'The first green roof we visited was the Cook and Fox Architects building in Manhattan. We were blown away.
'It was this beautiful green planted area in the middle of Manhattan in a sea of grey rooftops. We both gasped, we couldn't believe this beautiful garden was on the roof in the middle of the city.
'We were so impressed in Switzerland and Germany, where it is now mandatory for any new building with a flat roof to install a green roof.'