Lighting maintenance for efficiency and safety
LEE BENSLEY explores the issues surrounding the maintenance of lighting systems, including emergency lighting.There is not much worse in any working or retail environment than a gloomy and depressing atmosphere created by large numbers of lights not working. It has a negative effect on staff morale and productivity and creates a feeling of neglect and poor maintenance. In a retail environment, it also means that the goods are not being shown at their best and does little for the image of the store. This assertion is well accepted but clearly any re-lamping has to be carried out in the most cost-effective way. In a small building it may be economical to replace each lamp as it fails, provided, of course, that health-and-safety guidelines are adhered to. However, in larger premises tying up maintenance staff by making them roam the building with a box of lamps hardly makes the best use of their time.
Cost-effective In larger buildings, a group lamp replacement strategy is generally the most cost-effective approach. This identifies the optimum time to replace all the lamps at one time — calculated on the basis of making the most efficient use of the lamps. Such group replacement will often be carried out at convenient times to minimise disruption to staff and customers. It can often be timed to coincide with cleaning light fittings. The frequency of lamp replacement will vary with the type of lighting and how the lamps behave with age. Most discharge lamps (for example fluorescent, metal-halide and high-pressure sodium) give out less light as they get older, while consuming the same amount of electricity. To maintain appropriate lighting levels, these lamps will have to be replaced before they actually ‘go out’. Some lamps also change colour with age, so timely replacement will avoid a patchwork of different-coloured lamps on the ceiling.
Maintained illuminance Ensuring that the designed lighting levels are maintained, referred to as ‘maintained illuminance’, is a very important factor in providing effective lighting in the workplace. It also affects energy consumption, increasingly important since the implementation of the Climate Change Levy. The ‘CIBSE code for interior lighting’ requires that maintained or ‘end-of-life’ illuminance levels are maintained at all times. It is thus clearly evident that using lamps with lower levels of lumen depreciation will ensure more economic maintenance regimes to users. Cost-saving opportunities can be presented by installers who embrace the principles of planned lighting maintenance, given that maintained illuminance is no longer just a desirable but an essential factor for a user who wants to avoid the costly ramifications associated with the violation of strict Health & Safety legislation. A lighting design that incorporates a maintained illuminance approach is based on the period of the lamp’s life when it is making the most efficient use of the electricity it consumes. This very often means that fewer light fittings can be used to achieve the required illuminance — so capital costs are reduced and each lamp achieves the maximum energy efficiency. This approach, however, depends on lamps being replaced just as they reach the end of their efficient phase and before they start to waste energy. That time is usually when the light output has fallen below the ‘service life’ of 80% of the initial value, from a combination of lumen depreciation and electrical failures. If group lamp replacement is used from the time the light fittings are installed, the age of each lamp is known, and it is easy to ensure that subsequent group replacements maintain the efficiency of the system. Numerous studies have shown that this is the most cost-effective approach for the building operator, and professional lighting designers now recommend this strategy for most buildings, whether it is an office, factory or store.
Whole-life costing Customers today are becoming more interested in the concept of whole-life costing. These solutions include design capability, refit capacity, best-practice planned lighting maintenance and recycling capability, which becomes increasingly relevant as the market expects the imminent implementation of the Waste Electrical & Electronic Equipment Directive (WEEE). All of this, coupled with additional energy-saving expertise, guarantees customers optimum illuminance in the most cost-effective manner.
Emergency lighting Of all the health-and-safety criteria that apply to a building, emergency lighting is one of the most important. Building operators who do not ensure their emergency lighting is up to scratch can face stiff penalties under fire-safety legislation. Emergency lighting plays two critical roles; it helps identify emergency exits when the building has to be evacuated and it helps people get to those exits safely if the general lighting has gone out. Emergency lighting is not needed most of the time, making it essential that it is regularly tested and properly maintained. This principle is now embodied in law. The first stage in arriving at a reliable and effective emergency-lighting system is to ensure that the fittings are designed and manufactured to a high standard. To help building operators choose the best fittings, the Industry Committee for Emergency Lighting (ICEL) has devised a scheme that provides independent testing of every aspect of emergency luminaires. Only if the luminaire complies with all of the criteria, can it carry the ICEL mark.
Testing Once ICEL-approved luminaires have been installed, they need to be tested regularly — and there are a number of aspects to the testing. The tests must fully duplicate the emergency operation, they must record any faults and they must minimise the risk of the building being inadequately protected while the batteries are being recharged. The first test is of a short duration to ensure that the circuits are healthy and the lamp operates. For manual systems this check should be made at least monthly; with automatic systems the frequency should be at least weekly. Short-duration tests need to be backed by full-rated discharge tests once a year, as this checks battery capacity. After this test, of course, batteries must be recharged, which makes the timing critical. It is relatively easy to organise for batteries to be recharged in buildings that are unoccupied for periods of 24 hours. In buildings that are permanently occupied, such as call centres, nursing homes and hotels, there are two possible approaches. For self-contained luminaires, alternate luminaires can be tested and recharged so the building always has at least 50% cover. For central-battery systems there are a couple of possible solutions. Two separate battery systems supplying alternate luminaires can be used, but this is expensive and probably only appropriate for ultra-high risk premises. It is also possible to use sophisticated monitoring of battery voltage and current, which enables the test to be conducted for two-thirds of battery capacity, so there is a safety margin if evacuation is required. Vital to all these tests is accurate recording of test results, reporting of any faults found and evidence that such faults have been rectified. In many cases, regular testing of the emergency-lighting system can give early warning of problems and allow maintenance and remedial work to be planned for the most appropriate times.
Lamp disposal Once the lamps have been replaced, the old ones have to be disposed of, and environmental legislation is becoming increasingly strict on how this is done. WEEE is now being implemented throughout Europe and will bring even more stringent requirements. There are two elements to the aims of WEEE in regard to lamp disposal. One is to ensure that dangerous substances such as mercury, which is found in virtually all discharge lamps, is disposed of responsibly. The second is to encourage the recycling of the components used to make lamps. WEEE will require building operators to ensure that their lamps are disposed of in accordance with these aims, which will usually require the services of a specialist contractor. Where such services are outsourced, the contractor carrying out the group lamp replacement will have an arrangement with a lamp-disposal company — but there will still be an onus on the building operator to check that such a disposal company is fully qualified and accredited. To that end, the Lighting Industry Federation is working closely with Government and the waste-management industry to ratify the most efficient and compliant collection system to ensure the user has peace of mind when it comes to lamp disposal.
Lee Bensley is national sales manager, specification lamps with Philips Lighting, Philips Centre, Guildford Business Park, Guildford GU2 8XH.
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