There's nothing unusual looking about Gamblesby Village Hall, an old Victorian schoolhouse in the fell-foot village of Gamblesby, a few miles east of Penrith.

From the outside it doesn't look like much has changed here in the hundred and fifty years since the school was built, even the warm red sandstone looks in pretty good shape for its' age. But things here are not what they seem; this is no grimy Victorian schoolhouse but a clean, green 21st century eco village hall, a transformation led by the local community following a nasty accident which led to the hall's closure.

"The village hall had been deteriorating over many years," explained Bill Mitchell, secretary of the hall committee. "It got to the stage where somebody leant back on a chair and went through the rotten floor. Then we knew we had to close and renovate. It was run-down, cold draughty and damp; the only heating was four electric heaters that burnt the top of your head and left your feet cold," he explained as he invited us inside.

Family on a bike arrives at Gamblesby Village Hall

Having seen a pub, shop and church close, the prospect of losing another community amenity ensured there was wide ranging community support for a hall refurbishment project. So, with the community behind them the committee developed plans for a project which used innovative renewable energy and insulation technology to attract grant funding, reduce the building's carbon footprint and ensure low running costs. It all proved very fashionable, practical and popular in a small village with limited funds, no gas main and ever reducing community amenities.

"Now we use a small ground source heat pump to run an underfloor heating system in the hall," explained Bill. Standing in the car park in the cold spring air, it was hard to believe that water pumped through large coils buried under the ground beneath our feet could pick up enough heat from the ground to warm a pancake let alone a village hall. But by a miracle of physics and technology that's just what a Ground Source Heat Pump does.

Dig down a few metres almost anywhere in the UK and the average soil temperature in the UK is between 8 and 13ºC year round; enough to warm up cold water slowly circulating in underground pipes by a few degrees. That's your ground source. If you couple that with a heat pump, a kind of fridge in reverse, then you can take this low grade heat and with a bit of technological trickery concentrate it to heat water up to 50ºC and feed your underfloor heating system, radiators or hot taps. This approach is cleaner, greener and involves lower running costs than heating with gas, oil or electricity.

And as if to prove the magic while it was no more the 5ºC outside, once inside the hall we were a positively comfortable 18ºC. Bill pointed to the old electric heaters still mounted high above our heads. "We kept those for back-up," he explained, "but we've not used them.We can't quite believe how good the system is. The first time we turned it on and watched the temperature rise to over 40 degrees it was like watching a miracle."

Of course it's not energy for free; the heat pump needs electricity to do its' business, and there's the capital costs of installation to factor in, but all in all the Gamblesby hall committee reckon the running costs of ground source are about one quarter of those for their old electric system, and with lower carbon emissions, they're feeling good about saving money and the planet.

But the people of Gamblesby are not content to stop there. The goal of the second phase of their project is real magic; to try and reduce the running costs and carbon emissions of the hall further by installing a small wind turbine, using wind generated electricity to pre-heat water, run the heat pump and possibly even generate a small income by selling any excess power to the grid.

Bill Mitchell, Secretary of Hall Committee

The whole project has had quite an impact on the community and the benefits go beyond cost savings and carbon reductions. The hall committee brought together long term residents and newcomers, farmers, tradesmen, engineers and other skilled professionals, who all put their skills to work for their community. "We learnt a lot together, really worked together, doing PR, fundraising, negotiating and hard labour," explained Bill, "and some in the village are now experts in heat pumps too." And alongside their commitment to developing their know-how and using green technologies, the committee made a commitment to go local, sourcing materials locally and placing contracts with local businesses and tradespeople. "The whole community was incredibly supportive and keen to lend a hand," explained Bill, "and we had a lot of volunteers who wanted to help too. So we used the skills, tools and heavy equipment available in the village and on the farms and just got on with it ourselves. It all helped keep costs down, made the whole project viable, built a great community spirit and got people thinking about energy efficiency and using renewables at home."

Bill showed us a video of the locals at work, shot and edited by a local camerman after a tap on the shoulder by the committee. As we sat and watched villagers in hard hats ripping out the old floorboards, hacking away at old plaster, trundling wheelbarrows, laying hardcore, digging trenches, laying floorboards, plastering, painting and hanging curtains, it was obvious that the Gamblesby project was no ordinary refurbishment project and the resulting hall was no ordinary village hall.

Once the video finished, Bill showed us around the hall, pointing out the fresh yellow paintwork, low energy lighting, polished wooden floors and bright red drapes. As we walked and talked it struck me how ordinary it all looked, how there was nothing here that looked that special apart from the pride that Bill evidently had in the whole project. He opened up a small wooden wallbox and showed us the rather ordinary looking set of pipes, valves and dials used to feed the underfloor heating. He handed us a few tufts of the Herdwick sheeps wool used to insulate the building and finally took us outside to a little shed where he showed us an unprepossessing box about the size of a small fridge. "And that's the magic, the heat pump," he explained. And even that wasn't all that impressive to look at.

The hall's smart but ordinary appearance conceals its' magic

I came to Gamblesby to see renewables at work, to see first-hand the magic of a Ground Source Heat Pump but what I found was a project that was much more than that, that not only used renewables and reduced emissions but also enhanced community skills and spirit, created an amenity that villagers feel a great sense of pride in and ownership of and encouraged people to think about the impact of their own energy consumption. Now that's the kind of eco-magic we could do with a lot more of.