MONITORING & METERING
WHERE’S ALL THE ENERGY GOING?
O
ver the last year, every business in the UK has seen a dramatic increase in its energy bills. In many cases, these have more than doubled, with a typical small business, at the time of writing, paying at least £0.40 per kWh for electricity. Small wonder that business owners and managers are scouring their premises for equipment that they can unplug or switch off in order to make savings. There’s no doubt that this is a useful exercise, and that it can deliver valuable cost savings but, to obtain the best results, it needs to be carried out carefully and with a little thought. An essential point to bear in mind is that there are large differences in the amount of energy consumed by the various appliances and gadgets that are found in business premises. A fan heater or electric radiator, for example, might well consume 300 times as much energy as a desk light, so remembering to turn off your desk light before going home, while laudable in itself, is unlikely to produce savings anywhere near those that could be achieved by turning off the heater in a meeting room promptly when the meeting has finished. The table below provides an idea of how much energy is used by items found in many offices and business premises. Note that the figures in the table are intended as a guide only and there are large variations between brands and models of equipment. A few explanations are necessary. Looking at the table, the friend of all
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employees – the electric kettle, seems to be one of the greediest appliances for energy usage. So it is, but only for the time it’s in use, which is probably just a few minutes out of every hour in even the thirstiest of offices. On the other hand, an electric radiator, which is just as greedy as the kettle, may well be in use continuously for hours on end. In other words, when assessing where energy can be saved, it’s necessary not only to look at the rating of the
ENERGY MANAGER MAGAZINE • APRIL 2023
item, but also when and for how long it is used, and to bear in mind that some appliances like storage-type water heaters are constantly switching themselves on and off when they are not in use. This means that they only consume energy intermittently. An interesting point that can be seen from the table is how much more efficient LED lighting is than other types. Until recently, fluorescent tubes were widely used and were considered to be one of the more efficient types of lighting, but now a 6-foot tube consuming 70 W can be replaced by a plug-in LED equivalent which consumes only around 25 W, reducing running costs from £0.28 per ten hours to £0.10 per ten hours. That may not sound like a big saving but for a business that has dozens or even hundreds of fluorescent tubes in use for eight or more hours per day, the figures quickly mount up, so the moral is clear: bin those oldfashioned fluorescents. (Actually, don’t literally bin them – they contain mercury so must be disposed of properly.) While the table provides some guidance on which appliances use the