Emory Knoll Farms in northern Harford County, near Baltimore, grows plants for green roofs.
Five generations of the Snodgrass family have prospered at Emory Knoll Farms in northern Harford County. Its 365 acres have evolved from a 19th-century dairy operation to a crop farm for most of the 20th. Now Ed Snodgrass runs a 21st-century roofing business - one that is environmentally friendly and has nothing to do with slate, tin or asphalt.
Snodgrass, 56, grows plants that make roofs green. In the past eight years, he has supplied colorful, resilient and fast-growing plants to cover nearly 2.5 million square feet of rooftops across the U.S.
Green roofs insulate buildings in winter, cool them in summer and prevent weather damage all year, said Snodgrass, who has 15 greenhouses at his farm in Street. Snodgrass, who with his wife, Lucie, co-wrote Green Roof Plants, a primer on the technology, lectures on the advantages of living rooftops and spoke at the World Green Roof Conference in London last fall. His talks focus on managing urban problems with living systems, not mechanical ones.
The door to his office, once his grandfather's milking barn, has a sign that reads "Green roofs. They grow on you." The sweet smell of citrus, from orange and lemon trees in the greenhouse, wafts in. The roof has been green for about three years and has never needed watering or fertilization, he said.
"It keeps the office cool in summer because the sun is not beating down on the roof," he said. "It is working for us, and not making us work on its maintenance."
About 10 years ago, after visiting several cities in Europe, where green roof technology has long been popular, he established greenroofplants.com. The Web site helped his business expand quickly, and he expects continued growth as businesses learn that green roofs deter runoff and lower energy costs.
"I do see a time when green roofs will be required, especially when people understand their value," he said. "The Earth is built on a balance between plants and animals. If it gets out of balance, there are consequences to be paid."
In Baltimore, Emory Knoll has worked on green roofs at Loyola College, Morgan State University, the National Aquarium, the Mikulski Workforce Development Center and the National Bohemian Building. Snodgrass can also point to his efforts at Harford Community College in Bel Air, Northwest Honda in Reisterstown and many federal buildings in Washington. The Orioles are looking to go green at Camden Yards, he said.
The Baltimore Sun asked Snodgrass about the technology.
What makes up a green roof?
A green roof is actually a system with several layers that begin with decking and waterproofing. The layers, which include drainage, filter and growing medium, work together as a unit. The roof can be built on various decking surfaces, if the right engineering, waterproofing, drainage, insulation and protective components are put in place. [Herbaceous perennials are the most desirable rooftop plants because they offer the greatest color, texture and seasonal variability; those that work best include species of phlox, dianthus and viola.]
Why should builders invest in green roofs, which cost twice the typical roof to install?
We have to re-establish vegetation in urban areas. Imagine what Baltimore looked like before there were houses. Plants produce oxygen, reduce heat and have so many other benefits. People are moving back to the cities, and cities have to become more livable. One way to do that is with more vegetation to make cities cooler, more attractive and more energy efficient.
With cities requiring developers to decrease impervious spaces and demanding better management of runoff from buildings, you should vegetate the top of the building and you won't have to use additional real estate for a retention pond.
How do green roofs lower energy costs?
Living systems run cheaper and better than mechanical ones. You realize immediate savings on operational costs with a better-looking, energy-conserving habitat in an urban environment. Maintenance also is low, with maybe an occasional weeding. As energy costs rise, business must respond. People got a taste of high energy costs last summer. Gas prices are down because consumption is lower, but the cost of extracting oil is just as high.
What plants are best suited for rooftops?
You want ornamental plants but that is not the primary function. Look for low-ground-cover vegetation and certain physical characteristics such as plants that live long, those that provide rapid ground cover and those that will not do harm should they fall off. You don't want anything that would accrue weight over time, and that narrows the list. You also make trade-offs depending on the climate of the region.
You want plants that can live on rainfall and do not require irrigation.