KJ Tait have been involved in the redevelopment of 1-7 Harley Street for the Howard de Walden Estate since 2019 when we assisted with the successful planning application for the property. The property is Grade II listed and has many Heritage features that needed to be protected and retained which complicated the scheme with restrictions on space available for the cooling and heating plant.
As its location would suggest, the 3,000m2 base build scheme has been developed to provide a healthcare facility offering Consulting and Diagnostic accommodation although there has been a lot of interest from potential Tenants for more clinically demanding applications including theatres.
Work commenced on site in 2023 and completion of the shell works is expected in early 2026. Work on site to date has involved the construction of the basement while retaining facades and perimeter rooms with Heritage considerations. Basement works included 12 thermal closed loop boreholes at an average depth of 205m to assist in the heating and cooling of the building.
A milestone was recently reached on site where the Contractor has now started building up from the new Basements and tying in the retained rooms and facades.
Primary heating and cooling of the scheme will use an all-electric decarbonised solution. This is in line with National and Local guidance (London Plan) and allows the scheme to take advantage of electricity’s lower carbon intensity. The final energy strategy utilises a combination of Air Source and Ground Source Heat pumps to overcome the restrictions on roof plant and overall site area.
Heating will be generated centrally using air three Air Source Heat pumps (ASHP) mounted on the building’s roof and two ground source heat pumps (GSHP) located within the basement. The heat pumps will produce low temperature hot water (LTHW) for use with the air handling units, fan coil units, radiators, and underfloor heating. These units will also operate to provide the building’s cooling when there is a cooling demand. Hot water is provided by a further two high temperature heat pumps to step up temperatures from the base heating circuit.
A small PV array located on air handling unit roofs provides 7.6kWp of potential electrical generation. Other locations reviewed were restricted due to the planning restrictions.
As well as our involvement with the base build scheme we are now advising on feasibilities for potential Tenants for varying Healthcare uses and the base scheme has stood up well to serving more intensive requirements.
The scheme is targeting a BREEAM Excellent.