Building controls - saving energy and carbon

The Building Controls Industry Association believe that controls offer a highly cost-effective solution to the challenges of reducing energy and carbon emissions. By Ian Ellis, BCIA President.

Energy efficiency has been called the fifth fuel, and this certainly highlights the growing importance of cutting energy waste in our buildings.  In November 2010, the EU Parliament passed a resolution stating that: “Energy efficiency should be a key priority of Europe’s energy strategy for 2011 to 2020.”

There are a number of reasons why the BCIA believes that building controls can offer a highly effective solution to the challenge of cutting energy waste in buildings. Controls have an impact on building energy performance in many ways. They provide effective automation and control of heating, ventilating, cooling, hot water and lighting systems that lead to increased operational energy efficiencies.

Also, building controls and building management systems can be used to configure energy saving functions and routines, based on the actual use of a building, depending on real user needs. This can help to reduce unnecessary use and CO₂ emissions.

Steve Harrison, Vice President of the BCIA, agrees: “The most economically viable and readily available opportunities for reducing CO₂ emissions are related to building energy use.”

The growing range of building management systems puts sophisticated controls strategies within the reach of more end-users and their buildings. “Control systems are now available that can control heating, ventilation and air conditioning (hvac) plant in a holistic way,” says Harrison.

“For example, pre-programmed controls are now on the market that can ensure hvac equipment will operate according to industry best-practice from bodies such as BSRIA and ASHRAE.”  As well as controlling the building’s operation, this type of building management system will also produce reports for facilities and energy managers to track how each area of the building is using energy, and help them to identify areas of waste so that it can be more easily reduced.

These days, any energy efficiency solution has to prove its cost-effectiveness. Thanks to research carried out in support of the European Energy Performance of Buildings Directive (EPBD), there is a document that can identify the potential energy savings of a wide range of generic building controls, and their impact on energy use in several different types of building.

BSEN 15232 (2007): Energy performance of buildings – impact of building automation, control and building management may not be the kind of document that leaps from the shelves, but for anyone trying to calculate the cost-benefits of building controls it is an invaluable tool.

BSEN 15232 is a European and British Standard that provides a structured list of controls and building automation technologies which have an impact on the energy performance of buildings. The document deals with a range of controls products such as automatic detection devices, demand-based controls such as CO₂ sensors,  and also controls-based strategies, for example night cooling.

It also gives a method to define minimum requirements for building controls for buildings of different complexities. Most usefully, the Standard provides detailed methods to assess the impact of building controls on the energy performance of a given building.

The Standard can therefore be used to demonstrate the energy savings of different types of building control, to compare against the costs. For clients and specifiers, BSEN15232 can be used to identify levels of control required in a new building, or refurbishment project – the Standard identifies four classes A, B, C and D of controls giving estimates of how much energy is saved at each level.  Table 1 shows the classes in more detail.

In terms of calculating the impact of these different classes of control, BSEN 15232 offers real insight, based on extensive modeling of different types of buildings such as offices, hospitals, schools, lecture halls and retail buildings. With class C controls taken as ‘standard’, the amount of energy saved compared to this level is shown for each building type. Table 2 shows examples of these figures for thermal efficiency.

Steve Harrison points out that the procurement route for controls should also be considered. “Increasingly, we are seeing hvac equipment supplied with factory-fitted controls. This can be more cost effective as it saves on-site installation time, and also reduces the supply chain. Factory-fitted controls now also make use of open communication protocols such as Lon, BACnet and KNX. This means that they can be integrated into a building management system more easily by an approved system installer.”

Perhaps the most cost-effective approach that any facilities or energy manager can take is to use their existing building controls as effectively as possible. It is surprising how much energy a simple audit of areas such as sensors and detection devices can identify problems that can easily be rectified, saving energy immediately. Building controls can become the backbone of an energy efficient building. At a time when budgets are constrained, it is important to deploy what cash there is to get the most effective return.

Ian Ellis is President of the Building Controls Industry Association (www.bcia.co.uk) and marketing manager of Siemens Building Technologies. Steve Harrison is Vice President of the BCIA, and control systems manager (Europe) for Johnson Controls.

Table 1: Classes of building control from BSEN 15232

Table 2: Potential impact of controls on the thermal efficiency of non-residential buildings

(table reproduced from EN15232)