Lessons from Wavertree House

Featured in this year’s Sustainable House Day program, Wavertree House is an off-grid home in Darwin River inspired by the tropical architecture of 1930s government architect Beni Burnett. Andrew Spiers discusses the ideas behind the project and what contemporary Australian housing can learn from designing with climate rather than against it.

NATHAN SCOLARO: For readers who may not be familiar with Wavertree House, can you tell us a little about the project and what motivated you to build it?

ANDREW SPIERS: Since getting married in 1971, Helen and I had always had government jobs in remote areas that required us to rent a government-supplied house. So when we finally moved to the Big Smoke (Darwin) in 2002, we had to, for the first time in our lives, find a house of our own. We had lived in Jabiru, in Kakadu National Park, for 16 years, so we had plenty of time to evaluate the kinds of house designs in use in the Top End and how they performed in the climate here. The most common house design incorporated a lot of thermal mass, poor reflectivity and poor to non-existent airflow, relying on a bevy of air-conditioners to try to compensate for its design inadequacies.

Our search for a well-designed house on the market was fruitless. The remaining famous post-war elevated houses in Darwin turned out to be poorly designed, poorly built, uncomfortable to live in and had not aged well because the government department that built them had skimped on everything (which is why most of them had blown away in 1974). The best passively cooled houses seemed to be those built before World War II, designed by the government architect at the time, Beni Burnett.

However, people who owned those houses were understandably reluctant to sell them.

We concluded that our best option was to buy a block of land and design and build our own house. Well, building it would require some professional help, but having completed a Planning degree that included architectural design, I felt confident that I could tackle the design task.
Wavertree House draws inspiration from the work of 1930s architect Beni Burnett. What first attracted you to his designs?

We visited some friends who had bought a Burnett house that had been moved from the CBD to a rural area. It was the first house we had seen that incorporated most of the design elements I thought would perform well in the wet-dry tropics.
I discovered that several Burnett houses had been preserved in the Myilly Point Heritage Precinct in Darwin, and I was able to look more closely at what Burnett had been trying to achieve in making Commonwealth public servants comfortable in a town with no reliable water or electricity supply at the time, and an employer who refused to provide fans.

Which elements of Burnett’s architecture had the greatest influence on Wavertree House?

Having spent all of his career to that point in China and Singapore, Burnett was not chained to the conventions of British middle-class suburban architecture like his Australian peers. He already knew that a tropical house had to have high reflectivity, low thermal mass and high airflow throughout. To this he added a high roof pitch and a sturdy frame to withstand tropical storms and cyclones. He was also careful to orient houses to make the best use of natural breezes where possible.

I wanted to incorporate all these elements into my house design. I felt that the new availability of materials such as Zincalume cladding, steel frames and Aircell reflective insulation would enable a modern version of his design to outperform the 1930s model.

Burnett was designing for Darwin’s climate nearly a century ago. What do you think he understood about housing that we’ve since forgotten?

Post-World War II, the Commonwealth government decided to provide cheap housing in Darwin. The houses they designed watered down or ignored most of Burnett’s design elements. After Cyclone Tracy, they ignored the fact that Burnett’s elevated houses had survived the winds and instead built concrete and brick bunker-style houses at ground level. This suited southern architects and builders because they could mass-produce the type of British middle-class housing they had been populating Australian cities in the temperate zone with for decades. It was wrong for the tropics. It still is, even with the advent of solar-powered air-conditioners.

It created a demand for electricity that Darwin’s power provider was unprepared for. Even the most modern housing developments in Darwin have high thermal mass, making them effectively pizza ovens that stay warm all night; little to no airflow because the windows are small or badly located; houses that are too close together and not oriented to make use of natural breezes; and, in most cases, roof pitches that are too low. There was even a period when roof reflectivity was banned by regulation.

Having now lived with the house, what aspects of the design have performed particularly well?

As I mentioned before, the use of modern building materials enables our house to outperform its 1930s forebears. There is no wood in the structure, so maintenance is low. The lack of thermal mass does mean that when night-time outside temperatures are low, the inside is very cool too. This sees us donning woolly jumpers and putting an extra quilt or two on the bed during the dry season.

Has anything about living in the house surprised you?

I guess we are always surprised when something we have worked hard for and overcome many obstacles to achieve actually meets our expectations. We are therefore constantly and pleasantly surprised that our house is so enjoyable to inhabit.
The house relies heavily on passive design and natural ventilation. What has it taught you about comfort and the way Australians think about cooling their homes?

Our modern built environment, coupled with the advent of vehicle air-conditioning, means that most inhabitants of our cities—and Australia has, contrary to our popular bushwhacking myth, one of the most urbanised populations in the world—can never acclimatise to real-world weather. A passively cooled house is comfortable, but it also allows you to appreciate the natural world, with its weather highs and lows.

Modern building codes rely heavily on air-conditioning and, in some cases, effectively make it mandatory by restricting the number of windows, preventing air exchange with the outdoors and insisting on the use of materials with high thermal mass in some types of development. The inhabitants of modern cities often do not realise there are alternatives available to them. Their aspirations for housing are shaped by what they see around them, what they grew up in, what their friends are buying and what developers are promoting.

