The evidence-based design wheel
Evidence-based design (EBD) is an approach to environmental design (architectural, interior, and landscape) that aspires to base design decisions on documented research and well-established best practices, with the aim of improving outcomes.1,2,3 Evidence-based design is increasingly common in the design of healthcare facilities, where the approach has found support among healthcare administrators, many of who are familiar with the conceptually comparable notion of evidence-based medicine. Healthcare environments designed on the basis of solid research evidence are intended to improve patient safety, reduce stress, increase care delivery effectiveness, and enhance quality of care3—objectives that contribute to the overarching goals of improved patient, staff, and organizational outcomes.1 These are achievable when the environment is designed to be therapeutic for patients, supportive of family, efficient for staff, and restorative for all.1,4,5
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Environmental design research in healthcare settings has increased steadily over the last several decades. The most extensive review of the research literature to date (covering more than 600 studies) was conducted in 2004 by Roger Ulrich, Craig Zimring, and colleagues in a report for The Center for Health Design and supported by the Robert Wood Johnson Foundation.3 This impressive study organizes the substantial research knowledge base on the effects of the environment in terms of various outcomes: staff stress and fatigue, effective care delivery, patient safety, patient stress and other patient outcomes, and overall healthcare quality.
In my work as a director of research and education in an architectural firm, I have conceptualized the collective findings of the studies reviewed by Ulrich et al, as well as other rigorous, high-impact studies identified in our own research endeavors in terms of 12 outcome-linked environmental factors that directly contribute to the healing environment. This conceptualization is illustrated in a colorful and engaging graphic device, the EBD Wheel (figure). Whereas Ulrich et al approach the EBD research literature from an outcomes perspective, the EBD Wheel represents a factors-oriented view, prompted in part by a reading of an earlier article by Ulrich on the effects of healthcare environmental design on medical outcomes, which organizes the literature in terms of “environmental characteristicsé that can affect outcomes”.5
It should be noted that some factors are relatively objective (single patient room, air quality), while others are relatively subjective (access to nature, positive distractions)—yet all are equally important to the healing environment equation. To ensure against interpreting the 12 factors as a mixed medley of elective features, they are conceptually linked in the EBD Wheel within the unifying construct of the healing environment to which the factors contribute. Taken together, the 12 environmental factors and the overall healing environment concept comprise a comprehensive, strategic, values- and evidence-based set of design responses that create therapeutic healthcare environments,4 i.e., curative settings that support healing and improve the healthcare experience.
At Kahler Slater, we have found the EBD Wheel very helpful in our efforts to increase designers’ and clients’ knowledge of EBD issues and in fostering clients’ understanding of the negotiated complexities that must be navigated in the course of the healthcare design process. In addition, the wheel has been useful in talking with clients about shortcomings in existing facilities, highlighting responsive features in our own designs, and focusing discussions throughout the design process.
The 12 factors and the healing environment construct that comprise the EBD Wheel are summarized very briefly here; unless otherwise noted, primary references for the research findings described in these summaries can be found in Ulrich et al,3 which provides a thorough overview of the evidence base for environmental design research in healthcare settings.
Theorizing in response to our work at Kahler Slater, I propose that the healing environment construct be defined as a multisensory setting that engages the physical, emotional, spiritual, and social dimensions of the individual for the purpose of restoring and maintaining health and well-being. Consistent with the guidelines of supportive healthcare design4,5, a healing environment maximizes an individual’s control over the environment, supports one’s social network (i.e., thoughtful accommodations for families and visitors), and affords unrestricted access to nature and other positive distractions. The 12 factors are listed and briefly explained below.
1. Single patient rooms.As reported in a recent review of the literature,6 single patient rooms have shorter length-of-stays, fewer medication errors, lower costs, higher occupancy rates, lower rates of hospital-acquired infection, fewer patient transfers, increased privacy and control, less noise, fewer sleep disturbances, and higher patient satisfaction. The most recent AIA guidelines for new construction stipulate that all patient rooms be private7.
2. Noise.Noise negatively affects patients and staff, yet hospitals are notoriously noisy places. Noise disrupts sleep, impedes healing, and causes stress3. Sound levels in hospitals (typically 65-85dB, comparable to a loud restaurant or heavy street traffic) result from a cacophony produced by a combination of sources: people walking, talking, and simply doing their jobs; buzzes, beeps, and alarms from equipment; and the many hard surfaces that are easy to keep clean but do little to absorb noise. Reducing noise can be achieved by adopting a systemic approach to sound control that requires attention at four levels: noise-attenuating materials selection and installation, proximal location of support spaces and equipment, operational and behavioral changes by staff, and equipment maintenance.8
3. Windows.Patients in rooms with windows, particularly windows with pleasant views to nature, have shorter recovery times and fewer complications, and request less pain medication. Employees with access to windows and nature views experience less stress, better health, and higher job satisfaction.
4. Light.Bright light, either natural or artificial, can improve patient outcomes, affecting such factors as depression, agitation, sleep, circadian rest/activity rhythms, and length of stay. Sunlight has been linked with shorter stays, lower stress, less pain, lower intake of pain medication, and even lower mortality. For staff, ensuring that appropriate, nonglare light levels are brought to the tasks at hand can improve staff accuracy and effectiveness.
5. Access to nature.Research has repeatedly demonstrated the emotional and physiological benefits of visual and physical access to nature: stressful and negative emotions decrease while pleasant emotions increase. Patients viewing nature recover faster, have less stress, anxiety and pain, and require less pain medication. Gardens located in healthcare settings offer patients, visitors, and staff the opportunity for direct interaction with the restorative, calming effects of nature.
