This week, Boston is hosting the annual convention of the American Institute of Architects.
One of the hottest topics at the gathering is sustainable design, and part of the conversation starts at the top: with "green roofs."
They're lush and energy efficient...and also controversial.
WBUR's Andrea Shea has this story on green roofs sprouting in the Hub.
Sound of raking
ANDREA SHEA: As he rakes soil a few dozen feet above ground installer Chip Sinkler says the phrase 'green roof' can conjure images of Tolkien's character Bilbo Baggins.
CHIP SINKLER: That's what a lot of people picture I think a little Scandanavian Hobbit house (laughs) in the middle of the woods.
ANDREA SHEA: This soon-to-be green roof isn't in middle-earth...it's in the middle of Newton. When it's done it will be covered with soil and plants. Not like a rooftop garden but more like a carpet of vegetation. While they've been popular in Europe for decades, Sinkler says green roofs are new to most Americans.
CHIP SINKLER: What people usually ask is do you mow it? Do you have to water it? And what happens if there's a leak? There's specific fears that people have and it's new technology so it's good to educate people on these things.
ANDREA SHEA: You don't have to mow or water this green roof. And probes will detect leaks. It's on top of the Aircuity Center for Green Building Technology. The entire building...an old mill...has been converted to showcase eco-innovations. On this day, though, a good old-fashioned crane hoists bags of dirt-like stuff...1,800 pounds each...up onto the roof.
Sound of crane then big bags being opened and poured
ANDREA SHEA: Sinkler says structural analysis determines if a building can support a green roof, but he describes the system as light. 3 inches of vermiculite, crushed terra cotta, and expanded shale top a drainage layer. The plants are sedums that can go 60 to 80 days without water.
CHIP SINKLER: Sedums are a unique plant that can hold all of its water in during the heat, and it's extremely effective in dealing with the harsh conditions of a roof.
KAREN WEBER: Conventional roofs can get up to 150-200 degrees. You can almost fry an egg on some of those roofs.
ANDREA SHEA: Sedum plants keep roofs between 77 and 90 degrees, according to Karen Weber. She's runs Earth Our Only Home...a consultancy....and is a sales rep for Roofscapes, the national green roof company behind this project. Weber says these roofs stabilize ambient temperatures inside and out.
KAREN WEBER: By putting vegetation on roof tops you can create a cooling effect that not only brings the temperature down but in doing that increases energy efficiency, not just for one building but across the board.
ANDREA SHEA: Greening reduces CO2 in the air. It also helps absorb storm run off...a big problem in old cities. Boston has a few green roofs downtown...on the World Trade Center and the Four Seasons Hotel. Proponents would like to see more. They say companies concerned about their 'green image' should pave the way...companies such as Staples...which recently won a green award from the city for selling recycled products and designing energy-efficient stores. Staples says it considered a green roof for its new retail site in Roslindale...but opted for something else. But Weber says Staples dropped the ball in Roslindale, where the company is building a new retail site. She's not alone.
Sound of birds and street noise
MAGGIE REDFERN: You can see the metal roof that they just put on and you can see the parking lot that's coming around the backside of the building right here.
ANDREA SHEA: Maggie Redfern lives behind the new Staples. Her two-family home overlooks the roof. Redfern and other Roslindale residents advocated for Staples to install a green roof. She says the company was amenable at planning meetings. Now Redfern is disappointed.
MAGGIE REDFERN: You would hope they would take that on to show that they aren't just selling recycled paper but they are interested in the environment by having a living roof on their building to take care of the environment around them.
ANDREA SHEA: But while the 17,000 square foot roof isn't 'living' Mark Buckley, Vice President of Environmental Affairs at Staples says...
MARK BUCKLEY: It's still a green roof (laughs) it's a highly insulated roof, the other technologies we have deployed on the roof with the skylights and the heliostats and hopefully the solar panels will make it a very green roof, we believe.
ANDREA SHEA: While Staples is considering living green roofs for new stores in warmer states...Florida, Texas and California...Buckley says the timing wasn't right for Roslindale. Cost was also a factor. Green roofs generally run twice as much as conventional ones.
PAUL EPSTEIN: Cost to one person is an investment to another.
ANDREA SHEA: Paul Epstein is Associate Director for the Center for Health and the Global Environment at Harvard Medical School. He says big companies with big roofs...such as Staples...are key to kick starting a cumulative greening effect...before it's too late.
PAUL EPSTEIN: We really are underestimating globally the amount of vegetation we need to provide the oxygen and draw down the carbon dioxide to support animal life on earth so green roofs are a part of cleaning our local environment, making it healthier and helping to stabilize the climate.
ANDREA SHEA: Plus, Epstein says, green roofs are lovely to look at. Newton homeowner Alex Macalad agrees.
ALEX MACALAD: You can actually climb up through the window here and once we have the planting there's going to be a little walkway here too.
ANDREA SHEA: Macalad decided to add this space outside his bedroom window as part of an overall 'green renovation' of his entire house.
ALEX MACALAD: And we had the opportunity because of this new technology that's been evolving that we could actually do something that contributes to the planet as well. And it's beautiful, it's cost effective and I think it's a win win win situation all around.
ANDREA SHEA: Once the roots are established a green roof is said to be cost-effective in the long run...but installation can run from 15 to 25 dollars per square foot for residential projects and between 7 and 17 dollars a square foot for commercial buildings. But they last a long time. In Germany some green roofs are still 'living' 50 years later.
For WBUR I'm Andrea Shea.
Audio for this story will be available on WBUR's web site later today.
This program aired on May 15, 2008. The audio for this program is not available.