The Regional Cancer Collaborative at St. Mary's Hospital in Green Bay, WI, recently installed a "living roof" on its newest addition, the latest in a long line of environmentally-friendly initiatives at the facility that officials say have an economic benefit as well.
The roof features interlocking, pre-vegetated modules which contain plants specifically picked for the rooftop because of their extensive growing season. Each one foot-by-two-foot module locks together, like bricks, across the rooftop.
While the initial cost for the 22,000 square foot rooftop garden is approximately $400,000-$450,000, St. Mary's officials say it is a wise investment because of energy savings in the long run.
"With the green roof, your air conditioning costs and your heating costs are significantly reduced by anywhere between 10%-50% because of the insulating factor," says St. Mary's Environmental Services Director Corrine Vercauteren. "That is like a continual payback that helps offset the costs."
The roof is environmentally-friendly in other ways as well. Soil in the roof system acts like a sponge and absorbs excess rain water, and it will have a rainwater device to collect 99% of all rainwater. Not only will it self-irrigate the rooftop plants, but rainwater will be stored and used to irrigate other gardens on the campus.
While a standard tar roof lasts 20 years, the living roof at St. Mary's is guaranteed to last 50-plus years before it needs any type of maintenance, Vercauteren says.
"And what they are telling us is that is a very conservative estimate, because in Europe they have seen green roofs that have been around for 100-plus years and have never had to be replaced," Vercauteren added.
The living roof is the latest in green initiatives at The Regional Cancer Collaborative facility. It incorporates "heat reclamation," a process during which a system "reclaims" all of the heat off the machinery and the function of the facility's equipment—otherwise known as "waste heat" that would normally be vented out of the building.
Vercauteren says the waste heat that is reclaimed for use at the Cancer Collaborative would heat and cool 72 2,000-square-foot Wisconsin homes year round.
"At the same time, because of this project we were able to reconfigure some things with our boiler and our HVAC equipment that saves us 2,800 gallons of water per day," Vercauteren says.
The facility also features energy saving "daylighting" in all of its atrium areas. Using this system, the lighting adjusts to the sunlight coming into the facility so the lights automatically dim to adjust to the amount of lighting coming in, saving energy in the process.
"So that's another piece that is very environmentally sound, yet gives us a continual payback in our energy costs," Vercauteren says. "If you invest a few more dollars, it can have a long-lasting impact.
For the last 10 years, the Collaborative has used a storm water management project that takes all of the water runoff from the campus' 13 acres and runs it through a system that makes the water come out 99% pure as it goes into the Fox River, which Vercauteren says is a nearby, major waterway that dumps into Lake Michigan. That project cost approximately $330,000, but $300,000 of that was accessed through grants and donations.