Green roof creates healing within hospital by Natasha Tourish
Currently under construction, Palomar Medical Center West-a new 360-bed hospital in San Diego is being transformed into a healing garden that is not only calming for hospital patients and visitors but is environmentally restorative for the site.
CO Architects in collaboration with Spurlock Poirier Landscape Architects set out to create a “healing environment” with two equally important components – a humane place of healing for patients, and a model of sustainability in the larger environment.
“Nature promotes healing,” says Frances T. Moore, AIA, LEED AP, Associate Principal at CO Architects. “Evidence shows that access to nature reduces stress associated with the typical clinical environment and has a positive healing effect on patients.”
‘The garden roof created the opportunity to accommodate a 1.5-acre green roof and public terrace. Its undulating form houses the most technologically intense part of the hospital while bringing nature closer to the patients in the Tower above,’ said Andrew Spurlock, FASLA, Principal, Spurlock Poirier Landscape Architects.
Through close collaboration with the landscape architect, green roof consultant, mechanical engineers, structural engineers, and steel fabricator, this roof is an example of the thorough integration of architecture, landscape, systems, and program, and the ultimate integration of nature and technology.
Garden Context: Nature
The master plan is built around a central garden mall. A landscape pedestrian walkway extends the length of the site to create a strong framework connecting all elements of the campus.
The landscape structure of the Master Plan places the most active and social gardens near each facility, and quieter, more reflective spaces in more distant but connected locations. The largest and most developed gardens are the Horizontal Gardens at the Hospital where the mall flows into and through the Tower lobby to a large Central Garden. Three acres of Horizontal Gardens include an arrival garden, a park-like gathering space, five intimate gardens, internal courtyards and a hilltop view garden.
The Vertical Gardens
“From the beginning, there was a strong desire to bring natural and social types of gardens up into the buildings. The initial diagrams tested the possibility of a two- or three-story organization that gave all patient rooms a visual connection to landscape gardens. The resulting walking distances were too great; functions that required immediate adjacency were dispersed. The challenge, then clearly defined, was to bring the qualities of a horizontal garden hospital to a vertical organization. In the case of Palomar West, that meant 11 stories.” Said Mr. Spurlock.
He continued: “The rooftop has a community room and garden with a panoramic view of the surrounding valley and hills. To bring elements of the natural world to patients and staff in the technological world of the D&T, garden courtyards intersect the large, two-story floorplates. The fully glazed courtyards not only bring garden views deep into the D&T wing, but also act as natural light-boxes.
Water shortages in hot climates
“As with all projects in Southern California, the issue immediately came up of how a building can justify an extensive green roof—or the other terrace gardens, considering the ongoing shortage of water throughout California. Low rainfall and high transpiration rates are part of the reasons very few green roofs have been completed south of the Bay Area. The design team interviewed several experienced consultants and brought in Rana Creek to develop the approach to sustainability as well as the integration of nature with healing, and nature with technology and mechanical systems of the green roof.
“At their urging, the design team began to look at the green roof playing a functional healing role in treating on-site wastewater. “This would address the water use issue head-on. The team completed a preliminary design to treat cooling tower water with a wetland on the roof to reduce alkalinity, and then use the treated water to irrigate the on-grade gardens,” said Spurlock.
Section of the Wetland Green Roof
Ultimately, this concept is not being implemented and the green roof that is under construction is a conventional green roof using municipal reclaimed water for irrigation.
Treating Wastewater with the Roof
“When the well is dry, we learn the worth of water.” Benjamin Franklin
Mr Spurlock added: “Statistics show a substantial amount of potable water is used as make-up water in cooling towers. Palomar West Hospital is expected to generate approximately 5 million gallons of wastewater from the cooling towers, which would normally be disposed of as in the municipal sewer system. A great opportunity exists to offset this wastewater consumption and reuse it for landscape irrigation. However, the blow down water from the cooling tower contains high concentrations of dissolved salts due to evaporation of the makeup water by the cooling tower system. Salt concentration can be harmful to many plants and irrigation systems.
“Through close collaboration, the team first designed a closed-loop ecological water treatment system for the cooling tower water. Instead of sending wastewater to the municipal sewer system, the blow down water from cooling tower would be sent to the 60,000 sf extensive green roof over the D&T wing to support a diverse wetland planting community. The 1.5 acre green roof could treat the total 5 million gallons per year. Using principles of biofiltration and nutrient recycling, this roof would in turn remove the salt from wastewater through natural processes and return the water to the ground level for irrigation. With Rana Creek’s ability to calculate the approximate level of treatment with this process, the feasibility study demonstrated substantial savings in water use that would offset nearly 60 percent of the need for potable water for irrigation and would save the hospital significant water and sewer fees.”
“The Owner’s concerns included the appearance of this large roof garden and discomfort being the first to build of this type of roof in North America,” said Spurlock. Other major concerns included the intrinsic insects and fungi in the natural system and the perception that they could be a health issue. Ultimately, despite the financial advantage of this system, the obstacles could not be overcome, and the wetland will not be built.
BENEFITS OF THE HEALING ROOF AS DESIGNED
(Using Reclaimed Water from a Municipal Source)
- Contributes to healing gardens
- Brings nature to people at all levels of the hospital
- Integrates technically with Diagnostic and Treatment
- Retains and slows runoff
- Uses reclaimed water from municipal system
- Provides habitat
- Reduces heat island
- Provide evaluation opportunity in inland Southern California
ADDITIONAL BENEFITS OF A HEALING ROOF THAT TREATS WATER
(Using On-site Wastewater from Cooling Tower Water Source)
- Reduces overall site water use
- Reduces wastewater runoff
- Deeply integrates technical and natural processes
- Provides scarce wetland habitat
- Provides cutting edge research into natural process for treating water
The green roof that is under construction will be irrigated with reclaimed water from the municipal water district. The roof will incorporate both outdoor terrace garden that is part of the dining facility and 60,000 sf extensive green roof. The extensive green roof will be planted with naturalized and native plants that will provide habitat and spectacular foreground view to the surrounding hills from garden terraces and patient rooms.
Types of soil: The soil is engineered lightweight growing media contains scoria, sand and humus, designed to drain quickly.
Planting design concept: All plant species are native to southern California, and chosen to make this a regenerative, sustainable landscape. It will continue to reseed itself and become self-sustaining.
Plant palette: Arctostaphylos glandulosa; Festuca brachyphylla; Leymus condensatus; Salvia clevelandii; Penstemon heterophyllus; Penstemon spectabilis; Yucca whipplei; Eriogonum fasciculatum; Eriophyllum confertiforum; Mimulus longiflorus; Aristida purpurea; Bouteloua gracilis; Zauschneria Californica; Achillea Millefollum; Salvia Apiana
Biotrays: Use of new technology that were used in San Francisco California Science Institute to retain the steep slope of the green roof. The biotray is a biodegradable product.
Irrigation: Below grade drip irrigation system. Netafim’s drip and micro-irrigation products incorporate advanced water conservation practices and technologies for enhanced landscape irrigation. Water is applied directly to the plant's root zone to optimizing water usage.
Undulating roof: Create interesting form with different plant types. Planting palettes between valley and ridge are different to accentuate the undulating roof.
Sustainable: storm management, heat island effect …
Healing the environment: important of views from the nursing tower over the site to distant hills and mountains. Green Roof provides a foreground landscape.
Design: Provides a setting for the café terrace at the third level with views, especially to the mountain to the east. Green Roof is part of the plan for the garden hospital and integrating nature and technology.