Tracking energy use

The pressure to cut energy waste is particularly strong in the public sector. Expected to lead by example, public sector buildings have been targeted with Display Energy Certificates to publicly track the success (or otherwise) of energy reduction programmes. More recently, the Carbon Reduction Commitment (CRC) began its first phase. Again, the public sector will be expected to lead the way in this scheme, which is a cap-and-trade mechanism targeting organisations based on their energy use.
One problem for the public sector is that it has been very successful in reducing its energy waste, so finding further cost-effective reductions is something of a challenge. However, within most buildings there is existing technology which can be used as the platform for a low-cost energy efficiency drive: building controls or a building management system (BMS).

Monitoring energy
Approximately 70 per cent of building services equipment in existing buildings is controlled by a BMS. Controls influence every aspect of a building’s operation: heating and hot water, ventilation, cooling and air conditioning, lighting, windows and shading.
Controls can therefore monitor and control every watt of energy used by the building at all times, so there are enormous opportunities to save energy simply by ensuring that the BMS is working correctly. This provides a cost-effective solution which can produce quick-wins for any organisation.
The best place to start with a controls-based energy saving programme is probably with an energy audit. This will provide a clear picture of how your building is performing in terms of energy at the current time. It also means that energy and cost savings can be tracked. This is also a good opportunity to check the BMS itself to ensure that you are aware of problems such as number of alarms or maintenance call-outs so that improvements in these areas can also be monitored.

Conduct a review

A review of your current building controls and your control strategy is vital. Maintenance and commissioning, or re-commissioning, are the first steps to effective operation of controls. Simple steps can achieve immediate savings.

For example, a walk-around check can identify where sensors may be broken or controls switched permanently to manual override. Another common problem can be that office moves have changed the internal environment, for example a photocopier placed under a sensor can result in cooling operating when it is not required.
It is also advisable to ensure that meters are connected to the building management system. This can be overlooked, leading to energy use data not being logged or stored. Data collection is increasingly important for building managers, but it should not be collected for its own sake. It is possible to be so swamped by feedback from meters, that it is difficult to tell what actions need to be take. An adequate storage system is important so that the system can be managed.
Building or facilities managers should also examine the controls strategy. Are your set temperature points too high or too low? This is a widely acknowledged cause of high energy bills. A few degrees can make a big impact on energy use. Also, if occupants are uncomfortable they can unintentionally sabotage energy-saving programmes by using under-desk heaters if they are cold, or desk fans to keep cool. Occupant comfort is therefore an important element of energy efficiency.

The use of controls is not only an option for new buildings. Controls are relatively easy to retrofit, and offer a scalable solution for most businesses. With wireless technologies, retrofitting has become much simpler and older buildings can benefit enormously from better controls. This is also a scalable technology, offering a wide range of options according to client needs.
Metering is a growing area for buildings where Part L of the Building Regulations and Energy Performance of Buildings Directive require their installation. 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.
While metering can track energy use over time, without added functionality from building controls, meters provide only part of the picture. 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. Even simple control systems can work alongside required energy meters to reduce out-of-doors equipment operation, or prevent heating and cooling systems running simultaneously. Advanced BMS can also help match energy use exactly to occupant requirements. So for example, presence detection can ensure that lights are only on when required; or an automatic room booking system can set a meeting room to the required temperature only when a meeting is booked to start.
Metering is needed to keep track of energy use, and 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 in the long term.

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