Exploring the potential for water source heat pumps

In 2021, Darwin College commissioned an estate-wide review of the buildings and their heating systems. A working group of College members was subsequently tasked with developing an ambitious but achievable plan to decarbonise the entire built estate over the next decade. It examined the scope for fabric improvements to reduce energy demand and the various options for renewable heat: air source heat pumps, ground source heat pumps, direct electric heating powered by on-site PV generation, and a closed heat network fed from a water source heat pump using the river Cam as a heat source. In 2022, in a collaboration with six other riverside Colleges, Mott MacDonald were commissioned to monitor water flow, depth and temperature at four locations on the river and to produce a detailed hydrology study. The report, delivered in 2023, confirms the considerable potential of the river to supply heat for space and hot water heating for the adjacent Colleges.

A summary of Darwin’s work towards harnessing the river for heating purposes is available here.

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Funding the future

Darwin has been awarded two grants by Salix under Phase 3b of the Public Sector Decarbonisation Scheme and Phase 4 Low Carbon Skills Fund. These awards allow the College to embark on significant and innovative projects to decarbonise its estate. The first award, under the Salix Public Sector Decarbonisation Scheme for £141,000, contributed to the cost of refurbishing Frank Young House, an offsite hostel with 30 rooms. Existing gas-fired boilers have been replaced with air source heat pumps, and double glazing, and opened to students from 1st January 2024. Darwin is now working up a decarbonisation plan for its main site. Following a grant award of over £200,000 from the Salix Low Carbon Skills Fund in June 2023, work is underway to design an on-site heat network, to a RIBA Stage 3 level. The design includes a heat network capable of feeding all 14 buildings on site from water-source heat pumps at the edge of the estate, and the associated building fabric upgrades. The final report, due in March 2024, will form the basis of a proposal that will work through 2024, with the aim of the works being undertaken in 2025/6.

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Energy sources and demand reduction

Renewable energy of origins contract

The College is committed to reaching carbon zero (scope 1 and 2) by 2032. A key factor in achieving this is to ensure that all energy is sourced renewably. The College is already supplied with renewable electricity through the College consortium for electricity. This Renewable Energy of Origins (REGOs) contract is valid until 2027 for the main site, guaranteeing 100% UK-generated renewable electricity.

Smart thermostatic radiator valves

In 2023, the College conducted an energy management trial with Ecosync, installing smart thermostatic radiator valves (TRV)s in student houses, Newnham Terrace 3 and 10, for dynamic energy management and temperature control on a room-by-room basis. The trial aims to compare energy usage with and without the smart radiator valves, to see if energy consumption can be reduced without compromising on student comfort. This will be evaluated in early 2024

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