Last edited 30 Sep 2020

Building energy management systems BEMS

Building Energy Management Systems (BEMS) are integrated, computerised systems for monitoring and controlling energy-related building services plant and equipment such as heating, ventilation and air conditioning (HVAC) systems, lighting, power systems and so on.

The phrase Building Energy Management Systems is sometimes used interchangeably with Building Management Systems (BMS), however, strictly speaking, Building Management Systems can be used to monitor and control a wide range of building systems, including fire, smoke detection and alarms, motion detectors, CCTV, security and access control, lifts and so on. Building Energy Management Systems relate specifically to energy-related systems.

Small buildings may have independent controls for energy systems, but for larger or more complex buildings, sites with a number of buildings, or organisations with buildings on a number of sites, the integration of systems operation through a single Building Energy Management System offers greater control and can achieve significant savings. NB Increasingly, simple BEMS are being developed that are suitable for even the smallest buildings.

BEMS provide real-time remote monitoring and integrated control of a wide range of connected systems, allowing modes of operation, energy use, environmental conditions and so on to be monitored and allowing hours of operation, set points and so on to be adjusted to optimise performance and comfort. BEMS can also trigger alarms, in some cases predicting problems and informing maintenance programmes. They allow records to be kept of historical performance, enable benchmarking of performance against other buildings or sites and may help automate report writing.

In 2014, BSRIA reported that the global BEMS market was worth $3.5 billion, or 3 billion Euros, and was growing globally at more than 10% per annum. This increasing interest has resulted from the rising cost of fuel, concerns over energy security, increasingly aggressive environmental targets and the reduced cost of sensors, analytics software and data storage.

Claims for the scale of savings that can be achieved by BEMS range from 10% to 25%. Operated properly, they should allow energy use to be optimised without compromising comfort or performance. However this requires a thorough understanding of how buildings are supposed to perform, and how different systems within them interact.

To function correctly they must be properly designed, installed and commissioned and must have a user interface that is easy to operate. They should then be continually assessed and fine-tuned as performance is better understood over a number of seasons and modes of operation, and changes are made to buildings or operations. Maintenance is also necessary to ensure systems continue to operate correctly, for example, replacing sensors and batteries, checking connections, checking the operation of dampers and valves, upgrading software and so on.

BEMS can be independent installations with separate maintenance contracts, or manufacturer installations which include maintenance. They can be wired or wireless systems. To determine whether a wired or wireless system is the most appropriate, buildings should be audited to test how well signals can be received and how likely disturbances are. Choosing the correct BEMS system then depends on the size and usage of the building, the scale of the project and the budget. As a general rule, larger, more extensive projects tend to be best suited to wireless solutions.

BEMS may have remote outstations that can be interrogated locally, or may be accessible from mobile devices. However, major buildings may be vulnerable to cyber attack, especially when they are associated with prominent organisations. This can be a particular issue where functions operate in the 'cloud', such as cloud-based analytics, and the ability to access and manage multiple buildings remotely. The ability to access live analytics, or receive alarm notifications from hand-held devices has great potential benefits, but may also bring additional risks.

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