Delivering UK net zero requires a massive switch to carbonless heat and power in all our buildings - but the tools and systems to make that switch don't currently exist. The team look at the scale of that challenge, and ask what can be done, particularly in jobs, skills and supply chains. They are joined by Jo Patterson from Cardiff University's Welsh School of Architecture, and Nigel Banks from zero-carbon housing developer Ilke Homes. Fraser chats with Nathan Gambling, a leading trainer of heating engineers.