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

Jump to:

  • What Is a Green Roof?
  • Benefits of Green Roofs
  • Types of Green Roofs
  • How Long Does a Green Roof Last?
  • How Much Does a Green Roof Cost?
  • How to Incorporate Green Roof Concepts at Home

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 Hoerr 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.”

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What Is a Green Roof?

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 Hoerr 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:

Benefits of Green Roofs

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.

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    Green roof for residence by Hoerr Schaudt Landscape Architects

    Types of Green Roofs

    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

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    How Long Does a Green Roof Last?

    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.

    How Much Does a Green Roof Cost?

    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.

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    How to Incorporate Green Roof Concepts at Home

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

    FAQs

    What are green roofs and cool roofs What environmental advantages do they offer? ›

    Green roofs also capture or slow water runoff. Cool roofs reflect more incoming sunlight than traditional darker roofs do, which in turn reduces the heat of the roof surface and surrounding air and so the cooling load of a building.

    How do green roofs help the economy? ›

    Green roofs also contribute to energy savings, leading to annual savings of about $0.023 per square foot of the roof's surface. Additionally, cities offer incentives such as tax abatements, density credits, or loans to combat initial green roof cost, enhancing long-term economic savings.

    How do green roofs reduce energy costs? ›

    Reduced energy use: Green roofs remove heat from the air through the process of evapotranspiration, and also act as insulators for buildings, reducing the energy needed to provide cooling and heating.

    Do green roofs really work? ›

    Because of their insulating effect, green roofs reduce energy usage by decreasing the need for heat and cooling systems to be at full throttle 24/7. This may also translate into financial benefits by providing lower energy costs year-round.

    How long do green roofs last? ›

    Green roofs have a life expectancy of around 40 to 50 years, giving them a lifespan that outperforms a number of alternative roofing options considerably.

    What are the 4 main benefits of a green roof? ›

    The benefits of green roofs
    • Improve the drainage system. Sustainable drainage is an important component of any building, as a way to counter flooding in the event of excess rainfall. ...
    • Increase the lifespan of the roof. ...
    • Boosting thermal performance. ...
    • Helping out the environment. ...
    • Supporting wildlife habitats. ...
    • Aiding air quality.

    What are the challenges of green roofs? ›

    Whereas intensive green roofs will always require an irrigation system. This is due to intensive roofs needing deeper growing mediums, and therefore higher irrigation maintenance, allowing for the growth of trees and shrubs. In short, a lack of water supply is a big reason green roofs tend to fail.

    How long does it take to build a green roof? ›

    High-rise buildings are an 18-month build from breaking ground to completion. The longer the lead time, the better everyone will be able to do what they need to do and get done in less rushed fashion. If it's a small residential green roof, we'll likely get going in only a few months or so.

    Why are green roofs so expensive? ›

    Factors That Determine Your Green Roof Cost

    An intensive green roof usually costs more than its extensive counterpart, because the soil depth is doubled or more. A highly accessible roof will cost less than one that's very high up.

    Do green roofs increase property value? ›

    Increased Property Values

    According to one study, installing a green roof can raise property values 7 to 11 percent. That's a big deal, especially if you plan to sell the building in the next few years.

    How much money does a green roof save? ›

    Believe it or not, green roofs can provide an energy savings of between 10 and 15 percent. If you assume that cooling an office building amounts to 17 percent of your energy bill, then that kind of cost savings can result in cutting around 2 percent off your bill, assuming a one-story building.

    What are the threats of green roofs? ›

    Whereas intensive green roofs will always require an irrigation system. This is due to intensive roofs needing deeper growing mediums, and therefore higher irrigation maintenance, allowing for the growth of trees and shrubs. In short, a lack of water supply is a big reason green roofs tend to fail.

    What are the hazards associated with green design roofs? ›

    Damage: Green roofs may be provided with irrigation pipework susceptible to freezing. Leaks in waterproofing membranes due to root growth or temperature fluctuations may expose the underlying roof structure to damage or corrosion. Drainage systems may become blocked by soil and vegetation.

    Why aren t green roofs popular? ›

    While the benefits of green roofs are well known, high upfront costs have prevented green roofs from becoming a common technology. Green roofs were an afterthought (if anything) during the design and construction of the majority of North America's housing stock.

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