A lot of Australians are living in "glorified tents" which are stifling in summer and freezing in winter, leading to exorbitant power bills for their inhabitants. But there are ways to fix it.

You don't need to be as rich as Elon Musk to build a new home - or renovate an older abode - which is geared towards sustainability while being energy savvy. Robust climate resilient designs also don't need to look like they're from Futurama or The Jetsons.

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Award-winning builder Adam Souter renovated his Unanderra home and built possibly the nation's greatest treehouse - a "granny flat" constructed around an old tree - as an example of how stunning sustainability can be.

Known as Peppertree House and designed by Alexander Symes, the structure is used as a home office, parents' retreat and Airbnb. It comfortably keeps the inside temperature between 20 and 25 degrees all year round and doesn't need underfloor heating - it uses 90 per cent less heating and cooling than a standard Aussie home.

It's most recent accolade was winning the top gong for Sustainable Architecture at the NSW Architecture Awards.

Not all of Souter's clients are as focused on sustainability as he is, but that is okay because his business incorporates responsible practices and tries to use sustainable and recycled materials anyway.

"As a First World country our building technology is probably the worst in the world," Souter said (a common gripe from the experts the Mercury spoke with).

New builds or renovations costing more than $50,000 need to abide by the BASIX regulations for energy, water use and thermal comfort - but Souter said those standards were outdated and meant "essentially everyone was living in a tent".

He believes the more who utilise sustainable products and practices in building the more the costs will come down, but still strongly believes you can make a home more comfortable without having to outlay millions.

"People look at the cost of building and look at the numbers then and there ... but they don't look at the running costs," Souter said.

"Your house is your biggest investment in your life but no-one says how much the house is going to cost you to run every bill for the next 30 years."

The builder also said Australians were hung up on oversized homes whereas the easiest way to be more sustainable was to "live smaller".

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A recent Climate Council report Tents to Castles: Building energy efficient, cost-saving Aussie homes, said the current energy standards left people with homes that were too expensive and uncomfortable to run while also noting excessive cold contributed to six per cent of deaths - double that of Sweden.

"As many as 85 per cent of us experienced bill shock last year," Climate Councillor and report co-author, leading economist, Nicki Hutley, said.

The report found the typical home was so draughty that a room's air changes 20 times an hour making it expensive to heat and cool.

"Australian homes are energy guzzling compared to those built to higher minimum standards overseas," Hutley said.

"A Tasmanian home built today uses more than double the energy of a similar sized house built in Ireland."

Hutley said greater energy efficiency meant fewer greenhouse gas emissions but also could improve people's health and well-being, reduce electricity bills, strengthen our energy grid and create jobs.

Award-winning architect Alexander Symes has been passionate about sustainability his whole adult life and has designed many gorgeous new homes and stylish extensions around the Illawarra and beyond.

He is a big advocate for getting the outer shell "design" of a new build or extension right as well as capitalising on "passive house principles" to enable the natural elements to heat and cool a building rather than relying on appliances.

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This means using the right materials and design for a home to withstand more extreme weather events like severe heatwaves, bushfires and flash flooding with what is predicted for years to come due to climate change.

"You need to think about what's the stuff that needs to last 50, 100 or 150 years and then what's the stuff that might be more temporal and ensure you invest in that overall building envelope," he said, noting interiors were easily changed down the track.

Symes also advises people to work out their home's master plan and whether they could break it up into stages over time, to be more cost effective.

Jamberoo building designer Nadine Ryan was the daughter of a plumber and grew up in the building industry while her sister Belinda Gibbons (a UN Principles for Responsible Management Education board member) helped shape her sustainable development goals.

Ryan may run a small business but she is striving to become carbon neutral and has vowed to support the realisation of the United Nations Sustainable Development Goals through her home designs, building partnerships and donation support (such as to the Southern Youth and Family Service).

She also specialises in additions, and recently worked on an extension for a 100-year-old cottage.

Currently there as a huge trend to "knock-down rebuild", she said, which was practical in some cases (like a 1960s red-brick abode not built to withstand 50+ years) - but there was also a "massive" reason to keep old homes.

"There's a massive amount of waste in this country, especially carpet as carpet is not recyclable ... all of the carpet in our country goes to landfill," she said.

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Many older homes can be saved with retrofitting and sleek additions. But not every block or existing home faced north so that's where clever design comes in with placement of windows plus shading by awnings and plants.

Ryan recently completed a beautiful design for a Shell Cove family and although the backyard faced south she added in a north facing courtyard to gain as much natural light as possible into the home, which would also help with warmth in winter.

She has also created stunning designs for families across the Illawarra including an incredible extension at the back of a century-old miner's cottage. You'll notice quite a degree of variation in her grand designs as: "no two families are the same".

Ryan said popularity was increasing for passive houses - built in the style of energy-efficient European homes - while there was an increase in sustainable building products on the market too like Weathertex cladding and some styles of Boral concrete.

"There is change and it's up to us as designers to specify with sustainability in mind, the goal being to specify materials that are sustainable and that don't burden the client financially - it's certainly possible," she said.

Creating beautiful bespoke and affordable homes to suit their inhabitants to a tee is one of the driving forces behind Ryan's passion.

"A good price guide for a new custom home is to allow around $3000 per square metre on average for house, garage and outdoor entertaining areas," she said.

"But this can vary on a client's interior and exterior sections, going down or up."

Other things to consider were demolition costs (if needed), the angle of the block and access.

Building designers, also known as "draftspeople", can be a less expensive option than an architect but often with the same result.

Dan Daly is a research fellow with the University of Wollongong's Sustainable Building Research Centre with expertise in energy efficiency, and has done a lot of work on how to make social housing more liveable.

He has also been renovating his own family home on the South Coast, what he calls a "little holiday fisherman's shack" made out of concrete Besser Block.

Like the other above mentioned experts, he believes some strategies should be mandatory for every renovation and new build: putting in as much insulation as possible, making the building as airtight as possible, installing ceiling fans plus energy efficient lighting and hot water systems. Daly did all of the above to his own home renovations as well as adding solar on the roof.

"It is a high upfront cost for solar, but especially as power prices are increasing it's a pretty good financial investment," he said. "It's probably better than sticking money into stocks".

He also recommends getting an "energy audit" or assessment done on existing homes to work out what needs to be improved (assessors can be found online via www.homescorecard.gov.au) which prioritises upgrades.

Or, at the very least, he advises homeowners to live in it for a year and establish how much energy is used in summer and winter, and how cold, hot and draughty it gets.

"There's a lot of things you can do for a very low budget that can make a huge difference to not only your comfort but energy use as well," Daly said.

"On a windy day, walk around your house and work out where the draughts are coming in. Buy some cheap adhesive draft-sealers and go around with a corking gun and fill up the gaps."

Other ideas he suggested were planting deciduous trees and installing temporary shade cloths over windows to block the summer heat.

"It's good design, it's thinking about building a home only as big as it needs to be and doesn't have unnecessary rooms added on," he said for new builds and extensions.

"Make sure the build quality is good, insulation and air tightness are important and putting in the most efficient [appliances] that you can."

One thing all experts agreed upon was the more people who choose sustainable design and materials, the more it would push prices down because everyone would be doing it.

For more information, check out: www.yourhome.gov.au

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