Beautiful Green Roofs in Amsterdam That Manage Rainwater

Take a stroll to the rooftops of certain social housing buildings in Amsterdam, and you’ll find lush green gardens brimming with life. What you might not see at first glance, though, is the hidden technology beneath these flourishing plants—a clever reservoir system designed to collect rainwater during storms.

These innovative “blue-green” roofs are making waves in Amsterdam. They don’t just provide an eye-catching splash of greenery—they also help the city tackle flooding, keep buildings cooler during heatwaves, and boost biodiversity. Here’s how these rooftops are changing urban living.

The Challenge of Managing Rainwater

Amsterdam’s recent history with heavy rainfall highlights the growing need for solutions to urban flooding. A particularly severe storm in Copenhagen over a decade ago, where six inches of rain fell in just two hours, was a wake-up call for many European cities. Like much of the world, Amsterdam faces increasingly frequent and extreme weather events caused by climate change.

Old-fashioned sewer systems are struggling to manage the growing amounts of rainwater. And in a city as densely packed as Amsterdam, there’s not much room for creating new green parks to absorb rain. City planners had to think differently—and that’s when the concept of using existing rooftop space came to life.

How Blue-Green Roofs Work

Traditional green roofs already have soil and plants that can soak up some rainwater. However, during heavy downpours, the water often runs off the roof once the soil becomes saturated. Blue-green roofs take things a step further by adding a hidden reservoir beneath the plants and soil.

This reservoir holds rainwater temporarily during storms, reducing the chance of it overwhelming the drainage system. Cleverly, the system connects to weather forecasts and can release water in advance if more rain is expected. This ensures the roofs are always ready to handle excess water when needed.

The results are impressive. While a basic green roof might absorb around 12% of rainfall, studies show that blue-green roofs can retain anywhere from 70% to 97% of water during heavy rain. They effectively act as “squeezable sponges,” releasing or retaining water as conditions require.

But their benefits don’t stop there. These roofs also allow water to slowly travel back up to feed the plants during drier periods, helping them stay green and healthy, which in turn keeps their cooling effect intact.

Cooling and Protecting the City

Amsterdam’s blue-green roofs offer more than just rainwater management. By evaporating water through their plants, these roofs help cool the surrounding areas during hot weather. This offers relief from the urban heat island effect—where built-up areas can trap more heat than their rural surroundings.

The reservoirs can even be linked to other systems, such as cisterns, to supply water for landscaping or flushing toilets. These benefits make blue-green roofs a valuable tool in making cities more sustainable and resilient.

The Resilio Project

To put this idea into practice, Amsterdam launched a pilot scheme known as the Resilio Project. Completed in 2022, this initiative focused on installing blue-green roofs on older social-housing buildings in flood-prone areas.

With funding from the European Union, over 100,000 square feet of rooftops were transformed into thriving, water-managing ecosystems. The roofs were chosen strategically—not only for their need of repair but also for their location in areas with the highest flood risks.

The outcome is inspiring. Computer models showed that while one blue-green roof might not drastically change flooding patterns, converting multiple rooftops in a neighbourhood could reduce flooding by as much as 60%. This demonstrates the potential of scaling up this technology, especially as Amsterdam faces wetter weather in the years to come.

A Blueprint for the Future

Heavy rain is a challenge for many urban areas, but Amsterdam’s innovative blue-green roof systems prove there are creative ways to adapt. These roofs not only manage rainwater during storms but also act as a defence against droughts, foster biodiversity, cool cities during heatwaves, and even support the plants they host.

The success of the Resilio Project shows what can be achieved with forward-thinking investments in urban planning. While the effort and financing required might be significant at first, the long-term environmental and social rewards make it a worthwhile pursuit.

Why Cities Need Blue-Green Roofs

Urban areas worldwide can learn from Amsterdam’s example. By transforming overlooked rooftops into multi-functional assets, cities can reduce flooding risks, counter rising temperatures, and create more inviting environments for people and wildlife alike.

If you’re planning an urban project or looking for ways to make your building more sustainable, blue-green roofs might just be the answer. They’re not only a step towards solving water issues but also a way to create greener, healthier cities for generations to come.