What do we mean by thermostatic control?
A building with good thermostatic control means the heating system brings the temperature of the building up to the set temperature, and then maintains it at a constant level. The heating required and therefore gas consumption should vary linearly with how cold it is outside i.e. the colder it is outside the higher the gas consumption for heating.
The heating system can then adjust for internal heat gains due to people, electrical equipment and sunshine warming the building. It can also adjust for losses due to ventilation. Poor thermostatic control is likely to cause poor thermal comfort (occupants feel too hot or too cold), and the thermal comfort is then often maintained by leaving windows open leading to excessive gas consumption and carbon emissions.
In summary, poor thermostatic control means:
- Teachers and pupils often feel too hot or too cold.
- It often causes excessive gas consumption as teachers and pupils maintain a comfortable temperature by leaving windows open.
Reasons for poor thermostatic control
Unfortunately, many schools have poor thermostatic control. This can be due to poorly located heating thermostats. A common location for a thermostat in schools is in the school hall or entrance lobby where the heating, internal gains and heat losses are not representative of the building as a whole, and particularly classrooms. Halls are often poorly insulated with few radiators which means they never get up to temperature, causing the boiler controller to run the boiler constantly which causes the better insulated classrooms to overheat, and more gas consumption than necessary.
Poor thermostatic control can also be due to a lack of thermostatic controls in individual rooms, which leads to windows being opened to compensate. If it is difficult to provide local thermostatic control in each room, for example, Thermostatic Radiator Valves (TRVs) cannot be installed on radiators you could ask your boiler engineers whether 'weather compensation', which reduces the temperature of the circulating central heating water in milder weather can be configured for your boiler as an alternative.
How to improve your school’s thermostatic control:
- Check the siting of the main heating thermostats – halls and corridors are not good locations
- Check the thermostat settings or TRV radiator settings every two weeks in the winter to make sure they haven’t been turned up – they should be set to keep classrooms at a recommended 18°C
- Configure ’weather compensation’ on your boiler (ask your boiler engineers)
Further reading