Australian Architects Peter Poulet and Michael Harvey contemplate concrete’s green side with The Concrete House, a free-flowing assembly of gravity-secured precast columns and slabs that the designers call a “commitment to living sustainably”. With renewable energy systems, a green roof, rainwater harvesting and waste minimization, the design tries to prove that concrete is an environmentally appropriate choice.
The challenge is part of an ongoing debate. Worldwide, concrete is the most widely-used construction material with over ten billion tons produced annually. In the US, the dubious manufacturing process churns out over two tons of concrete per person per year with a heavy CO2 burden – in total about 7% of global CO2 emissions come from concrete production.
At the same time, the material possesses a unique structural efficiency and inherently green qualities like a capacity to reduce recurring embodied energy, high solar thermal performance, low maintenance requirements and high durability. Variations of concrete with high solar reflectance are considered for heat island mitigation, and with no-offgassing, concrete is an interior finish that meets IAQ standards. Substituting Portland cement with fly ash, using recycled aggregate and a locally fabricated supply can reduce concrete’s environmental impact.
In The Concrete House, curvilinear thermal mass on the southern exposure transfers constant temperatures to open spaces on the north where folding doors allow natural ventilation and daylight. A green roof helps increase the structure’s thermal performance and is central to on-site graywater recycling and rainwater harvesting. The water can be stored in the precast concrete columns.
Intended for solar thermal hot water and solar photovoltaic power, the pavilion-like design creates an immediate connection with the environment that carries through to energy and resource consumption. Based on an inexpensive, widely available and easily applied material, The Concrete House can be assembled in less than a day.
Poulet and Harvey’s design puts concrete in its best light with a concept that highlights the energy laden material’s role in green building. In a minimalist application such as The Concrete House it seems that concrete’s greenness is not cemented in black or white but filled with innovative shades of gray.