A Green Roof Could Slash Your Energy Bill in All This Heat (2024)

Green roofs turn an outdoor space into a sustainable environmental solution that’s practical and beautiful. Essentially, a green roof is just what it sounds like: a vegetative layer grown on a rooftop. That description might make you picture something out of The Hobbit, but we’re not just talking about turf houses; raised garden beds and planters can turn any flat roof or small balcony into a green roof. You might think of them as features of hotels, office buildings, and other commercial spaces, but your home can have one too.

Over the past two decades, green roofs become increasingly popular, especially in cities. “From a sustainability standpoint, it offers heating and cooling benefits,” Nick Fobes, partner at ho*rr Schaudt Landscape Architects, says. “But it’s also a green space to go enjoy nature and have a respite from the cityscape of buildings and concrete.”

A green roof has several components. Typically, a green roof involves a barrier to prevent water damage to the structure, a drainage system, filter cloth, lightweight growing medium, and plants. On a small scale, it could be a layer of vegetation growing on the rooftop. On a grander scale, it could be a park complete with trees.

One amazing example of a large green roof project is the transformation of the iconic Old Chicago Post Office. This Art Deco building, constructed in 1921, sat in decline for 50 years. The ho*rr Schaudt landscape design team transformed its rooftop into a full-scale park, with one and a half acres of meadows, using more than 40,000 plants. It’s now a mixed-use office hub with a stunning green roof design that echoes the building’s Art Deco style.

Read on to learn more about green roofs and how to apply the concept in your home:

Green roofs are designed to provide both environmental and aesthetic benefits.

Manages Stormwater

Green roofs help manage stormwater runoff so it’s absorbed instead of spilling off onto nonporous surfaces like concrete, where it’s then swept away along with pollutants directly into local rivers and streams.

Improves Energy Efficiency

Green roofs can reduce a building’s energy usage by cooling the roof. This can help extend the lifespan of systems like heating and air-conditioning.

Creates a Natural Habitat

Green roofs attract pollinators and provide a habitat for birds and insects. This can help improve the surrounding ecosystem.

Reduces Heat and Noise Pollution

Green roofs help reduce the “heat island” effect in cities, where concrete and asphalt absorb solar radiation. They also absorb sound rather than amplifying it the way traditional roofing materials do.

Improves Quality of Life

A building’s tenants benefit from the beauty a green roof brings to its outdoor space. It makes nature accessible and provides a place to gather.

There are different types of green roofs, with varying levels of complexity:

• Extensive green roofs are simpler, using hardy plants such as sedum and a shallow growing medium; they don’t require a lot of structural support and need little maintenance
• Intensive green roofs are more complicated and similar to a park setting with trees and shrubs; they require structural support and require ongoing maintenance

A conservative estimate for how long a green roof will last is 40 years, according to a 2012 University of Michigan study. That’s much more than twice as long as a typical roof, which it puts at 15 years.

Green roof costs vary widely depending on the type of green roof, the size and scale of the project, and where you live. HomeAdvisor estimates a green roof costs from $12,000 to $40,000, or $10 to $30 per square foot upfront. As for annual maintenance, it pegs the cost at $22,000 on average.

You can expect to save about $200,000 in total over the life of your green roof, mostly from reduced energy costs, according to the University of Michigan study.

Green roofs have become more common in commercial settings in many cities, though some people also choose to incorporate them into homes. While constructing a green roof on your home isn’t a DIY project, you can use employ basic green roof concepts to improve your own outdoor space, no matter how big or small, says Fobes:

• Maximize what you have. “You can create a green space even if you only have a small balcony,” Fobes says. “Make it your own by planting intensively and maxing out every square foot with plants.”
• Go big. Tiny pots of plants don’t have the same impact. Instead, go fill up negative space by adding a cluster of three large planters in varying heights to a corner.
• Create a vertical green wall. “Look at all the different surfaces where you can grow plants,” Fobes says.
• Hang window baskets. It’s an easy way to improve the view from inside and out.
• Use good design. “It’s most impactful if you limit your plant palette,” Fobes says. Instead of using many different plants, stick with three. Always include the thriller (a tall plant in the middle), filler (lower growing plants to fill in), and spiller (plants that trail over the edges of the pot) technique to build your planters. Use different textures to heighten interest.
• Try self-watering containers. These can be useful if you have an environment that’s full sun because you may not need to check them every day.
• Fertilize. Containers need to be feed regularly to keep blooming.

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