SCHOOLS RETROFIT | HEAT PUMPS The dash from gas With the need to switch from fossil fuels to renewables becoming ever more pressing, one heat pump retrofit schools project in Yorkshire could be the example to follow. Phil Lattimore looks at the project funded by the governments Public Sector Decarbonisation Scheme E ven before the war in Ukraines impact on future gas prices, steep increases in energy costs were highlighting the urgent need for many organisations in the private and public sectors to reduce energy consumption, which, of course, goes hand in hand with reducing carbon emissions. A government initiative the Public Sector Decarbonisation Scheme (PSDS) offers the opportunity for organisations to get grant funding for heat decarbonisation and energy efciency measures. A 5m PSDS-funded project at the Abbey Multi Academy Trust (Abbey MAT), in Yorkshire to replace existing gas boilers in ve schools with a heat pump-based system is an example that other education providers may be keen to follow. Installed over the summer holidays in 2021, the new system has eliminated the trusts reliance on gas for space heating and hot water, and aims to reduce its carbon emissions by an estimated 9,000 tonnes over the 12-year lifetime of the scheme, saving an estimated 84,000 a year in energy costs. The project involved the installation of 38 CIAT AquaCIAT TD300 air source heat pumps in the ve schools, as well as LED lighting to reduce electricity consumption and solar photovoltaic (PV) arrays, designed by services specialist Robert Whetham Associates, that partly power the heat pump system. During the summer, when the school is closed, electricity produced by the PVs feeds into the Grid, providing an income for Abbey MAT. The trust aims to optimise system performance by adjusting owrates and set points, to ensure comfortable indoor temperatures for students and staff throughout the day and over the year, as the seasons change. One of the initial challenges for the project was the short timescale available to put together Abbey MATs grant application to Salix Finance, the PSDS scheme administrator. It required detailed proposals for each school to be collated within a two-week period because of delays in the process, tendering, and the logistics involved in getting contractors on site to do the work during the summer holidays. The trust worked with decarbonisation specialist Energy Management Group (EMG) to prepare the application. Another key challenge was assessing the requirements for upgrading existing radiators to take account of the lower water temperatures delivered by the heat pumps. Detailed surveys were carried out by BREng Hull, in collaboration with EMG and Toshiba Carrier distributor Cool Designs. We have done a lot of work on these type of projects, in terms of assessment and modelling classrooms, and that experience enabled us to meet the very tight timescale by applying our accumulated knowledge from those school projects to these buildings, says BREng Hull director Rob Smelt. The school buildings ranged in age from the 1960s through to 2006, and the audit took account of the type and size of existing heat emitters, glazing, building fabric, room orientation, insulation and occupancy levels. We had the details of recent fabric improvements, so we could evaluate room heat losses, says Smelt. This enabled us to provide a rough estimate for tender purposes, based on what was in the room. The air source heat pump-based system connected largely to the school buildings existing infrastructure, such as pipework, Bishop Young C of E Academy, one of the Abbey MAT schools. The air source heat pumps can be seen in the bottom right of the picture 36 April 2022 www.cibsejournal.com CIBSE Apr 22 pp36-37 Schools heat pump Supp.indd 36 25/03/2022 15:19