House Willett is the most quietly radical home in England: a Baufritz zero-energy self – build in the Surrey Hills where Tesla Powerwalls bank the sun, a Microlino sits where the Range Rover once stood, and the electricity bill is, essentially, an afterthought.

Drive south from London on a clear morning and the Surrey Hills will eventually present you with a house that does something quietly extraordinary: it produces more energy than it consumes, charges its own car, and filters its own air, all without a gas boiler in sight. House Willett is the new Baufritz prefabricated timber frame home.

A London couple relocating from a Victorian terrace in Clapham , came to Baufritz UK’s architect Anthony Cooper with a brief that was, at first, very neat. They wanted to leave the grid as much as the grid would allow. They wanted to be warm without burning anything. And they had already sold the family’s second car, a diesel SUV, and were waiting on a Microlino , the Swiss-Italian egg-shaped electric microcar that has become, among a certain set of south London professionals, a statement of cheerful automotive apostasy.

At Baufritz, the conversation about energy always begins with the wall. House Willett was specified with the company’s AAA system: a 46-centimetre-thick prefabricated panel achieving a U-value of 0.14 W/(m²K), a thermal performance that outperforms the Passive House standard. The insulation is HOIZ, Baufritz’s own patented material made from recycled wood shavings, breathable enough to regulate moisture naturally, dense enough to hold internal temperatures steady through the cold of a Surrey February and the occasional ferocity of an English summer. The windows are triple-glazed, their frames achieving a U-value of around 0.8 W/(m²K), which is to say they lose barely any heat at all. Then there is the question of leakage. A home can be clad in the most impressive insulation on the market and still lose warmth through every gap around a socket, a window reveal, a loft hatch.

Baufritz factory prefabricates its panels under controlled conditions, meaning the tolerances are architectural rather than site-dependent. House Willett achieved 0.6 air changes per hour at 50 pascals of pressure , the threshold for Passive House certification — on its first blower-door test. “That number tells you the building envelope is performing exactly as designed,” says Ole Heins, Baufritz UK’s smart home and insulation specialist. “After that, the mechanical systems are amplifying something the walls have already done.”

THE MECHANICAL LAYER

With the envelope doing most of the work, the services at House Willett are lean. An air source heat pump handles all heating and domestic hot water, drawing renewable energy from the air outside, even on a cold morning. A mechanical ventilation and heat recovery unit (MVHR) captures up to 90 per cent of the warmth from stale outgoing air and transfers it to the fresh supply, so the house breathes clean, filtered air continuously without losing the energy it took to heat the interior. For a family with young children, the filtration alone, removing pollen, particulates, and the residual pollution that drifts this far from the A3, was worth the specification.

The storage layer is where House Willett becomes genuinely unusual for an English home. The south-facing roof carries a photovoltaic array sized to cover the household’s typical annual demand. Surplus generation — which in a well-insulated home can be considerable even in sunshine — flows into a pair of Tesla Powerwalls installed in the plant room beside the heat pump. The Powerwalls store up to 27 kilowatt-hours between them, enough to run the house through a cloudy night, power the underfloor heating through a cold morning, and and charge the Microlino in the garage without drawing a single watt from the National Grid.

The Microlino, is a 90-kilometre-range, two-seat electric microcar that occupies roughly the footprint of a large sofa. For a Surrey household whose second-car journeys are school runs, station trips, and the weekly shop, it is a rational object. Its 10.5-kilowatt-hour battery charges from empty in under four hours on a standard home wallbox. At House Willett, that wallbox is fed by the Powerwalls. The car costs, in practice, nothing to run.

INTELLIGENCE ON TOP

The final layer of House Willett is its brain. Baufritz integrates KNX-based smart home technology throughout — an open, manufacturer-neutral protocol that coordinates heating, shading, lighting, and ventilation in a single system. The occupants can warm a room before they arrive home, drop the blinds on the west elevation at the moment the afternoon sun would otherwise overheat the living space, and schedule the Powerwalls to charge from the grid overnight on the rare weeks when the solar yield is genuinely poor. Ole Heins estimates that intelligent automation of this kind typically delivers a further 10 to 30 per cent reduction in energy use on top of what the envelope and services already achieve — the system uses energy only when and where it is needed.

The result is a home that, across a full year, produces at least as much energy as it consumes. In the months between April and September, it produces considerably more, selling surplus back to the grid. The annual energy bill — accounting for the modest grid imports of deep winter — is projected to be close to zero, and in a good year, negative.

What House Willett demonstrates, more than anything, is that zero-energy living is not a lifestyle proposition or an act of ecological self-denial. It is an engineering outcome, the natural consequence, as Baufritz puts it, of doing the building correctly in the first place. The house is warm, quiet, and unusually clean-aired. The car is cheerful and costs nothing to charge. The electricity meter, on a July afternoon, runs backwards.

That is, by any reasonable measure, a pleasant way to live.

house willett baufritz