6. Positive distractions.The term “positive distractions” refers to several socioenvironmental features—music, laughter, pets, and realistic art (preferred over abstract by most patients),9 as well as natural elements such as trees, flowers, and water—the presence of which improve mood and relieve stress. These positive distractions attract and sustain attention, produce positive reactions, and alleviate stress and anxiety.
7. Furniture arrangements.In public areas, different types of furniture arrangements can either discourage or promote social interaction.5 For example, seating arranged around the perimeter of a room (as in the archetypal healthcare waiting area) and large open dining areas furnished with long banquet tables (such as in the typical hospital cafeteria) are institutional, noisy, and inhibit interpersonal interaction. Arrangements that promote social interaction in waiting areas include comfortable, supportive furniture positioned in small, flexible groupings, with seating placed at right angles. Large dining areas should be subdivided with tables seating four to encourage social interaction, enhance relative privacy, and improve eating behavior.
8. Air quality.Poor air quality and ventilation allow the transmission of bacteria and put patients and staff at risk of hospital-acquired infections.10 The type of air filter, direction of airflow, air pressure, air changes per hour, humidity, and ventilation system maintenance have all been linked to infection rates. The risk of infection can be reduced through the careful design and maintenance of hospital HVAC systems, use of HEPA filtration, and implementation of preventive measures during renovation and construction.10
9. Flooring materials.The three main flooring options for healthcare settings—carpet, vinyl, and rubber—each have unique benefits and limitations. Based on findings from our own research, we advise clients that flooring decisions for patient care areas be made on the basis of materials performance in line with four (often divergent) criteria: infection control, ease of maintenance, potential to contribute to a systemic program for sound control, and specific patient population needs and preferences.8
10. Wayfinding.Disorientation in built environments is embarrassing and stressful, wastes time and, in some cases, is even fatal. One study estimated the cost of confusion in a large regional hospital to be at more than $220,000, much of which was in the hidden cost of staff time spent giving directions (4,500 hours—the equivalent of more than two full-time employees). Support for wayfinding depends on more than signage and colored lines on the floor—a good wayfinding program requires an integrated, coordinated system in which three elements—human behavior, environmental design, and organizational policies and practices11—all work in harmony to ensure that patients, visitors, and staff can effectively navigate the environment.
11. Building layout.Perhaps the most discussed aspects of building layout in healthcare settings today are workstations: Should they be decentralized, centralized, or some combination of the two? Workstations that are close to patients result in fewer errors, decrease nurses’ travel time and distances covered during the day, increase nurses’ time spent caring for patients and families, and improve job satisfaction. Decentralized workstations that incorporate supplies are convenient, improve delivery time, and reduce supply costs.
12. Ergonomics.Patients and staff in healthcare settings benefit from improved ergonomic designs of furniture and equipment. Among patients, injuries such as falls decrease in environments that are designed from an ergonomically conscientious perspective. Patient comfort during medical procedures and hospital stays is improved with thoughtfully designed furnishings. Improved ergonomic designs of patient beds, assistive equipment, and workstations reduce stress and injuries among staff.
The Center for Health Design and Healthcare Design are terrific resources for information on evidence-based design. Also, The Architecture of Hospitals by Stephen Verderber and edited by Cor Wagenaar (2006, NAI Publishers) has several good chapters on evidence-based design written by leaders in this growing field.
Special thanks to Amy Beth Keller, Jim Rasche, and Kahler Slater for their support in the development of this idea; Carla Minsky and Jerry Weisman for their thoughtful critiques of an early draft of this article, and Kahler Slater graphics professionals Kurt Thieding and Bill Miksich for their artful rendition of the concept drawing. HD
- Hamilton K. The four levels of evidence-based practice. Healthcare Design, November 2003:18-26.
- Ulrich R. Evidence-based design to enhance patient safety. In The environment for care: An NHS estates symposium. London:The Stationary Office, 2004.
- Ulrich R, Zimring C, Joseph A, Quan X, Choudhary R. The role of the physical environment in the hospital of the 21st century: A once-in-alifetime opportunity. Center for Health Design:Concord CA, 2004.
- Ulrich R. Pre-symposium workshop: A theory of supportive design for healthcare facilities. Journal of Healthcare Design 1997; 9:3–7
- Ulrich R. Effects of healthcare environmental design on medical outcomes. In: Design & Health–The therapeutic benefi ts of design. Proceedings of the 2nd Annual International Congress on Design and Health. Karolinska Institute, Stockholm Sweden, June 2000:49–59.
- Chaudhury H, Mahmood A, Valente M. Advantages and disadvantages of single- versus multiple-occupancy rooms in acute care environments: A review and analysis of the literature. Environment and Behavior 2005; 37:760–786
- American Institute of Architects. Guidelines for design and construction of healthcare facilities. Washington DC:American Institute of Architects Press, 2006.
- Geboy L, Keller AB, Schnuck K. Assessing a hospital sound environment: Findings and evidence-based recommendations for architectural design and behavior. Presentation made at the Environmental Design Research Association annual meeting, Atlanta, GA, May 2005.
- Ulrich R. Effects of health facility interior design on wellness: Theory and recent scientifi c research. Journal of Healthcare Design 1991; 3:97–109 [Reprinted in: SO Marberry, (Ed.) 1995. Innovations in healthcare design (pp. 88-104). New York: Van Nostrand Reinhold.]
- Joseph A. The impact of the environment on infections in healthcare facilities. Center for Health Design, Issue Paper #1, July 2006.
- Carpman J, Grant M. Wayfi nding: A broad view. In: Bechtel RB, Churchman A (Eds.), Handbook of Environmental Psychology, NY:John Wiley & Sons, Inc., 2002.