Off-grid or bust

Eco-businessman Andrew Mercer has called in the diggers to start work on the foundations of a pioneering eco-house on a hillside above Bath. So confident is he that the four-storey glass structure will fulfil its promise, he has signed a binding agreement with Bath and North East Somerset Council to demolish the property if it is not off-grid within 12 months.

He has also pledged to knock down his family’s existing house in Batheaston within six months of moving into his new home 50 yards away.

Mercer and his wife Annette hope their radical home, designed by eco-architect Bill Dunster, will become a national prototype for zero-carbon construction.

Rather than using it as a money-spinner, they hope to grow old within its glass walls, long after their daughters Sarah, 16, and Katie, 13, have moved out.

Although diggers are now preparing to move on site, Mr Mercer is unsure how much it will cost to deliver the Bath Springs vision.

“I’ve no idea how much the final bill will be but this house is very important because we want to live as sustainably as possible,” he said.

“This is like our mortgage with the planet and we will have to pay it back by sticking to the principle of becoming zero-carbon.

“That means we have to generate more renewable energy during the building’s life than is used to build and then sustain it.

“We will be using reclaimed stone from Bath stone, installing super- insulated solar panels and triple- glazing, and the roof will go on first to prevent the foundations getting damp and needing electricity to dry out.”

Although the house will contain 7,500sq ft of space, its annual energy bill is expected to come to no more than £200.

Other sustainable features include low-flush toilets, wind turbines, a wood-burning water heater, a mechanical air conditioning system and a computer system that integrates different energy sources. It will be built into the hillside for natural insulation.

Mr Mercer said: “If we aren’t off-grid within 12 months the council will ask us to pull the house down, which shows how committed we are.

“It’s a sensitive site because it’s at the foot of Solsbury Hill, so it’s close to a World Heritage Site and an Area of Outstanding Natural Beauty.”

Mr Mercer founded Bath-based green energy company 2OC and business mentoring firm Footdown, and recently organised an Entrepreneurs with Conscience event to raise awareness of global warming with Live Aid pioneer Midge Ure.