Green Roofs: Growing Possibilities of Sustainability
News—————13 March 2024
Our world is facing unprecedented challenges, the most of which are climate change. The construction and maintenance of buildings are responsible for over 40% of emissions currently. How we build and what we build can profoundly impact the world around us. Sustainable design utilizes techniques that limit negative impacts and increase positive impacts of buildings on people and the environment. There are many strategies that encompass sustainable design, from energy-efficient design to low-emitting materials. Green roofs are one of these strategies that often take advantage of an underutilized and frequently forgotten space— a roof. A green roof is a roof covered in plant vegetation and growing medium and contains a drainage and irrigation system.
The roof systems of KIPP DC’s Legacy campus and the neighboring Ferebee Hope Recreation Center are completely green roof systems, which better regulate the buildings’ temperatures and improve their energy efficiency.
What are the Benefits of Green Roofs?
Our cities today are almost completely impervious, meaning the majority of surfaces in a city, from roads to buildings, don’t allow water to be absorbed or drained through them. Therefore, water and melted snow can overwhelm city stormwater systems during increasingly common extreme weather events. Green roofs reduce this flooding and stress on public stormwater systems after rain or snowfall by slowly absorbing the precipitation and using it as irrigation for its plants.
Additionally, green roofs can significantly improve a building’s energy efficiency. Traditional roofs contribute to the “heat island effect” by reflecting the sun’s heat and increasing temperatures surrounding the building. Urban areas usually experience the “urban heat island effect,” meaning urbanized areas are significantly warmer than surrounding rural areas. However, green roofs absorb heat and increase a building’s insulation, lowering the surrounding temperatures internally and externally. Ultimately, this significantly improves a building’s energy efficiency and decreases a building’s energy use and costs.
Green roofs also improve the aesthetics of a building and can provide a habitat for plants and animals. Green roofs improve urban biodiversity in urban spaces that don’t often have space for living things. Finally, green roof construction can also provide a supplementary tool for improving noise abatement and air quality.
The Challenges of Green Roofs
It is true that green roofs can be expensive to install due to the more complex construction methods required and additional structural support. Upfront costs of green roofs can be significantly more costly than traditional roof construction. However, the energy savings and, thus, decreased energy expenses provided by green roofs often match and cancel out these upfront costs in the long run. In fact, green roofs are expected to last twice as long as conventional roofs. In addition, the increased property value of properties with green roofs can make green roofs a wise economic investment.
Compared to traditional roofs, green roofs require more long-term maintenance, particularly to care for the plants and identify potential water infiltration. Maintenance issues can be minimized with proper green roof detailing and correct waterproofing techniques completed in the design stages.
Case Studies
Studio 27 has extensive experience designing and implementing green roofs in our projects. From educational to multi-family residential, we have broad expertise in designing green roofs for various needs and conditions.
Our new construction school building for KIPP DC’s Legacy campus utilized a green roof system over the entirety of the new roof. Similarly, our additions to Mamie D. Lee School, Richard Wright Public Charter School, and Two Rivers Public Charter School employ green roofs to decrease energy use and improve water absorption on their respective sites.
Our adaptive reuse multi-family residential project, Chapman Stables, employs multiple green roofs to improve the development’s aesthetics while decreasing energy use. To introduce variety and contend with various conditions on the site, S27 utilized three different types of green roofs, each with a different depth, and thus, could support different plantings. Due to the poor existing structural conditions, we worked with a structural engineer to design and detail a new roof structure on the existing building that could support the latest green roof.
Because of Chapman Stables’ unique condition of being a combination of adaptive reuse and new construction building, the different roof conditions demand different types of green roofs. One of the green roofs is a courtyard built over the parking garage, and its extensive depth can support larger plants such as trees.
Because of Chapman Stables’ unique condition of being a combination of adaptive reuse and new construction building, the different roof conditions demand different types of green roofs. One of the green roofs is a courtyard built over the parking garage, and its extensive depth can support larger plants such as trees.
DETAIL DRAWINGS:
In today’s society, we must do everything we can to limit our impact on the environment. By applying sustainable design principles and techniques to our buildings, we can dramatically decrease our emissions while improving the health and quality of life of the people and the environment around us. Green roofs are a vital component of these larger goals. For anyone looking to build, sustainable design practices – specifically green roofs – provide extensive benefits that continue for years to come and look good while doing it.
All photos copyright Hoachlander Davis Photography & Emma McAlary
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