Energy conservationist Andrew plans to build a radical, self-heating home by storing the warmth of the summer sun into insulated earth banks. But will this gigantic thermal experiment work?

Kevin McCloud revisits professional deep-sea diver Adrian Corrigall and his wife Megan, who planned to build their new family home in rural East Sussex almost entirely out of concrete, with construction involving cutting-edge technologies conceived in Switzerland and never used to build a house before. With both the schedule and the budget under strain, Adrian was forced to resume work as a North Sea diver, leaving Megan juggling this messy and challenging build, all the while looking after three young children. By 2018, water leaks were still to be addressed, the majority of the spaces were raw and unfinished, and the family were still a long way away from moving into their concrete dream. Two and a half years later, with the house now fully complete, Kevin returns to see what living in a cutting-edge concrete bunker is really like.