The less-than-startling outcome from the Copenhagen Conference highlights the need for sustainability to be a grass-roots movement.

"It's time for people to just do it and let the politicians catch up when they can," Northrop Engineers sustainability consultant David Gribble said.

In November last year, the Sydney Morning Herald reported that the size of the typical Australian house cruised into the number one spot globally at 215 msq a good five per cent ahead of the Americans. The shrinking average family upsizing the family home is placing unjustifiable stress on global resources.

"My parents raised four children in a house of 100 msq. I raised three children in a house of 150 msq. Today's parents have been sold on needing 215 msq to raise 2.5 children," Mr Gribble said. "And with the cost to get into home ownership going through the roof, isn't it time to stop, take a deep breath and consider to what benefit?" Mr Gribble said it didn't even make sense to pursue the "McMansion dream". "Smaller houses cost less to buy, so more families can afford to buy them. On a square metre basis they can cost a little more to build. As margins usually relate to cost there should be more profit for the developer or builder," he said.

"Across the industry, there are more labour hours per square metre in a smaller house, so more jobs. Smaller houses can be built on smaller lots, so less land is taken up, which also means less infrastructure per lot reducing costs to services authorities."

Mr Gribble said that buildings consume 25 per cent of the world's harvested timber and 40 per cent of material and energy used annually, and Australia has one of the highest ecological footprints in the world.

"There is little point demanding action by others while continuing to fuel demand ourselves," he said.