract the new lighting cost from the old and this gives the annual savings in pounds
- this figure can then be compared to the investment and a payback calculated
Check list for implementing LED lighting
- understand the lighting needs of your organisation
- for a major scheme, consider a qualified lighting advisor/consultant
- keep any affected staff informed and involved
- present a well worked business case to senior management
- on approval, obtain quotations from a number of suppliers
- place the contract with the bidder you trust the most; the lowest bid may not be the best
- ensure the new lighting is properly commissioned
- make sure the new installation is properly maintained
The new LEDs lamps are flickering.
Check the control gear is compatible. If necessary change to dedicated LED drivers. Consider changing one or two lamps before changing them all.
The new lighting is not bright enough.
The supplier’s claims for ‘equivalence’ are wrong or the loss of spill light has changed the appearance. Always test lamps in situ to check performance.
The lighting control system no longer dims smoothly, or at all.
The LEDs are not compatible with the existing controls. A test before full installation should reveal this.
Questions to ask
Are the LEDs fully CE marked and is there a genuine Certificate of Conformity available?
How long has the supplier been in business? How many LED installations have they done?
What lighting qualifications or experience has the supplier got? Can the supplier provide references, and / or previous case studies?
When are LEDs not appropriate? Can we change one or two lamps before changing them all?