Published on : July 08, 2011

Case Studies – Green Roofs on Health Care Facilities

Case Studies – Green Roofs on Health Care Facilities

National Institute of Health's green roof recycled over 40 tons of their old roof system, courtesy of Rick Truett, Furbish Co.

 

Roofing is a hot topic in the world of hospital design and management – quite literally.  Temperatures on a typical low-slope roof can reach over 170° F, impacting building energy use, and accelerating the aging process of the roof membrane.  This is of particular concern to hospitals, which spend so much of their energy in heating and cooling.  Even “cool” reflective roofs can reach over 120° F.  Large spans of hot rooftops are a major contributor to energy use in buildings, and also to the rising heat island effect in urban areas.

Why are hospitals and medical office buildings particularly focused on their rooftops?  Along with the normal hassles of roof management, healthcare facilities have the added disruption to their facility operations with repairing and replacing their roofs.  Many hospitals are rambling buildings with multi-level roofs that patients view from their beds and waiting rooms.  The roofs can radiate massive heat loads into the windows and down through the roof deck.  Patching and replacing roofs leads to patient privacy concerns, along with offensive noise, odors and sometimes carcinogenic off-gassing.  Even when functioning properly, waterproofing and rooftop mechanical equipment are unattractive to view from the windows of an already stressful environment.

Many hospitals and medical office buildings are incorporating vegetated roofs to help alleviate these concerns.  Green vegetated roofs, ecoroofs, roof gardens and landscaped plazas are all names for the rooftop application of plants, soil, drainage components and waterproofing.  The primary functions of green roofs are to cool the building (green roofs are closer to 77° F on the same day other roofs reach over 170° F), also control storm water, and extend the life of the roof membrane.  When properly designed and maintained, they can offer compounding economic and environmental benefits to their buildings and surrounding community.  As new green building trends are tested and vetted, covering low-sloped roofs with vegetation is becoming more widely understood and practiced, particularly in healthcare.  

Economic and Environmental Benefits of Green Roofs

  • Conserve energy – temperatures can be 100 degrees cooler than traditional roofs
  • Manage storm water – plants and soil absorb, clean, and evaporate storm water before it reaches the sewer system
  • Extend lifecycle of the roof membrane by double or more
  • Cools the Urban Heat Island Effect and provides habitat for native species
  • Cleans pollution and CO2 from air and storm water


Benefit to Healthcare Facilities

Hospitals and medical office buildings are quickly becoming leaders in vegetated roofing, as they gain several additional benefits unique to the health care industry.  Research has long shown better overall clinic outcomes of patients who can view nature during recovery, rather than only seeing the built environment.  Studies demonstrate that patients who are provided at least visual access to greenery have lower blood pressure, use less narcotic pain medications, have fewer post-operative complications, and experience greater overall satisfaction with their treatment.  Lower stress levels and greater satisfaction with the facility are also experienced by visitors and staff members who can view nature, especially when the green areas are accessible.

Drawbacks to Consider

Despite the benefits, the decision to add a green roof is no simple choice.  Drawbacks of vegetated roofs include the initial cost, which may take more than 10 years to recover through the reduction in costs of building operations.  Decisions in healthcare facilities are often based on first-cost rather than lifecycle payback, and least-cost green roofs may cause greater liability over the long term.  Also, the weight may be more than the roof deck can support.  This is not a problem for new construction, but existing facilities considering a green roof should first consult with a structural engineer.  

Then there is the concern of leaks – chasing down a leak on any roof can be an endless process of flood testing, patches and repairs, and ultimately leads to re-roofing.  Several of the facilities mentioned below get around this concern with the use of electronic leak detection systems.  The detection system can be used to locate a breach in the waterproofing and show its location on the roof within a square foot.  The vegetated roof components can then be cut away just from that area, the repair made, and the components replaced.  But more importantly, when properly designed, the layers of green roof components protect the membrane from premature aging and leak concerns.  The industry standard is to at least double the expected life of a roof membrane that has a green roof protecting it.

While there are drawbacks to be weighed, many hospitals across the United States, and in fact world-wide, are increasingly incorporating vegetated roofs into current and long-term plans for their facilities.

