Professor Ralph Horne, from RMIT’s Centre for Design, has a warning for new homebuyers: don’t rely on the sticker price.

For the last four years, he’s been working on a project called Lifetime Affordable Housing in Australia. The research was spurred by controversy over the way minimum energy ratings influence the price of housing.

“Some people argue that the regulations make houses more expensive to build and therefore, less affordable – and that they exacerbate an already serious problem in Australian cities,” Professor Horne says.

“So we set out to discover what impact energy bills have on housing affordability. From a household’s perspective, is it better to buy an eight-star house than a five-star house?”

His team analysed over 80 designs from volume builders, modelling changes that raised the ratings as much as possible. Rather than making major alterations to the plans, the researchers upped the standard of the materials, insulation and glazing.

They calculated the cost of stepping each home up from five to six stars, then to seven and eight. Next, they compared those upfront costs with predicted energy savings over time frames ranging from five to 40 years.

“We think the optimal star rating for a house in Melbourne is somewhere between seven and eight stars,” Professor Horne says. “Below that level, householders are worse off: over its lifetime the house will be more unaffordable than if it were built to a higher standard.”

There is a catch, however. The best returns accrue to householders who stay put for the long haul. But while a new house has a lifespan measured in several decades, many people move on within years.

Professor Horne found that when costs are measured over a 40-year time frame, houses that reach eight stars become the most affordable. Based on these results, he argues the case for standards much more stringent than the current six stars.

“When you buy a house, you don’t know how long you’re going to be there. The energy efficiency regulations provide a ‘social payback’ over the lifetime of the building, because they give you the comfort of knowing that if you move, it will be into another eight-star house,” he says.

“We can confidently improve the standards in building regulations without Victorian families being out of pocket. In fact, it would improve the resilience and the ability of those households to pay their bills in the future because those bills will be much smaller.”

Even in the absence of tougher rules, he argues that householders should go beyond the minimum requirements. “For a Victorian family buying a new house they intend to live in, I think a seven-star home is a good place to start. If you go above that, you’ll need to stay there quite a while if you want a private return.”

Professor Horne and his team found that the most flexible designs achieve higher standards most cheaply. Shifting the orientation of a home – to make sure living areas face north – can boost five-star plans by up to a star.

“If you’re building a new dwelling, it is worthwhile pushing your builder to deliver a more energy efficient home. You will save money in the short term and you’ll save even more money in the long term.”

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To slow climate change we must know our own impact

IF you want to deflate your household’s black balloons, you should first pinpoint exactly how many there are, says energy efficiency expert Alan Pears.

Last month, the Environment Protection Authority Victoria launched the latest version of its free online Greenhouse Calculator.

The tool, developed by Mr Pears, RMIT’s Centre for Design and Education Services Australia, connects our household habits with their greenhouse repercussions. It covers car use, public transport, flights, heating and cooling, hot water, lighting, appliances, cooking, shopping and waste.

“One of the crucial messages is that there are lots of ways to cut your carbon footprint,” Mr Pears says. “For example, if you can cut your food waste by not letting it go off in the fridge, it would reduce your expenditure on food – and that by itself would make a big difference.

“The idea behind the calculator is that instead of people throwing rocks at each other or feeling disempowered, they can get a sense of what the issues are, with enough sophistication to look at different ways to solve them.”

In a matter of minutes, the calculator’s “quick mode” will give you a good idea of your greenhouse emission profile. It graphs the results against both a typical and a green household, by way of comparison.

You can then delve into the detailed sections to better understand the areas that interest you, or those in which you fare the worst.

The options are astonishingly comprehensive. You can factor in the withered seals on your fridge or the lack of ventilation space behind it, and watch the emissions rise up accordingly. You can examine the effect on your car’s fuel efficiency when you inflate the tyres, schedule regular services or install roof racks.

“It’s very empowering,” Mr Pears says. “You can explore a much wider range of options for cutting your carbon footprint than you can with any other calculator in the world.

