The way to reduce the ecological impact of our built environment is to build with nature, not against it.
In order to fulfil his brief to create a ‘comfortable house’ for a family in the Sydney suburb of Kirribilli, Luigi Rosselli harnessed the elements: earth, water, wind and light.
Rammed earth is the most conspicuous element of Kirribilli House. Not only is it aesthetically striking – lending the building a high degree of textural interest and an earthy, orange colour – it is also a highly-effective and economic means of insulating the residence.
The materials for the rammed earth – a locally quarried mix of clay, sand and gravel – were stored, mixed and formed on-site; a process that required a large amount of space. However, unlike other materials such as brick and cement, this quarried mixture was not reliant on energy-intensive production methods. Neither is rammed earth dependent on steel reinforcement for its ongoing structural integrity.
A contractor was brought on to mix the quarried materials and to place the resulting combination within the formwork. Once mixed and placed, pneumatic rams were then used to compress the earth layer by layer. Each layer of rammed earth was approximately 30 centimetres in width, meaning the walls needed to be between 300 and 450 millimetres to accommodate the process.
The final result is a rammed earth wall that runs the length of Kirribilli House, providing climactic comfort and textural interest. The home’s rammed earth ‘spine’ links all levels of the house, capturing heat during the day and keeping the house cool through the warmer months. The stored heat ensures the home is kept warm at night, resulting in minimal extraneous energy needs.
The other stand-out feature that rounds out Kirribilli House’s temperature control is the staircase. As well as providing the main physical circulation for occupants of the building, the staircase helps to circulate air throughout the home via the water frontage outside.
Extending all the way from the lower level of the home to the green roof, the staircase draws cool sea breezes and basement air up from below resulting in what Rosselli calls a ‘chimney effect’. Running alongside the rammed earth wall, allowing the wall to draw moisture from the airflow through evaporation and effectively cooling the wall’s temperature. Together, these two complementary elements form a built-in, ecological air-conditioning unit for the home.
In winter when there is not as much available heat to collect, linear skylights to the north of the rammed earth wall step in. Strategically placed to capture the sun’s rays, this glass roof maximises light and heat from the day, while adjustable glass louvers allow the building’s occupants to control the light’s intensity.
A green roof, solar power, an integrated rainwater collection system and a landscape design by Terragram round out the ways Rosselli has ensured a low ecological footprint for Kirribilli House. In doing so, he also secured for himself a 2011 Australian Institute of Architects NSW sustainability award.
