Designing 10 Star homes

The more energy stars your home has, the more comfortable it is, with less need for heating or cooling. A 10 Star home should need no heating or cooling whatsoever.

All new buildings in Australia have to be built to a minimum 6 Star rating. Stars are calculated using Nationwide House Energy Rating Scheme (NatHERS) software which uses computer simulation at design stage to assess the thermal performance of a home. NatHERS looks at elements such as orientation, layout, construction materials, insulation and glazing.

The Australian sustainable building guide, Your Home, estimates that 38 per cent of a home’s energy use is for heating and cooling, so a 10 Star home should save significant greenhouse gas emissions and money on bills, year on year.

So why are so few 10 Star homes built in Australia?

Lack of knowledge in the building industry is holding back affordable high-performance solutions, says Tim Adams, principal of F2 Design and former president of the Building Designers Association of Victoria BDAV).

Adams has been instrumental in promoting 10 Star homes in Australia. He helped launch the BDAV’s 10-Star Challenge in 2011, a competition that awards the best 10 Star designs. “The idea behind the contest was to get building designers and energy raters to go through the process of designing a 10 Star house,” he says. “By going through that process they gained an understanding of what’s required to design to 10 Stars, and from then on designing 7 or 8 or 9 Star homes was so much easier.”

Dick Clarke from building design firm Envirotecture agrees: “Striving for 10 Stars is useful as it can develop techniques and materials that will trickle down to make the broad adoption of 8-plus Stars more affordable.”


But is 10 Stars economical? It can depend on where you live, says Tim Ellis from Timothy Ellis Building Design. “Having done 10 Star designs for both Victoria and northern Queensland, I have found that in general the measures required for 10 Star housing in Victoria add more to build costs. Designing for cooler climates tends to be a more expensive proposition.”

But the savings can be more significant, says Trivess Moore, research fellow at RMIT’s College of Design and Social Context. He says moving the discussion away from ‘affordability versus sustainability’ is vital.

Sustainable home design basics

Building or renovating a home can be one of the most challenging – and rewarding – experiences in a person’s life. The results will be with you for years, and perhaps a lifetime, so getting it right from the beginning is crucial.

Here’s our list of things to consider when designing, renovating or making small improvements to your sustainable home.

Create a comfortable eco home with passive design

A passively designed home makes the most of natural heating and cooling methods to keep its occupants comfortable year-round. Orientation, spatial zoning, thermal mass, ventilation, insulation, shading and glazing are the seven core components of passive design, explains sustainable designer Dick Clarke of Envirotecture.

Orienting your home correctly is particularly important in temperate and cool climate zones. When a building is able to let the sun in during cold seasons and shut it out when it’s hot, the other six principles of passive design can be balanced to create homes that require minimal active heating or cooling. Good orientation from a passive design perspective generally means locating living areas on the north side of the house, with glazing having clear access to sunlight even in mid-winter.

Design for your climate

Different climates need different houses. Australia has more than 80 climate zones but these are often simplified to eight, ranging from tropical to alpine. Make sure you employ a designer who is familiar with your zone and who designs climate-appropriate buildings – for instance lightweight and ventilated in hot, dry climates; well-insulated and with good solar access in cool climates.

In tropical and hot, dry climates, orientate the house to exclude the sun year-round and to maximise cross-ventilation. In all other climates, your aim should be to minimise summer sun and maximise winter sun, which basically means a northern orientation. Couple your passive solar design with thermal mass (materials such as concrete that absorb heat energy, or a ‘proxy’ such as a phase change material) to retain the warmth of winter sunlight and/or the cool of summer shade.

Design for life

Make sure your home is designed for the long haul, and that its materials are durable and able to be easily reused or recycled. Crucially, when designing your house, think ahead. Will your family grow, will it shrink or will it stay stable? How will your own health impact your needs in 10 or 20 years time? With these things in mind, you can design a house that not only meets your current needs, but can adapt to your changing needs without you later incurring the cost of an extension or renovation.

This approach doesn’t only apply when you’re designing a new home; it is relevant when you choose appliances for your kitchen, furnishings and more.

Size matters

Australians have some of the biggest houses in the world. Yet the smaller a home, the easier it is to achieve higher energy efficiency standards, and the lower the upfront and ongoing costs, says Trivess Moore, research fellow at RMIT’s College of Design and Social Context.

