Benefits of Installing a Green Roof

Green roofs are environmentally sustainable

Green Roofs have been an up & coming environmental initiative in the last 20 years. Green roofing specifically targets urban and overpopulated areas, although can be just as beneficial in suburban or country areas. Green roofs typically are roofs of flat top buildings that are covered in plants, greenery or vegetation, instead of concrete or shingles. These plants can be anything from flowers to even produce crops- the options are endless.  Since every installation is unique, the sustainability benefits and technical performance vary by region, climate, and building type, however, all designs serve to better the environment around them. These benefits are for humans, animals and the environment, and can impact a variety of sustainability factors.

Benefits of Green Roofs

Although the installation of a green roof usually involves higher upfront costs in comparison to their more traditional counterparts, they have many sustainability benefits that outweigh their associated costs. These benefits include:

Retain Rainwater/Stormwater Runoff

During heavy or continuous rain events, water runoff can overwhelm stormwater infrastructure and potentially cause damage to waterways, roads and even animal habitats. This is specifically true in highly urbanized, overpopulated areas, where infrastructure is limited for rainwater/stormwater runoff. Green roofs assist in redirecting the water, as they naturally retain water in the soil. Even when stormwater does leave the roofing structure, it is delayed, cleaner and reduced in volume due to the retention. There is also an environmental benefit to watering these plants with rainwater, instead of using new fresh groundwater, depending on the frequency. Additionally, there is also always an option to add a rain catching basin to the green roof, to catch even more stormwater/rainwater. This helps to ensure the plants are always being watered using rainwater and also reduces the amount of stormwater runoff an urban area might see in a heavy rainfall event.

Energy Efficiency

Green roofs provide a barrier between the sun and the outer surface of the building, allowing for a reduction of heat flux through the roof. With less heat being able to penetrate the building, that building will require less energy for cooling in the summer months. This is great for longevity of machinery as it does not have to work as hard to perform its cooling task, as well as minimizes energy outputs and costs. Green roofs are just as economical and energy efficient in the winter months. During the colder part of the season, green roofs have the ability to minimize heat loss, as they provide an extra layer of insulation on the roof. This allows for a reduction of heat expenses, as heat is more easily trapped in the building and less able to leave through the roof (since heat naturally rises). Reducing building energy outputs not only benefits bottom line expenses, but it also translates directly to a reduction in greenhouse gas emissions. Win-win!

Improves Air Quality

In general, it is fairly well known that plants absorb airborne pollutants and emit oxygen. So, naturally a green roof has the ability to improve air quality in the areas around them. Again, this becomes more important in urbanized areas, where pollutants are heavier and emissions are higher. However, air quality improvement in any area is a benefit to humans and the environment. More green roofs means more plants and more plants is better for the environment.

Improves “Urban Heat Island Effect”

This benefit is directly applicable to more urbanized areas, but some suburban areas might have some minimal benefit in this regard as well. The urban heat island effect is something that occurs due to the ‘concrete jungle’ lifestyle that urban areas have. All of this asphalt, concrete and paved surfaces absorb solar radiation and re-radiates it as heat, which creates the ‘urban heat island effect.’ Generally, through this effect, urban cities are approximately 5 degrees warmer, on average, then rural areas. Green roofs help to benefit this in a few ways. The first and most obvious is that less paved areas equals less re-radiated heat. However, green roofs also use solar radiation to evaporate water from the growing vegetation. Believe it or not, this process actually lowers the temperature of green roofs, by using heat from the area to evaporate the water.

Animal Habitat

Green roofs assist with providing a safe and natural space for animals that otherwise might not be able nest or find habitat. Animals have been pushed out of their natural habitats through urbanization, and so to ‘give back’ to them in a way, green roofs provide them habitats that they have otherwise lost. This is great for animals who need a safe place to bear young, nest or otherwise rest. This is even more relevant in the context of pollinators and biodiversity creation, which is a trending and important environmental topic as of late. Creating more areas for pollinators to flourish is an environmental win for everyone.

Social Benefits

In addition to a plethora of environmental and economic benefits, green roofs provide a social benefit as well. Obviously, they are more aesthetically pleasing then their common counterpart, but they also provide a more natural look. Green roofs provide a more setting where people can relax and enjoy nature in areas where they otherwise would not be able to access such a beautiful scene. This is especially beneficial in hospitals, for patient recovery and for staff benefit. Another social benefit is if the green roof chooses to plant food crops. This can become a teaching space for local students, or provide food for the building’s occupants or local community. There are many options in the design of a green roof, and incorporating direct human benefit is fantastic for the morale of a community.

Costs of Green Roofs Compared to Conventional Roofs

Since the way a green roof is designed can vary so much from building to building, the costs associated with a green roof consistently differ. However, the average 1,500sq foot build costs anywhere between $15,000.00 – $40,000.00 (according to just to install, with an average build for this size costing around $22,000.00. This equals out to about $20-$35 a square foot. In addition to a large initial upfront cost, there are also assisted maintenance fees that go with a green roof installation to up keep vegetation and ensure nothing gets too ‘overgrown.’ Again, these maintenance fees vary widely depending on the type of green roof installed, but on average it costs about $0.75-$1.50 per square foot to keep up annually. Given this, keeping in the specs of a 1500sq foot green roof, the average annual maintenance cost would be approximately $1500.00 a year. And that is only if you do all the work yourself. If you have to employ someone to manage and take care of the green roof, you need to factor in wage.

This is where it looks as though a conventional roof is much more cost effective, and it is, up front. A conventional, shingled roof costs between $5000.00-10,000.00 (depending on shingle quality, labour etc). Once a shingled roof is installed, it requires very little to no maintenance, making its per annual costs almost null (unless of course there is a leak or some other issue). However, in the long term, this roof will not make you any money back, it only deteriorates and will eventually need to be replaced again within a 25 year time frame.

Green roofs actually have a longer lifespan than traditional roofs (they protect from the sun, rain and other weather events better), and in the long term, a green roof can actually save you money. As mentioned earlier, a green roof provides insulation, which reduces energy needs, and has other underlying human and environmental benefits.


It is clear that although they are expensive upfront in comparison to their common counterpart, their benefits surely outweigh the costs. The best part about green roofs for me personally, is the fact that it makes the most of a generally unused space. Green roofs provide all of the same benefits that a normal roof provides (shelter, water protection, etc), while also adding additional economic, social and environmental benefits. It is time that we all need to start thinking innovatively about how we utilize normal everyday spaces to be more sustainable, and green roofs provide that level of thought.

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