This is Welham Studios — designed by Mark Merer, the building was constructed from structural insulated panels, and features an EPDM roofing membrane with a built in root barrier, plus 100mm of substrate with a wild flower turf on top. It doesn't just demonstrate how well green roofs can be used, but also how one-off rural buildings can be both architecturally striking while still suiting their rural surroundings. Kind of like the Mimetic House did. More on Welham Studios here.