Set point
In the construction industry, the term ‘set point’ (or sometimes set-point or setpoint) typically refers to the point at which a building system is set to activate or deactivate.
For example, a heating system might be set to switch on if the internal temperature falls below 20°C, an extract fan might be set to switch on if the relative humidity in a room exceeds 65% and so on.
Set points can be fixed, adjustable or variable. An adjustable set point might be controlled for example by a manually-operated thermostat. A variable set point might be controlled by some form of calculation, for example, set points for air conditioning systems may be programmed to be higher when outdoor temperatures are higher as people are more conditioned to, and dressed for those higher temperatures. Alternatively, if a building is unoccupied, the set point for the heating might be programmed to reduce to just 5°C to prevent pipework from freezing.
The set point at which something is activated may be different from the set point at which it is de-activated. This prevents continually switching on and off if the conditions are very close to the set point.
Set points may be fine-tuned during the commissioning process, and building occupants may be given control of some set points, perhaps within prescribed parameters.
Set points should be monitored, and checked regularly to ensure that they are correctly set and that they are delivering the required result. Seemingly small changes in set points can have a significant impact on performance and energy use. In addition, some building spaces may house critical operations requiring very specific, closely-controlled set points.
It is important therefore that building operators and occupants are provided with an explanation of set points, their operating ranges, and the impact of adjustments on performance and energy use.
NB Guide to Controls (BG 83/2023) written by John Marrow and published by BSRIA in June 2023, defines setpoint as: ‘An adjustable level of a parameter, such as temperature, humidity or pressure, which a control system aims to achieve.’
[edit] Related articles on Designing Buildings
Featured articles
Check out some of the best features and news from Designing Buildings as well as key stories from around the web.
Why being a mentor can help your career.
Channel 4 broadcaster to host 125th anniversary ceremony.
Listed structures on the rail network
Heritage interests and operational requirements must be balanced.
Historic England publishes research into embodied carbon when retrofitting traditional buildings.
New Prime Minister delivers on ECA call for cut in electricity costs.
CIOB reacts to the announcement of Andy Burnham as Prime Minister.
Heritage and conservation science workforce survey - Have your say.
England's Suburbs 1820-2020. Book review.
New, more proportionate and targeted approach for higher-risk building assessments.
Government brings British Steel into public ownership.
UKCW Birmingham returns with bold new theme and focus.
New guidance published on competence requirements for self-certification schemes.