Advocate Healthcare

Undersized storm sewers and drains caused regular flooding at the Advocate Healthcare facility in Oak Brook, IL.  Rather than succumb to the massive costs and facility disruptions of rerouting their whole plumbing system, Advocate installed a living roof.  The intention was to capture and use the rain before it reaches the ground.  They chose a roof section in need of replacement, and added a 6,500 square foot area of extensive green roof.  The term “extensive” generally refers to vegetated roofs with 6” or less depth of growth media (soil).  Extensive green roofs use very low-maintenance groundcover plants such as sedum.  They are usually the least expensive, lightest weight, and easiest to maintain.  

Advocate replaced their aged roof with a cold-applied built-up waterproofing system.  This type of roof membrane does not require torches or hot kettles to install, limiting the fire risks, odors and disruption of operations at the facility.  Plants were chosen that could withstand the harsh environment of the greater Chicago area, and a soil blend was designed to support the plants.  Together, the plants and soil absorb rain before it reaches the drains.  On-site flooding has been significantly reduced, and while keeping the facility dry, their roof also serves as a living demonstration of Advocate’s green initiatives.

St. Mary’s Hospital

St. Mary’s Hospital took the leap as the first facility in Madison, WI to install a green roof.  Their decision was primarily based on the benefits to their patients, visitors and staff - providing access to a relaxing area to balance the stress of the hospital environment.  Their decision was supported by benefits to long term management of the facility (mainly through energy conservation and extended life of the waterproofing membrane), as well as their overall commitment to environmental responsibility.

20,000 square feet of roof area was converted into a fully accessible intensive green roof.  “Intensive” generally refers to a park-like setting with public access.  St. Mary’s green roof includes benches, planters, and landscape features, and makes a nice setting for fundraising events.   

National Institute of Health

The National Institute of Health, on the outskirts of Washington, DC, is the Federal Agency responsible for medical research.  Their facility includes a 4,600 square foot roof plaza, previously covered in concrete pavers.  When it was time to renovate the plaza, NIH decided to add landscaping and outdoor meeting spaces.  By salvaging much of the existing roof tiles, which were converted to pathways and hardscape, an estimated 42 tons of debris was kept out of the landfill.  A cistern was added to capture and reuse storm water runoff.  Several solar panels power the accent lighting, irrigation and cistern pumps.  Some of the garden space was set aside for studying the medicinal qualities of various plants.

Oregon Health and Sciences University Hospital  

Oregon Health and Sciences University is a towering hospital and university campus overlooking Portland, Oregon, Known as one of the nation’s leading green health care campus, OHSU has made the most of their extensive roof areas.  The campus, a towering mountain-top hospital and university system overlooking Portland, incorporates a variety of green roofs.  They have everything from low profile groundcovers, to fully landscaped memorial gardens with trees and water features.  Along with the benefits to the facility, OHSU recognizes ecoroofs as a way to demonstrate their campus’s commitment to sustainability.  

When compared to other sustainable building features, ecoroofs have a unique quality of not only creating a more sustainably operable facility, but also of actively reversing existing environmental concerns in the surrounding community.  OHSU’s green roofs help manage serious the storm water and air quality issues in Portland.  The vegetated roofs also provide native and migratory pollinator habitat in an urban setting.  

 

Van Ness Medical Office Building

The Van Ness Medical Office Building in San Francisco is one of several new facilities on its campus to incorporate green roofs.  It includes multi-level roof areas that allow for natural ventilation, rainwater harvesting, and close-up nature views from many windows.  The green roof design will contribute to a host of LEED credits, including Storm water Quality and Quantity Control, and Urban Heat Island Effect.  

The Nature of Green Roofing

While the benefits can be attractive, a major setback for the green roof industry is that there is really no way to create a broadly applicable baseline for the benefits of adding a green roof.  Energy savings in the building, the capacity for storm water control, the exact number of years you can extend the life of the roof membrane – these factors shift with each unique building situation and green roof system.  They are living organisms and their functions vary widely with each microclimate, building type and method of install.  The lack of an easily quantifiable return on the investment can prove challenging in the early planning stages.  Despite this, green roofs seem to speak for themselves by how widely they have been adopted, and how rapidly they are changing the “nature” of hospital rooftops.

 

About the Author

Elizabeth Hart CDT GRP, LEED GA, she is a founding member of Portland, Oregon’s GRiT (Green Roof info Think-tank). She is currently the Sustainable Technologies Specialist for Tremco, Inc., an international roofing manufacturer. She works with architects, landscape designers, contractors and building owners to be sure each unique vegetated roofing system will function as intended.

She may be reached at: ehart@tremcoinc.com