Reasonable control
Published:  03 August, 2011
Controls, BMS, CIBSE, Part L

Hywel Davies gives an insight into what the Building Regulations have to say about controls for building services.

Readers will be well aware of Part L of the Building Regulations, which sets requirements relating to energy use in buildings. Part L is just a few short paragraphs, requiring that ‘reasonable provision shall be made for the conservation of fuel and power...’ and that ‘fixed building services [shall be] energy efficient [and] have effective controls’. These requirements are in the Building Regulations, so they must be satisfied. But what might reasonable provision of effective controls look like?

The Approved Docu­ments are the officially approved guidance on how to comply with the requirements in Part L, along with the non-domestic compliance guide. The guide provides detailed guidance relating specifi­cally to ‘fixed building services’ systems for non-domestic building services and covers systems for lighting, hot water, heating, ventilation and cooling. So we can go to the compliance guide to see what ‘reasonable provision’ could look like.

There is guidance on what sort of controls may be appropriate, where they should be installed, and in some cases suggestions about the degree of automation that should be included. After all, more than 40 years after we put men on the moon the idea that a finger pressing a switch is ‘reasonable control’ might sometimes be worth challenging. There are sensors and micro-processors that can ensure that systems come on when required, go off when not needed, and deliver the desired heat, cooling, light or air changes in between.

There is guidance on a wide variety of control mechanisms, which is well worth reviewing. But it is vital to remember that Part L is a technical regulation and that the guidance is technical guidance. There is one particular type of control that the compliance guide does not cover. That is the type that comes with two arms, two legs, inquisitive eyes and digits — digits that can poke, switch, turn, or adjust any other type of control that those eyes might see.

These controllers come in two variants. There is the variety that occupies the building, wants to be comfortable, and wants to adjust and alter the controls to suit. And then there is the variety that has the task of managing the building. In the absence of any formal guidance in the Approved Documents or the Compliance Guide, what are we to do? Perhaps a first step is to ask some questions about how we design and install services.

• Do we take account of human behaviour when designing services and controls?

• Do we consider how a system will be controlled when it is being designed?

Controls, BMS, CIBSE, Part L

• Do we give users and operators information on how to use the heating, lighting and cooling?

It is important to think about how real users will react to controls. There is a balance to be struck between deciding what users want, fixing it, and allowing users a degree of personal control over their working environment. It is well known that people are more comfortable when they perceive that they have a degree of control over their conditions. But if users are allowed too much freedom over systems, there can be unintended consequences — including unintended energy consumption and costs.

It is also important that users can understand controls. On/off switches are easy, but some control panels require a further degree to understand. We need to think about the human factors of controls, because if we don’t then inevitably users will struggle with them, systems will default to on, and energy use will rise dramatically. If building controls are not intuitive and simple to understand then it’s vital to provide clear instructions on how to use them. Better still, don’t buy such controls in the first place — buy simple intuitive ones instead!

Building managers need clear, understandable controls too. Not just controls around the building, but the BMS, too. If it is not easy to use then it is very likely that it will be misused, or not used. The BMS and systems it controls need commissioning to ensure they are correctly set up and calibrated. That is now required by Regulation 40 of the Building Regulations.

Regulation 44 requires building users to be given information on operating the building, and the Approved Document suggests providing a building logbook. Why is this? Because it is vital that the technology installed in the building to meet the technical requirements is usable, not just by controls engineers, or commissioning engineers, but by building managers too. Ideally, they should also get training on the controls. At present, suppliers have limited incentives to address these issues, but as building owners face ever-increasing costs for energy consumption and carbon emissions, they will ask more difficult questions about how energy use is controlled.

If we want buildings to show reasonable energy consumption then we need to think about the users, the hardware, and perhaps remember to KISS — keep it simple….

Hywel Davies is technical director of the Chartered Institution of Building Services Engineers.




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