Optimise Settings to Heating and Hot Water Controls

Space and water heating accounts for by far the largest proportion of energy usage in schools, and as such also presents a major opportunity for efficiency gains, and for saving money.

The Carbon Trust report identified that the control of heating could be improved in all schools surveyed, both in terms of timing and temperature settings.

Timers should be set such that the heating is not on unnecessarily out-of-hours.  Modern boiler controls often have "optimiser controllers" (see below for further information) - for this type of controller you should set the on-off times to match occupancy, and the controller will automatically ensure that the boiler fires earlier than the set time so that the building is heated in time for the first arrivals.

Temperature settings should be in accordance with guidelines for the area of the school being heated - see below.  If settings are too high, the school could be wasting thousands of pounds each year through overheating.  It's also worth remembering that children have higher metabolisms and require lower temperatures to keep warm.

• Classrooms and staff rooms   -   18^oC

• Corridors, toilets, gymnasia, assembly halls   -   15^oC

• Medical/isolation rooms   -   21^oC

For every degree you heat over these figures, you will raise your heating bills by around 8% - i.e. if a secondary schools heats classrooms to 19^oC rather than 18^oC it could add around £2000 annually to its gas bill.

Suggested measures

1. Ensure all time set-points are optimised to ensure areas are not being heated out-of-hours.  For example, for school occupancy the time could be set at 8.15 – 8.30am to 3.15pm.

2. Different time settings should be trialled to find the most suitable for each building.

3. Temperature set points should be set corresponding to the requirements of the school.  This may require fine-tuning.

4. Frost stats are set at approximately 5^oC.

5. Make sure there are thermometers positioned around the school for staff and pupils to monitor temperatures.  Consider the purchase of a data logging thermometer for around £40 to track room temperatures overnight and at weekends - these make great educational tools.  Some also have remote outside sensors so you can see how the inside temperature is affected by the temperature outside, and the ability to download data to a PC.

Optimiser controllers

An optimiser is a time controller fitted to a heating system (which can include ventilation plant) and incorporates an internal and an external temperature sensor.

Using these sensors, the controller uses algorithms to learn the response rate of the building and then minimises the start-up period (preheat) of the heating system dependant upon the prevailing outside temperature to achieve the required occupancy temperature by the start of the occupancy period - this is called optimum start.  Similar facilities are available at the end of the working day - optimum stop.  By fully utilising these controls savings will be achieved.

These controls are very cost effective, but the start and end times need to be the actual occupancy times.  Most optimum start controllers will also provide features such as optimum off, day economy and automatic frost protection.

Summary of actions

1. Investigate all areas where control can be improved setting times and space temperatures accordingly e.g. to occupancy only.

2. Install optimum start controls to all heating systems as standard.

Relevant Carbon Trust publications:

CTG002 - Technology Guide - Heating Control

CTV002 – Heating Control

For further information, contact Property Services Energy Manager, Alan Dowdell - telephone 01962 847768.