Case Study: Hospital Chooses Aluminum, SHGC/U-factor Optimization for Condensation and Daylighting PerformanceOctober 28, 2011
Jerry Schwabauer, Azon
In the health care field, window and curtain wall designers and specifiers must prioritize the sector-specific missions of reducing health care errors, discouraging the spread of infectious agents, decreasing sound attenuation, providing natural daylighting and fresh air ventilation, improving patient well-being and enhancing physical security. Windows are uniquely at the crossroads of all of these factors, and today’s heath care facility designers are challenged to look beyond standard product offerings to work with manufacturers and contractors to simultaneously solve a number of location-specific and application-specific problems.
The goal of the project is to reduce condensation while providing daylighting for building occupant comfort, health and energy-savings to ensure healthy surroundings for all of the hospital’s patients.
The new patient tower at Shady Grove Adventist Hospital in Rockville, MD, is a good example of how a development team can meet those challenges. The new four-story tower added 144 private patient rooms to Shady Grove, increasing the hospital's overall private rooms from 32 to 82 percent. Forty-eight private rooms in the new tower are dedicated to Shady Grove's mother/baby unit.
The smooth, hard surfaces provided by aluminum framing discourage the collection of dust and are easy to clean, while also discouraging the spread of infection.
The American Institute of Architects (AIA), in its Guidelines for Design and Construction of Hospital and Health Care Facilities, recognizes the health and psychological benefits of natural daylighting for patients. The Guidelines note that “windows are important for the psychological well-being of many patients, as well as for meeting fire safety code requirements.” The Center for Health Design has further reports that patients in brightly lit rooms have a shorter length of stay, and those exposed to increased intensity of sunlight experience less perceived stress and had 20 percent less pain medication costs.
Beyond its structural and longevity benefits, aluminum framing enables narrow sightlines that help to maximize daylighting.
Natural ventilation has been shown to be a quantifiably effective weapon in reducing the transmission of airborne infections. Operable windows and doors maximize natural ventilation so that the risk of airborne contagion is much lower than with costly, maintenance-intensive mechanical ventilation systems.
Operable windows also work to reduce indoor pollution – particularly important in hospitals, where inadequate dilution of recirculated air with outdoor air can result in exposure of patients to higher levels of indoor-generated pollutants. AAMA’s brochure, Operable Windows in Healthcare Facilities was developed by the AAMA Architectural Window Council to encourage architects, specifiers, building owners and other industry professionals to use operable windows in health care facility applications as a means of addressing fire safety needs while providing other benefits as well, and which is available in AAMA’s Online Publication Store.
At Shady Grove, as in most northerly climates, the aluminum framing and the expanses of glazing that let in daylight need enhancements to be viable energy conservators.
Maryland is located in a climate zone where winter heating predominates. The building designers recognized the advantages of a high solar heat gain coefficient (SHGC) for this type of architecture and traded that advantage for a slightly higher U-factor. To help offset some of the differences in U-factor while keeping the SHGC and visible light transmission (VT) high, warm-edge spacers were used in the insulating glass (IG) units.
At Shady Grove, project planners teamed Trifab® VersaGlaze® windows by Kawneer, with Warm-Light® warm-edge spacers by Azon to deliver peak performance for the sensitive healthcare environment.
It is also especially important in the health care environment to reduce condensation, which can provide fertile fields for growth of bacteria and mold that can be dangerous to people with compromised immune systems or otherwise interfere with the proper operation of sensitive diagnostic or imaging equipment. Particularly in cold weather environments, when windows and doors must be closed and because the relative humidity level is always high in hospitals, improving the Condensation Resistance Factor (CRF) of windows and curtain wall installations is crucial. The higher the CRF, the more efficient the fenestration units are in resisting the formation of condensation.
Energy-efficient windows also typically have a high condensation resistance factor (CRF), although this is further enhanced through use of new technology such as warm-edge spacers in insulating glass units. The Shady Grove fenestration assembly achieved a CRF of 71.
Insulating the interior from intrusive outdoor noise sources is an obviously desirable characteristic for health care windows. Acoustic performance ratings (Sound Transmission Class [STC]) and Outdoor-Indoor Transmission Class [OITC]) guide the selection of windows that preserve restful environments. As in the case of condensation, energy efficiency design features also improve sound attenuation.
The Shady Grove Hospital project exemplified the coordinated implementation of technologies that enhance the energy efficiency and condensation resistance of aluminum windows – structural polyurethane pour-and-debridge thermal barriers, low-E glass coatings and warm edge spacers in the insulating glass unit. This is a vital step in demonstrating how aluminum, as part of a holistic system approach, makes dramatic contributions toward achieving sustainability in buildings and ensuring healthy surroundings for all patients in healthcare facilities.