Control systems
There are numerous methods by which heating and other building services within buildings can be controlled. Most systems seek to control either by:
- Time i.e. when a service like heating or lighting for instance is provided and when it should not be provided or
- A parameter representative of the service like temperature for space heating. This can also vary with time.
The main parameters controlled in an energy efficient and healthy building should be:
- Room temperature
- Room heating and cooling
- IAQ during occupied hours
- IAQ during non occupied hours
- Solar shading
- Night ventilation during summer
- Preheating of ventilation air during winter

Thermostats and TRVs were the first control equipment to be adopted in the building sector owing to the first energy crisis. Building management systems developed in the ‘80s in the residential and services sectors, as simplified applications of systems and technologies already developed in the industrial sector in the ‘70s to automate production processes and to optimise plant performance.
Examples of typical control methods are described hereafter:
Time Control Methods (for heating):
- Time switches turn on and off the heating (or water heating) system at preselected periods of the week)
- Optimisers: these controls start the heating system in a building at a variable time to ensure that, whatever the conditions, the building reaches the desired temperature when occupancy starts.
Temperature control methods:
- Frost protection generally involves running heating system pumps and boilers when external temperature reaches a set level (2°C) or less in order to protect against freezing
- Compensated systems: which control flow temperature in the heating circuit relative to external temperature thus allowing a rise in the circuit flow temperature when outside temperature drops
- Thermostatic radiator valves: these units sense space temperature in a room and throttle the flow accordingly through the emitter (radiator and convector) to which they are fitted
- Modulating control: can be applied to most types of heat emitters and is used to restrict the flow depending on the load demand and thus control the temperature
- Proportional control: involves switching equipment on and off automatically to regulate output.
Other methods:
- Occupancy sensing: In areas which are occupied intermittently, occupancy sensors can be used to indicate whether or not anybody is present and switch the heating/cooling and ventilation on and off accordingly. Detection systems are based on ultrasonic movement or infrared sensing.
- Other methods can be thermostats and user interactive control