SCHOOLS | ICT COOLING TAKING THE HEAT OUT OF THE CLASSROOM Increased use of computing in schools is causing a rise in cooling loads that can result in air conditioning being in conflict with heating. Science teacher Chris Baker looks at four methods of reducing cooling requirements at Parrs Wood High School G as consumption has decreased in schools because of improved building fabric, but electricity consumption has increased, and is generally attributed to greater use of information and communications technology (ICT) equipment1 and associated comfort cooling. For new build schools, ADL2A gives guidance on measures to avoid cooling fighting heating.2 However, this is often not possible in existing builds, where air conditioning is retrofitted into computer rooms sited in larger, wet central heating zones. This report considers four methods available to existing schools to minimise increased energy consumption resulting from cooling fighting heating. It shows that, with careful planning, significant savings can be made at little or no cost and that, for schools, low energy hybrid thermal mixing (HTM) units are currently not a financially viable retrofit alternative to a traditional air conditioning unit. Research for the report was carried out at Parrs Wood High, a large state school in Manchester, and much of the data was collected by the student sustainability CO2 team. Simultaneous cooling and heating occurred in 12 (7.5%) classrooms, each of which has a split air conditioning unit under full occupant control (in total, 30kW of electrical power). The building is divided into heating zones, each with seven rooms, a zone-thermostat in one of them. Typically, one or two of these rooms have been converted into computer rooms, increasing each rooms peak cooling loads by around 1.6kW. This has caused them to overheat not only in summer, but also in winter, when the heating was on and occupants turned on the air conditioning. Turning the heating down wasnt an option, as the other rooms in that zone would be underheated. Thermostatic radiator valves seem an obvious solution, but they are easily tampered with and, to date, we have not found any that are robust enough to survive in a school environment. run-on time and set point were limited by using the password-protected features of the room controllers although, in a few instances, older controllers did not have these features, so the units were time-limited by installing an occupation sensor in the room, at a cost of about 100. The operating times of the air conditioning units were monitored using low-cost data loggers, and the operating times during occupancy were found to be reduced by 47% (400 hours) over the heating season considerably greater than the target reduction of 25%. (There were further savings from the avoidance of overrun outside of occupancy hours, but these are not included here.) This equates to around 7,200kWh of electricity, giving annual savings of 792 and 3tCO2. A thermal comfort survey and monitoring of room temperatures showed no marked change in thermal comfort levels. Greater use of ICT equipment in schools accounts for their increased electricity consumption Method 1: Improve control of air con units Cooling fighting heating was minimised in two ways. First, occupants were stopped from using excessively low airconditioning setpoints. As the heating was set at 20C, the cooling setpoint was limited to no lower than 21C. Second, the operating times of air conditioning were minimised. An analysis of the main-school computer rooms showed that, during occupancy hours, they were empty for 25% of the time because of free periods and lunchtimes. Use of a run-on timer reduced waste operation caused by units running when rooms were empty. The 52 September 2020 www.cibsejournal.com CIBSE September 2020 p52- 54, 56 School cooling and covid.indd 52 21/08/2020 17:11