Smart heating and cooling

Active heating and/or cooling may be necessary in many Australian homes but don’t rush to buy a heater or air conditioner when you may not need one. First, consider how you can improve your home to make it more comfortable. Australian homes are traditionally ‘leaky’ and draughts can be responsible for up to 25 per cent of your heating costs – a similar amount if you air condition. Seal any leaks, use curtains and blinds, make the most of the sun’s heat and shading to moderate your home’s climate, and insulate. If you need air-conditioning, make sure you also have ceiling fans, which significantly increase its efficacy.


One of the most effective ways to save money on energy bills and make your home more comfortable is to insulate. Insulation acts as a barrier, preventing heat passing in and out of a house. By reducing this heat flow you can more easily maintain a comfortable temperature inside, regardless of the temperature outside. In winter, once your home has been heated to a comfortable level, it will stay that way with less energy input than an uninsulated home. In summer, an insulated home will take longer to heat up, requiring less energy for active cooling. Insulation is not just limited to the roof – you can insulate your walls and floor for maximum energy efficiency.

Be energy smart

Lighting makes up about 11 per cent of the energy consumed in a typical home, about the same as refrigeration. Households can reduce energy use for lighting by 50 per cent or more by making smart lighting choices and using more efficient technology. Spending a little time and effort to get the lighting right in your house can save you money on energy bills and make rooms more comfortable and enjoyable.

It is important when considering the energy consumption of lighting to look at wattage, not voltage. Wattage measures electrical power, while voltage measures the electrical pressure or force a device runs at. Some bulbs, especially halogen downlights, are sold as ‘low voltage’, with many people thinking this equates to low energy consumption. This is not the case. The important factor is the power rating – 50 watts, for instance, is exactly that regardless of the voltage at which it is supplied and used.

Use sustainable materials

Your choice of building materials can have ramifications far beyond your home. Inappropriate use of materials in building means one thing: waste. All materials have an embodied energy, which is the energy used over their lifecycle, from processing of raw materials, to manufacturing through to product delivery. If you build your house with poorly chosen materials, their embodied energy could diminish or cancel out the benefits of years of sustainable living.

Generally, the more processed a material is, the higher its embodied energy. So choose sustainably sourced timbers, recycled and locally sourced materials, and low volatile organic compounds (VOC) paints and finishes. When building, keep material use to a minimum. If you’re renovating, reuse what you can from the pre-existing building.


Windows and glazed doors can let in (and out) substantial amounts of heat. So even if you’ve installed insulation, go for double glazing. As a general guide, the total window area of your home or a room should be less than 25 per cent of the total floor area. Most windows should be located on a home’s north side where good solar access is easiest to manage.

Be water wise

Use three or four WELS star-rated shower heads, toilets and water fixtures. Catch your rainwater in tanks for use in the bathroom and garden and look into getting a wastewater treatment system. Use drought tolerant landscaping.

Select efficient appliances

An inefficient appliance can mean a lot of wasted energy as well as more heat in your home – which can be a problem in summer or in hotter climates.

When looking for an appliance, try to select the most efficient one that meets your needs and budget. Don’t forget to check product reviews – a high-efficiency appliance that has a high early-failure rate will cost you and the planet more in the long run.

Stay engaged

Our final sustainable home design tip is to stay tuned in to your home – its needs and yours – to make the most of passive solar design. Open and close blinds, doors and windows to let sunlight and breezes in or keep them out. Remaining engaged can help lessen your environmental impact and ensure your home is performing as well as it can, all the time. “As a sailor adjusts the sails on a yacht, sail your home through the year’s changing climate, working with the forces of nature to power its natural comfort,” says Dick Clarke.


Speed date Sustainable Designer Adelaide wrap

Downton talked about ecological architecture, asking what designing with nature is. “Being green has got lots of different ways of being achieved.”

“Fundamentally what we’re trying to do is fit our human habitation on the planet and work with the forces of nature in a positive way rather than the negative way we’ve possibly managed to do almost entirely up until now,” said Downton.

“Generally sustainable building requires and understanding of processes. Architects and builders for many years have dealt with gravity very well because we’ve noticed that if things fall down it’s a problem. What we have appreciated yet is that ecologies, ecosystems can also collapse and be damaged and cause problems and impact on us. But because it happens very slowly, and we don’t understand the processes, we don’t really get it. We’re beginning to understand, and I think many people here…but the living environment is what we need to be concerned about.”

