Dering Street

Located in the heart of Mayfair, 19-24 Dering Street deploys a deep retrofit approach to create an exemplar new commercial building while minimising both embodied and operational carbon. Embodied carbon [A1-A5] is targeted to be less than 530 CO₂e/kg.

The proposal extends and reconfigures an existing 1920s building to create an 8 storey office-led development. The existing foundations, double-storey basement, and superstructure up to Level 3 are retained, with the original stair cores and structure above Level 3 removed to facilitate the 4-storey extension. A new facade to both the existing and retained structure provides an elegant, contemporary addition to the Mayfair conservation area while also providing improved thermal performance, enhanced internal daylight and natural ventilation to the office floors. The proposal supports Westminster’s Retrofit First policy while also providing an uplift of Grade A floorspace adjacent to the Hanover Square Elizabeth Line Station.

The proposal was informed by critical analysis of the surrounding architectural context, urban form and material expression. The massing was rigorously tested to ensure that it sits comfortably in its content, and multiple townscape views informed the location of entrances, windows and terraces,

The form and proportion of the surrounding buildings informed the sculptural, carved qualities of the proposed facade. The primary elevations feature a white handset brick and cast stone material palette and are articulated through deep set window reveals. Scalloped horizontal bands and chamfered vertical piers allow daylight deep into the office floorplate through the morning and midday, while then providing shading in the afternoon.

Set-backs at levels 6 and 7 create rooftop terraces with views across Mayfair. Both are generously planted to provide pockets of greenery for future tenants while also improving local biodiversity. A white finned ceramic facade provides a delicate counter to the robustness of the main building, while also sharing a material quality with the clay bricks below.

The proposed extension ties into the existing structural grid, helping optimise the frame for efficiency and load distribution and thereby minimising the embodied carbon in construction. Building services are selected to minimise operational energy with displacement ventilation providing fresh air, with perimeter trench heating and chilled beams at ceiling level.

The building is designed to achieve BCO Grade A and BREEAM Excellent ratings, in addition to targeting WELL Platinum, NABERS 5.5* and WiredScore Certification.