Green roofs: it isn’t all rose colour in this eco trend

An idea that is flourishing in cities around the world, where many acres of potential space are found above buildings and houses.

An aerial view of most urban spaces shows strips of asphalt and black tar. Heat radiates out of dark ceilings and water rushes on hard surfaces. However, there is a new trend that breaks the monotony: green or living roofs. For a long time, mainly in Europe, this technique began to attract homeowners, businesses and even cities as an attractive way to promote ecology. Green roofs complement the traditional vegetation without disturbing the urban infrastructure as they take up an abandoned space to be useful.

Green roofs are not new. But in the last decades, architects, builders, and landscapers around the world have begun to use green roofs not because of their beauty but because of their functionality and ability to mitigate the environmental extremes that are common to conventional roofs.
Increasingly, researchers are looking at the practical benefits of green roofs. They help quantify their performance and provide a measure of their ability to reduce stormwater runoff, increase energy efficiency, and improve the urban landscape. This is the case of a group of researchers from CONICET, at CCT Mendoza, which explores and designs new techniques to incorporate vegetation into roofs and walls.

As it happens in many cities, this region undergoes an unplanned growth process that distances it from its foundational urban design, characterized by a strong presence of squares and tree-lined alignment along the streets “, clarifies about the city of Mendoza Alicia Canton, director of the research project.

Extensive planting within cities is widely recognized as a means to improve air quality. Green ceilings, therefore, contribute to the reduction of a number of air pollutants and other compounds. According to the European Federation of Green Roofs Associations, these vegetated surfaces last longer than conventional roofs, reduce energy costs with natural insulation and absorb rainwater, which could reduce the need for complex and costly drainage systems.

The architect Cantón emphasizes that, at the international level, this new trend also impacts on the reduction of the island heat effect and on the thermal conditioning of the buildings, which can reduce the energy consumption between 35% and 95%, according to the amount of vegetation and the climate of the region.

Green roofs have to be designed to meet specific biodiversity conservation objectives. That is why each roof is an experiment in itself.

The native plants are those that evolve with the fauna and the flora of the region, in contrast, the exotic ones were brought by the man, without taking into account that in the future they would have a biological disorder.

One of the biggest failures of this trend is that it does not promote plant biodiversity on the roof. Green roofs offer the greatest benefit when planted with a diverse group of species adapted to local conditions.