“Some behavioural things have much bigger effect than you realise. For example, changing your heating and cooling thermostat by one degree in Melbourne really does make a big difference to your energy use,” he says.

Among other findings likely to surprise, Mr Pears identifies the super-low emissions of public transport and the dazzling inefficiency of halogen downlights. Likewise, a large flat-screen TV might gobble more electricity than the family fridge (unless it’s one of the “amazingly efficient” new 8-star screens).

And although our shopping habits are often overlooked, they account for over one-third of the average household’s carbon footprint. “I think a lot of people will be surprised by how significant food and consumer items are,” he says.

The calculator’s “weekly shopping” section allows users to compare different kinds of meat and all the food groups, as well as drinks, processed goods and other supermarket products.

Mr Pears says there’s a benefit to the online tool beyond its potential to spotlight excess carbon emissions. “In most households people become fixated on certain things. Someone will say, ‘It’s the kids’ computers’, or, ‘My wife does this’, or, ‘My husband does that’.

“But with the calculator you can specify how many showers you have, long they last and the flow rate of the showerhead. It’s a big opportunity to resolve longstanding arguments,” he laughs. “In that way, it’s potentially a household conflict-resolution tool.”

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Over a building’s life, greener is also cheaper

IN the construction industry, the accepted wisdom is that eco-friendly translates as hip-pocket hostile.

Perth-based engineer Richard Haynes disagrees. Last month, he launched eTool – web-based software that figures out the full greenhouse impact of your new home or renovation.

Both he and his collaborator, Alex Bruce, were surprised by the results when they tallied the long-term costs and impacts of different building materials.

“The most interesting thing we’ve discovered using eTool is that there’s a good relationship between sustainability and prices. Now, even if I was making purely economic decisions, I’d choose many things that are very sustainable, just to save on the costs,” he says.

The reason green products are often cheaper over their life cycle, Mr Haynes says, is because of the higher replacement and maintenance expenses of many conventional products. But those costs normally remain hidden.

Internal fittings and finishes, such as floor coverings, paint and plaster can eat up a hefty portion of a home’s carbon pie, over its lifetime. “When you build, the embodied energy of the carpet might only be five per cent of the carbon emissions, but if you re-carpet every ten or fifteen years, it becomes significant – and in a cost sense as well,” he says.

Similarly, a low-embodied energy rammed-earth wall that doesn’t need painting could prove cheaper than double-brick and plaster, even if it costs more to begin with.

The eTool software is free for householders. It uses life cycle assessment to provide an estimate of the building’s carbon footprint and its likely costs, both upfront and ongoing.

It takes into account the energy that goes into manufacturing the materials, as well as transportation, assembly and maintenance. The program also considers the energy required to run the home once construction is complete, by combining the building’s star rating with extra factors, including the lighting, hot water and heating systems, and the number of occupants.

“We’re engineers, so we’re all about quantifying,” Mr Haynes says. “But our motto is to be vaguely right, not precisely wrong. Any life cycle assessment could be out by a third, due to the differences in the way people operate the same house.”

Based on his research for eTool, however, he has clear advice for anyone considering a building project.

“The best thing you can do is to increase the design life of the home,” he says. “It’s an unfortunate reality in Australia that the vast majority of buildings get demolished for fashion or economic reasons, rather than the building envelope wearing out.”

So how can you prolong your home’s longevity?

Mr Haynes suggests investing in top-notch design, opting for higher density, or renovating instead of rebuilding.

“Better design means the home has a more timeless quality. It will be appealing well into the future,” he says. “And if you can surpass the average density for your suburb then it’s likely your building will be a lower priority for redevelopment.”

Renovating extends the lifespan of the existing home, but for long-term energy savings, you have to do it with passive solar design and energy efficiency measures in mind.

“By preserving the structure, you’re preserving that embodied energy,” Mr Haynes says. “You can make an enormous difference to the aesthetic value and liveability of your house by renovating.”

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