A green home can not only save money but even turn a profit. But how do you know if you own one? By Stephanie Chalmers

Key points: • Boral is developing lower carbon concrete products, using alternatives to cement • Industry-led Green Star ratings consider everything from building materials to energy efficiency to air quality • Changes to the National Construction Code will be implemented next year, but an energy efficiency rating for existing homes is voluntary • Jason York says his phone has been ringing off the hook for 18 months with people wanting quotes for insulating their homes.
A green home can not only save money but even turn a profit. But how do you know if you own one? By Stephanie Chalmers
"It's getting to the point where I'm having a lot of trouble getting stock in. Keeping up with demand has been a huge issue," he says. 

"When I started in 2016, there was seemingly a lack of confidence that insulation could even work." 

As the United Nations Climate Change Conference in Glasgow approaches, governments and major companies are facing scrutiny over their carbon emissions. 

But Mr York has also found a surge in interest from home owners hoping to regulate the temperature of their homes in an effort to make them more energy efficient and generate a lower carbon footprint. 

Buildings account for about a quarter of Australia's total emissions, largely from the energy they consume, and residential dwellings are responsible for 57 per cent of this, according to the Green Building Council of Australia. 

The Climate Council says poor building standards account for a large part of the emissions, due to heat loss in winter and gain in summer. 

In a report this week it again slammed Australian homes as "glorified tents", arguing that not only do building efficiency standards lag behind other major economies, most homes were built before the current standards were even introduced in 2005. 

As someone who looks inside roofs every day, its an assessment Jason York wholeheartedly agrees with. 

He wants to see building standards tightened to ensure the insulation he installs works as it should. 

"Insulation is obviously going to control thermal properties to a certain degree," Mr York says. 

"But there seems to be this misconception that the insulation is going to achieve magic on its own and it really comes down to the environment: you need to put it in a dry, moisture-free, airtight environment." 

What is a 'green home' anyway? 

Economist Diaswati Mardiasmo has studied the landscape in Australia compared to other countries, and says it lacks a mandated, national definition of what a green home is. 

She describes state and territory-based schemes as "a little disjointed". 

"Each of those standards has its own sort of language … whether it's a scorecard or whether it's a scheme or a grant. So there's always a little bit of misunderstanding and uncertainty as to what they actually are." 

The different measures include solar subsidies, low-interest loans for energy efficient appliances and disclosure schemes for energy efficiency. 

On a country-wide level, the National Construction Code (NCC) contains energy efficiency requirements, and compliance is managed through the Nationwide House Energy Rating Scheme (NatHERS), which gives homes a rating based on their potential energy use. 

A 2019 meeting of state and territory energy ministers agreed to consider changes to improve the current programs. 

Consultation has just closed on the latest round of updates to the NCC, to be introduced next year. 

There is also a new national scorecard to assess the energy efficiency of existing homes, broadening the focus out from new builds. 

Owners of existing houses can now request a NatHERS assessment of their property, but these assessments and the incoming scorecard are voluntary. 

Green homes sell for more 

Aside from reduced bills and greater year-round temperature comfort inside the home, there's another big reason why home owners might opt in to voluntary schemes to assess their home's green credentials, according to Dr Mardiasmo, who is chief economist at real estate firm PRD. 

Her research has found greener homes sell at a premium. 

"They're actually being sold at a much higher price compared to the median price for the suburb, and also [being sold] quicker as well." 

Dr Mardiasmo looked at existing homes with features such as solar panels, water tanks and grey water systems. 

The financial savings from energy efficiency features can be seasonal and depend on individual usage, meaning it can be hard to put a dollar value on the benefits. 

"Whereas if we can prove it from a capital growth perspective, of how much people are willing to buy and that it does sell quicker on the market, that becomes something that is more tangible that a lot of owner-occupiers or home owners will be looking at," Dr Mardiasmo explains. 

In addition to a higher price when owners go to sell, another emerging benefit is access to cheaper loans. 

The Clean Energy Finance Corporation is financing home loans that offer a 0.4 percentage point discount for homes achieving a certain energy efficiency rating under NatHERS. 

Bank Australia and non-bank lender Firstmac are currently issuing the discounted mortgages. 

"That is a sort of national movement, but it's not a mandated national scheme," Dr Mardiasmo says. 

She points to more widespread programs overseas, such as Canada's Greener Home Grants, and tax credits for energy efficient building products or home improvements in the US. 

"Those are the sort of things that I think will definitely make homeowners and home builders more keen and more likely to add on green or sustainable items into their homes." 

Rating green building materials 

The materials used in buildings contribute to their green credentials, including under the ratings system administered by the industry-led Green Building Council of Australia (GBCA). 

"Within the Green Star rating system, we take materials into account … what we're looking at is driving down the carbon in them," GBCA chief executive Davina Rooney says. 

The GBCA is made up of more than 500 members, including private and ASX-listed companies with a turnover of more than $46 billion. 

The GBCA'S Green Star rating system is used to rate everything from shopping centres to office buildings and multi-use developments, considering features like air quality, energy usage, waste water and plants. 

In recent months, the GBCA has expanded its reach in the residential sector, and now offers Green Star ratings for homes. 

It's gone for scale, targeting developers that build large volumes of new homes, such as Stockland and Metricon. 

Features that contribute to the rating include energy efficient appliances, induction cooktops, rainwater tanks, insulation, double-glazed windows and solar power. 

But so far, Green Star ratings are not available for existing properties. 

"When you look at something like a fridge, you go in and buy it, you see a star rating, you can work out how efficient that fridge is," Ms Rooney says. 

"But the biggest asset in your entire life, your house, we don't have a national disclosure system for that in Australia." 

Ms Rooney hopes the ratings system created by the GBCA as an industry body can spur changes to policy, showing market demand is there. 

"The role is for us to put in voluntary standards to lift the market up and make space for regulation to come in underneath," she says. 

"It's our role to show that the pathway is possible and then work with government to bring the standards there as quickly as we can." 

Searching for greener building materials 

In Sydney, a team of researchers is experimenting with concrete — a major contributor to carbon emissions, mostly generated during production of its binding agent, cement. 

According to the International Energy Agency, cement production accounts for 7 per cent of global emissions; carbon dioxide is released when the materials used to make cement, including limestone, are heated in a kiln. 

Dr Louise Keyte, co-director of a research partnership between UTS and Boral, says the recipe for concrete is looking very different from two decades ago. 

"To move to a low-carbon binder, we need to use other substitutes instead of cement," she says. 

"Every gram of cement we take out, we reduce the CO2 content." 

Boral has lower carbon concrete products already on the market and development continues — but they need customers willing to buy what they're selling. 

"When you think about construction, and particularly high-rise or key infrastructure, there's always going to be an element of conservatism," says Boral CEO Zlatko Todorcevski. 

"It's up to us to work with those specifiers to make sure they understand how our products perform under different conditions, and give them the comfort that these things will last for multiple decades, if not longer." 

Mr Todorcevski says several state governments have recognised new Boral products for road building, which helps prove the business case. 

"That's great, but you know, it's early steps and quite small steps," he said. 

"We'd love to see governments and other specifiers go on the front foot and be really proactive."