Over the past few years, legislation has placed increasing emphasis on reduction of energy use in commercial buildings. The Energy Performance of Buildings Directive and Part L of the Building Regulations (2006) require building designers and managers to make efforts to minimise energy use, and to measure how much energy is being used – and where.
Part L includes metering and sub-metering requirements for commercial buildings. These rules are designed to ensure that building operators know how much energy is being used, and how energy consumption differs across zones in the building. Information gathered from meters is also used for energy certification and benchmarking.
The Part L wording on metering is that: “Reasonable provision shall be made to enable building operators to effectively manage energy usage”. While metering can help track energy use over time, without added functionality from building controls, meters provide only part of the picture.
Building controls not only track energy use, they also help to automatically reduce energy consumption. By linking each meter so that its output can be used as an input to a corresponding control loop, the system can automatically optimise performance and reduce energy.
The next iteration of Part L is due out in 2010. One of its main proposals is that carbon reduction targets (closely linked to energy use) for new buildings should reflect the wide variety of uses to which buildings can be put. For example, mechanically cooled offices use energy very differently than hotels – hence the options for reducing energy use will be different for both. However, building controls can work to cut energy waste in any type of building, from a school to a high spec HQ office.
Even simple control systems can work alongside required energy meters to reduce out-of-hours equipment operation, or prevent heating and cooling systems running simultaneously. Advanced building management systems can also help match energy use exactly to occupant requirements. So for example, presence detection equipment can ensure that lights are only on when required; or an automatic room booking system can ensure a meeting room is set to the required temperature only when a meeting is booked to start.
Metering is needed to keep track of energy use and to identify areas of high energy consumption in a building. But metering on its own cannot achieve energy reductions. Monitoring and management are vital if information is to be used for controlling and minimising energy use in the long term.