The Science of Green Roofs & How they Work

Green roofs are not just a pretty addition to urban landscapes. They are a carefully engineered, sustainable feature that can dramatically transform the way we interact with our cities and the environment.

Our GrufeKit green roof system is a modular, all-in-one kit that provides a low risk, long-term green roof solution. The GrufeKit being modular means there is no handling of the separate components and everything is in one place. The GrufeTiles are pre-grown, they are established for 12-18 months making them fully acclimatised and more resilient.

The Science Behind Green Roof: Benefits

Green roofs offer numerous benefits to the environment, the building, and its occupants. Understanding the science behind these advantages is crucial for appreciating how a GrufeKit green roof works:

1. Temperature Regulation
During the winter the plants on your GrufeKit green roof can keep the building warmer by preventing snow and ice from building up on the waterproof membrane. It is possible to gain up to an extra 25% insulation in dry conditions by installing a green roof, as well as reducing heat loss due to wind by up to 50% compared to a bare roof.

Our GrufeKit green roofs can also have a cooling effect during the summer months as the plants absorb the sun’s rays, keeping the building cooler. The cooling effect that green roofs have can be referred to as ‘Evapotranspiration’. Evapotranspiration is the process in which water is transferred from the land to the atmosphere by evaporation from the soul and other surfaces, as well as by transpiration from plants.

Evapotranspiration is particularly important for cooling as it consumes heat without warming up its surrounding surfaces (Blanusa & Vas Monteiro, 2015).

Temperature regulation is particularly important in urban spaces. The Urban Heat Island Effect occurs when cities replace natural land with pavements, roads, and buildings. By adding a green roof to a city building, it will help regulate the temperature, making it cooler in the summer.

2. Air Quality Improvement
The lack of plants in urban areas leads to a concentration in polluted air. Green roofs can support a broad range of plant species which can help mitigate issues with air pollution. As roofs are often unused spaces, they make an ideal place to incorporate some greenery into built up areas.

Changing one roof to a green roof in a city would have limited impact, however, if green roofs became an accepted part of building practice, the impact on air quality in cities could be huge.

3. Rainwater Retention
Green roofs are a type of natural flood management. In urban areas roofs make up large areas of hard standing and runoff can be huge. The plants on a green roof use up a small amount of water, however, the substrate (soil) beneath them will soak up a significant amount of water. The saturated soil will slowly release water off the roof, but the green roof slows the process down reducing the risk of a flash flood.

A green roof can retain around 75% of the runoff in summer. Green roofs alone would not prevent flooding, however, as part of a wider rainwater management scheme they can be a useful contribution.

4. Biodiversity Support
By adding green roofs and wildflower roofs in cities we can massively increase the habitats available to birds, bees, butterflies, and insects. Specific plant mixes can be planted to bring local plants back to the environment and other features such as log piles, rocks, bird baths, insect hotels and bee hives can be included to boost the ecological impact of the green roof. These reasons make a GrufeKit green roof a perfect solution for Biodiversity Net Gain. Biodiversity Net gain is a strategy to develop land and contribute to the recovery of nature. It is a way of making sure the habitat for wildlife is in a better state than it was before development.

5. Longer Roof Life
Structural protection is another benefit of a GrufeKit green roof. The green roof will protect the roof membrane from the elements such as UV radiation, temperature fluctuations, and mechanical damage, increasing the lifespan of a roof from the average of 20 years to 50-70 years. Therefore, saving maintenance and replacement costs.

6. Aesthetic & Psychological Benefits
Finally, the presence of greenery can have a calming and aesthetically pleasing effect on people. Apart from looking visually pleasing, it has been found that green roofs can have psychological benefits. This can include improving productivity, offering relaxation, decreasing stress and improving concentration levels, (London Living Roofs and Walls Report, 2019).

Green roofs are not just beautiful additions to city skylines, they are intricate, science-based systems that provide a wide range of environmental and economic benefits. From improving air quality to reducing energy consumption and supporting urban biodiversity, the science behind green roofs really can outweigh the aesthetics.

If you would like to find out more about our range, you can view it here or if you have any further questions, please do not hesitate to get in touch!