On the nightly TV news in large cities, the meteorologist sometimes talks about the heat island effect. That’s where all the blacktop roofs and asphalt parking lots soak up the heat and increase the temperature on a hot summer day. One major U.S. city is trying to do something to reduce that effect. To set an example, the mayor decided to start with City Hall. The Great Lakes Radio Consortium’s Lester Graham reports:
On the nightly TV news in large cities, the meteorologist sometimes
talks about the heat island effect. That’s where all the blacktop roofs
and asphalt parking lots soak up the heat and increase the temperature
on a hot summer day. One major U.S. city is trying to do something to
reduce that effect. To set an example, the mayor decided to start with
City Hall. The Great Lakes Radio Consortium’s Lester Graham reports:
Standing on the roof, eleven stories up, isn’t really far enough to escape
the noise of the city below. But this rooftop is an escape. It’s a garden, a
big one. There are even trees. Not in pots, but actually planted on… or…
in the roof.
Marcia Jiminez is the Commissioner of the City of Chicago’s Department of Environment. She says Chicago wants building owners to
do what they can to cool the city down… and planting gardens on the
roof is one way to do it. So that’s what the city did on top of City Hall.
“Well, the garden on the rooftop is addressing what we call an urban heat
island problem. By putting the garden with light colored pavers and the
green plants on top of the roof, we’re actually helping to use less energy
inside the building and it actually helps to keep the building cooler.”
Cooling down the building is just the beginning of this garden. Despite
being eleven stories up in the middle of downtown, the roof is alive with
bugs and butterflies.
“Actually birds and all of the insects, many of them, have found their
way up here. We’ve actually put up birdhouses to study what kind of
birds are coming to the rooftop garden. This is a place of
respite as well as a place to feed.”
The whole rooftop has become something of a lab. Scientists research
what animals have made a home here… and they’re monitoring how the
plants are spreading.
Kimberly Worthington worked on the City Hall project to see it go from
the drawing board to rooftop. She says they chose plants for color, form
and for survivability.
“The design that we went with was low maintenance, was what we were
looking for in our plant selection. And the landscape architects that were part of the design team focused on plants that would require less water. And they also wanted to keep as many native plants as possible. So, there are a lot of prairie plants up here.”
The Chicago City Hall rooftop project also reduces rain water runoff. 75-percent of a one-inch rain will be soaked up right here in the garden. That’s good because too much rain overflows sewers into Lake Michigan. If enough buildings in the city had rooftop gardens, stormwater runoff problems would be curtailed a bit.
While the city is touting the environmental benefits of its rooftop garden, in another part of the city a planned rooftop garden is all about people.
Brenda Koverman is with the Schwab Rehabilitation Hospital in Chicago. We’re up on the roof where she’s showing me landscape renderings of how the surrounding area will look once the planting begins. Stone paths, fountains, flower gardens and shrubs.
It’ll look beautiful. And it’ll probably cool things down up here. But Koverman
says this is for the patients who are learning to be mobile after disabling injuries. The hospital hopes that patients in rehabilitation will find the rooftop garden more pleasant and helpful than institutional tile floors and plastic obstacles as they learn to
“You know, so, are patients more able to maneuver their wheelchairs in the community? Are patients able to use their hands better so they can cook better at home? Are patients able to stay out of the nursing home and go to their home? So, if we can get any kind of
those outcomes, then it’s a huge success.”
It might be more interested in the patients, but the hospital will still be helping Chicago reduce its heat island effect.
There aren’t very many of these projects in the city, so it’s hard to say whether the rooftop gardens could cool things down all that much. But Environment Commissioner Marcia Jiminez says all you have to do is go up on the roof on a hot day. City Hall sits right next to the County Building. In fact they look like the same building. But not from the roof. Only one side is garden.
“In last summer in 2001 on the hottest day, while it was about a hundred degrees on the city hall side, it was 165 on the opposite end of the building where’s there’s a blacktop roof.”
Even if you’re not interested in planting a garden on your roof, the city still requires some effort to cool things down. City ordinance calls for light colored material when a roof is replaced. And parking lots have to plant some trees before they can get a permit to resurface. Rooftop gardens aren’t mandated… but city officials say they’re learning first
hand that it’s a much better use of space in the city.
For the Great Lakes Radio Consortium, this is Lester Graham.