Measuring the real value of controls and BEMSs

Arguing the case for knowing how much energy controls save — Ian Ellis at the recent BCIA conference.

Ian Ellis of the Building Controls Industry Association explains how the long-term value of controls and BEMS can be calculated and outlines the latest development in assessing the effectiveness of BEMS in new and existing buildings.

It has never been more important for building-services products to be able to prove their worth to specifiers and end-users. The performance and payback for equipment is monitored, whether it's a boiler, air handling unit or heat pump. Building controls and BEMSs are no exception, and finding a way to show that they bring value to the built environment is a key goal for the industry.

There is a number of reasons why the BCIA (Building Controls Industry Association) 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.

However, the effectiveness of controls is also measurable with more robust methods. The Energy Performance of Buildings Directive (EPBD) first published in 2002, focused on reducing energy consumption in Europe's domestic buildings and non-dwellings. This included the development of 40 European (EN) standards to standardise the methods for calculating energy use in buildings — to ensure that the outcomes were based on the same calculations across Europe.

One of these supporting standards was EN 15232, which has also been adopted as a British Standard. BS EN 15232 deals with the impact of building controls and building energy management systems on energy efficiency. It provides a structured list of controls and building-automation technologies which have an impact on the energy performance of buildings.

The standard deals with a range of controls products such as automatic detection devices, demand-based controls such as CO2 sensors, and also controls-based strategies such as 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, BS EN 15232 can be used to identify the levels of control required in a new building, or refurbishment project.

The standard identifies four classes of controls and gives estimates of how much energy is saved at each level (Table 1).

In terms of calculating the impact of these different classes of control, BS EN 15232 offers real insight, based on extensive modelling 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.

Of course, one of the main challenges of energy efficiency is maintaining progress; a well-designed building may be energy efficient at the start of its life, but can this be maintained? A new development from The European Building Automation Controls Association (eu.bac) aims to address this problem.

Eu.bac has spent many years developing certification for building-controls products, and at the end of last year introduced a new method for certifying building-management systems — eu.bac System. Based on the principles of BS EN 15213, eu.bac System provides certification of energy performance of the controls and BEMS in a building — not only at first delivery but throughout the lifetime of the system. It can be applied in new or existing buildings.

Eu.bac System certification is carried out by trained assessors, who visit the site and verify that claimed functionality is available in the building and that it is working as required. Using a checklist, the system can be assessed and graded according to its element parts. Perhaps the most significant element of this new certification procedure is that it requires 'periodic' inspections of the system in order to retain certification.

Ian Ellis is president of the Building Controls Industry Association.

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