Featherbeds – a low-energy, passive eco-house, designed for family living in the heart of Cornwall.
Words by Jamie Crocker
Harmonising seamlessly into its rural setting, this passive-house inspired project is a testament to a symbiotic blend of nature and cutting-edge design. Featuring a main family home and a separate building which houses an indoor swimming pool, yoga room, workshop and garage, this residence not only complements its surroundings but enhances them.
The journey began with a plot that came with planning permission to convert and extend a poorly constructed barn. However, it was quickly realised that the standing building was hardly fit for purpose and would actually require demolishing. The new owners, realising the pitfalls that can often beset a project that steps beyond the original consent, decided to find an architect who could help them achieve their vision. ARCO2 was that choice. Their ethos was a good fit with their own. With over 21 years’ experience in building exceptional, bespoke, sustainable and award-winning buildings, they are a company that offers a comprehensive approach to projects, that starts from the initial conception of the very first idea through to completion.
Bringing onboard Cornwall Council and the Parish Council proved to be not such an onerous task, with all parties maintaining channels of communication, subscribing to the vision of a replacement dwelling that exuded quality, sustainability and respect for the setting. The goal was a family home for the owners and their two children that would be as self-sufficient as it was beautiful, making full use of natural light and offering private views of the secluded valley.
The client’s brief was an ambitious one. To replace the sub-standard barn with a sustainable family home. The design needed to maximise the site’s potential, ensuring every room was bathed in natural light and framed by views of the valley below. The home was to combine single and double-storey areas using natural materials like stone and timber, along with modern elements such as zinc. This contemporary design would respect the local vernacular while enabling indoor-outdoor living spaces, drawing inspiration from Californian, Balinese and Cornish architectural styles – a considerable challenge, indeed.
It became a place where craft met design. The house was designed to flow with the landscape, incorporating various levels to maintain harmony with its surroundings. The north-east single-storey wing, housing the kitchen and dining areas, appears to float over the new pond, offering direct garden access via decking. This area embodies a Californian aesthetic, complete with a mono-pitched wildflower green roof.
The two-storey section features a shallow pitched gable roof, housing a lounge that benefits from evening sunlight within a private walled courtyard – an ideal safe haven for the family’s dog. The first-floor master bedroom, with its Balinese-inspired design, offers stunning views over the site and captures both morning and evening sunshine.
The entrance wing, designed with a contemporary Cornish look, includes three bedrooms and a playroom, all opening directly onto the garden. Each room boasts views of the eastern woods and private garden areas, characterised by a mono-pitched zinc roof and natural stone walls. One of the design’s most significant challenges was blending these differing architectural styles while minimising visual impact. Cleverly hidden behind a spline wall, the Californian and Balinese wings are concealed from the driveway, presenting a smaller, cohesive contemporary Cornish façade upon approach.
The project’s second phase introduced a complementary pool building with a yoga room above. This structure needed to harmonise with the main house, merging Cornish and Balinese architectural elements into a unique style. The landscaping around both buildings was designed to flow freely with the existing terrain, incorporating a large pond and a Japanese garden.
Constructed on an encapsulated cast in-situ concrete raft made locally using secondary aggregates, the house is both robust and eco-friendly. The walls, comprising two independent timber frames spaced 400mm apart, are insulated with recycled newspaper, eliminating cold bridging. The roof uses engineered I-joists to lessen timber usage while maximising span and minimising thermal bridging. Internal stone walls, limestone flooring and multiple layers of plasterboard provide thermal mass, ensuring smooth temperature regulation.
Exceeding minimum Passive House thermal standards, the home maintains consistent comfort throughout the year. Despite its size and the addition of an indoor heated pool, its energy demands are minimal. A high-performance water source heat pump, with slinky pipes submerged in the large pond, heats the pool water, space heating and hot water, greatly enhancing efficiency. Future plans to install PV panels and battery storage on the pool building roof are expected to further reduce running costs and carbon emissions.
There were some challenges that presented themselves en route. Securing electricity for the site was a daunting and a costly endeavour. Although the team considered running the property off-grid, the potential for winter energy shortfalls necessitated mains electricity installation. During construction, ADD Sustainable Construction used a biofuel-powered generator to mitigate environmental impact.
In terms of sustainability the project included extensive landscaping and renewable technologies with a focus upon waste reduction, recycling and using environmentally responsible materials.
Key features of the building’s technical specifications include a MVHR (Mechanical Ventilation with Heat Recovery) system that provides fresh filtered air into a building whilst retaining most of the energy that has already been used in heating it. In this instance high-efficiency Vent Axia Sentinel Kinetic Plus units, with automatic humidistat boost control and summer bypass, were chosen. A Mastertherm Aquamaster Inverter 45i water source heat pump was installed along with underfloor heating in both ground and first floors controlled by programmable thermostats. All lighting is 100% low-energy lighting whilst every appliance is A-rated. Before demolition, a dedicated bat building was constructed, thus mitigating the impact upon the local bat species. The new pond, wildflower roofs and additional planting have significantly boosted site biodiversity.
Designed for minimal upkeep, the house features self-cleaning glass in hard-to-reach areas, durable zinc roofs and natural stone and timber finishes requiring little maintenance. The heating system, MVHR and treatment plant are robust, requiring minimal annual servicing. The pool employs an ozone system, reducing chlorine use and subsequently reducing its environmental impact.
The whole project champions low embodied CO2 content, with materials chosen for their sustainability and low energy footprint. Examples include Warmcel recycled newspaper insulation, FSC and PEFC accredited timber and various recycled and low-toxin building products.
This passive, low energy house stands as an exemplar of sustainable living, enhancing its landscape while providing a comfortable, eco-friendly home for its residents. The project demonstrates that with thoughtful design and innovative construction, a house can indeed make the landscape more beautiful than it was before – a sentiment echoed by Frank Lloyd Wright.