Architects can improve the sustainability of our cities in diverse ways. Repurposing existing buildings rather than demolishing them is an obvious one. Specifying greener construction materials such as timber in highly insulated, low-energy (or even net energy-producing) new buildings is another. Then there are off-the-wall approaches, such as completely enclosing an existing building in a greenhouse — as some Scandinavian architects have done — creating a Mediterranean micro-climate where grapes and figs flourish.

One of the entries shortlisted for this year’s World Architecture Festival’s Building of the Year award combines all three of these measures. First, it will repurpose a 19th-century nail factory in Nydalen, Oslo, into 110 apartments. Second, the central nave of the 150-year-old brick building will be transformed into a public winter garden with a glass roof. Third, accommodation will be in tower-block extensions constructed from engineered timber (such as cross-laminated timber, a form of jumbo plywood as strong as steel).

The project, in WAF’s Future Residential category, is I Love Nydalen by Norwegian firm SAAHA.

The firm is only four years old. “As a relatively new company [being shortlisted for WAF] gives us international exposure,” says Adnan Harambasic, partner at SAAHA. The young firm’s work has been mostly in Norway, where Harambasic notes that “even traditionally conservative clients are taking steps towards more sustainable buildings”.

The winter garden in I Love Nydalen © SAAHA

Meanwhile, still on the drawing board, the three timber towers proposed to sprout from the former nail factory in Nydalen will range in height at six, eight and 16 storeys. Unusually, SAAHA has designed these upward extensions to be constructed entirely of engineered timber, even the core of the lift shafts, which are usually made of concrete and steel. The idea of living in a wooden tower block may seem foolhardy. But massive engineered timber does not catch fire; instead, it chars, protecting the interior. “We have the necessary knowledge to build high-rise timber structures with high fire safety,” says Harambasic. “Properly used, wood is a light, lasting, renewable construction material with excellent fire-resistance as well as soundproofing and hygrothermal [humidity moderating] properties.”

Harambasic makes a strong argument for building with wood on a bigger scale. “As the Earth’s life-support systems begin to reach the point of no return, the need to make a transition to a more sustainable way of living and working is not only necessary and desirable, it is urgent,” he says. “In this context, reducing greenhouse gas emissions is one of the pressing issues for the building industry. Wood is the most significant building material we use today that is grown by the sun. When harvested responsibly, wood is one of the best tools that architects and engineers have for reducing greenhouse gas emissions and storing carbon in our buildings.”

Read the whole article at Financial Times