To include all the elements of my design, I would have needed to apply for an exemption to the building code. Nobody told me that option was available, so I designed around it to get what I wanted. I doubt that my builder, engineer and architect knew about this clause either. “They didn’t ask!” replied the planning officer I complained to.

If the professionals are kept in the dark, how can we expect the layperson ever to know? If all we have ever seen is British middle-class housing, that is what we will aspire to own. If our house cannot be comfortable without lots of air-conditioners bolted to the walls, then the more, the merrier.

Climate change is increasing the frequency and intensity of extreme weather events. How did resilience shape the design of Wavertree House?

The weather in the Top End is naturally extreme and it is home to the largest species of termite in Australia. If the house is to be located on a natural bush block with a river running through it, it has to be prepared to withstand frequent bushfires and the occasional flood. I knew that I had to design a house that was waterproof, non-flammable, inedible and capable of surviving high wind loadings.

One might ask what more climate change could throw at us than that. But it is true that Darwin may become nigh on uninhabitable with the rise in temperatures forecast for this century. Our passively cooled house includes design elements that allow some spaces to be air-conditioned during heatwaves, and we have upgraded our solar power system to cope with that. We chose a location on the block to minimise flood risk. We upgraded the insect screens to better resist ember attack from the frequent human-caused wildfires we have been experiencing. We also upgraded window protection for cyclone resilience by installing both louvres and roller shutters on large windows.

During earth tremors, the steel frame is very elastic. We rock around a bit and then return to normal without the usual legacy of cracks and fissures that brick, block and concrete houses in Darwin often display.

Which climate-related risks do you think Australian homes are least prepared for?

I think we are already seeing that the current Australian housing stock is ill-prepared for floods and wildfires.

Heatwaves are taking an increasing toll, especially on those who cannot afford to install or run air-conditioning, or when our antiquated power grids become overloaded during extreme events. Lower-income families and pensioners are the most vulnerable because low-cost housing is often substandard when it comes to climate resilience.

That is not to say, however, that resilient housing must be more expensive than the mass-produced but substandard houses we commonly see today. Good design can produce resilience without an accompanying higher price tag. I think we demonstrated that with Wavertree House.

As climate change intensifies, what lessons from Burnett’s architecture could help shape more climate-resilient housing across Australia?

Burnett was realistic about the climatic demands that would be placed on his houses and designed accordingly. Today’s developers prefer to offer profit-maximised kit houses no matter where they are located. They like to squeeze as many dwellings as possible into the available space, regardless of local conditions. Little or no thought is given to climate, landscape or social amenity. Marketing overrules good design sense.

A classic example is the number of Darwin developments that boast outdoor entertaining spaces while being located within midge fly zones around coastal mangroves. The hapless purchasers never get to use their BBQ areas or balconies and cannot open their windows to enjoy the evening breeze. If we have not got that right now, what hope is there that we will make appropriate adjustments to future developments? Of course, housing in many of these locations may become uninhabitable due to sea-level rise in any case.

Many Australian homes are still built to standard designs regardless of climate zone. Do we need a more regionally responsive approach to housing?

As I have alluded to above, the one-size-fits-all approach to planning, designing and siting housing has failed miserably. Profit-seeking has overridden good planning to the extent that whole suburbs and even towns are now, or will soon become, uninhabitable and will need to be demolished or relocated.

An American geomorphologist once said that the floodplain is part of the riverbed—only the river is not there all the time. “Anyone who is living on a floodplain and is surprised by a flood hasn’t been paying attention.” Our planners, local authorities, governments and developers have not been paying attention for a very long time in Australia. Climate change is beginning to wake them up.

Based on your experience, what are the most common mistakes people make when designing or renovating homes in a warming climate?

I do not work in the building or renovating sphere, so I can only draw on conversations I have had with people about their hopes and plans.

Few people these days, including builders and designers, know much about basic physics. Good tropical and climate-responsive design should be based on an understanding of heat conduction, convection and radiation. It took me four years to find a builder in Darwin who would agree to build our house to our specifications. Most refused to depart from the techniques and materials they learned during their apprenticeships—techniques that seemed largely unchanged for hundreds of years.

They were happy to ignore the installation specifications provided by insulation manufacturers, preferring their own “much easier” methods. As a consequence, the insulation could not do its job. I was taught to include an air gap between roof cladding and reflective insulation in my architectural design course in the 1960s. Yet in the twenty-first century builders were still refusing to do that, and architects had largely capitulated. “You won’t find a builder in Darwin who will do that, so I don’t include it in my drawings anymore,” one architect told me.

Society as a whole has become reliant on technological fixes, many of them energy-hungry and contributing to global warming. Good design based on simple physical principles often does not occur to people.

Staff in Darwin’s planning department once insisted that any passively cooled house I designed could never be cooler inside than the outside shade temperature. They had proved this, they said, by placing heat sensors in many different styles of houses throughout the city. A basic knowledge of mammalian biology would have told them something their sensors could not: if you move the air inside the house, the people living in it will feel cooler than the shade temperature because of our built-in evaporative cooling system.

Even John Knight, the government architect in Palmerston (now Darwin) in the nineteenth century, recognised this and incorporated it into the design of his own house.

Many people who have visited Wavertree House during Sustainable House Day have said: “This is the type of house we wanted to build, but they told us we could not.” If the regulators, builders and even designers cannot get it right, how can homeowners ever achieve their dream of a sustainable and resilient house?