AFFORDABLE, environmentally sustainable living is creeping closer with Andy Lemann's 'Greeny Flat'.
Mr Lemann said he had always had an interest in environmental sustainability, energy efficiency and solar power.
"I have an environmental philosophy that lead me to build homes that don't use fossil fuels," he said.
After studying architecture, Mr Lemann spent 20 years in Montana, America, building energy efficient homes in a really cold environment.
"I've been building and designing energy efficient buildings in the states for a while," he said.
"I recently moved back and just wanted to see if I could make something energy efficient that didn't cost a fortune."
This led Mr Lemann to designing his 'Greeny Flat' and building it in the backyard of his mum's investment property in Mittagong.
"It was perfect to build the passive, solar, energy efficient granny flat because it has really good north aspect," he said.
"The northerly aspect will work in conjunction with features like window placement, room layout, thermal mass floor and a reflective exterior to keep the interior cool in summer and warm in winter without the need for any additional heating or cooling."
Mr Lemann said the affordability goal was addressed in terms of both initial construction costs and long-term operation and maintenance costs.
"The energy positive, water conserving, low-maintenance and recyclability features all help to improve the long-term affordability of the project," he said.
"Every design decision has been carefully weighed in light of the balance between initial and long-term affordability."
With construction on the flat nearing completion, Mr Lemann plans to live in it for the next 12-months to test his claims.
"In the world of environmentally sustainable design there are a lot of claims with not much to back them up," he said.
"Before marketing the flat I want to prove that it does what it says it can do.
"Then, if the interest is there and the cost is reasonable, the idea is to turn it into a business."
For more information visit www.greenyflat.com.au