It’s Saint Patrick’s Day and that means everything is turning green: milkshakes, the Chicago River, even the beer we drink to celebrate! Our gardens are greening up too. Every day more leaves emerge from the ground as the soil warms and hours of daylight increase. These transformations got me thinking about another form of green — a living roof.
The house I grew up in had a green roof — green shingles that is. While there was certainly nothing environmentally friendly about the roof on my childhood home, the concept of a beneficial green roof intrigued me. This curiosity moved me to do some additional research. I learned that living roofs serve several purposes for a building such as reducing rainwater runoff, providing insulation to minimize cooling and heating needs, creating a pollinator habitat and offering improved aesthetics for passersby.
Green roofs are becoming more and more common in major US cities like Chicago, Atlanta and Portland, where regulations encourage their use and offer financial incentives. Apparently, the Chicago City Hall green roof was one of the first green roofs in the US, planted as an experiment to determine the effect a green roof would have on reducing temperatures. Estimates based on this study and others determined that if all the roofs in a major city were living roofs, urban temperatures could be reduced by up to 13 degrees Fahrenheit. That’s pretty significant. I’m sure we can all agree that we feel the difference between 80 and 93 degrees! Europe also widely uses green roof strategies. During a recent visit to Portugal, I saw a number of buildings with green roofs in the busy city of Lisbon.
According to some studies, green roofs can attract beneficial insects even when they are as tall as 19 stories. With increasing development and shortages of natural habitats, having more resting spots for migratory birds provides a key advantage. The main disadvantage of green roofs is that the initial cost of installing a green roof can be double that of a normal roof. Maintenance costs may also be high since a living roof requires debris removal, weeding, deadheading and moisture control.
I was pleased to learn that Penn State University, in my home state of Pennsylvania, has performed cutting edge research on green roofs, offers classes focused on the topic and has implemented four green roofs on campus. Penn State faculty and students evaluate storm water quantity and quality management, energy balance, plant selection and performance, and more. Another Pennsylvania-based organization, The Phipps Conservatory in Pittsburgh, claims to have one of the greenest buildings in the world through its Center for Sustainable Landscapes (CSL) which inspires others to follow in its footsteps.
The average homeowner should not try to install a green roof unaided by a professional. Fortunately, there are a number of companies focused on this market. Ed Snodgrass, who recently spoke at the Delaware Center for Horticulture on the topic of green roofs, is a fifth-generation farmer. When he was forced out of farming due to financial issues, he founded North America’s first nursery specializing in green roof plants. In an interview I read, Ed said the genus Sedum is the best plant to install if you want a successful green roof. Sedum can live on existing rainfall, adds limited weight to a structure, regrows roots quickly and offers food for pollinators.
While I find the concept of a green roof on my property enticing and can see myself installing one on my garden shed in the future, I’ve decided to start small. My bluebirds are the first beneficiaries with green roof birdhouses. I’d say they already support the concept and are grateful for their well-insulated and attractive nesting spaces.