Downton was amongst three speakers and over 20 sustainable home design and living experts who held speed dates with over 180  Adelaidians at Speed Date a Sustainability Expert last weekend.

The event, held by Sanctuary’s publisher the ATA in conjunction with the City of Marion, partnered householders with leading Australian sustainable architects, building designers, water saving and permaculture gardening experts to give them advice on homes and lifestyles that are more environmentally responsible.

Architect Emilis Prelgauskas said the householders he had ‘dates’ with varied in their focus and interest in sustainable homes.

He said it is key that householders understand from the beginning of their home improvement journey that a small increase in initial build costs can benefit them in reduced maintenance and operating costs and increase lifespan.

“Sustainable build experts have an obligation to continue to inform intending homeowners about what has already been achieved, and what best practice [sustainable design] is aiming for in the coming years,” he added. “The general public impression that minimum compliance ‘6 Star’ energy ratings is somehow even scratching the surface of sustainable homes needs to be put into proper perspective.”

ATA chief executive Donna Luckman said Speed Date a Sustainability Expert was an excellent opportunity for people to learn how to make their homes more comfortable and save money while lessening their environmental footprint. “Adelaide has some of Australia’s most creative and thoughtful green architects and designers,” Ms Luckman said. “This event gave people a chance to speak directly with them for free. It’s lively and it’s fun!”

Hemp house opens for Sustainable House Day

On Sunday, September 8, an 8-Star energy efficient house with hempcrete walls in the Melbourne suburb of Northcote will be open to the public as part of Sustainable House Day. It is designed by leading sustainable architect, Steffen Welsch.

A family of four – Michelle and Chris and their two children – live in the hemp and rammed earth house. It’s an outstanding example of sustainable design with a cleverly conceived courtyard that maximises natural sunlight, lots of thermal mass and a range of energy and water saving measures.

The not-for-profit Alternative Technology Association (ATA) is co-ordinating the public opening of the house and will feature it in the next issue of its sustainable home magazine, Sanctuary.

Sarah Robertson, the editor of Sanctuary, said the home was not solely an example of sustainability in action, but beautiful to be in as well.

“The exposed hemp and rammed earth walls give the living spaces amazing texture and create very homely and peaceful spaces,” she said.

“Sustainable House Day will allow people to see this home and learn from the homeowners. It’s a real treat to visit.”

Steffen Welsch said hemp had strong environmental credentials as a fast-growing plant that stored carbon dioxide.

“It’s very easy to resource, has very low embodied energy and the potential to make a wall carbon-neutral,” he said.

“You need a good client who is prepared to take a risk and Michelle and Chris were happy to try a relatively new material.”

To find out where this and other open sustainable houses are, go to the house location page on Sustainable House Day website and search for Northcote.

Sustainable House Day 2013

Homeowners around Australia are aided by community groups and volunteers as they set this Sunday aside to guide visitors through their homes in the name of sustainable design and living.

Solar passive house design, energy efficient appliances, solar power and solar hot water, sustainable products and innovative and recycled materials are just some of the features you can expect to see in homes on the day. It’s a chance to see what resourceful homeowners, whether they are owner-builders, renovators or designers, have done to make their homes energy efficient, environmentally responsible and built for life.

It’s the homeowners who really make SHD a success. They share their triumphs, challenges and their learning experiences from their journey to create a liveable and sustainable home. Many have found past SHDs so helpful for their own projects they are happy to share their own experiences.

“We opened for Sustainable House Day in 2012 to allow other people to benefit from our learnings as we have learnt from others. We also wanted to show people that building a sustainable house is not a daunting task,” says Melbourne homeowner Peter Whelan.

Running since 2001, the day always attracts thousands of visitors. In 2012, over 200 homeowners opened their doors to over 40,000 visitors around Australia. This year, a similar number are expected to open again. The 2013 event will also feature some special events. In Western Australia, Josh Byrne will officially launch his Josh’s House Project. In South Australia, the Zero Carbon House will be open for the first time to the public and in the ACT a people will be able to visit a carbon zero dairy farm.

This SHD special features houses from around the country that will open this year or have opened in the past. Inside, you’ll also find tips on the basics of sustainable design.

See Sanctuary Issue 24 for profiles and interviews with homeowners who have opened their doors on Sustainable House Day in previous years.

More information on the Sustainable House Day website.