constructireland.ie - Alive and well

Alive and well

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Designing sustainable buildings doesn’t always mean hi-tech solutions. From green roofs to living walls to constructed wetlands, sometimes it’s just a matter of embracing natural solutions. Lenny Antonelli investigates the emerging technologies and designs that use nature to improve the performance of buildings.

When Erik van Lennep says he wants buildings to be greener, he means it literally. “Our goal is to maximise green roof coverage in Dublin,” he says. That goal could soon be within sight, as Dublin City Council takes the first steps towards embracing green roofs.

Van Lennep, the founder of sustainability consultancy Tepui, has prepared guidelines on the types, functions and advantages of green roofs for Dublin City Council’s planners. His guidelines also recommend the introduction of a green roofs policy for the city, and the installation of green roofs on existing council buildings. “At the moment we’re just giving advice to our planning department. It’s up to them to request green roofs,” says Mairead Stack, Dublin City Council’s biodiversity officer, who along with van Lennep has been at the forefront of pushing green roofs in the city. “We’ll be strongly trying to incorporate a green roofs policy into the council’s next development plan,” she says.

Such a policy could request developers to include green roofs in certain cases. The Greater London Authority’s latest development plan demands major developments to “incorporate living roofs and walls where feasible.” In Basel, Switzerland, all new and renovated flat-roofed buildings must be greened to a depth of at least 10cm, while in the Austrian city of Linz all new flat-roofed buildings over 100m2 must include green roofs.

Green roofs aren’t a new technology. Newgrange is the earliest surviving Irish example, while in northern Scandinavia sod roofs and walls, some still surviving, have been around for centuries. The development of modern green roofs began in 1960s Germany, and it is estimated that ten per cent of the country’s flat roofs have since been greened.

There are three basic types of green roof. The extensive variety reaches a depth of 200mm, is light and easy to maintain, and features moss, sedum and grass species. Intensive green roofs can be up to 500mm deep, and the roof must often be designed specifically to support this heavier load. Regular maintenance is needed, but they can support all types of trees and shrubs, and act as true rooftop gardens. Semi-intensive green roofs sit in between; they require moderate structural support, and are limited to shrubs, perennials and grasses. German company Bauder has been supplying both extensive and intensive green roof systems to the Irish market for many years, including landmark eco buildings featured in previous editions of Construct Ireland such as Navan Credit Union, Daintree, and Mater Orchard, to name but a few.