Many technologies have promised these qualities, but few have been commercially viable. What's been lacking is the performance data needed to demonstrate that these technologies are durable, genuinely environmentally beneficial, and suitable to be insured. Over the past 13 years, our Department of Architecture & Civil Engineering has led on research into straw as a low-impact building material. This work, which has included developing a unique straw bale panel as well as scientific monitoring and testing, has now culminated in crucial industry certifications. The BM TRADA’s Q-Mark certification guarantees a straw building’s energy efficiency, fire safety, durability and weather-resilience and means that developers and homebuyers can now get insurance and mortgages for straw homes and buildings. The innovative straw walls in the new houses provide two times more insulation than required by current UK building regulations. Based on monitoring a residential straw-bale development in Leeds, fuel bill reductions up to 90% can be expected. The walls have been built using ModCell technology; prefabricated panels consisting of a wooden structural frame infilled with straw bales or hemp and rendered with either a breathable lime-based system or ventilated timber or brick cladding. This technology combines the lowest carbon footprint and the best operational CO2 performance of any system of construction currently available. In fact, as an agricultural co-product, straw buildings can be carbon negative as straw absorbs CO2 when it grows.