Towards a fourth skin? Sustainability and double-envelope buildings

In several well publicised designs for ‘green’ office buildings, the zone of mediation between inside and outside has been increased by the addition of a second building envelope. When interpreted as exemplars of sustainable architecture, the addition of a second wall in these buildings is questionable both biophysically and psychoculturally. More constructive design strategies acknowledge the wider biophysical contexts of the human ecosystem, the prudent use of material and energy resources throughout a building's life, make realistic use of climate, and promote psycho-cultural needs arising out of ecologism.