The power of one
Ian Ellis of Siemens UK explains why assembling your building controls as a single system can lead to a more usable, powerful tool for measuring, monitoring and controlling your building and its energy use.
Building controls come in many shapes and sizes these days. They may be part of the building-services equipment, such as inverter drives or pressure-independent control valves. Equally you will find that the latest air-conditioning kit or boiler will be delivered with its own built-in controls. Some of these controls can be sophisticated enough to offer online access so that you can control temperatures and measure performance via the web.
As controls are now delivered into a building from many sources, it is important to make sure that they work as a single system. That is why it is important to work with controls professionals, who can ensure that they operate as a single building energy management system (BEMS).
However, even with the best advice, it can still be a challenge to achieve this holistic goal. The issue of controls software languages, or protocols, is often cited as a barrier to good BEMS practice. This is much less of a problem now than it was 30 years ago. The use of open systems such as BACnet or KNX has created much more flexible platforms that allow for the integration of most building-services equipment into the BEMS.
Also, the contracting approach of the construction industry can have an impact on integration. For example, while controls and BEMS may be specified in the mechanical contract, lighting is more likely to fall under the electrical contract. It takes some effort, usually on the part of the client, to draw the electrical and mechanical elements together and insist that the control system for a building is viewed as a single whole. But without this approach, the benefits of the building controls can never be fully realised.
A lack of holistic thinking may lead to other problems. For example, it is not uncommon to find that building-integrated renewables (such as solar PV or biomass boilers) are not integrated into a BEMS because the equipment was installed by an independent team. This can mean that the benefits of renewables are lost because the controls system cannot ‘see’ the renewables and use them when it is most effective or appropriate.
One of the benefits of ensuring that the BEMS encompasses all elements of building services is that strategies such as demand-based control can be applied.
Demand-driven use of building services is a simple, but effective, way to ensure that energy is not used unless it is required. If a space is unoccupied, then heating, ventilating and lighting are not required. As a corollary of this, boilers, fans and lamps are used less — reducing maintenance and replacement costs.
Although this seems like an obvious approach, it is surprising how often lighting control operates on a system that is completely separate from the rest of the BEMS. Planning ahead and aiming for a single-system approach, will create greater opportunities for energy savings – as well as giving occupants more control over the space.
The other enormous benefit of ensuring that the BEMS is an inclusive system is that data gathering is more comprehensive and accurate. By ensuring that the entire building is under the BEMS umbrella, the building managers will be able to track alarms, respond to unexpected patterns of energy use, plan maintenance and ensure occupants are comfortable.
The era of building information modelling (BIM) seems to promise a more holistic approach to the construction process. It is to be hoped that a single-model view of a building will give contractors and consultants a better understanding of how the ‘system’ can be brought together.
As building-controls technology advances at a fast pace, the ability to create a single-system approach is now open even to owners of smaller buildings. The BEMS is no longer the preserve of multi-building sites or large headquarters, because technology is available that will allow small offices or schools to take the demand-driven approach to reducing energy use.
Seamless communication between various disciplines such as heating, cooling, lighting and blinds is the best way to ensure a high-performance and energy-efficient building. With this sort of approach, properly executed, energy savings of up to 30% are not unrealistic.
Ian Ellis is marketing manager for Siemens Building Technologies in the UK.