CSR's eight-star demonstration house, built five years ago in Sydney's west, showed how a new home could be designed to cut heating and cooling needs by half compared with conventional ones. Credit:karl schwerdtfeger As outer suburbs filled with more McMansions squatting fenceline to fenceline bereft of shade from trees, it was inevitable demand strains – not to mention the quarterly bill shocks – would eventually hit home. "One way that we could have avoided all the power blackouts is having people use less because their homes are more efficient and their appliances are more efficient," says consultant Tony Isaacs, an energy expert. Efficiency standards for new appliances have been basically frozen in Australia since the Abbott government took office in 2013. The situation is worse for new residential buildings, with standards largely unchanged since 2010 – excluding a modest improvement in NSW last July – and unlikely to be revised before 2022. The current six-star minimum energy rating imposed on new homes in most states and territories was already unambitious at its introduction.

McMansions were always going to result in high power bills for residents. Credit:Frances Mocnik As Fairfax Media reported on the construction of CSR House in late 2012, an eight-star rated house built in western Sydney showed how – for about $15,000 more – a new home could be designed to cut heating and cooling needs by half compared with conventional ones. "The real tragedy of housing and buildings in Australia is they haven't kept pace with global trends and opportunities," Rob Sindel, managing director of CSR, says. He estimates most of Australia's 9 million homes would have just a one-star rating. "People are getting these horrendous energy bills and are saying, 'my God!'. Exactly what we thought would play out, has played out." Real barbecue stopper

The doubling of energy costs in the past decade has propelled the issue into the public debate as literally a barbecue stopper. Still, perhaps because of its nebulous nature, energy efficiency rarely draws the attention it deserves, particularly on the home front. Isaacs notes the International Energy Agency has pegged energy efficiency as delivering 40 per cent of emissions reductions needed to meet climate goals, eclipsing the 35 per cent cut it expects from renewable energy. "Renewables are sexy but energy efficiency is not," he says. "The cheapest watt you can generate is the watt you avoid using." The Australian Sustainable Built Environment Council had a stab at the sector's potential in a report for ClimateWorks in 2016. Efficiency opportunities using available technology could provide almost $20 billion in savings for owners of residential and commercial buildings by 2030 – a figure likely to have ballooned given energy price increases since the report's release.

"Evidence suggests most business and households could reduce energy consumption by around 30 per cent with a payback of under four years," says Henry Adams, formerly the head of the NSW Office of Environment and Heritage's energy efficiency policy, and now a director of consultants, Common Capital. The sector could also contribute more than half of the federal government's national energy productivity target of lifting efficiency 40 per cent by 2030, compared with 2015. Along with the benefits of lower energy use for the same – or even better – comfort levels, more efficient buildings would also place less load on the electricity grid. That's particularly the case if they are built "solar ready" for panels to be added, CSR's Sindel says. Developers Stocklands and Mirvac, for instance, now build housing projects requiring only a $5 million sub-station when previously they would have spent double that, he says. Emissions role

Being smarter on the home construction front can also significantly cut Australia's greenhouse gas emissions. That's a role made important by the Turnbull government's insistence in its proposed National Energy Guarantee that the biggest single emitting industry - electricity generation - need do no more than a "par" share of the country's Paris pledge of cutting 2005 carbon pollution levels 26-28 per cent by 2030. According to the ClimateWorks report, efficiency gains in building's energy use could deliver more than a quarter of the reduction target if renewable energy is included in the design. The costs of any delay in grabbing these opportunities, though, increase rapidly given buildings are usually with us for decades. For instance, a five-year delay would cost an extra 176 million tonnes of "lost emissions reductions" – roughly a third of Australia's current total annual emissions – as well as blowing $24 billion on wasted energy expenses out to 2050, the report said.

'Golden moment' The commercial sector - at least for buildings larger than 2000 square meters of space - has moved relatively quickly with the initially voluntary and now mandatory National Australian Built Environment Rating System (NABERS). Not so, the residential sector. Despite a COAG agreement in 2004 to introduce ratings on homes, progress has stalled. "There was a golden moment about 10 years ago, when all states and territories agreed to have a mandatory disclosure program," Isaacs says. Elections of particularly "conservative" governments saw that consensus lost. CSR's Sindel blames the building industry: "The great battle has been with groups like the [Housing Industry Association]."

