Architect Malcolm Worby has built Adobe brick and mud, as well as straw bale, mansions for rock stars in Hollywood. In the US, he says, it’s the most expensive form of building because of the labour cost and bricks. And they have not a grain of rustic about them.

Now, based in South Africa, he works as a consultant and drives the Homeless and Poor People’s Initiative – www.happi-online.org. The project goes around to communities and re-educates people to build buildings for themselves.

His presentation was truly amazing. Technical, making it hard to re-explain, but he wielded the same level of precision regarding environmental building as Alejandro Aravena’s precision regarding low-cost building. Imagine what they could do together!

Although... He says that the closest a building can get to being completely “sustainable” (in adjectival form) is 40%. [**Note exciting correction below]