A green roof not only looks beautiful but it has many economic, ecological and societal benefits. They are becoming an important addition to the raft of considerations available when setting out to create healthy and ecologically responsible buildings. What’s more, people are happier when they are surrounded by greenery.
These benefits include saving you money, reducing heating and cooling costs, reducing ambient noise inside a building, reduced and slowed rainwater runoff, reduction of urban heat island effect, purifies the air, reduces greenhouse gas emissions, increases biodiversity, increases wellbeing and extends the life span of a roof. That’s a pretty impressive list right there! Not to mention how stunning they can look. We’ll briefly explain the benefits for you in more detail below.
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They can save you money
The installation of a green roof usually involves higher upfront costs than a traditional roof, but you can save money through reduced energy costs over its lifespan. The University of Michigan did a comparative study between a conventional roof and a green roof over a 40 year period and they estimates a green roof would save about $200,000. Nearly two-third of this is from reduced energy costs.
Reduced heating and cooling costs
Plants absorb and reflect sunlight so this helps to create a cooler and more comfortable indoor temperate in the hotter months. Plus, the extra layers of green roof serve as insulation which decreases the amount of heat able to pass into the building. This means the air conditioning doesn’t need to be used as often, which saves you money.
Reduces ambient noise
Soil and vegetation can act as a sound barrier to your building. A green roof can acoustically insulate your home from noise of nearby traffic, planes, trains, industry and loud neighbours, providing a quieter indoor environment.
Reduced and slowed rainwater runoff
A green roof also helps to control stormwater runoff from your building. Increasing urbanisation has resulted in less green space in our towns and cities, which means more water is running off roofs and into stormwater systems. A green roof can retain the water in the plants and growing medium, which slows or reduces the amount of water becoming stormwater, helping to reduce flooding and erosion. Green roofs can capture up to 80% of rainfall during storms, compared to 24% for a conventional roof.
Reduction of urban heat island effect
The temperature in cities is often higher than in surrounding rural areas, which is called the heat island effect. Large amounts of sealed surfaces absorb solar radiation and re-radiate it as heat, which increases the local air temperature. The temperature in cities can be 3 degrees higher than less urbanised areas. Green roofs help to lower the temperature because plants absorb less heat than a dark roof surface. The plants also lower the temperature on the roof by using the heat from the air to evaporate water through the evapotranspiration process.
Helps to purify the air
Plants filter airborne particulate matter and convert C02 into oxygen. Plus, the plants on a green roof will capture pollutants which would normally wash off a conventional roof and into the stormwater system.
Reduces greenhouse gas emissions
The reduction in the use of mechanical cooling (or air conditioners) reduces greenhouse gas emissions from any fossil fuel combustion used to power that equipment.
The sedums, herbs, grasses and plants that can be planted on a green roof help promote the habitat of birds, butterflies and insects. This is especially important in a city environment which has more built areas and less green spaces.
Increases wellbeing and lowers stress
Living and working amongst plants, or with a view of greenery, can help improve wellbeing and reduce stress.
Extends the life span of a roof
A green roof can potentially double the life span of your roof. By protecting the roofing material from sun, rain, wind and temperature fluctuations you’ll extend the number of years before it needs replacing, as compared to a standard roof. There’s also the added benefit of reducing the potential waste from the removal of the aged conventional roof.
Nadine is the founder and editor of Eco Edition and founder of the Eco Edition Design School. She’s an experienced interior designer, sustainable materials consultant, speaker and serial home renovator.