Curious about green roofs? In this post, you’ll learn about what they are, how they benefit us, the different types available, and where to find them. Let’s get started!

What is a green roof?

A green roof is a type of green infrastructure that uses vegetation, soil, and a waterproofing membrane to capture stormwater and avoid dumping it onto the street below. The vegetation absorbs heat energy, and provides a habitat for animals and insects. Finally, they are often very beautiful and enjoyable for humans!

Why do we need green roofs?

Green roofs benefit us in many ways by:

• Reducing stormwater runoff
• Improving air quality
• Insulating buildings and reducing energy costs
• Providing habitat for wildlife
• Increasing the aesthetic value of buildings
• Creating a relaxing environment for people to enjoy

What are the different kinds of green roofs?

There are three main types of green roofs: extensive, semi-intensive, and intensive.

1. Extensive green roofs are the lightest and least expensive type of green roof. They have a shallow growing medium, typically 2-6 inches deep, and are planted with low-maintenance plants such as succulents, mosses, and sedums. Extensive green roofs require little maintenance and can be installed on most types of roofs.
2. Semi-intensive green roofs have a thicker growing medium, typically 6-12 inches deep, and can support a wider variety of plants, including grasses, herbs, shrubs, and even small trees.
3. Intensive green roofs have the deepest growing medium, typically 1 foot or more, and can support larger types of vegetation, including trees, shrubs, and flowers. Intensive green roofs are the most expensive and heaviest type of green roof.

In addition to these three main types, you might come across terms for specialized green roofs, which include: 

• Blue-green roofs – Designed to retain and store stormwater. They typically have a layer of water-holding material beneath the growing medium.
• Solar roofs – Include adding photovoltaic solar panels among green roof vegetation. This type of roof can generate renewable energy while also providing the other benefits of a green roof.
• Biodiverse roofs – Attract and support a variety of wildlife. They typically include a variety of plants and other features, such as nesting boxes and water sources.

Where can you find green roofs?

Let’s take a look at five notable examples of green roofs around the world:

1. Vancouver Convention Centre

This 6-acre green roof is the largest in Canada and one of the largest in North America. It is home to over 400,000 native plants and 240,000 bees, which provide honey for the convention center’s restaurant.

2. Chicago City Hall Green Roof

This green roof is one of the largest in the U.S. and is home to over 20,000 plants, which include over 150 species, including shrubs, vines and two trees. The plants were selected for their ability to thrive in the sunny, windy, and arid conditions on the roof. Most are prairie plants native to the Chicago region.

3. ACROS Fukuoka Prefectural International Hall in Japan

This building has a terraced green roof that is home to over 38,000 plants. The accessible landscaped roof is configured into 14 garden terraces that add up to one hectare, or about 2.5 acres. The green roof helps to significantly reduce the building’s energy consumption and reduces the urban heat island effect.

4. Swedish Green Roof Institute in Malmö, Sweden

Located in southern Sweden, the Institute is home to the Scandinavian Green Roof Association and organizes green roof courses and tours. It has been instrumental in helping green roofs to evolve across Sweden, Denmark, Norway, and, in the last few years, Finland.

5. Di Tella University in Buenos Aires, Argentina

The green roof of Di Tella University in Buenos Aires is home to native and adapted vegetation, trees, shrubs, herbaceous, and ground cover plants of low water requirement, which were chosen according to the depth of each sector of the roof. Large containers were specially designed to house the roots of the trees (Bahuinia candicans, or Brazilian Orchid Tree, a native tree with white flowers) and also serve as furniture.

Curious about other types green infrastructure? Check out this post: An Introduction to Green Infrastructure

If you are interested in collecting environmental data to measure green infrastructure effectiveness, please contact us to learn how Temboo can help you!