Amidst widespread claims of how hard, expensive and unwanted highly sustainable houses are, there’s one development in the midst of displayhome-land at Kellyville in Sydney’s north-west that is bucking the trends.

Not only are the 145 houses in the Bel Air precinct highly sustainable, the houses are fully sold, even at prices ranging from $690,000 to $1.4 million.

The houses all have solar tiles (not panels) on the roof, high R-value insulation in walls, roof and in the ceiling between floors, double glazing, extremely low air leakage and 40 of the houses could go off grid tomorrow.

Even better is that the housing estate’s proximity to Homeworld display houses means the word is spreading to average first home buyers. So demand for Viridian’s double glazing product has shot up, some customers have tried to take the specifications for the estate’s houses to conventional developers (and been knocked back) and rival developers have taken more than a passing interest.

But additional to the impressive profile of this estate is that lead sales consultant for the project, Abdul Khan, principal of ASK Property, further bucks the trend with a high level of knowledge about housing sustainability. The industry, we’re told, is rife with agents who don’t understand sustainability in houses and in commercial buildings – they ignore even high Green Star and NABERS ratings in their marketing.

Abdul Khan

Khan has had plenty of time to absorb the knowledge.

He’s been working with the developer of the project, Darren Pearson of Diversified Property Group, for several years, watching while Pearson turned around the shape and intention of the family company that had been building regular but high-quality housing in the area for 40 years.

Getting the first sale completed when the project launched in 2012 was tough, Khan says.

“Initially it was a bit of a struggle and it took about two months before we got the first sale under way,” he says.

“But once the first home was up, it wasn’t an issue. People could walk in and touch it. We loved it when they came in off the street and it was 40°C outside and inside it was 20-23°C.” With no airconditioning turned on.

Another good selling trick was closing the window on the jackhammers on the construction site next door. Suddenly it was quiet, thanks to the double glazing.

In reality, Khan says, his team is instructed not to sell, but to walk the clients though the property, explain features and how they work and then suggest customers visit the competition. Typically they take 11-12 weeks to come back and buy, Khan says.

Industry background

All of this is against a backdrop of deep cynicism about sustainability in the residential market and a pervasive complaint that the buyers “don’t’ know/don’t care” about sustainability.

The highly regarded National Energy Efficient Building Project, which we recently reported on, found widespread disregard if not outright rorting of the energy efficiency requirements in residential and commercial buildings by builders, certifiers and assessors, with councils themselves turning a blind eye.

High insulation

At Bel Air the bigger houses have four kilowatts of solar tiles on the roof; three-phase battery systems supplied by BYD, the company that the investment guru Warren Buffett has bought into, and which are guaranteed to perform at a minimum of 85 per cent of original capacity after 25 years;, internal sound insulation of R1.7 and R 4.1 on the ground floor and R6 on the roof, plus sarking; “whirlybirds” on the roof and eave vents to evacuate hot air; and thermal wrap systems under the gyprock finish.

Most of the products come from CSR, in particular its testing lab CSR House, led by Stephen Powell who both Khan and Pearson credited as a critical driver of some of the materials solutions.


“The average house in this estate will use 12.15 killowatt-hours a day, probably less than a third of what normal houses will use,” Khan says.

The low energy consumption has a lot to do with a high level of air tightness. Tests on 10 of the houses shows an average of 9.1 to 11 air changes an hour, which compares with a BASIX rating requirement of 20 an hour and an average in regular houses of 45-70.

The houses aren’t small, though. The biggest size is 489 square metres, but even the smaller single-storey houses have mostly the same finishes apart from a smaller solar system and a slightly lower level of insulation, Kahn says.

The last stage of 45 houses is under way now.

So what’s the secret with the selling success?

In Khan’s view, it’s that the sustainability is not an add-on proposition, he says.

“If it’s incorporated from Day 1 and you say this is what you’re building, the buyers don’t have an issue with that.”

The difference with other developers is that they may offer the sustainability elements as extras. If that’s a $70,000 hike it’s likely the buyers will turn down the option, he says.

