From private residences and schools to cultural institutions and businesses, green roofs are sprouting up on more buildings around the world. Made with hardy varieties of succulents, grasses, wildflowers, and herbs atop several structural layers—including a waterproof membrane and levels for drainage, insulation, and filtering—these self-sustaining living architectural features can bring natural beauty to urban buildings or connect rural structures to their surrounding landscapes. The sky-high functional gardens also have a wide variety of ecological benefits, such as the ability to absorb carbon dioxide, reduce stormwater runoff, limit heat absorption, and provide habitats for insects, birds, and other wildlife. Factor in lower heating and cooling costs, extended roof life, and tax incentives (depending on the city), and it’s easy to see why this building trend continues to grow.
Europe’s DACH region—the continent’s German-speaking countries of Germany, Austria, and Switzerland—has emerged as a pioneer in the field of green roofs. In Basel, Switzerland, the practice is even enshrined in law, while Austria now has entire forests on top of buildings by artist and architect Friedensreich Hundertwasser. In Germany, Hamburg leads the way with at least 70 percent of new buildings and roofs awaiting renovation to be green in the future. A particularly striking example of the conversion of empty roof areas is currently taking place at the St. Pauli Bunker, an urban oasis more than 150 feet above street level whose panoramic rooftop can be reach via a planted “mountain trail.” Yet, despite that progress, most of the world is not using available rooftop space for gardens and greenery.
What are the benefits of green roofs?
The benefits of green roofs are enormous. They contribute to better stormwater management and reduce the effect of urban heat islands as their plants play a cooling role during hot summer months. Green roofs can also be surprisingly effective against pollution as plant photosynthesis improves air quality. With their insulating effect providing additional protection against solar radiation, green roofs can also reduce the amount of energy needed to regulate building temperatures, whereas conventional roofs lose heat in the winter but heat up in the summer.