How Darwin College, Cambridge, will be heated by water from River Cam thanks to new pump house

Water from the River Cam will be used to help heat buildings at Darwin College.

Cambridge City Council has approved plans for a river sourced heat pump at the University of Cambridge college, which said the “vitally important” project will help contribute towards its aim to become carbon neutral by 2032.

A report to the council’s planning committee last Wednesday (2 April) said the pump would help “eliminate the use of fossil fuel on site and the associated carbon emissions”.

A pump room will be built adjacent to the river where the water will be extracted and returned. It will be located on the college’s southern boundary, beside the Granta pub and to the rear of unlisted student accommodation buildings in Newnham Terrace.

There will be clear views of the intake and primary water filtrating system from the river, and parts of Laundress Green and Sheep’s Green.

Swift boxes and habitats for bats will be included in the pump house.

Carbon Neutral Cambridge wrote in support of the scheme, noting that water heat pumps are more efficient than air source heat pumps, but stressing it was important the facility was not used for cooling in the summer as that could increase the temperature of the river.

The college buildings are also due to have improved insulation, which the master, Dr Mike Rands, said would reduce the energy demand by around 70 per cent.

The college also sought permission to infill the ‘undercroft’ area currently used for car parking, beneath the dining hall, to create a new garden room for students. And it asked to extend The Hermitage building to create stairs and a heavy goods lift.

Dr Rands said the Darwin College site was “constrained” and said they “really need more space for working and socialising”.

He said the two projects were “vitally important” part of a wider masterplan to improve the college facilities and to decarbonise the estate.

Dr Rands said: “Having celebrated [the college’s] 60th birthday last year, this scheme sets the college up to meet the needs of the next decades, so the college can continue to make its contribution to the life and beauty of the city.”

He noted that the college was one of the few in the city to let people visit for free and said they would be able to show people how they are switching to renewable energy.

Councillors supported plans to build the river sourced heat pump.

Cllr Nadya Lokhmotova (Lib Dem, Trumpington) was “very excited” by the idea.

And Cllr Naomi Bennett (Green, Abbey) said: “I think this is one of the most interesting and well thought-out applications we have seen for a long time.”

Cllr Katie Porrer (Lib Dem, Market) felt the college’s access was important as other colleges had previously come forward with plan said to offer public benefits despite the fact that “the public cannot get in”.

She did have concerns about the extension and highlighted the chimney “sticking out in the wrong way”.

Cllr Katie Thornburrow (Lab, Petersfield) agreed there are public benefits, but also had some concerns about the design.

She was “a bit concerned about the proportion and scale” of the windows proposed in the Hermitage extension.

A conservation officer said the glazing had been chosen for the extension as they were “more comfortable” with it, compared to using bricks which they thought would be “too heavy”.

The officer understood the concerns about the chimney, but confirmed it had been designed to match part of the building and believed it would be acceptable.

Cllr Dave Baigent (Lab, Romsey) queried the 11.2-metre height of the plant room by the river and asked why it could not have been moved closer to the college buildings.

Cllr Robert Dryden (Lab, Cherry Hinton) shared concerns about the plant room, and feared the council could see more applications for similar size buildings along the river.

Officers said it was better to locate the heat pumps closer to the river, noting that the college site is constrained and if the plant room was closer to the buildings it would have an impact.

Cllr Porrer, who had visited the site, thought the area proposed for the plant room was right.

She said the river had an “industrial heritage”, explaining that there would have been mills based along the River Cam in the past.

Cllr Bennett agreed the river had a “substantial industrial heritage” and said the pump house would be “returning to that heritage”.

Councillors voted unanimously to approve the plans.