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Why building controls should matter to you

Contractors should consider advising on controls as an increasingly important part of their role in increasing the energy efficiency of buildings. Ian Ellis explains why
Last month's issue of HVR highlighted a survey by OnePoll, indicating that more than half of UK businesses are concerned about the rising costs of energy in their businesses. And of those, many are at a bit of a loss when trying to work out where to start with an energy efficiency strategy.

These figures will come as no surprise to contractors and installers of hvac equipment who are probably well aware of the growing emphasis on energy efficiency. Boilers, fans, air handling units - most of the equipment they are specifying and installing has become increasingly energy efficient as manufacturers have invested in R&D to push the boundaries of product performance.

The driver of this investment has been largely from the client-side. Legislation such as Part L of the Building Regulations is forcing careful analysis of carbon emissions, and hence energy use, in both new and existing buildings. Add to that the driver of energy certification for buildings, and it is easy to see why energy efficiency is the new hot topic for commercial building owners and occupiers.
But the installation of energy efficient equipment is not enough to ensure long-term efficient operation of a building.

Good control is a prerequisite

The most energy efficient air conditioning system will waste energy and money if it runs 24 hours a day where it's not required. A boiler could be ninety-six per cent efficient, but if it is heating an empty building every weekend, then that is far from desirable.

Good control of the hvac system is an absolute prerequisite for an energy efficient building. Without controls that are correctly set-up and used, a building can never achieve its efficiency potential, no matter how much has been invested in energy efficient building services plant.

It's well known that good maintenance is the key way to ensure lifelong efficient operation of hvac installations. But controls shouldn't be neglected either. Poor maintenance of control systems can result in systems running continuously because timers have been overridden; or simultaneous running of heating and cooling systems.

Leaving a building energy management system and related building controls unchecked can lead to energy drift - a 5 per cent increase in energy use year-on-year caused by small but significant issues in the system. That adds up to a lot of extra cost on the energy bills.

Simple maintenance procedures can be carried out when other hvac checks are taking place. They aren't time consuming, but can keep long-term energy efficiency on track. Walking around a building is a good way to make some initial assessments. A simple check of the basics could identify energy-draining faults that can be quickly corrected.

For example, look at set-points: have they been moved or switched to manual override? Sometimes alarms on a system can be ignored because building occupants don't understand what they mean.

Some contractors and installers may consider the building controls to be someone else's job. Up to a point, this is true - special knowledge is required to design and install a building energy management system (BEMS) and this is properly done by the controls engineers. However, hvac contractors and installers play an increasingly important role in the area of controls. And they also have the best knowledge of how the building services equipment should operate effectively.

Sophisticated built-in controls

Furthermore, we are seeing a growing trend towards HVAC kit being supplied with increasingly sophisticated built-in controls. Manufacturers have realised that good control is important if end users are to benefit from the full energy-saving potential of their equipment. The contractors are therefore responsible to a large extent for what can be controlled within a building - because they are the ones specifying and installing this equipment.

For contractors then, it is important to have a knowledge of controls, and how they fit into the whole BEMS (as even simple buildings can now have a building-wide control system). Understanding that every part of the hvac system should, wherever possible, be linked and operating within the BEMS will help to ensure that the building is energy efficient over the long term.

One area where this is particularly important is where low-carbon technologies are used. Equipment such as biomass boilers, heat pumps or solar thermal systems needs careful attention in terms of how it is controlled. One problem that is seen too frequently on both new-build and retrofit projects, is that these low-carbon technologies are left outside of the BEMS system, operating as stand-alone installations.

This is problematic, because more often than not, traditional equipment, such as gas boilers, is installed as a backup system. If the low-carbon technology and the backup equipment are not controlled correctly, it can result in both operating simultaneously; or it can mean that the gas boiler is used to heat the building before the low-carbon option: a wasted opportunity to reduce carbon emissions.
Contractors have a great deal of influence in the supply chain, often specifying the equipment and overseeing correct installation. This influence can be used to help building owners and operators achieve long-term energy efficiency.

The Building Controls Industry Association (BCIA) offers a number of courses for controls engineers, to help them understand hvac systems because as an Association we think this it is vital for them to understand what they are controlling. However, it's also increasingly important for hvac contractors to get to grips with controls, because they should understand how that equipment is operated in the long-term.

// The author is president of the Building Controls Industry Association //
7 October 2012

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