-By Bill Rostenberg, FAIA

Although both evidence-based design and sustainable design are having a significant impact on current healthcare architecture, too often, healthcare institutions rely on one or the other rather than both. There is a perception that the two can be at odds with one another. For instance, how does the sustainable design goal of conserving water reconcile with the evidence-based design goal of encouraging caregivers to wash their hands more frequently? However, while some specific implementation strategies may appear incompatible, these two design approaches can support each other in a number of ways. As the fields mature and there is more dialogue between experts in each, combining the two in ways that can harmonize with each other will become more common.

Both practices share similar goals, after all. Evidence-based design, as defined by the Center for Health Design, is "the process of basing decisions about the built environment on credible research to achieve the best possible outcomes." Sustainable design encompasses all practices that reduce the negative impact of development on ecological health and indoor environmental quality. At its strongest, sustainable design seeks to go further than simply minimizing harm, and it shapes buildings and products that are safe, profitable, and regenerative, producing economic, ecological, and social value—what architect William McDonough and chemist Michael Braungart of McDonough Braungart Design Chemistry call "eco-effective design."

However, there are challenges—both perceived and real—in incorporating both practices in the same facility design. A recent research study, "Sustainability and Evidence: The Intersection of Evidence-Based Design and Sustainability," was jointly funded by the Boston Society of Architects, the American Institute of Architects/College of Fellows Upjohn Research Initiative, and Anshen+Allen, and carried out by researchers Bill Rostenberg, Mara Baum, and Dr. Mardelle Shepley, with Rachel Ginsberg. The study surveyed administrators at 16 U.S. healthcare facilities considered by national experts to represent best practices in either evidence-based or sustainable design—eight in each category. Twenty percent of executives at the evidence-based design facilities said they ignored sustainable strategies due to perceived conflicts with evidence-based design. Twenty-five percent of executives at the sustainable facilities ignored evidence-based design strategies due to perceived conflicts with sustainability. In half of the cases, sustainability and evidence-based design were seen as supporting each other. Forty percent of facility executives saw no relationship between sustainability and evidence-based design.

Participants were asked to note specific overlaps, synergies, and apparent conflicts between the two. Overlaps include improving indoor environmental quality and acoustic conditions; increasing access to daylight, views, and nature; enabling users to control their own environments; and incorporating nontoxic materials. A number of strategies have synergistic relationships that support each other, such as evidence-based design goals of providing opportunities for respite and for positive distractions, increasing choices for patients, and designing lighting to reduce medical errors, and sustainable design strategies of providing open space, green roofs, and energy efficient lighting and controls.

Survey participants considered a few strategies in each category as primarily in conflict with the other category. Evidence-based design calls for separate circulation paths for patients, staff, and materials, typically resulting in larger floor plates—which conflict with the sustainable design goal of reducing energy and material use. The sustainable design strategy of right-sizing air change requirements might conflict with evidence-based design's emphasis on life-cycle flexibility, which would involve designing the air change rates to a higher level than needed for present needs in order to accommodate future changes to the way a space is used. However, determining whether strategies conflict or synergize or support each other is not always easy; for instance, right-sizing air change rates is in synergy with the evidence-based design strategy goal of noise reduction, because unnecessarily high ventilation rates can lead to overly loud mechanical systems.

Careful design can balance the requirements of both approaches. Consider the challenge of daylighting. Configuring a hospital as narrow blocks arranged around courtyards and connected with bridges or corridors can maximize natural daylight, a sustainable strategy, but it may result in longer travel distances for staff and vulnerable patients than a densely packed, deep floor plate would. However, at Palomar Pomerado Health's Palomar West Hospital in Escondido, Calif., courtyards were placed to separate the procedural zone from the pre-op and recovery zone, a strategy that allowed each zone to have a relatively deep floor plate. The critical travel distances are still short, yet daylight can penetrate into the interior spaces and facilitate wayfinding.

Both sustainable design and evidence-based design are relatively recent influences on healthcare design—sustainable design in particular. Both are becoming increasingly common in new and existing facilities, making the incorporation of strategies drawing on both approaches more likely. Additional research needs to be done to carefully study potential conflicts and synergies, so the two approaches can be combined to forge healing environments that are healthier for all who inhabit them as well as for the planet.