Wednesday, January 26, 2011
County officials are giving the final green light for the Chattanooga-Hamilton County Health Department’s green roof project, which will provide an educational and energy oasis for the building.
“My take is looking at the holistic aspect of health,” said Becky Barnes, Health Department administrator. “To me, leading healthy lives means needing a healthy environment to live in. A green roof helps protect and improve the environment.”
The project was given final approval during the Jan. 5 meeting of the Hamilton-County Commission.
Approximately 4,000 square feet of the Health Department’s rooftop will be resurfaced with standard rolled rubber roofing before green roof elements such as grass and low plants are added. Part of the funds for the project — $250,000 — was funded by an Energy Efficiency Conservation Block grant for the county. Additional funds were donated by a local nonprofit organization. Artech Design Group’s principal architect Rice Williams is leading the project’s design efforts.
“A green roof could also be a well-insulated and highly reflective roof surface,” Williams said. “However, this roof will be a vegetated roof system and what that entails is soil and a low planting area that essentially captures rainwater and absorbs the rainwater for the plants, so rain stays out of the roof drainage system that ultimately goes into the city’s stormwater system.”
Williams said in dense urban areas the danger of flash flooding is increased because of the speed at which rainwater collects and runs off impermeable surfaces like traditional roofs, roads and parking lots. A vegetated roof can also help counteract the urban heat island effect. In cities, the temperature is usually higher than the surrounding areas because sunlight is absorbed in surfaces that retain heat, like the Health Department’s current black rubber roof, which are more prevalent in congested urban areas.
“There is an energy-saving component to it,” Williams said. “For the building itself there is some insulation value to the thickness of the soil and planting. The sunlight is captured essentially by the plants instead of being absorbed by the roof surface, which eventually trickles through the roof insulation system and affects the inside temperature.”
Along with traditional grasses and short plants, Williams is incorporating ideas like a living wall of vines that will be fed by stormwater runoff. The entire system will be kept healthy during dry seasons with a state-of-the-art sprinkler system that is not set on a timer, but evaluates the moisture level in the soil, watering only when necessary. Williams is planning to incorporate a rooftop terrace for designated meetings or small guided tours.
Erlanger hospital and Siskin Hospital for Physical Rehabilitation patients and employees will be able to catch glimpses of the oasis from several windows and walkways. Sabrina Novak, environmental scientist for the Health Department, envisions the project as an educational initiative for both employees and visitors, proving a green roof is more than just an aesthetic oasis.
“I believe this is the first green roof within the county government,” Novak said. “We’re looking at the public education aspect of it. We’ll have signage and brochures explaining why anyone would want that as part of a building.”
There will be monitoring equipment on the rooftop gathering empirical data on the differences between the original rooftop and the green area, providing facts on resulting energy savings and water conservation. If the results outweigh the costs, Novak said the Health Department may try to find additional grants to continue the project and eventually expand the green area.