Given that lighting in ambient warehouses typically accounts for 65% of the total energy consumed it makes sense to review one’s lighting regime if it has remained unchanged for many years, not just from the financial perspective but also legislative pressures that require the Government to cut total carbon by 34% between 1990 and 2020 and 80% by 2050. There are also health and safety considerations. The incentives and technical developments in lighting over recent years also emphasises the need for a fresh look at lighting issues.
There is a wide choice of warehouse lighting technologies from the most costly to run (metal halide) to the T5 fluorescent type, and more recently the fast-growing LED lamps. But before choosing new lights it might pay to look at natural lighting that affects light usage. Is there, for example, scope for making better use of natural daylight through more transparent roof panels? If using such panels already are they kept clean often and regularly? On the loading bay why not consider having almost 100% clear PVC for fast-acting roller doors to let in as much natural light as possible?
A good starting point, however, is to conduct a site survey and for this there is help from the Carbon Trust. Many warehouses will have discrete areas that are lit but not always occupied but is there any zone-based switching? Are light switches badly labelled so staff cannot tell which lights are controlled by which switches? If so, they should be clearly labelled so supervisory staff or teams can turn off the lights when an area is unoccupied for lengthy periods.
It is, of course, important to meet H&S lighting levels and to ensure this one should consider a lux meter. Good practice states that lighting levels should be 150 lux in loading bays, the same in racking areas, and 300 in packing and despatch. If lighting uses automatic light sensitive controls then they should be checked to ensure that they are calibrated correctly and that lights do not remain switched on when daylight is adequate.
Lighting quality is important for H&S reasons. A 60-year old forklift driver needs six times the light level of a 20-year old to discern his surroundings clearly. The Health and Safety Executive reports show that substandard lighting is regularly cited as a contributory factor in workplace accidents and hefty fines have been imposed.
Site surveys will show that warehouses with lighting that has not been replaced for at least 10 years will likely have 250W or 400W SON or Metal Halide lighting. Surveys will also show that there will be areas unoccupied for long periods when the lights could be turned off. The long re-strike times of these fittings, however, mean that people are unwilling to turn lights off because of the length of time it takes to get them back to full light output when turned on. These fittings, therefore, should be replaced with high bay, fluorescent T5 luminaires in either four or six-lamp configurations to give better light output, less energy consumption and amenability to automatic controls such as PIR motion detectors, without any re-strike concerns. However, the latest light technology making serious waves in warehouses is undoubtedly LEDs, despite their higher initial cost. Owing to their multiple benefits, including much longer life, typically 10 years, and far less maintenance costs, payback can be as little as one year, and experience shows that the longer the operational hours then the greater the payback.
Justifying the CAPEX issues for new lighting can be eased by the incentives available from the Carbon Trust for SMEs. These include 0% loans of up to £100,000 over a 1-4 year repayment period. Then there is the enhanced Capital Allowance scheme which provides 100% first-year capital allowances. Beyond that, installation companies offer various leasing packages in which the repayments are often offset by one’s monthly energy savings, effectively self financing.