Controls for comfort

In these energy conscious days it is important to remember that the need to control energy consumption has to be considered alongside the requirement for occupant comfort, but finding a balance between the two need not be difficult.

Occupant comfort can be challenging to measure and assess. Post-occupancy surveys are often cited as the ideal way to find out if a building is giving occupants what they require, but these surveys are not carried out as often as they should be. In addition, comfort is the result of many factors, not all of them related to HVAC or other building services factors. These include occupant density and noise issues.

However, it is certainly the case that a building which is too hot, too cold, too bright or too dark (as far as occupants are concerned) results in a greater number of complaints to the facilities manager. It can also result in energy-depleting actions such as use of under-desk heaters to counteract perceived low temperatures, or desk fans in overheated offices in summer. In fact, uncomfortable occupants can unwittingly increase an organisation’s energy use, just because they are trying to be comfortable enough to work.

Building controls play a key role in ensuring that occupants are comfortable. Not only do building controls offer an automatic response to outside conditions (eg turning on air conditioning as external temperatures rise) they also increase user satisfaction. According to the BCIA report ‘Controls for End-Users’ written by Bill Bordass, Adrian Leaman and Roderick Bunn: “Case studies in non-domestic buildings reveal positive relationships between occupant satisfaction and levels of perceived control.”

Finding a balance between complete automation and some autonomy in the control system is important. Complete automation can probably achieve higher energy efficiencies, but by giving occupants direct control over their environment, building controls can help to create a more productive workplace – which is ultimately the purpose of a commercial building.

For specifiers, this means being aware of occupant requirements, finding out at the early stages of design what exactly they want from the building and discussing this with their controls supplier. And where users come into contact with the controls, the aim should be clarity and simplicity. Complex user interfaces can lead to confusion, and to misuse creating discomfort and often unnecessary energy use.

There is increasing emphasis in legislation on ensuring that building occupants know how to operate their building – with log books and commissioning becoming increasingly important. An explanation of the controls systems should also be included – the more building occupants understand how to operate controls, the more comfortable and productive they will be.

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