"Members say it's going to make homes more expensive," he said. "The costs of energy now have got to the point where it's just ludicrous that we haven't improved the standards." Industry response Kristin Brookfield, the HIA's chief executive for industry policy, defends her group's role. "HIA has supported the introduction of mandatory disclosure for over a decade," she says. "However this needs to be done in a way that is cheap, practical and focuses on the readily available information in a home. A home owner or real estate agent should be able to easily do an assessment."

The Masters Builders Association, another industry group, says its members are concerned that further regulation provides a "level playing field" so that those complying by the rules aren't undercut by those who don't. "Australia has a climate very distinct from northern Europe and also distinct conditions in different states and territories," the group tells Fairfax. "We are currently seeing numerous issues with condensation and poor indoor air quality due to the push to overlay US and EU standards onto Australian buildings and Australian families." 'Absolute nonsense' As it stands, the existing Nationwide House Energy Rating Scheme (NatHERS) for new homes contains some odd elements. For instance, as CSR's Sindell notes, "in Queensland, if you've got a fan on your deck on your back verandah, you get a star - that's absolute nonsense".

In Victoria, "there's a heavy bias toward winter performance in the building code", says Alan Pears, a senior industry fellow at RMIT University who helped design appliance energy standards. Perversely, houses with narrow eaves, black roofs and large north-facing windows, can boost a home's rating even though those features mean homes work "like ovens" in summer, he says. Pears is among those advocating a split summer and winter rating for homes to help residents know what they're in for, a proposal that may win approval by the next program revision in 2019. 'Moderate uplift' Adding to the complexity is NSW runs its own scheme.

The BASIX scheme specifies summer and winter performance and also attempts to account for more than the energy performance of the house shell, taking into account the appliances used by the household. BASIX got an upgrade last year bringing it close to the NatHERS six-star minimum. The revision "was a very moderate target uplift … we were pushing for a stronger target", says Melinda Dewsnap, sustainability engagement co-ordinator at the City of Sydney. Instead of waiting for NSW to move again, the council has a range of its own schemes aimed at reducing energy waste amount the city's 2000 apartment buildings and other structures. "There's a whole lot of untapped energy efficiency potential in apartments," she says, adding paybacks on investments can be as short as one or two years.

'Appalling leakage' Michael Ambrose, a senior experimental scientist in CSIRO, led one of the few studies to examine how homes actually performed compared with the ratings – derived as they are by desktop assessment of the housing plans. His team found homes were often performing at least one star below the designed standard, suggesting many buyers weren't receiving what they paid for or was required. "Stakeholders believe that code compliance is poor and, further, that Australia's building energy performance falls a long way short of best practice," Ambrose says. "It's just appalling the leaky buildings you're allowed to build here," Ambrose says. "We did a study that found on average new houses were achieving leakage rates four times higher than the rate allowed in Germany."

"I'd love to see a push coming from the residential client. CSIRO is working on Build4Life and Liveability expressly to increase consumer demand, so hopefully it's going to happen, although we will still rely on regulations." The Victorian government is trialling an energy scorecard that could help residents in that state better understand how their homes can be improved, a scheme that has drawn interstate interest, says Isaacs, who helped develop it. A spokeswoman for NSW Environment Minister Gabrielle Upton says the government has consulted about a range of plans including a trial of a ratings systems for homes. A similar scheme has been operating in the ACT for almost two decades. Warming up Policy debates aside, however, there's a creepy reality that is discounting the ratings values themselves.

NatHERS is seeking to rebase its ratings because they currently "comprise of climate data from before 1986 to the end of 2005". According to the Bureau of Meteorology, Australia is warming at an accelerating pace, with temperature anomalies rising from 0.18 degrees in the 1980-89 period to 0.61 degrees for 2008-17. "NatHERS is based on some very old climate data," says an energy efficiency consultant who advises governments. Since homes will last for decades, they should be rated according to "the kind of weather we expect in 20 or 30 years".