Earthwise Construction was appointed as main contractor to carry out a full retrofit of a 1960s house in the Westbury on Trym area of Bristol. The works included a large extension to the front of the house and demolition and erection of a single storey extension to the rear.

Prior to the renovation works, the building comprised of a draughty un-insulated four-bedroom house, conservatory and workshop/garage space. The building was completely gutted, the front and back walls of the building were removed, the conservatory demolished and the entire ground floor was dug up.

We carried out Passive House modelling to influence our client’s choice of the measures we installed. These were: External wall insulation, roof insulation, ground floor insulation and underfloor heating, triple glazing and MVHR.

Our client was very engaged and hands on throughout the entire project, which created a very collaborative approach to the project. The house not only got a well needed energy efficiency upgrade, but the client also got to re-design the house and finishes to their custom specification.


Working with an existing building always provides unique challenges. This project was no different. The house needed to have the roof extended in all directions to allow for the thickness of the external wall insulation. This provided the opportunity to try to make this junction more airtight, which was technically challenging, and it took great care and attention to get it right.

Materials used

Graphite XPS insulation was used for the external wall insulation. Internorm Triple glazed windows were fitted throughout. A Paul Novus 350 Mechanical Ventilation with Heat Recovery (MVHR) system was fitted to provide ventilation requirements.

Ben and his team did a total refurbishment of my house and also extended it at the front and back. A very important part of my project was to achieve a very energy efficient house. Ben is an expert in this area and fully understands the need for airtightness and the insulation requirements. He also has the skills to install the heat recovery ventilation system (MVHR). We are now living in a very warm house with minimal heating bills. Ben has a highly skilled team who take pride in doing a quality job. Earthwise Construction is an excellent building company that you can trust. I would highly recommend them.

Ken Mills