Chester Balmore, London

Chester Balmore, a mix of 53 council rent, shared ownership and private homes, demonstrates that a building can be designed to meet the specific demands of a particular site and still achieve the Passivhaus criteria of super-insulation and high levels of airtightness.

It is the UK’s largest Passivhaus mixed-tenure residential scheme. The ultra-low energy scheme, designed by Rick Mather Architects, fits seamlessly into the upmarket Dartmouth Park conservation area of Highgate, north London.

The design fits enough one-, two- and three-bed flats and maisonettes onto the compact triangular site to cover the £10m cost of the development without it looking overcrowded or out of context with its neighbours. To break up its mass, Chester Balmore is divided into three blocks.

The most prominent corner of the site is occupied at street level by commercial units with four floors of flats above; the two five-storey blocks to the rear incorporate a mix of maisonettes and more apartments.

Each block is set into the sloping site, keeping its height to a minimum to respect the area’s three-storey brick-built Victorian terraced housing and Edwardian mansion blocks. In addition to helping to define its height, the scheme’s neighbours also dictated that the Passivhaus project would have to be constructed using brick, outwardly at least. 

The final scheme used a modified brick-block cavity-wall construction capable of achieving the super-insulation levels required by Passivhaus, based on a 250mm-wide cavity filled with expanded polystyrene balls. The party-wall construction changed from masonry block to in-situ concrete; this had the added benefit of improving both airtightness and acoustic performance.

The PassivHaus design needed to incorporate thermal breaks to minimise cold bridging on balconies, terraces, parapets and retaining walls. For example, Schöck structural thermal breaks have been used to support the scheme’s concrete balconies from the concrete frame. Chester Balmore is now fully occupied with residents benefiting from the comfort and low energy bills of Passivhaus levels of insulation and airtightness.

Words taken from ‘Keep it Tight’ article from Concrete Quarterly spring 2015.