From the Top Down
Hospitals Look to Vegetated Roofs to Improve Aesthetics, Efficiency
Ask a group of hospital facility directors about the benefits of installing a green roof and you’ll likely hear several answers: heating and cooling cost savings, long-term building material cost savings, environmental responsibility, space maximization and aesthetic improvement. All are correct responses, and all are motivators that are fueling an increased tempo in green roof installations at new and existing hospitals.
Live Roof, a Michigan-based provider of green roofs, lists several financial benefits for going green. On sunny summer days when the outside air temperature reaches 95 degrees Fahrenheit, for example, traditional roofs can easily reach temperatures of 175 degrees or more.
A vegetated roof can reduce the roof temperature to such an extent that indoor temperatures fall by six to eight degrees, depending on the size of the building, climate and type of roof. That temperature can contribute to a 25 percent to 50 percent reduction in summer cooling expenses, according to the company.
Additionally, vegetated roof components help to protect the roof membrane from harsh weather and extand the roof life cycle.
vegetated roofs also combat the effects of land development and the loss of open space. They help to control storm-water runoff, reduce smog in metropolitan areas, conserve energy, improve air quality, and create a habitat for butterflies, insects and birds. They can also turn otherwise unused areas into meditation and therapy space.
While the size, purpose and scope of vegetated roofs at healthcare facilities vary, most possess the same basic components: a layer of thermal insulation, a waterproof membrane, a root barrier, a drainage layer, a filter mat, a specially engineered light-weight growing medium, and vegetation.
Some hospitals have embraced low-maintenance, lower-cost extensive vegetated roofs on portions of their roofs, while others have installed multimillion dollar intensive installations that completely cover the roof, are open to patients and the public, and consist of elaborate designs, walkways and water features.
Semi-intensive vegetated roofs — a mixture of extensive and intensive green roof spaces — are also planned or installed at some hospitals.
Extensive Green Roofs
SSM St. Clare Health Center, a newly opened hospital in suburban St. Louis, recently finished the installation of a 4,000-square-foot vegetated roof atop the facility’s emergency services department.
Access to the vegetated roof is not open to the public, but it can be viewed from family lounge areas and east-facing patient suites. The garden contains 22 varieties of sedum, a plant commonly found in green roofs because of its succulent, water-holding nature.
All of the vegetated roof plants were chosen based on extreme drought tolerance, disease and insect resistance, life cycle, low maintenance and beauty, says Debbie Parker, spokesperson for the hospital. Beyond normal rainfall, the plants need irrigation only in prolonged hot, dry, sunny weather.
Working with a vendor, installation took only one day. Plants were placed in modules and grown to maturity in a greenhouse off site before they were shipped to the hospital. The modules were then lifted to the roof by a crane, placed on a smooth-surfaced rubber slip sheet and snapped into position. Should the hospital need access to that area of the roof, the modules can be removed.
Maintenance needs require an annual soil check and periodic weeding. However, the plant system discourages weed growth.
Other areas of the hospital’s rooftop were designed to hold similar gardens, and when funds become available, the facility may expand the green roof space. A $55,000 grant from the Home Depot Foundation funded the initial project.
Intensive Green Roofs
The Vince Lombardi Charitable Funds Healing Garden and the Agnes and Morland Hamilton Healing Conservatory on the roof of the patient tower at Aurora St. Luke’s Medical Center in Milwaukee is an example of an intensive vegetated roof.
The recently completed project at the 943-bed hospital consists of an elaborate 12,000-square-foot space that includes an indoor area, 19 ornamental trees, 381 flowering and evergreen shrubs, and more than 1,100 perennials.
While the core hospital was built in 1903, this newer part of St. Luke’s was constructed in 2004 with a roof of this caliber in mind, says Mike Connor, regional director of facility operations for Aurora Health Care.
“The fact that this is newer construction helped us to avoid installation challenges that could have occurred in an older facility where a conversion of an existing roof would have been necessary,” Connor says.
The roof also includes wide, wheelchair-accessible walking paths made from Minnesota limestone and an herb garden with herbs that will be used to create hospital meals. The $5 million project was funded entirely by philanthropic funds.
Converting existing space
While green roofs are becoming a standard in new hospital construction, some facilities have successfully converted older, existing roof spaces.
The Christ Hospital, a 555-bed acute care facility in Cincinnati recently converted approximately 4,000 square feet of space across three separate areas of rooftop built in 1929 and 2003 from gravel to an extensive green space.
Similar to SSM St. Clare’s green roof, each section of the Christ Hospital’s space is lined with specially designed trays planted with sedum that grows in an absorbent granular material that sits above a felt-like membrane that retains water.
The plants can draw on that water as needed, while any excess goes into the storm drains. The plants were grown to maturity elsewhere and then lifted to the roof using a crane.
“The roof was scheduled to be replaced, so we opted for a green roof,” says Rick Perkinson, facilities director for the Christ Hospital.
The vegetated roof was approximately $15 more per square foot than a conventional roof. Structural engineers were heavily involved in the process to determine if the existing structure could hold the weight of the plant materials.
The hospital plans to install another 27,000-square-foot intensive vegetated roof that will be accessible to patients and families if pending reports indicate the roof can hold the weight of the project.
Common Roots
Successful green roofs have a few common roots. First, like other hospital construction projects, careful planning can mitigate unforeseen installation challenges. Structural engineers, architects, plumbers and irrigation contractors should be involved in pre-planning and experienced green roof vendors should be called for consultations. Permit issues should be considered, and native plants should be researched.
“The weight of the system should be your biggest consideration,” says Thomas Cox, president of Bi-State Roof Systems of Valley Park, Mo., which oversaw the installation of SSM St. Clare Health Center’s green roof. “Make sure the structure can take the added weight of the specially engineered soil, plant life and water retention from the rain.”
While green roofs can cost more initially, experts say the payback comes with reduced air-cooling expenses, extended air conditioner life due to reduced load, and the extended life of the roofing materials.
“The secret is to discuss the concept with your engineers when you’re designing your facility,” says Don Wojtkowski, executive director of design and construction for SSM St. Clare Health Center. “[An extensive] green roof is just another way of ballasting the roof. It’s no heavier than rock ballast.”
Connor says when a green roof is up for consideration, it will play into facilities’ storm water management plan. Less guttering may be needed, and green roofs can reduce infrastructure costs.
Numerous local and state governments and utility companies offer rebates and tax incentives for green roof initiatives.
“This type of roof is more expensive,” Connor says. “But with time, costs will likely decrease. You have to consider the appropriateness of a project of this caliber. Look at the situation and determine if it has a positive effect on patients and betters the environment. If it does, than it’s there for consideration.”