With the nation facing a housing affordability crisis, two men at the forefront of environmentally sustainable building design say a potential solution is to quit our addiction to big houses and energy consumption.

The great Australian dream is slowly becoming the great Australian nightmare for first-home buyers, and there is an urgent need for solutions.

Wollongong architect Andrew Conacher and Mittagong energy efficiency consultant Andy Lemann have both weighed into the debate.

For Mr Conacher, one potential answer is obvious — stop building such big houses.

"We have the third-highest energy use per capita in our houses after Canada and America, which have much more difficult climates than the east coast of Australia," he said.

"We're addicted to cheap power and if you ask someone to make the choice between comfort and environmental responsibility, they'll regard the latter as a government responsibility and we just want to have our air conditioner."

Australia, and the mother country Britain, have a long-held love for home ownership.

A person's home is treated as their 'castle' and remains a symbol of status and source of profit.

"The family home is considered sacrosanct and it would be a foolhardy government that tried to turn that around," Mr Conacher said.

"People build what they can afford and a bit more so they can sell it at the end. They're investing in their own homes as a form of superannuation."

The expectation of a big house

Mr Conacher said people needed to realise that building a big house when you did not need one was not financially or environmentally responsible, and compounded the housing affordability problem.

"We've created an expectation that you can have a big house and that's a good idea.

"It's like having a big car — we're almost over the big car now we've realised a small car can take you to Brisbane or Canberra comfortably, but we're yet to reach that point with houses."

He said the issues of environmentally sustainable building and housing affordability were closely linked.

"A house that's cheaper to run will be cheaper to afford, and when you come down to it, nuclear families are not the biggest family in Australia — there's single people, couples, retirees, empty nesters and not all of them need a big family home.

"We seem to be supplying that portion of the population more than any other."

Wollongong architect Andrew Conacher says housing affordability and energy efficiency are closely linked. ( ABC Illawarra: Justin Huntsdale )

Setting an example by living in a small house

Inland from Wollongong in the Southern Highlands of New South Wales, Mittagong energy efficiency consultant Andy Lemann has been living in a custom-designed, two-bedroom granny flat for three years.

He has been analysing why people choose not to add energy efficiencies in their new buildings, and said some of the key factors included cost, regulations and design guidelines in new estates.

"Cost is often cited as a big reason and there's no question that building the same size house with energy efficiencies does cost more," he said.

"We need to bear in mind we're building the biggest new homes in the world, and our family sizes are getting smaller and our population is ageing and retiring.

"The simple answer to things costing too much is to just build a smaller house and then you can afford to put the money into those energy efficiencies."

He has also said the New South Wales Government's Building Sustainability Index (BASIX) did not force new home owners to install enough energy efficiencies into their homes.

"BASIX is a complete failure as a measure of sustainability, and we need better regulations and the market to recognise that a home that's built with passive solar design will have lower running costs and will be more durable and healthier."

New estates can be prescriptive about what people can build there to maintain their aesthetic value, and Mr Lemann said this often came at the cost of energy efficiency.

"I was looking at one [estate] recently outside of Bowral and a regulation is that the living areas have to be on the street side of the house," he said.

"If the street happens to be on the south side of the house you'd have to put your living room on the south side of the house, but in a passive solar design you'd put your living room on the north side of the house.

"Another rule is that solar panels have to be hidden from the street, so if the street is on the north side, the solar panels have to go on the south side, which doesn't work [for solar power].

"Those sorts of design guidelines make it very difficult."

Andy Lemann out the front of his granny flat. ( ABC Illawarra: Justin Huntsdale )

We won't act until it becomes a crisis: Conacher

By international standards, Australia has cheap power, and even when considering recent significant increases in electricity prices, it is still affordable to power a home.

Mr Conacher said this had lured Australians into a dangerous sense of not just security, but entitlement.

"Some people are early adopters [of energy efficiencies] and these people have done that because it's sensible and saves money, and they want to get the best bang for their buck," he said.

"Everyone else has more interest in their footy team and affordability of energy or house loans are not on the horizon.

"These things haven't hit their radar yet, but when they do, people will struggle and then we'll do something," he said.