﻿Meter and monitor energy — but don’t forget to manage it
Installation of sub-meters in non-domestic buildings is required under Part L of the Building Regulations and cover electricity, gas, LPG and oil. They also specify that energy consumption is broken down by end use — lighting, heating, ventilation, pumps. The aim of making metering compulsory is to encourage reduction of energy use in non-domestic buildings by 5 to 10%.
There can be no doubt that the legislation has been successful in driving greater use of metering in buildings. Building managers need to be aware of how much energy is being consumed, and knowing where the energy is consumed adds an extra dimension to this information.
However, the key question, as with most business information, is what are building managers doing with it? Doug Robins, president of the Building Controls Industry Association says: ‘Metering and tracking energy use is a good start to a programme of reducing energy waste, but unless you can control how much energy is consumed there is not much you can do with the information.’ He believes a building-management system (BMS) is crucial to ensure energy savings can be made.
Harry Swinbourne, sales director for Honeywell Automation & Control Solutions agrees: ‘You need to meter, monitor and manage. In many buildings these steps are not linked. If you are only metering energy, you will know how much you are using — but what are you going to do with that data?’
One of the challenges for manufacturers and installers of building-management system is that while metering is specified in some detail in Part L, the installation of a BMS is recommended, but not required, by law. This is not the ideal situation, says David Kitching, business-development manager for Siemens Building Technology: ‘Users should be able to see the effect of changes in building operation on their energy use. For example, they should be able to see the effect of moving to low-energy lighting on their metered energy consumption. In this way, they can see the benefits of investments in technology, or of changing the behaviour of occupants.’
Harry Swinbourne agrees, but does not see metering and control in competition: ‘Metering, monitoring and management of energy provides an excellent opportunity for the key elements of metering and control technology to demonstrate that the savings created by using them together are even greater than when they are used separately.’
Owners and managers of commercial buildings are under increasing pressure to reduce energy use, year on year. The Carbon Reduction Commitment (CRC), a carbon-trading programme for organisations not covered by the European Carbon Trading Scheme, begins its first phase in 2010. Participants will have to measure their energy use and demonstrate annual reductions for the whole 3-year period of the CRC. Building controls will be vital to achieve this goal.
‘At the moment, you are only measuring energy used,’ says Harry Swinbourne. ‘It is true that the more you meter, the more you know. But if there is a meter installed it should link to a building-management system. There must be a control loop which can take action as a result of information input from that meter.’
All the experts agree that there are many advantages to specifying a building-management system early in the design process for a new building. ‘Today’s building-management systems can help to reduce energy waste in a variety of ways, while also providing exactly the right kind of useful data that building managers need. However, these features must be specified at the start of the process, not at the last minute,’ says David Kitching.
BMSs also offer cost-effective solutions for reducing energy use in older buildings, which is important since existing buildings represent 90% of our building stock. For existing buildings, maintenance and commissioning are the first steps towards their effective operation.
Doug Robins says: ‘It is important to ensure that people carrying out maintenance on the BMS are controls experts, or problems can be easily overlooked. For example, sensors can be broken or controls switched permanently to manual override.’
The three steps of metering, monitoring and managing energy are important steps in the drive for carbon emission reduction. The controls and metering industries can demonstrate leadership by promoting their energy-saving capabilities ahead of legislation.
Doug Robins says: ‘Around 70% of building-services equipment in existing buildings is controlled by a BMS, so there are enormous opportunities to save energy simply by making sure the BMS is working correctly — a cost-effective solution which can produce quick-wins for any business.’