Thursday, April 11, 2024

Where’s all the energy going?

Over 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 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 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 old-fashioned 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 most energy and are, therefore, the most useful to target in an energy-saving campaign, it has to be admitted that it is only the most approximate of guides. A more accurate assessment can be made by inspecting the rating plates fixed to appliances, which should state the rating in watts, or, if all else fails, consulting the appliance handbook or data sheet. These can usually be found online if the physical copy has been mislaid.

A useful benefit of looking at the handbook or data sheet is that it will (usually!) give details, where appropriate, of the power the device uses when in standby mode. Despite febrile warnings in the press about ‘vampire devices’ that suck energy day and night for no useful purpose, modern devices usually have very low standby requirements so switching them off or unplugging every day may actually be more trouble than the savings that result are worth. This is especially true in the case of some printers that use expensive ink to flush the printheads every time they are switched off and on. Nevertheless, it is always worth checking!

Even with the manufacturers’ data to hand, it can be difficult to decide the true running costs for some types of appliances, such as fridges where the motor runs only intermittently. To provide a truly definitive answer to the question of where all your energy is going the best solution is, therefore, to measure it. This is not as difficult or expensive as it may seem if an instrument like the new Chauvin Arnoux compact PEL51 power and energy logger is used.

This can be quickly installed in a distribution panel, often without needing to turn off the supply, and will monitor energy usage – along with many other power parameters – continuously and log the results. By inspecting the results, it is possible to see exactly where energy is being used and, just as important, when it is being used. Almost unbelievably, a recent survey by British Gas revealed that no less than 46% of energy used by the 6,000 SMEs monitored was used outside of business hours, so this really is a situation where knowing exactly what’s happening can save a lot of money.

Armed with the information provided by a PEL, it is easy to see where the biggest and most effective energy savings can be made, but that’s not the end of the story. When energy saving measures have been put in place, repeating the measurements with the PEL will confirm their effectiveness and, of course, when any changes are made to the electrical installation, the PEL will allow the effect of these changes on energy usage to be accurately assessed.

Given the current high price of energy, and that this price shows absolutely no sign of falling anytime soon, it literally pays to know where all the energy is being used in your business. As we’ve seen, a basic knowledge of which appliances use the most energy, guided perhaps by our table, is a great starting point, while checking rating plates and handbooks will provide an even better guide. The best solution, as always, is to measure what you want to control, and the easiest way of doing this is to get your hands on a Chauvin Arnoux PEL. Contact us for more details – you’ll be surprised how much you can save!

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