William Ainge Court | Welshpool
Passivhaus Certified Affordable Housing Scheme
The development of a steeply sloping brownfield site adjacent to William Ainge Court in the centre of Welshpool marks the first collaboration between MWP and Hiraeth Architecture on behalf of Barcud Housing Association.
A new, detached three-storey stepped apartment block is designed to Passivhaus standards, incorporating a highly insulated, offsite-fabricated twin-stud timber frame, ensuring exceptional energy efficiency.
The development consists of 17 one- and two-bedroom affordable flats, including accessible units, all designed to meet Lifetime Homes standards, Secured by Design and the Welsh Government’s Development Quality Requirements. The project also represents the first Passivhaus-certified scheme for all three organisations.
The late Victorian red brick Lansdowne House occupied a heavily sloping site off Brook Street just outside the conservation area of Welshpool and sitting at the centre of the existing William Ainge Court. Built in 1976 the existing development of William Ainge Court is a collection of 2 storey pitched buildings containing 23 one bedroomed retirement flats. Constructed in a pale buff brick and operated by Barcud Housing Association the buildings step up from Brook Street to Bowling Green Lane to the south, by a full storey height. With the demolition of the derelict Lansdowne House, MWP created a unique opportunity to transform the existing development, forming a central courtyard and principal frontage with a new infill development and complementing the retrofit of the existing buildings.
The redevelopment of the brownfield site was undertaken as a partnership between MWP and Barcud Housing Association. This marks the second collaboration between the two, following the successful completion of the IHP-funded Crofts Court.
MWP’s dual role as both main contractor and developer offers a unique model, underpinned by their commitment to delivering all projects to Passivhaus standards. This aspiration led Harry of MWP and Rob of Hiraeth to meet and complete Passivhaus Designer training in 2020. Their chance encounter led to a review of proposals for the site, including an early-stage Passivhaus Planning Package assessment and the appointment of Hiraeth as architects and Passivhaus Designers under a Design-Build arrangement.
The project comprises 15 units—a mix of one-bedroom, two-bedroom, and accessible flats—arranged in a stepped L-shaped plan. This layout aligns with the existing development to create a central communal courtyard. The building’s design responds to the challenging topography with a series of half-level changes organised around a six-level lift and corresponding stairs, generally presenting as a three-story structure that integrates seamlessly into the existing context.
A generous colonnaded corridor overlooking the courtyard acts as the building’s central spine, connecting the new stairs and lift core up to the second floor. This corridor also links to the original terrace via a grillage bridge, significantly improving site-wide accessibility.
The project faced notable challenges due to the constrained access, with steep and narrow approach roads and construction taking place adjacent to occupied buildings. The construction strategy incorporated in-situ retaining slabs and walls to form a plinth for the high-performance, off-site fabricated twin-wall timber frame. Despite the complex level changes, the project team meticulously eliminated thermal bridging elements and implemented a robust airtightness strategy. This approach delivered exceptional performance metrics, including U-values of 0.13 W/m²K and an airtightness test result of 0.39 ACH @ 50 Pa (0.56 m³/(h·m²)).
The building’s external finishes reflect its technical strategy: textured buff brickwork on the lower levels references the conservation area’s light stone and brickwork, while crisp white render and black tile roofs define the upper stories.
The exceptionally airtight fabric is paired with highly efficient Mechanical Ventilation with Heat Recovery to each dwelling, which recovers up to 95% of the heat from outgoing stale air and transfers it to incoming fresh air, significantly reducing heat loss.
Despite the challenges posed by site constraints, Hiraeth’s redesign simplified the building form, reducing the form factor (heat loss area relative to floor area) and optimised solar gains through the orientation and size of openings. These measures result in an exceptionally low heating demand, met by efficient electric heating systems and supplemented by 1.2 kWh of photovoltaics per flat. As a result, residents enjoy significantly reduced annual fuel costs and improved thermal comfort.
The project was successfully submitted to the Passivhaus Institute for Passivhaus Certification with flats generally achieving a Space Heating Demand of 12kWh/m2a and achieving an EPC rating of 92A.
