Innovation is at the heart of sustainability. Yet often that innovation is about enhancing what we have already got. The Solasyphon is a perfect example. A plumbing innovation that speeds up and simplifies the retro-fitting of solar water heating in existing homes, it saves the cost and carbon impact of buying a new water tank. So far 1,300 Solasyphons have been sold and there is strong interest from companies as far afield as the US and New Zealand.