The Importance of Intensive Green Roofs

As our cities continue to grow and expand, the need for innovative and sustainable solutions becomes increasingly important. One solution that has gained popularity over the years is the intensive green roof. Rooftops are more frequently transformed into green spaces, which not only improves the aesthetics of roofs, especially in urban areas, but also have many benefits for the environment. In this blog, we will explore the importance of intensive green roofs and how they contribute to a greener, and more sustainable urban landscape.

Understanding Intensive Green Roofs

Intensive green roofs, also known as a roof garden, is the most involved type of green roof, which can be designed to be like a garden environment. One of the main differences with an intensive green roof is that it has deeper soil, allowing for more design creativity than with an extensive green roof. The deeper, richer substrates mean the range of vegetation is much broader, including, but not limited to: lawn turfs, shrubs, hedging, trees. Maintenance will vary depending on the type of vegetation and the requirements of the site and client.

Intensive green roofs are designed to create recreational and amenity spaces for people to enjoy. They are generally accessible and contain features similar to traditional gardens. Intensive green roof systems involve using greater substrate depths (usually above 200m) and often create a larger weight loading on the roof. They require a higher level of maintenance, including regular irrigation.

Typical characteristics of an intensive green roof include: being heavier in weight (typically over 250kg per m2 saturated weight), higher maintenance, deeper substrates (over 150 mm and up to 1000 mm) and can be designed for limited or full public access or high visibility.

Environmental Benefits of an Intensive Green Roof

One important factor about an intensive green roof is that it can be designed to maximise biodiversity. The design of an intensive green roof can include shrubs and trees as well as wildflowers, which attract a variety of species to your green roof. By creating ecosystems high above the ground, they offer habitats for various plants, insects, and even birds. This increase in biodiversity can help the conservation of local species and the promotion of urban wildlife.
Green roofs also play a crucial role in mitigating the urban heat island effect, a phenomenon where cities experience higher temperatures than surrounding rural areas. The vegetation on intensive green roofs cools the surrounding air through the process of evapotranspiration, reducing the heat absorption of concrete and asphalt in urban areas. This cooling effect can lead to decreased energy consumption for air conditioning, which in turn reduces greenhouse gas emissions and air pollution.

Psychological Benefits of an Intensive Green Roof

Beyond their environmental impact, intensive green roofs also provide various psychological benefits. The presence of green spaces in urban environments has been
linked to reduced stress levels, improved mental well-being, and increased productivity. Access to nature, even in the form of a rooftop garden, can offer respite from the concrete jungle and promote a sense of tranquillity. (Biophilic Design, Mott MacDonald)

Our Intensive Green Roof Case Studies

We have some real life examples of intensive green roofs that we have recently worked on. One of our intensive green roofs that we worked on with ANS Global was 1 New Street Square. This project was a 275,000 sq ft office building, where the aim was to improve the look of the building as well as increasing biodiversity. The majority of the plants used for this project were focused on pollinator planting, and as a result you can often see honeybees enjoying the different plants, even at 70m up in the air!

The second project where we created an intensive green roof was Victoria Way Car Park in Woking, which is a classic example where the ANS GrufeKit was used for dual-purpose, extensive and intensive green roofs. The plant palette was developed to cater to the project drivers, to enhance biodiversity and improve air quality. We designed and installed 4,200m² of green roofs over two levels of the car park.

The green roofs were spread over two levels, Level 11 included an extensive green roof (4200m2) and Level 10, with an intensive green roof (800m2). The intensive green roof part of this project involved an 800m² intensive green roof, which is a green roof that has a deeper substrate and therefore allows greater design scope and plant choice. The purpose of the green roof on level 10, of the car park, was largely improving local biodiversity, and to screen the adjacent hotel windows from the car park view.

The focus for this level of the car part was air quality, which our Sedum GrufeTiles are perfect for as they help purify the air and absorb polluting particles.

At GrufeKit we have the experience and knowledge needed to advise you on your green roof choices. For more information on how we can help, or if you’d like to discuss your green roof project with an expert, contact our friendly team today – we’re always happy to help and are standing by to answer any questions you have.