Bonaly Retrofit and extension

An exemplary retrofit

This project is a retrofit and extension of a typical 1960s suburban house in Edinburgh. From the outset, the approach was ambitious: the building fabric is designed to exceed current building regulation standards, making this an exemplary example of how an existing home can be upgraded for energy, comfort, and sustainability. The client’s brief was to improve performance and adapt the house for a growing family, but the starting point was not technology—it was the site.

Like much developer housing of its era, the original house was efficient but blind to its surroundings. Orientation, sunlight, views, and wind were rarely considered. Early in the project we asked: which parts of the site catch the sun? Where are the views? Where is shelter from the wind? How can we strengthen the connection between house and garden? These questions shaped every decision that followed.

Compact, connected, Considered

The garden faces east, with glimpses south toward the Pentland Hills. Rather than extending in every direction, we chose a focused two-storey rear extension. It grows the house economically, preserves the original front elevation, and maximises daylight, views, and garden connection—all while keeping the insulated envelope compact and efficient.

Continuity and contrast

The extension is clad in high-quality timber, which weathers evenly to a pale grey, complementing the existing white render. Cladding lengths and window proportions create a relaxed, modern rhythm, while a reinstated corner window nods to the original house in a contemporary way.

Design first, technology second

The existing house—likely a Mactaggart & Mickel design—was sound but outdated in energy terms. By treating the extension as an opportunity to upgrade the whole building, we combined enhanced insulation, triple glazing, and airtight construction with a highly efficient extension and an air source heat pump. The result: minimal reliance on fossil fuels, greatly improved comfort, and a genuinely low-carbon home.

By asking the right questions early—about orientation, sunlight, wind, and use—the project demonstrates how thoughtful design drives low-carbon outcomes, with technology amplifying rather than defining the approach.

Location: Bonaly, Edinburgh

Client: Private Client Structural: David Narro Associates Contractor: Robert Reid Joinery Key Suppliers: Russwood Cladding  Nordan Windows Holte Kitchens Photography: Fredrik Frendin Photography