Meadowcroft: Building the House I’ve Been Researching for almost 30 Years
After nearly three decades working with bio-based construction materials, I’ve spent much of my career asking a simple question: can we build homes that are genuinely low carbon, energy-efficient, and practical to deliver?
The books front cover - available now from the apple bookstore here.
Last year, I had the opportunity to answer that question in the most direct way possible — by building one for myself and my wife, Jo.
Meadowcroft is a single-storey home in North Waltham, Hampshire, delivered using the ADEPT® modular system developed at Natural Building Systems. The project brief focused on minimising both embodied and operational carbon, while still achieving high levels of comfort and buildability. Key requirements included an ultra-efficient building envelope (with an overall U-value target of 0.1W/m²K), minimising concrete and fossil-fuel-based materials, and optimising the roof to accommodate as much PV as practical. The design also specified an air source heat pump, triple glazing, and timber cladding.
A practical point that matters here: Meadowcroft was delivered on time and within budget. In many ways, that’s the story. There’s a lingering assumption that low-carbon homes bring extra risk — higher costs, longer programmes, more uncertainty. This project shows a different outcome is achievable with the right approach and a disciplined system.
At the heart of the build is HempSil®, a bio-composite developed through my research work as an evolution of traditional hemp-lime. It is designed to support high performance with lower water demand and improved thermal characteristics, and it’s been developed for use within the ADEPT® panelised system.
What has been especially rewarding is the building’s in-use performance. The build cost was £2,320 per m². The EPC rating is 114A. The house is carbon negative in construction, and close to zero energy in use — even while running two electric vehicles. Since moving in nine months ago, we’ve consumed a net 725 kWh.
Comfort has been consistent and largely effortless. The internal temperature remains around 22°C in summer and winter, and the underfloor heating has almost never been used. That stability comes from a highly insulated, well-detailed fabric combined with bio-based materials that support a healthier indoor environment.
Alongside the technical story, Jo has documented the self-build journey in her book, Meadowcroft: Diary of an Eco Build which you can download for free. It’s written from her perspective and captures what the process feels like day-to-day — the decisions, the uncertainties, and the lived experience of building your own home.
I’m currently preparing a research paper for a special issue of Sustainability (expected early 2027), analysing Meadowcroft’s carbon footprint and energy use in more detail. I’ll share that work when it’s published.
For now, Meadowcroft stands as a built example of what can be done: an ultra energy-efficient home that meets high performance targets, is delivered quickly, and achieves genuinely low (and even negative) carbon outcomes — without a cost premium. If you’re interested in building your own house or project using the ADEPT® system then please contact the team through enquries@naturalbuildingsystems.com
You can view the full ADEPT® project case study here.
