What in the world are Green Roofs anyways…
In the United States, green roofs are growing in popularity. These state-of-the-art roofing systems use soil and green plants to mitigate heat naturally. The environmental qualities of a living roof sound amazing, but are green roofs actually sustainable?
The Makeup of Green Roofs
Green roofing consists of many different layers of natural and synthetic materials. Every green roof is unique, but these are the most common layers.
- Roof structure
- Waterproof membrane
- Root barrier
- Water retention and drainage layer
- Filter cloth
- Soil or other growing media
- Plant species
The purpose of these layers is to create a good growing medium for the plant life above while simultaneously protecting the building below from moisture. A lightweight growing medium supports a wide range of different plants, essentially creating a rooftop garden.
The Question of Sustainability
The plant layers of a green roof offer exceptional sustainability. As living and breathing ecosystems, these lush roofs can incorporate a huge variety of plant species that can be responsibly sourced. Sedges, grasses, succulents, herbs, and other plentiful types of ground cover are frequently used, as well as new seedlings or small trees.
Are green roofs 100% sustainable, though? Not at the moment. While many living roofs utilize recycled materials, they still rely on some unsustainable resources to work correctly. For example, a heavy-duty rubber membrane is necessary to provide a waterproof layer for the underlying building structure. This rubber membrane is not sustainable.
However, it’s important to note that virtually no type of roofing for buildings is currently sustainable. While responsibly harvested wood shakes have sustainable qualities, the support layers for residential and commercial roofing generally rely on fossil fuels or mined materials.
The Benefits of Green Roofs for the Environment
Green roofing provides numerous benefits that can be attractive to eco-focused individuals and businesses:
Offering biodiversity and wildlife protection: When planned carefully, green roofs soon become full of life, and more than just the plant varieties that are present. Birds, butterflies, insects and other types of fauna can enjoy increased green spaces in urban environments. This is especially important for migratory species.
Reducing landfill waste: Living roofs last approximately 2–3 times longer than traditional roofing, cutting down on the amount of waste sent to landfills. Building HVAC systems last longer as well thanks to natural cooling.
Retaining stormwater and reducing runoff: During summer months, green roofs filter and absorb enormous amounts of rainwater. This reduces the effects of runoff on the surrounding areas.
Cooling urban spaces: When numerous buildings use green roofing, it can make an enormous difference for city temperatures. By covering black surfaces with green plants, the amount of sunlight absorbed is reduced. Also, plants have a major cooling effect on buildings.
Improving air quality: Plants have the ability to filter harmful gases and decrease smog levels in urban environments. This results in better air quality.
Increasing energy efficiency: One of the biggest environmental benefits of utilizing green roofs is significant energy savings. The layers of plants and growing medium provide superior insulation during summer and winter, making it easier to keep indoor temperatures stable and cutting down on electricity usage by 75% or more.
Increased amounts of plant life also have wonderful benefits for social interaction. Many homeowners and employees find green spaces relaxing and beautiful. This marriage of modern structures and rich greenery may represent a brighter future for human interaction with nature.