POTHOLES have been a problem in Oxford since the weather last winter – but a series of 55m-deep holes in one school car park are helping keep students warm.

The innovative network of 18 pipes at Magdalen College School help heat its new building, and are one of the reasons it has taken the city's top sustainability prize.

The new block even has automatic windows to stop students falling asleep in lessons.

The school shared the honours in this year's David Steel Award, run by Oxford City Council, with Brasenose College.

Alistair Weir, assistant bursar at Magdalen College School, said it had been determined to make its building as green as possible.

He said: “Our professional team researched and investigated every environmental aspect of the pro-ject. The main thing is the ground source heat pump, which includes 18 holes, each 55m deep, that pick up heat from the earth's core temperature, and that feeds into the underfloor heating system.

“We also have automatic windows that operate on temperature and CO2 levels.They open in stages, dependent on indoor conditions.

“It is the CO2 that makes people go to sleep in the classrooom.”

The three-storey building, in Cowley Place, houses the school's dining room, along with its theo-logy and art departments.

Brasenose College, in Radcliffe Square, received the award for its new student accommodation in Hollybush Row.

Dr John Knowland, who was bursar of Brasenose College when the building was under construction, said: “The college was keen to have as many environmentally friendly features as possible, and installed ground source heat pumps to provide heating in winter and cooling in summer, solar panels to heat water, and storage tanks to collect rainwater, which is used to flush the lavatories.

“With a very high level of thermal and acoustic insulation, the building requires very little energy and provides comfortable and quiet accommodation for its occupants in a busy part of Oxford.”

The award is named after council officer David Steel, who died in 2006. Entries are judged by a panel of city councillors and officers.

Lord Mayor of Oxford John Goddard, who presented the awards at a ceremony at the Town Hall on Thursday, said: “This award is a tribute to David, who worked hard on the climate change issues within Oxford.

“We have continued with his work and both winners have worked hard to make their buildings environmentally friendly.”

Previous winners of the award include the Ruth Deech Building in Woodstock Road, part of St Anne's College and David Hammond, for his zero-carbon house in East Street, Osney Island.