Earthwise Construction was appointed as main contractor to carry out this retrofit and extension of an ex-industrial unit (in the Montpellier area of Bristol) into a four-bedroomed house, to meet the AECB’s low energy Silver standard.

Prior to the renovation works, the building comprised of a single storey live/work unit split into a one bedroom flat and an open plan office. With no outdoor space and limited room to extend the house sideways, the new development added a second storey and roof terrace over the majority of the existing building. The downstairs is characterized by a generous entrance hallway, and by the unexpected geometries of the bedrooms and bathroom. Upstairs, the wide curved roof and large open plan kitchen/living room are striking features. The front terrace extends the living area and is finished with flagstone tiles and vertical larch cladding.


The building is situated in a conservation area in central Bristol, on a narrow cul-de-sac which is the only access to the site. The building occupies the whole site apart from a small strip of hard-standing to the front, making the logistics of the build a real challenge.

Hitting the airtightness target was one of the biggest challenges given the condition of the existing building. The preliminary air pressure test achieved better than hoped for with a result of 0.83 m3/hr/m2 .

Materials used

High performance phenolic foam insulation was used throughout with timber triple glazed windows. Other materials included: engineered FSC wooden floors, natural stone tiles, F.S.C larch cladding, exposed brick work, industrial insulated roofing sheets. A Paul Focus 200 Mechanical Ventilation with Heat Recovery (MVHR) system was fitted to provide ventilation requirements.

It was a pleasure working with Earthwise Construction, we couldn’t have hoped to have a nicer group of people in our home. Our house uses Passivhaus principles to create a very low energy home from a fabric point of view. Now, four years on, the energy performance of our home is better than predicted, which is testament to the skill of Earthwise Construction in executing many difficult details and achieving an excellent airtightness test value of 0.81 on a complex refurbishment project. I would have no hesitation in recommending Earthwise Construction to others and have already done so on many occasions.

James Walker