I was recently in Hay in a heatwave visiting Bishops Lodge. Built in 1888, the iron house was designed by the architect John Sulman to combat the Riverina summer heat.
On one of the hottest days this year, the interior of the house felt cool, despite it being built of lightweight corrugated iron and bereft of air-conditioning. Its deep verandas shaded the rooms, its shutters kept out direct sunlight, and natural Cyprus pine sawdust packed its walls and improved the insulation.
Often built at a time when energy was expensive, older buildings use natural heating, cooling, light and ventilation. They do not rely on the grid to let occupants cope with the heat because they have windows that open, and a smaller ratio of glass-to-walls, which reduces the temperature increase inside. Deep verandas cool older houses and wider overhangs minimise heat from the sun. Living rooms on the first floors of Victorian terraces often catch the breeze and escape radiant heat from the ground.
The Bureau of Statistics tells us that one in seven houses built in Australia simply replaces an existing house. Not only will the demolished house have been smaller, it will have consumed less energy. Think of all the energy that goes into those new buildings replacing the old. The building industry is a significant contributor to global resource consumption and greenhouse gas emissions, along with household energy use.
Building construction consumes 32 per cent of the world's resources, including 12 per cent of its water and 40 per cent of its energy. Buildings also produce 40 per cent of the waste that goes to landfill dumps and 40 per cent of air emissions. Household energy use contributes about 9.5 per cent of Australia's total greenhouse emissions.
Left unchecked, the energy consumption of our building industry and housing seem destined to continue to rise. Not only has the average floor area of new dwellings increased by about a third since 1986-87 but the number of people in each dwelling has reduced. We build the largest houses in the world - 44 per cent bigger than they were a quarter of a century ago.
Concrete production alone has increased 400 per cent since 1970 - accounting for an estimated 6 per cent of human-related carbon emissions. Home builders often claim their new buildings are more energy efficient but older houses have a role to play in retaining Australian heritage and reducing our emissions.
A study by the British Empty Homes Agency, New Tricks with Old Bricks, estimates that reusing empty homes could save 35 tonnes of carbon dioxide a property by removing the need for the energy expended on new building materials and construction.
They compared old and new buildings and found that not only did older buildings emit less carbon dioxide, but even a well-insulated new home would take several decades to make up for the large amount of embodied carbon dioxide used in its construction.
It is time to rethink our love of new homes and rediscover the old. And if you must build new, there are significant lessons to be learnt from the past. There is no better place to start than traditional bush architecture, and its construction techniques have never more relevant.
Think of corrugated iron. It is low maintenance, durable and recyclable. Add a veranda for natural ventilation and shading. Collect and store water from large roofs. Consider using earth in building, with its minimal embodied energy and heat storing thermal mass. Use timber - the most common frontier building material now recognised as a carbon-capturing renewable resource with low embodied energy and excellent insulation.
Being environmentally responsible begins at home. Old houses, as well as their potential heritage significance, have immense value environmentally as well as historically. If you seek proof, call in to Australia's oldest surviving homestead, Elizabeth Farm, at Parramatta. On a warm day, sit on its cool, shady veranda and understand that old and green belong together.
Kate Clark is director of the Historic Houses Trust of NSW.
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