Located in a quiet mews in a west London conservation area, the room layout of this Victorian house was eccentric, although the generous 8m x 8m floor plan had lots of potential.  Our clients wanted to transform the interior spaces by introducing more light, making the layout more open and making it more suitable for a young family. They wanted to achieve these aims in the most sustainable way possible, minimising carbon emissions during the work and in the long term.

The key intervention was to reposition the stairwell in the darkest corner of the house, introducing top light, airflow and visual connection between the floors. The timber stair and associated screens were designed in collaboration with joiner Tom Graham to invoke an artisanal feeling that the original stable might have had.

A whole house low energy retrofit plan included:

• Insulating plaster to the inside of external walls
• Sash windows with evacuated glass, which reproduce a multi-pane window convincingly while approaching the performance of triple glazing.
• An air source heat pump that provides both underfloor heating and summer cooling.

The heating consumption has been slashed by a massive 95% and the overall energy consumption by 82%.

Sustainability

Since completion we have carried out detailed post occupancy evaluation work to review energy use, air quality and performance of the building services. Based on the data so far:

• The heating consumption has been slashed by a massive 95% and the overall energy consumption by 82%.
• The total energy demand (51 kWh/m2yr) meets the recently published and ambitious targets set by LETI, and the RIBA Climate Challenge targets for new build by 2025.
• In terms of lifetime carbon, the project is projected to meet a 90% improvement over 60 years when compared with the house as we found it.

After only three years following occupation the savings in operational carbon will have ‘paid’ for the embodied carbon associated with the construction.

Highlights

The RIBA Awards jury commented : “The building’s clear and simple reconfiguration, along with its carefully specified and well-detailed fabric upgrade, delivers an exemplary family home with outstanding energy efficiency.”

At the heart of the house is a magnificent oak staircase from which light pours down into the lower floors.