Westminster City Council launches flagship Passivhaus schemes

Planning wins for not one but two Westminster City Council housing developments aiming for Passivhaus.

View of Carlton Dene and Peebles House green development

Westmead

The Westmead housing project designed by Child Graddon Lewis and Secchi Smith, has recently been granted planning permission for 65 homes aiming for Passivhaus. More to follow on this scheme soon.

Peebles House (& Carlton Dene)

Designed by PHT Member Levitt Bernstein, the South Kilburn proposal includes 22 family-sized apartments for affordable rent (Peebles House) aiming for Passivhaus, alongside a 65-bed extra care development (Carlton Dene) targeting the PHI Low Energy Building Standard (PHI LEB).

Peebles House

The Peebles House project will double the number of homes currently available on the existing site - providing a mix of one, two and three-bedroom affordable rented apartments aiming for Passivhaus certification. The larger family homes can accommodate up to five people. The homes will be available at social and intermediate rent for existing and new residents.

Key Stats

No. Units: 22 1-3 bed homes
Project stage: Planning permission granted
Form factor ratio: 1.73
Construction: Concrete frame with light gauge steel frame
Build start date: Expected early 2022
Completion date: Due late 2023

Carlton Dene & Peebles House maintains existing heritage views

We’re committed to building affordable homes for people at all stages of their lives and this is another exciting milestone. The 22 spacious family-sized homes available at social and intermediate rent are much needed in the area and will be available for existing and new residents to move in to. This scheme will not only benefit residents of the new homes but will also offer a range of advantages for the wider local community with a new café and hairdressers and improved public realm.

Councillor Heather Acton, Westminster City Council Cabinet Member for Communities and Regeneration

Peebles House Predicted Energy Performance

Thermal Energy Demand (≤15kWh/m².yr)	14 kWh/m².yr
Thermal Energy Load (≤10W/m²)	9 W/m²
Primary Energy demand (PE ≤120kWh/m2.yr)	33 kWh/m².yr
Airtightness (≤0.6ACH@50pascals)	0.6 ACH

All homes are dual aspect to increase daylight and encourage the use of natural ventilation. Fixed solar shading on the southern façades and moveable external louvres to the west will help reduce higher temperatures.

Sketch of Carlton Dene and Peebles House redevelopment (aerial view) Carlton Dene on the left & Peebles House (outlined in blue) on the right

Carlton Dene extra care

Due to several design constraints and additional considerations, the Carlton Dene extra care development will not satisfy all the criteria required to meet Passivhaus Standard. Instead it aims to achieve the PHI Low Energy Building Standard (PHI LEB) which was originally developed by the Passivhaus Institut (PHI) for buildings that may fall just shy of all Passivhaus criteria due to difficult site restrictions such as orientation or shading etc. The PHI LEB standard still undergoes an independent certification process and the quality assurance that entails, producing a scheme that will significantly exceed current UK building regulations. Key factors that meant the Carlton Dene extra care building did not quite achieve the Passivhaus standard include:

The extra care building is adjacent to a Grade I listed church. The project team must be considerate of the form, which affected the building’s form factor.
Ground floor north-facing communal spaces (café’s / entrances) overlooking the new church ‘square’ are suited to increased glazing. This optimises visual connections with public spaces but reduces thermal performance.
The project team designed the external walkways to be sheltered - increasing protection for vulnerable residents, which impacted on solar gain.
Best practice dementia design looks to maximise views and natural daylight that required the team to increase windows sizes slightly beyond the baseline Passivhaus target sizes.

Carlton Dene _Section perspective through courtyard

As a Practice, we have shifted to designing all our housing projects to Passivhaus standard as the default. Rather than a client having to ask us to pursue this, they would need to instruct us not to do so. This includes many exciting schemes that are on the drawing board, such as Melfield Gardens in Lewisham, Plashet Road in Newham and Carlton Dene in Westminster.

PHT member Levitt Bernstein