Exemplar Sustainable Building Awards: Small project WINNER: The Seed

WINNER: Small project category I 2025 Exemplar Sustainable Buildings Awards. Replacing a derelict building, The Seed is a co-living home for two households in a woodland garden near Dundee. The home is almost entirely timber and meets both Passivhaus Classic standard and RIBA 2030 embodied carbon requirements. It offers a shining example of how Passivhaus can work in locations with difficult site constraints and restricted solar gain.

The Seed was developed to carefully balance communal and private spaces for the two families co-living there. The existing house was in too poor a condition to be retrofitted but most of the existing building was reused or recycled within the construction of the new home. The woodland garden is covered by a Tree Preservation Order and the web of the mature tree roots restricted development, so careful design was needed to protect tree roots.

The project was built in off-site manufactured timber I joist frame, with recycled cellulose and wood fibre insulation. The house is built with steel screw piles foundation, to avoid the tree roots and to minimise the embodied carbon. Finishing materials include Scottish timber cladding and decking with zinc roofing. Reducing embodied and in use energy and carbon was a primary driver of the design and construction of the building and influenced every single decision.

Key Stats

Certification: Passivhaus, 2024

Date occupied: 2023

Treated Floor Area (TFA): 177 m²

Construction cost: Confidential

Annual running costs: £5.75/m²

Heat source: ASHP for DHW & heating, with wet radiators

Overall energy demand: 23 kWh/m²/a (measured EUI)

Embodied carbon: 582 kgCO2e/m²

Construction: Off-site timber frame with cellulose and wood fibre insulation

Key Team

Client: Private clients

Architect: Kirsty Maguire Architect

Contractor: Alpha Projects

Passivhaus consultants: Kirsty Maguire Architect

M&E Design: Max Fordham

Structural Engineer: Narro Associates

Timber frame: Eden Insulation

MVHR supplier: PAUL Heat Recovery Scotland

Certifier: Ingo Theobalt

"We are delighted to have won the Exemplar Sustainable Buildings ‘small projects’ Award, celebrating 20 years of the Sustainable Development Foundation. Our ethos is that all buildings need to combine comfort, performance, environmental responsibility and to be joyous spaces to inhabit to be 'good architecture'. These awards combine all of this.

What a milestone for the development of sustainable construction and there were fabulous projects on show and some very tough competition. It’s great to see how this is gaining traction in the mainstream now with some major housebuilders committing to 100% Passivhaus and the Scottish Building regs developing the ‘Scottish Passivhaus Equivalent’ as we speak."

Kirsty Maguire, Kirsty Maguire Architects