What are the Benefits of Green Roofing?

What does a green roof do, exactly, other than just sit there and look pretty? And just what is a green roof, anyway?

For those of you who aren’t familiar, green roofs are giant swaths of plant life—usually succulents, grasses, or other greenery—designed to cover the tops of man-made structures.

The benefits of green roofs, as it turns out, are many. While a green roofing project represents a significant investment of time, income, and other resources at the outset, over the long haul, it can help improve the longevity of your building, drastically reduce overall energy consumption rates, and contribute to a much healthier local environment.

Oh, and they’ll save you a heck of a lot of money—as much as $200,000’s worth on utility bills over a period of many years, according to the US National Park Service.

Interested to see more, and to learn what all the fuss is about? Here's why green roofs are a great investment.

Added protection from fires

As we detailed at length in a previous post, roofs are perhaps the most susceptible part of a building when it comes to fire exposure, as they offer tons of raw surface area for sparks and other burning debris to establish contact and spread flames.

Green roofs are the perfect flame retardant. The moisture-rich ground cover plants that typically populate green roofs can act as fire retardation if you implement the VF-1 Fire Design Standard for Vegetative Roofs, according to RoofingCompare.

This means that, when green roofs are burned or exposed to fire, they do not generate nearly as much heat as a regular roof would without plant matter on it, which bodes very well for the survival of the structure itself.

Neighborhood pollution control

In addition to being aesthetically pleasing, green roofs can play a significant role in combating local air and water pollution.

According to Pennsylvania State University’s Center for Green Roof Research, the plants and the porous membranes they are rooted on can absorb as much as 80% of the rainwater they are exposed to during storms, compared with only 24 percent for regular roofs. This means…

  • There’s less stormwater runoff overflowing sewer systems and causing rivers, streams, and other bodies of water to be exposed to contaminated water
  • Water that does run off is filtered naturally through the plants themselves, so nearby water channels are on average cleaner
  • There’s less erosion as a result of rampant water flow since more rainfall is captured and stored

Another benefit: through their natural process of respiration, plants convert molecules in the air into energy. Plants on green roofs are a boon for air quality, since—through this process of respiration—they draw in all kinds of polluted air and other contaminants, reducing the amount of toxic raw materials floating around.

Dramatic reductions in energy consumption

Perhaps the most attractive feature of green roofs is their outstanding energy efficiency.

Green roofs and their vertical counterparts, green walls, are major insulators. In addition to protecting building surfaces from ultraviolet radiation exposure, rain, and other forms of weather damage, green roofs and green walls preserve internal building temperatures and help to cool the buildings during hot summer months.

What’s more, when plants are installed around HVAC intake valves, they can significantly cool the surrounding air temperature, which results in the units needing to use less energy to cool the air they’re pulling in.

The benefits associated with green roofing practices are too numerous to encapsulate fully in a single article.

Do some more research on your own, and check out Arizona State University’s handy Green Roof Energy Calculator to see how much you’d stand to conserve energy-wise by making this kind of investment.

Want to see how much building an eco-friendly home would cost you, period? Check out our helpful primer on that very subject today for more insights.