Hounslow: thinking big

Hounslow Council plans for building up to 967 Passivhaus homes are taking shape as part of its masterplan for redeveloping its Convent Way housing estate in Heston. A hybrid planning application, including the outline masterplan with first phase in detail has recently been submitted.

Overview of Convent Way Hounslow Masterplan. Image credit: Bell Phillips Architects

Key stats

No. of homes: up to 967
Project stage: Planning submitted as a hybrid application (outline masterplan with first phase in detail).
Building forms: residential flats in both standalone and courtyard blocks, residential semi-detached and terraced houses, and non-residential uses at the ground floor of some buildings.
Certification: Aiming for Passivhaus

Convent Way, Hounslow. CGI view prepared by Secchi Smith for Bell Phillips Architects

Design

The masterplan vision has been shaped around four principles: greenery and ecology, health and security, community, and sustainability. A comprehensive design code is included with the application to protect these principles; this includes targeting 90% dual aspect homes, providing equal access to amenity for all, improving active and sustainable travel with each phase, and keeping the community together.

Supporting Hounslow’s climate emergency declaration, the homes themselves will address fuel poverty through a 69% reduction of operational carbon over Part L baseline and are aiming for Passivhaus certification. The masterplan for the redevelopment of the Convent Way estate will help set a new urban dwelling standard for the London Borough of Hounslow integrating Passivhaus design, landscaping, sustainable transport, and building quality.

The proposal has been modelled on a 2050 weather file to future-proof the design, and targets are aligned with RIBA 2030 climate challenge so that over time embodied carbon for the development will improve with each phase of delivery.

Convent Way, Hounslow. CGI view prepared by Secchi Smith for Bell Phillips Architects

Phase A

Detailed plans have been submitted for Phase A of the project. The form factor of the proposed buildings is crucial element of the early stage designs to help keep costs down, with the design team working to a form factor target of 0.8-1.8. To minimise the risk of overheating, shading strategies include integrated brise soleil on relevant facades, with further shading provided through the careful location of balconies.

Wall

Brick outer leaf

U value: 0.15 W/m²K

Floor

Reinforced concrete superstructure

U value: 0.13 W/m²K

Roof

U value: 0.11 W/m²K

Convent Way, Hounslow. Image credit: Bell Phillips Architects

Target energy performance

Airtightness (≤0.6ACH@50pascals)	0.6 @50pascals
Thermal Energy Demand (≤15kWh/m².yr)	13-15 kWh/m².yr (varies)
Thermal Energy Load (≤10W/m²)	10 W/m²
Primary Energy Demand (≤120kWh/m².yr)	79 or 81 kWh/m².yr (varies)
Primary Energy Renewable Demand (PER)	91 or 95 kWh/m².yr (varies)

Key team

Client: London Borough of Hounslow
Lead Architect and Masterplanner: Bell Phillips Architects
Passivhaus consultant & M&E Design: QODA Consulting
Passivhaus certifier: Etude
Landscape Designer: Gillespies
Structural Engineer: Conisbee
Quantity Surveyor: Turner and Townsend

Convent Way Hounslow Illustrative view by Bell Phillips Architects

Working closely with residents of Convent Way Estate from the very outset of the project has been the most rewarding aspect of developing this masterplan. Delivering Passivhaus homes set within new parks, streets and well-connected green infrastructure is a significant and challenging aspiration on such a constrained site; it is particularly special to be delivering these homes for a community of residents that are keen to stay at Convent Way and transform the area and share our vision to create a sustainable neighbourhood for future generations to enjoy.

Ashmi Thapar, Senior Architect, Bell Phillips Architects

Ashmi Thapar, from Bell Phillips Architects, will be discussing the Convent Way project as a Keynote case study during the UK Passivhaus Conference 2022 in Exeter and online on 26 October 2022.