Kevin McCloud visits a groundbreaking Grand Design

Kevin McCloud follows more of Britain’s most ambitious self-building projects, as intrepid individuals attempt to design and construct the home of their dreams.

Environmental consultant Duncan and solicitor Liz’s new home is set to be epic in every way: supersized, super sleek and super luxurious; but more importantly it’s also going to be groundbreaking. The ambitious couple bought a plot in the picturesque Cotswolds with plans to build a revolutionary eco home – the UK’s first certified Passivhaus Premium – which will use very little energy and also produce four times the energy it needs.

Effectively, it’ll be a mini power station…

Intent on project managing the construction himself, Duncan first moves out of their London house to live near the site, leaving Liz home alone and working to help fund the project.

Duncan’s utterly committed but has never faced anything like this before. This cathedral-like structure, consisting of giant glulam portal frames, walls of triple-glazed windows and three zig-zagging roofs, is technically complex and demands exhaustive attention to detail. Faced with this monumental challenge, almost inevitably their 18-month schedule spirals out of control and living apart takes its toll on Duncan and Liz.

In the end, the house needs to pass incredibly stringent tests to be a success as well as a UK first. Will it all be worth it?

GRAND DESIGNS, CHANNEL 4, 9pm