That's because creating all the other material people requires energy equivalent to burning about 12 parents.

BBC: Go Figure: Why does every person need 200kg of steel a year?

Ofcom ruled the channel broke rules on 8 June 2007 by broadcasting "adult-sex" material during a free-to-air slot, and material judged to be the equivalent of R18-rated film during the encrypted segment.

BBC: Channel fined over 'explicit' sex

The trick, he says, is to harness material efficiency so people can enjoy goods that are equivalent or almost equivalent.

BBC: Savings needed to meet future demand for resources