Inbuilt water and energy efficiency was Geoff Tonkin's primary motivation when he built his house a decade ago. Geoff wanted the house to use minimal embodied energy in the building process and to be sustainable for the rest of its life.

A low impact on the environment allowing a good quality of life was Geoff's goal.
"It doesn't cost any more to build an efficient house and the passive solar design means less to heat and cool, which means less hours going to work to pay for it and less impact on the environment further on," Geoff said.

An open-plan four-bedroom home of white limestone walls, granite, recycled timber, and a permaculture garden resulted.

A dry composting toilet and rainwater tanks make the house water efficient.

Geoff made the rammed limestone walls on-site and sourced all the construction materials locally; and a barter exchange supplied sufficient labour.
"I wanted it to be built as the children grew so they could be involved and feel a part of it, and to teach them some owner-builder skills," Geoff said.

The success of his house inspired Geoff to help design other energy efficent homes.
"I realize, after living in an energy efficient home, that the most important factor is the orientation and placement of windows," he said.
Geoff's home runs east-west with 70 percent glass on the northern side, 40 percent glass on the eastern side, 5 percent on the western side and 10 percent on the southern side.

In winter, the sun through the northern windows reflects off the limestone walls and creates a heat bank, which heats the house.

The window placement avoids the hot summer sun so the limestone walls and granite floor stay cool.

In the kitchen, cool boxes are recessed in deep concrete, which removes the need for refrigeration.
"If you are going to have an energy efficient house, you need to live a low energy lifestyle as well," Geoff said.

Geoff's house design incorporated the philosophy of permaculture which views the house and garden as a single system.

The lush garden is full of fruit trees, vegetables, and herbs. A return to productive home gardens is a trend Geoff is keen to promote.

Geoff runs a Permaculture Educationa dn Research Centre and his home is a practical demonstration of how simple it is to live in an energy efficient home.