Green roofs vs. heat: 99.5% of Dutch roofs remain unused

Heat waves are becoming increasingly severe, which means we need to think more carefully about how we cool buildings. A nationwide survey shows that only 0.5% of all buildings have a green roof. That’s a shame, because it’s a relatively easy way to keep buildings cool.

The numbers don’t lie. A nationwide survey by Rooftop Revolution and Natuur & Milieu reveals that only 0.5% of the 11 million buildings in the Netherlands have a green roof 🔗︎. Nearly two-thirds of these green roofs are smaller than 25 m², which means their impact on cooling, water retention, and biodiversity remains minimal.

Climate adaptation

Green roofs offer more than just a beautiful view. They contribute to climate adaptation by reducing heat, capturing rainwater, and increasing biodiversity 🔗︎. In urban areas, green roofs can lower temperatures by several degrees, which makes a big difference, especially during heat waves. They also help prevent flooding by storing rainwater and draining it gradually, thereby reducing the strain on the sewer system 🔗︎.

Major differences between cities

Regional analyses show significant differences in the utilization of green roofs. In Amsterdam, 60% of the roof area is immediately suitable for greening, but only 4.17% is actually being used 🔗︎. In Heerlen, more than 2 million m² of roof area is suitable, but currently only 0.44% of that potential is being utilized. In Eindhoven, new construction projects are more than ten times as likely to have a green roof as existing buildings 🔗︎. Cities such as Zwolle, Groningen, and Amsterdam are leading the way with several thousand green roofs, while municipalities in Limburg such as Venlo, Heerlen, and Sittard-Geleen are lagging behind with only a few dozen green-roofed buildings 🔗︎. These differences show that local incentives and policies play a crucial role in the adoption of green roofs.

Subsidies as the key to growth

Financial incentives are one of the most important tools for promoting green roofs. In the Netherlands, subsidies are available through municipalities, provinces, and water boards, but the amounts and conditions vary greatly by location 🔗︎. In Amsterdam, the subsidy covers up to 50% of the costs, with a maximum of €30–€50 per m² and a minimum area of 30 m² 🔗︎. In The Hague, 50% of the costs are reimbursed, with a maximum of €20,000 per application and special support for people with an Ooievaarspas 🔗︎. Amersfoort offers €20–€40 per m², depending on the water storage capacity, with a total subsidy cap of €100,000 for homes and barns 🔗︎. Provinces, such as Groningen, also offer subsidies for greening industrial parks, covering up to 45% of the costs and with a maximum of €200,000 per application 🔗︎.

Successful initiatives

There are, however, successful examples that show that green roofs can indeed be a success. In Rotterdam, **De DakAkker** is a notable initiative: a rooftop farming project covering approximately 1,000 m² on the Schieblock building, where vegetables, fruits, and herbs are grown, and bees are kept 🔗︎. The **Dakpark** in Rotterdam, covering an area of 100,000 m², is also one of the largest public green roofs in Europe and features walking trails, playgrounds, and sports fields 🔗︎. In Maastricht, a successful campaign was organized in which 160 roofs were transformed into rooftop flower meadows, offering residents 6 m² of green roof space for free 🔗︎. These initiatives demonstrate that green roofs are not only feasible but can also add value to the local community.

The number of green roofs is increasing

There has indeed been growth in the number of green roofs: over the past ten years, the number has increased by an average of 13% per year. This growth is primarily occurring in new construction and small private buildings such as sheds and outbuildings 🔗︎. Rob van Tilburg, Director of Programs at Natuur & Milieu, emphasizes that greening should be considered more often during renovations, sustainability upgrades, or roof replacements on existing buildings 🔗︎. Governments can accelerate this development with clear regulations and targeted incentives.