Green Roofs and Sustainable Structures: A Comprehensive Guide

Modern architects are leveraging innovative materials and techniques to create the most sustainable buildings possible. This not only helps improve the eco-friendliness of the structure, but it improves cost effectiveness by limiting ongoing maintenance. One of the most trending concepts in the realm of sustainable construction is the implementation of green roofs. Keep reading as we examine the various ways that green roofs are being used in modern sustainable structures.  

What Is a Green Roof?

Green roofs, sometimes referred to as rooftop gardens, use a layer of vegetation grown on the surface of the roof. Green roofing solutions are gaining traction for their utility in lowering rooftop temperatures, which can improve the energy efficiency of the building while lowering ambient temperatures in crowded urban developments.

There are two main types of green roofs: extensive and intensive.

Extensive green roofs are simpler and easier to maintain. They feature hardy plants with shallow root depth that can thrive with minimal attention. They can be incorporated rather seamlessly into various flat roof infrastructures and do not require major substrate renovation prior to implementation.

Intensive green roofs are more complex. Some intensive green roofs are full-scale parks with diverse vegetation, trees, and picnic areas. In some cases, the growing medium for intensive green roofs can be several feet deep. As these types of green roofs require significant load-bearing support, a major substrate overhaul is often required. 

Benefits of Green Roofing Systems

Both extensive and intensive green roofs offer a number of benefits for sustainable structures. They provide shade, reduce the temperature of the roof surface, and remove heat from the surrounding air. The EPA estimates that green roofs have a temperature 30-40 degrees cooler than standard roofs and can lower ambient temperatures by as much as 5 degrees. 

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Some additional benefits of green roofing systems include improved air quality, reduced energy consumption in the building, fewer greenhouse gas emissions, local ecosystem development, and more effective stormwater management. They are also aesthetically stunning and have been linked to improved health and comfort of human inhabitants of the structure. 

Green Roofs vs Cool Roofs

Green roofs are sometimes mistakenly referred to as cool roofs. However, cool roofs, despite their own sustainability benefits, are a distinct category from green roofs.

Instead of using vegetation as a surface layer, cool roofs use highly reflective and emissive materials, such as light-colored rubber roofing pavers, that remain cooler during peak temperatures than standard roofing materials. By mitigating heat buildup on the roof and surrounding air, cool roofs can limit the amount of heat transferred into the building, limiting AC reliance and energy consumption during peak summer hours.

As cool roofs are generally more standard in appearance and design than green roofs, they are a good option for buildings seeking lower upfront costs and quicker installation for immediate energy savings. Green roofs will be the preferred option for buildings seeking a more holistic sustainability infrastructure that factors in ongoing lifecycle costs, public benefits, and broad environmental impact. 

Other Features of Sustainable Structures

As the building’s first line of defense against the sun and inclement weather, a green roof is a great place to start when creating a sustainable structure. The following are some other key features that should be incorporated to help the building achieve long-lasting, net-zero status.

Air Sealing and Insulation

Unwanted air transfer through the building envelope is one of the leading causes of excess energy consumption. As such, installing effective air barriers complete with sustainable insulation is a fundamental component of achieving sustainability.

Effective air barriers not only protect against bulk water transfer through the building walls, but they prevent moisture-carrying air particles from entering the building enclosure. This prevents mold, mildew, and rot from taking hold in the framing.

Important areas for insulation include the exterior walls, below-grade substrate, and roofs. This helps improve the R-value of the structure for a more stable interior environment that limits the reliance on HVAC consumption.

Natural Lighting

Sustainable structures leverage daytime sunlight to limit the use of electric lighting sources. This includes installing large windows for increased light transmission and open interiors with fewer walls that block natural light flow. During peak hours, shades and awnings should be used to manage direct sunlight so that it does not warm the interior to the point of discomfort. Many of the latest window treatments can be controlled with a smart device or are self-adjusting based on UV intensity. 

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Durable Materials

Durability is just as important as energy efficiency when creating sustainable structures. By limiting ongoing maintenance and reducing future energy required for renovation and repair, durable materials help ensure sustainability for decades to come. Structural steel frames, epoxy terrazzo floors, hurricane-grade storm windows, and nonporous quartz countertops are just a few of the most durable materials at the disposal of modern architects. 

Use Green Roofs As a Linchpin of Sustainable Construction

Of the numerous techniques used by architects to create sustainable buildings, green roofs are arguably one of the most exciting. In addition to providing a visually stunning aspect, they are proven to reduce rooftop temperatures of buildings and cool the surrounding air, helping reduce the urban heat island effect.