When many people hear the phrase ‘green building’ they immediately think high-tech features and finishes. They picture advanced glass, automated blinds that adjust to shield the sun’s rays, blackwater recycling systems, geothermal heating and smart meters that track energy usage.
While ‘green building’ does embrace and encourage the use of new technologies, new designs and new approaches, many new green buildings are revisiting the old designs, old approaches, old techniques and nature’s ‘technologies’ to get better, greener outcomes.
Take a simple concept like solar orientation. There is archaeological evidence that the ancient Greeks built their homes in grid patterns to make best use of the heat and light of the sun in the fifth century BC. ‘In houses that look toward the south, the sun penetrates the portico in winter, while in summer the path of the sun is right over our heads and above the roof so that there is shade,’ the philosopher Socrates observed about the Northern Hemisphere’s early ‘green buildings’.1
Greek playwright Aeschylus took his admiration of passive solar design a step further, noting that only primitives ‘lacked knowledge of houses turned to face the winter sun, dwelling beneath the ground like swarming ants in sunless caves.’
Other examples include the Ancient Romans, who developed the first solar-heated bath-houses and under whom access to the sun was made a legal right with the Justinian Code of Law adopted in the sixth century AD. The earliest green roofs date back to biblical times, such as the Hanging Gardens of Babylon, in modern-day Iraq.
However, sustainable design was not simply a feature of classical civilisation. Many cultures followed basic principles of sustainable design that remain as relevant today as they were thousands of years ago. Nepalese home designs, with their passive solar orientation and shading, high-insulation roofing and rock walls with high thermal mass, have barely changed over centuries. The Cappadocians in Turkey built thermally efficient homes by hollowing out soft volcanic rock, in much the same way that the people of Coober Pedy do today in outback Australia. In America, the Pueblo Indians built their dwellings with south-facing adobe walls to absorb the sun’s heat during the day and then warm the home’s interior at night.
Indigenous Australians used simple, passive design principles to ensure they gained shelter from our nation’s blazing sun while still allowing air flow. The magnetic termite mounds of the Northern Territory are miniature ‘termite cities’ oriented with their broad faces towards the north and south to minimise exposure to the heat of the sun. Their structures keep temperatures stable within the mound, allow air flow and help shed excess rainwater without being washed away. Similarly European settlers soon developed climate sensitive design features. The old Queenslander houses are perched on stilts to improve air flow. Inner-city Victorian terrace houses are pushed up against each other to provide internal thermal mass for stabilising temperatures and the ubiquitous verandah of older Australian buildings provides shade and shelter.
These examples demonstrate that until fairly recently human beings were adept at living in harmony with our climate and our environment. Where did it all go wrong? The post-war economic boom required many homes to be built as quickly as possible. Later, a focus on minimising costs resulted in suburb-upon-suburb of brick boxes. Many were inadvertently designed in a way that ensured they would trap the sun’s heat in summer or block it out in winter, requiring energy-intensive mechanical conditioning to provide thermal comfort.
The invention and commercialisation of air conditioning has led us to lose touch with the concept of building our shelters around the seasons. When the same building design is applied everywhere from the Top End to Tasmania, little thought is given to the local climate and ecosystem. Air conditioning remains a valuable part of indoor environment quality, but should be used to complement good passive design, rather than as the assumed starting point to enable energy guzzling, thermally uncomfortable design possibilities.
Recent multi-residential projects guided by Green Star have relearnt the lessons of the past. For instance, Monash University’s Briggs Hall and Jackomos Hall are outstanding examples of how the application of passive design principles on a relatively low cost ‘design and build’ project can achieve spectacular results. The Green Star multi-residential tool encourages passive design principles through the importance it places on the apartment thermal envelope energy rating scores. Designed by BVN Architecture, these student residences achieved the first five star Green Star – Multi Unit Residential (v1) rating in the country.
Adopting passive design principles enabled the project team to reduce the need to use mechanical air conditioning systems, which typically accounts for 40 per cent of the overall energy consumption within residential buildings. The buildings’ high-performance façades were designed to maximise natural ventilation and manage the solar heat loads. At the halls, window shading, double-glazing, high-performance insulation, trickle ventilation and ceiling fans maximise thermal comfort for the student residents in the warmer months. In the cooler months, energy-efficient gas-fired central boilers provide supplementary heating to the apartments via hydronic radiant panels. These features reduce greenhouse gas emissions, minimising unwanted heat loss and gain year round.
At Victoria Harbour, developer Lend Lease has employed passive design principles on a number of its Green Star-rated developments, including Convesso, Serrata and Forté. Lend Lease believes that passive design plays a large role in keeping down development costs. The installation of high-performance façade glazing and insulation in apartment walls and ceilings has negated the need for air conditioning to individual apartments. Optimal building orientation, open plan layouts and operable windows maximise natural light and cross ventilation while keeping apartments at comfortable temperatures in both summer and winter.
The design principles being applied to these multi-residential developments evoke the attention given to the design for cross ventilation in the Queenslanders of yesteryear. The shift to sustainable building is thus less of a progression and more a return to simple, common sense methods of sound, passive design.
Robin Mellon is Chief Operating Officer at the Green Building Council of Australia. He combines his love of the environment, his passion for gardening, his qualifications in real estate and his experience with heritage buildings to become one of Australia’s experts on sustainability in the built environment.
1. M’Sirdi, Namaane, Howlett & Jain (eds), Sustainability in Energy and Buildings:Proceedings of the 3rd International Conference on Sustainability in Energy and Buildings, Springer-Verlag Berlin, 2012