Changed central heating operating times

Implement our guidance on setting the morning start time and heating end time to save energy

30 points for this action


Energy Sparks provides in depth analysis of heating times for schools as often they are poorly controlled with the heating coming on too early in the morning and going off too late at night. To see this analysis, go to the ‘Adult dashboard’ for your school, click on ‘Review your energy analysis,’ scroll down and click on the boxes in the ‘Boiler control’ section of the web page, in particular ‘Morning start time.’ 
  • On an average winter day, the heating should come on no more than two hours before the school opens (an earlier start time may be necessary on a Monday).
  • Heating should go off at about the time school closes as residual heat in the school should be enough to keep after school clubs warm without the need for the heating to be left on.
  • There should be no need for gas consumption between school close (e.g. 4pm) and 5am the next morning, unless it is very cold weather and frost protection has kicked in. (Some of the charts show half-hourly consumption on individual days or you can drilldown to an individual day by clicking on the gas consumption chart on the adult dashboard page.) Even in frosty weather, only a small amount of gas needs to be consumed to lift the temperature in the school by a few degrees.
  • Heating should start earlier on a Monday by about two hours to compensate for the fabric of the school cooling down over weekends but for the remaining days of the week, the heating should be turned on as late as possible.

Optimum start control

Many schools have ‘optimum start control’ configured which looks at the outside and inside temperatures and automatically schedules the heating to start earlier in colder weather and later in milder weather.

Unfortunately, this does not work properly at most schools and is the cause of heating coming on before 4am. This is mainly due to boiler thermostats being positioned in the wrong place, such as corridors. As a result, the corridors might come up to temperature by the time the school opens but the classrooms have wastefully been up to temperature since the middle of the night! We generally recommend, if this is the case, to turn ‘optimum start control’ off and try switching to fixed times e.g. 6.30am to 3.30pm and see how it goes. 

Another issue with ‘optimum start control’ is that the time you set in the boiler controller is the ‘Occupancy time’ and not when you want the boiler to turn on. So, you should typically set it to 8:15am, on the basis that you want the school up to temperature for 8:15am and not, for example, 5:30am in the mistaken belief that this is when the boiler will come on. If you set it to 5:30am, all that will happen is that the ‘optimum start control’ will start the boiler earlier to get the school up to temperature for 5:30am!

If you are reliant on your boiler service engineers to configure these settings, you need to be quite forceful with them and make sure that they understand that incorrect settings are costing the school money. If they make any changes, you can then review your gas or storage heater data on Energy Sparks a few days later to check the heating is now coming on at the correct time.