But in general, Khan says, the clients tend to be well educated.

“They’re generally quite comfortable with the sustainability issues. Some come from parts of Europe and even China and they understand what’s happening with sustainability and they say, ‘How long will it take for double glazed windows to catch on here?’”

Challenges still to be dealt with

Khan says there are few challenges to sustainability that concern him. Water is one. He prefers not to elaborate but says the barriers erected by authorities prevent much innovation. There are highly efficient taps in the houses but beyond that it’s been difficult to push the agenda, he says.

Another concern is that feeding solar energy back into the grid may not be guaranteed, given surge issues, and that Queensland has already imposed restrictions, he says.

And a frustration was with suppliers struggling to keep up with innovation. Even though the airtightness of the houses meant airconditioning units about a third of the size, suppliers would not guarantee a small system so market expectations for bigger systems won out.

Operation of the houses

Of course as one market observer told The Fifth Estate several years ago, “You can have a 10 star house but have a 2 star occupant”.

According to Khan some of the occupants are highly engaged but others don’t understand some of the principles, such as running appliances in the heat of the day when the solar power is at its maximum capacity.

Another habit is leaving the windows wide open.

On the wishlist, he says, is a manual that can be developed for the houses, much like those produced for cars.

Next round has smaller offerings

Khans says the next project by the group will be much further down the price scale, between $499,000 to $650,000 for two- to four-bedroom houses of about 170 sq m on 310 sq m blocks.

They will all have the same double glazing and high insulation qualities and finishes, a 2-3kW “plug and play” solar system but not solar batteries.

“You will walk into this house and it will have all the luxury fittings replicated. The philosophy of the developer is simple: the price is based on the size of the house, not the inclusions. There is no reason you should not have the same quality; they don’t believe you should discriminate.”

Low profile

According to Khan, the development company has kept a low profile on this development because of the tendency of some developers to over-promise and under-deliver.

However, for those interested to hear more Darren Pearson will be speaking at the NSW UDIA conference in Sydney next week.

Join the Conversation


Your email address will not be published.

  1. The comment about solar feed in and surge issues has also been thoroughly disproven in a recent study conducted in Alice Springs by the Australian Renewable Energy Agency.

    That old myth was generated by the highly resistant incumbent network owners and grid operators.

    The new estate seems a great leap forward, though looking forward to seeing some far more modest homes built with same qualities.

  2. Its fantastic to read this article and to know that things are moving since the Ecoliving Display Home project (Landcom/Clarendon Homes partnership, 2011-2012)in Kellyville in which I was heavily involved.Thanks for the story Tina.

  3. This is great to see a developer buck the trend, you would be amazed at home many people comment to us about sustainable design – for the industry to imply that individuals do not want sustainable design or are not aware of it, they must have their head in the sand!!

    We must break from the BAU mindset and uptake sustainability into residential designs. People really do love it & it offers huge opportunities to reduce out impact on the environment.

  4. I am interested in the air tightness testing that was completed as it is great to see this being adopted in Australia. It will also help the acoustics significantly. Double glazing helps but if it’s not fitted air tight then it doesn’t help at all. 10 air changes per hour is good for Australia, yes, but still under-performing compared to modern regulations in developed countries. The German high efficiency standard Passivhaus for example requires less than one air change per hour. The 20 air changes per hour is just a performance parameter for modelling in the regulations and is never tested. It would be good to see air tightness testing mandated for all buildings as they have done in the UK.

  5. HI Tina,
    Excellent article and development, but I want to take up your claim that “40 of the houses could go off grid tomorrow, if only the authorities permitted (they don’t, at least for now.” There is no law against going offgrid, so I’m not sure what you mean.
    I work on electricity market reform so this is my bread and butter, and if there is any barrier that this development has faced that I don’t know about it I’d like to!

    1. we will look into that. thanks. And the story has now been amended. There may be special agreements in place that relate to that site but our calls to industry sources say in general there is no legal barrier to going off grid.