Green roofs for a more sustainable city

In cities where most surfaces are sealed with concrete and asphalt, stormwater runoff is a major challenge. Traditional roofs send rainwater straight into the sewers, which can lead to overload and flooding. Green roofs offer a sustainable solution to this problem.

Green roofs, such as the ECCOsedum system, can buffer up to 35 litres of water per square metre​. When it rains, the sedum retains rainwater like a sponge, and the plants ensure that the rainwater is drained away gradually. In this way, the sewer system is under less strain and the water gets the chance to evaporate gradually or be absorbed by the vegetation. The plants themselves need very little water to survive.

In addition, the substrate of green roofs filters the rainwater, minimising pollutants such as oil and other urban contaminants​. This means that the water that ultimately reaches the ground is cleaner, which is essential for improving the quality of our groundwater.

Besides water management, green roofs are particularly effective at regulating temperature. Urban areas often have to contend with what is known as the urban heat island effect. This means that temperatures in densely built-up cities are higher than in the surrounding rural areas. This is partly because traditional roofs absorb and retain heat, leading to higher temperatures​.

Green roofs, however, function as a natural insulation system. The vegetation layer ensures that less heat is absorbed and retained, because direct sunlight is reflected. In addition, the moisture present in the vegetation evaporates, providing extra cooling. This can lower the indoor temperature by a few degrees, resulting in lower air-conditioning costs and reduced energy consumption​. Because of this heat-regulating effect, the ECCOsedum green-roof tiles are also highly suitable for use on commercial buildings with cold stores or buildings with air conditioning.

In winter, green roofs offer the opposite advantage: they help keep heat inside. The different layers of the green roof—from the substrate to the vegetation—form an additional insulating layer, meaning that less heat is lost. This ensures a more stable indoor climate and reduces heating costs​.

Installing green roofs not only helps improve water management and thermal regulation, but also creates a greener, more liveable city. Green roofs promote biodiversity by providing habitat for insects, birds and small animals​. In addition, they improve air quality because plants convert carbon dioxide into oxygen and filter particulate matter.

Green roofs also help reduce the ecological footprint of buildings. Using lightweight and durable systems, such as the ECCOsedum trays, reduces the need for heavy structural modifications, meaning they can be installed on almost any existing roof​. These trays are also made from recycled materials, which helps reduce the environmental impact of the construction sector​.

Installing a green roof is easier than you might think, especially with systems such as ECCOsedum. These trays are pre-grown and can be installed quickly, even on sloped roofs​. Thanks to the low weight (only 84 kg per square metre when saturated), it can be fitted to almost any existing roof without major structural changes​.

Maintenance is minimal, as the sedum plants require little care and are resistant to dry conditions. This means that a green roof is not only a sustainable choice, but also a low-maintenance investment for the future​​.

Investing in green roofs in the city offers numerous benefits, from efficient water management and improved thermal insulation to increased biodiversity and lower energy costs. Green roofs are therefore a smart and future-proof solution, both for homeowners who want to contribute to a sustainable future and for cities aiming for more greenery in public spaces.