Cambridgeshire selfbuild becomes one of the UK’s few Passivhaus Premium homes

Designed as a long-term home with comfort, resilience and future living in mind, Duck End Barns demonstrates what is possible when architectural ambition is combined with rigorous Passivhaus performance standards. The project is one of only a handful in the UK to achieve the Passivhaus Premium standard.

Duck End Barns is a new five-bedroom detached dwelling built on the edge of a Cambridgeshire village. The C-shaped footprint references the local farmstead vernacular, creating a sheltered courtyard that provides essential privacy from the road, and prioritises daylight, long views and a strong connection between inside and out. The house has also been designed for long-term living to support changing needs over time, with flexible accommodation.

The project is an all-electric, net-positive home meeting Passivhaus Premium requirements and features a large solar PV array and generous battery storage. A ground-source heat pump (GSHP) provides underfloor heating and summer cooling. The project has recently been commended in the Greater Cambridge Design and Construction Awards 2026 in the ‘Best new building under £3m’ category and has been shortlisted for Best Low Carbon Building of the Year and Best Residential Project of the Year in EastProp Awards 2026.

PHT member Archangel was Passivhaus Designer and architect on the project, with building services provided by PHT member Greengauge and Passivhaus certification undertaken by PHT member MEAD consulting.

Key stats

Construction: Prefabricated timber-framed, insulated cassettes on a piled concrete raft.
TFA: 394 m²
Form factor: 3.14
Build start date: 2023
Completed: 2024
Certified: Passivhaus Premium, 2026

Duck End Barns Passivhaus Premium. Image credit: Archangel Architects/ Richard Fraser Photography

For us, Duck End Barns had to be more than a house — it had to be a place we’d truly enjoy for the rest of our lives. Every material, every space, every detail was chosen with that intention.

Clients

The Duck End Barns project is an exemplar of energy efficient building services strategies –utilising optimal approache from the ground source heat pump to the waste water heat recovery systems. Targeting Passivhaus Premium certification has been a key driver in implementing these best practice approaches.

Oscar Garcia-Mendez, Senior Building Services Engineer, Greengauge

Construction

The project was procured through a negotiated two-stage tender process. The technical execution relied upon an integrated BIM workflow, where the fabrication model was coordinated with PHPP, other consultants and the timber frame supplier to ensure an easy transition from off-site manufacturing to on-site assembly. This digital coordination allowed for form optimisation to manage solar gains and for the precise scheduling of all PHPP-required information.

U-values

Roof: 0.10 W/m²K

Larsen-truss panels, filled with blown cellulose insulation (prefabricated)

Wall: 0.11 W/m²K

Larsen-truss panels, filled with blown cellulose insulation (prefabricated)

Floor: 0.08 W/m²K

Insulated, piled concrete raft

Building performance

PHPP thermal bridges modelling of all thermal bridges for inclusion in PHPP

Designed energy performance

Airtightness n₅₀ (≤ 0.6 ACH @ 50 Pa)

0.60 ACH @ 50 Pa

Space Heating Demand (≤ 15 kWh/m².a)

13 kWh/m².a

Heating Load (≤ 10 W/m²)

10 W/m²

Primary Energy Demand (≤ 120 kWh/m².a)

66 kWh/m².a

Primary Energy Renewable (PER) Demand (≤ 60 kWh/m².a*)

26 kWh/m².a

Primary Energy Renewable Generation

136 kWh/m².a

*+/-15 kWh/m².a allowance if offset by energy generation. See Passivhaus criteria.

Services

Achieving Passivhaus Premium required a highly coordinated approach across design, building services and fabrication, with energy generation and operational performance considered from the earliest design stages.

Heating & cooling: A ground source heat pump (GSHP) as a main heat source, connected to underfloor heating system within the home.The GHSP system has dedicated heat exchangers to provide passive (or free) cooling to lower the temperature of the home during the summer. The heat exchangers are connected to the borehole system to provide “free” cooling via the ventilation system and the hydraulic underfloor system. All first floor showers in the home have WWHR (waste water heat recovery systems) to recover heat from shower water.

Ventilation: A large MVHR (mechanical ventilation with heat recovery) system was designed for the project, complete with a brine heat exchanger to provide tempering via the ventilation system.

Renewables: As the project is targeting Passivhaus Premium certification, it aimed to use as much energy generated by the PVs on site. A large solar PV array on the roof with a 35kWp output is combined with a battery storage capacity of 40kWh.

Summer comfort: Form optimisation, external brise-soleils, electronically-managed external venetian blinds and shutters all contribute to ensuring high levels of summer comfort.

Challenges & lessons learned

Integrating building services with smart technology: The house uses a Building Management System (BMS) to control heating, cooling, domestic hot water, ventilation, lighting and security. All the building services controls for heating, cooling and ventilation needed to integrate well within the smart technology controls and into a single cohestive BMS.
Early digital coordination: Utilising an integrated BIM workflow aligned with PHPP made specification and procurement easier and helped a seamless transition from off-site factory manufacturing to on-site assembly.
Two-stage procurement: Involving the contractor early via a negotiated tender allowed for precise scheduling of Passivhaus data before construction.
Summer comfort: Passive cooling strategies significantly reduced overheating risk and eliminated the need for active cooling. Measures included architectural form optimisation with external blinds, brise-soleils, and cooling from the ground source boreholes.
Prefabrication: Using off-site prefabricated timber Larsen-truss panels delivered ultra-low U-values quickly and precisely.

Architect’s view

We recommended the Passivhaus Standard to the clients to ensure a high-quality, energy-efficient building with reliable performance. While the project demanded rigorous coordination and a high level of craft, particularly around the building envelope and airtightness, it has delivered an exceptional result.

The house incorporates the core principles that underpin Passivhaus performance: A highly insulated, airtight building envelope; Careful control of thermal bridges; Triple-glazed, high-performance windows
Mechanical ventilation with heat recovery (MVHR); An integrated renewable energy strategy.

Together, these measures are intended to deliver exceptional thermal comfort, excellent indoor air quality and very low operational energy use — outcomes that matter just as much to occupants as they do to the planet. These performance qualities underpin a house that feels quietly calm, designed for long-term enjoyment and lasting comfort.

The knowledge gained is already shaping how we approach future projects.

Apostolos Petrakis, Architect & Passivhaus Designer, Archangel

Key team

Architect & Passivhaus Designer: Archangel
Contractor: Seamans Building
Structural engineer: Andrew Firebrace Partnership
M&E consultant: Greengauge
Passivhaus Certifier: MEAD Consulting

More than a high-performance selfbuild, Duck End Barns highlights the growing potential for Passivhaus Premium to inform the future of net-positive residential design in the UK. Congratulations to the team for delivering one of only a handful of Passivhaus Premium homes in the UK. See the project for yourself as part of the Summer Passivhaus Open Days 2026.