Advantages and Disadvantages of Green Roofs

Advantages and Disadvantages of Green Roofs

Making the buildings green seems to be catching up with homeowners as well as owners of commercial properties nowadays. One of the features of a green building is green roofs.

With climate change and global warming making life difficult day by day on our planet, we need to do our bit to save our environment. As the average surface temperature on the earth is going up, relying more on electricity from thermal power plants to keep us cool is foolish and irresponsible, to say the least. 

At the same time, we are buying more and more electric and electronic devices to make our lives more comfortable. The electricity needed to run these devices is creating more havoc in the environment. 

So, what is the solution?

Though not one single solution is available to wipe away the damage done to the environment by the burning of fossil fuels for centuries, we have to start somewhere and do something. Installing green roofs is one such endeavor to improve our environment.

In this article, you will get to know more about green roof advantages and disadvantages.

What is a green roof?

The “green” refers to the eco-friendly nature of the roof and not its color. Green roofs are named so because of their sustainability and non-reliance on environmentally-harming substances and processes. Green roofs rely on what nature has provided to make life more comfortable for us.

One of the prominent features of green roofs is the presence of plants and vegetation covering them. You can even have a garden on your green roofs. You can grow grass, herbs, vegetables, flowers, and drought-resistant plants as cover on your green roofs. 

If you have trouble growing a garden full of diverse plants on your rooftop, don’t worry. You can pick one or two plants that are easy to grow and let them cover your roof. Such as grass or easy-growing creepers. You don’t need to have plants bearing vegetables, fruits, or flowers to make it a green roof.

The types of green roofs are semi-intensive, intensive, and extensive green roofs. 

Having a green top will give your roof a beautiful appearance and improve its thermal performance. By bringing down the temperature inside the building, it reduces the expenditure on grid power to keep it cool. 

Read on to know more about the green roofing benefits and flaws.

Advantages and disadvantages of green roofs

Green roof advantages

1. Takes some of the load off the drainage system

On a typical roof of an urban building, the rainwater is collected using a network of drain pipes and guided to flow into the sewage system. This is essential to prevent flooding in the immediate area. However, this gives rise to severe flooding where all the rainwater gets collected from various parts of the urban area. 

With green roofs, this can be minimalized. The plants on the green roofs will absorb most of the rainwater falling on them. This water will go back into the atmosphere directly without flooding the grounds. 

2. Protection from elements

Having a green cover on the roof means the roof will not be exposed to the earth’s natural elements. The ultraviolet rays in sunlight can do a lot of damage to the roof when left exposed. The same is the case with rain, wind, hailstorm, and even temperature variations. The green cover on the roof offers natural protection to it from all these elements of nature. 

This translates to a longer lifespan for the roofs. As the plants absorb the heat, sunlight, and rainwater to grow, they won’t reach the roof surface. This way, we can avoid cracks and other damage to the rooftops.

3. Serves as an insulating layer

Green roofs provide insulation in both summer and winter. In summer, the green cover prevents the sun’s rays from reaching the roof surface, thus providing protection from the heat of the sun. Without the green cover, the roof will get heated, heating up the air inside the building as well. On the other hand, in winter, a bare roof will result in heat loss from inside the building.

The plants covering the green roofs will act as an insulating layer for the roof, preventing the transmission of heat either way. This means less use of air conditioners during summer and reduced use of heaters in winter. Green roofs improve the thermal performance of the roof.

4. Absorbs carbon dioxide, releases oxygen

The root cause of climate change and global warming is the increase in greenhouse gas emissions. Carbon dioxide is one of the major greenhouse gasses and the major contributor is the burning of fossil fuels. During photosynthesis, plants absorb carbon dioxide in the air to make food and grow. In this process, it releases much-needed oxygen back into the atmosphere. 

Growing plants around us is a win-win situation. Not only does it bring down the main contributing factor to global warming, but it also increases the oxygen content in the air. 

5. Provides home to wildlife

The vanishing trees and bushes in the urban landscape are a serious threat to wildlife there. Most of them, especially birds like sparrows, are facing extinction because of the loss of their habitat. Even though the green cover on the roof may not be as good a substitute for those trees and bushes, it can definitely support some wildlife. Green roofs offer perfect homes to birds and insects.

6. Better air quality 

The amount of toxic gasses in the air is a major threat we are facing today. Air pollution is a reality that is causing serious health issues for humans including death. Plants can absorb many of these toxic gasses and allow the air around us to be cleaner and more breathable. By forming an eco-friendly barrier from the outside world, this green cover can help in filtering dust particles and prevent them from entering our homes. 

7. Reduces noise levels

None of the roof options we have now including tiles, slate, asphalt, metal, or concrete, can prevent noise pollution from outside. This can be hard to endure in urban areas where even nights are lively and vibrant. Having a plant cover on your rooftop will make a huge difference in reducing the noise inside. The green cover can absorb most of the noise, resulting in calmer interiors. 

You can choose between intensive and extensive green roofs, but if the noise level is a concern, it’s better to choose intensive green roofs.

8. Benefit from the harvest

If you use your rooftop to grow agricultural produce, you can ensure fresh vegetables, fruits, herbs, and flowers year-round. If you can manage to grow more than what you can use, you can even sell them. If you want to, you can have an organic farm on your rooftop. 

Green roof disadvantages

You may wonder how growing plants on rooftops can be disadvantageous to us. Just like everything else, this too has a few negative aspects. 

1. More expensive

Growing plants on your rooftop will involve extra expenses, both for planting and maintaining them. Moreover, the rooftops need to be sturdier to support the extra load of plants. You may have to spend more to build green roofs but over months, they will pay for themselves and more.

2. Increased weight load

With the additional green cover, green roofs tend to be heavier than normal roofs. Moreover, they need to be structurally sturdier to carry the extra weight load. Depending on the kind of plants you grow on your green roofs, the increase in weight load is in the range of 100-450 lbs/10 sqft. 

Also, the weight load is different for intensive and extensive green roofs. You may also have to retrofit your roofs to cope with the additional weight load. However, if you have a flat roof surface, you may not have to do anything extra as they are built to handle more weight load.

3. Additional maintenance

Growing plants require more time, effort, and expenditure. It needs as much care as you would give a garden. When it is not raining, you have to water it to ensure that they are thriving well. You also need to de-weed and add fertilizer to ensure their optimal growth. If you are fond of gardening, you may not find this tiresome and may even enjoy it. If not, you may have to employ someone to take care of your green roofs. All these will add to your expenditure.

4. Demands your time and effort

If you have a hectic lifestyle and aren’t interested in gardening, maintaining green roofs can be challenging. Plants demand your attention and time. You will need time for taking care of your green roofs – from watering as and when needed to keeping them healthy and safe from insects, pests, and other plant diseases. You need to be much more invested in your property and be ready to be a hands-on and dedicated owner to keep the green roofs in good shape.

Final thoughts on green roofs

Having more greenery around you is always good for your own health as well as for that of the environment. The list of green roofing benefits far outweighs its setbacks. As it requires some investment, it is better to weigh the pros and cons to ensure you are up for the challenge before going ahead with it.

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