Bill Butcher and Chris Herring, founders of 21 Degrees, share details of their own group build, a small terrace of three homes in Marsden, West Yorkshire, designed and built to Passivhaus Plus standard. Check out the show notes for more information.

Jon Broome and Nick Grant explain why they have written The Good Building Book, what's in it, who it will help and how best to put it all into practice. Check out the show notes for more information.

Janna and Seb Laan Lomas explain the ethos behind their self build which blends low energy design and natural building while reducing plastics in the construction and also minimising waste. The level of detail, the decisions made and the careful use of the budget have been instrumental in delivering this fantastic project, which makes a great home for them as well as a site that encourages wildlife. Check out the show notes for more information.

Mark Lynn from Eden Renewable Innovations explains how sheep's wool insulation is made, outlines the pros and cons, and suggests how it is best specified and installed. He also shares some common traits of natural fibre insulation as a category. Check out the show notes for more information.

Mark Doodes from Mark Doodes Planning explains what we mean by applying for planning permission to demolish and rebuild a house, how it is done, what some of the challenges might be and how to do as much as possible to improve your chances of a successful outcome. Check out the show notes for more information.

Dr. James Glockling explains how insurance works and outlines some of the challenges of insuring a natural building. Check out the show notes for more information

Hugh Franklin from Aeroseal UK explains how the airtightness of a building can be improved using a water-based, low VOC atomised polymer which is delivered when the building is pressurised. This simpler approach speeds up the process of air sealing and gives real-time feedback on the airtightness score. Check out the show notes for more information

Elly Deacon Smith and Kirk Rushby from Arbor Architects explain why they consider the embodied carbon of their projects, how they do it and how it is balanced with competing factors. Check out the show notes for more information.

Marion Baeli, author of "Residential Retrofit," offers hands-on experience of designing and retrofitting high performance homes. As well as drawing on her personal retrofit she shares the lessons learnt from revisiting properties that took part in the Retrofit for the Future competition over a decade ago. Check out the show notes for more information.

Jeffrey Hart from the Earthen Floor Company gives us the lowdown on natural earth floors, explaining what the components are, how they are mixed and the process of installing them. He also outlines the benefits and limitations, and highlights what makes them a great choice for an eco home. Check out the show notes for more information.