CONTROLS | SCHOOLS complied with Building Regulations, were monitored. They can be divided into two groups those that were easily tampered with and those that were not. In transient spaces, such as corridors, occupants do not have to endure excessive temperatures for long, and tend to use windows to control temperature. It is impossible for busy staff to check and correct radiator settings on a regular basis, and we found that giving occupants no control at all gave the best results. The occupant controls outlined below resulted in high annual operating times of around 4,000 hours, with 67% being outside of occupancy. With no occupant control, the annual operating time fell to just 850 hours, with only 1% outside of occupancy. Windows were left open far less frequently and the air temperature log showed it was within the CIBSE recommended range for corridors. What to avoid These occupant controls should be avoided: simple on/off switch (non-compliant with the Building Regulations); an override switch (so the unit remains on permanently); time clock; thermostat; night setback temperature. These all resulted in appalling results, despite some manufacturers claims that they were tamperproof (Figure 3). In an attempt to avoid tampering by occupants, a radio-controlled system was installed, with radiators operated by a central time clock that was not accessible to occupants. However, many of these systems have day and night setback thermostats on the radiator (Figure 4). These are easily tampered with and the night setback temperature was frequently set at its highest level of 21C so that the unit ran 24/7 trying to achieve this. Figure 3: A typical tamper-proof cover takes students about 60 seconds to open Our national survey of 80 institutions found that 89% suffered similar poor control issues, with the majority blaming contractors for installing over-complicated controls What worked well To remove all occupant control, the student efficiency team locked the day and night thermostats in place using a concealed match stick (day 18C, night 5C for frost protection). Their matchlock system ensured that, once turned off by the central timer, the units stayed off, saving the school around 1,000 a year with a payback time of just 19 minutes! That simple time- and temperature-limited occupant control will give the best results in classrooms, and no occupant control will work best in transient spaces seems obvious. Whats not clear is why so many controls are not configured in this way. Some large hotel chains have time-limited controls in rooms, but it is not common practice elsewhere. We conducted a national survey of 80 institutions (schools, universities, councils, fire and rescue, police and NHS estates), and found that 89% suffered similar poor control issues, with the majority blaming contractors for installing over-complicated controls. The problem is likely to be compounded by regulations such as EcoDesign Lot 20, which assumes more complex controls will result in better energy efficiency. However, Lot 20 control efficiencies are not measured values, but expected ones3 based on the assumption that occupants will adjust them to give optimum performance, which we have shown not to be the case. Rather than increased complexity, we need standardised simplification of controls, combined with legislation/guidance on how to actually configure them for efficient use. CJ C HRIS BAKER is a science teacher and coordinator of the student CO2 efficiency team at Parrs Wood High School. For further information, email c.baker@parrswood.manchester.sch.uk References: 1 Sung-Min Hong et al, UCL (2014). Improved benchmarking comparability for energy consumption in schools. London 2 Useable Buildings. (2017). BUS occupant survey. 3 Electric radiators direct (2017): Lot 20 explained: what does this mean for electric heating? Figure 4: Avoid occupant-controlled day and night setback thermostats 44 December 2019 www.cibsejournal.com CIBSE Dec19 pp42-44 Schools controls.indd 44 22/11/2019 15:42