Measure and manage your energy

CIBSEThe pressure on government offices to reduce their energy consumption, bills and carbon emissions is increasing, with the coalition government committed to reduce energy consumption in central government departments by ten per cent over the next twelve months.

Measure and manage
The key to reducing energy use is to measure it, and manage it. You cannot manage what you don’t measure, so the first task is to find out how much energy you use from meter readings. Larger government buildings may have half hourly metered data, but every building has meters. It may require perseverance to track down the data from past bills or, better still, regular readings. If you don’t have automated reading and the bills are estimated, then start a programme of weekly readings, or, if possible, every Monday and Friday, so you know what’s used at the weekend.

Once you know how much is being used, you can check for obvious clues to waste. If weekend use is 25 per cent of the electricity used during the week, it suggests either a lot of out of hours working, or a lot of out of hours waste. Things are being left on over the weekends, and probably overnight.

Turn it off
So its time to tackle the first task of energy reduction: reduce demand by switching off unnecessary equipment, systems and processes. In some cases that alone could achieve a ten per cent saving.
Its amazing how many cleaning contractors believe that the best way to clean is to walk through the building turning lights on at the start, and then repeat the process, turning lights off, at the end. Over a two to four hour shift that can be a lot of lights in winter.

How many monitors, copiers, and other machines are left running overnight? And how much of the building’s plant comes on too early, goes off too late, and runs at weekends. All these can be detected by a bit of observation and analysis of meter readings. Once the low hanging fruit is collected, then what?

Voltage Optimisers
One way to reduce electricity bills is to install voltage optimisers. These maintain a constant voltage in the building, avoiding the regular variations in grid supply voltage and maintaining the operational voltage at a constant and efficient value. The equipment is a transformer-like unit installed in-line or in parallel with the building’s electricity supply, normally in or near the intake room. There are several options, which include:
•    Parallel vs. in-line systems: parallel installations (as opposed to in-line) are cheaper and do not require shut-down to install but are much less effective and can normally be discounted.
•    Simple step-down vs. full optimisation: simple step-down equipment (a tapped transformer) is cheaper but is not effective if the mains voltage varies over time as it often does. So generally full voltage optimisation which maintains a constant supply voltage to the building is justified.

Further features concern improved security of supply such as overload protection and by-pass facility, and energy metering and monitoring additions.

There have been a number of high profile voltage optimisation installations. In one well known public building savings of six per cent of annual electricity costs were identified, with a three and a half year simple payback period. Greater annual savings are often claimed in proposals from suppliers, but these may be optimistic. This can be due to before-and-after comparisons of weeks from different seasons or when spanning periods which coincide with other energy management initiatives. However, for managers facing a call to cut electricity use by ten per cent, the options above taken together are likely to get them there with some room to spare.

The Carbon Reduction Commitment Energy Efficiency Scheme, known as CRC, started officially in April 2010 and is expected to have a wide reaching impact on all large scale energy users, as well as consultants and other service provides. CRC is a mandatory emissions trading scheme that aims to deliver energy and carbon reductions in large, non-energy intensive organisations. Central and local government is a prime target, with organisations with total electricity consumption greater than 6,000MWh affected. The scheme is intended to raise awareness in large organisations, especially at senior level, and encourage changes in behaviour and infrastructure.

CRC provides a financial incentive to reduce energy use by putting a price on carbon emissions. It also provides the opportunity for participants to save on energy bills through improved energy efficiency. Organisations buy allowances equal to their annual emissions, and there is a league table of all participants. Top performers will receive their payments back, with some additional money, whilst those at the bottom will only get some of their money back. It is up to individual organisations to determine the most cost-effective way to reduce their emissions, which could be through buying extra allowances or by investing in ways to decrease the number of allowances they need to buy.

Together with the financial and reputational considerations, the scheme encourages organisations to develop energy management strategies that promote a better understanding of energy usage. Further information can found on the website of the Department of Energy and Climate Change.