There are a number of indoor air pollutants that contribute to poor IAQ and the spread of airborne disease. These include biological contaminants such as molds and bacteria, and combustion pollutants like carbon monoxide and toxic particles. Even the building itself is a factor, since toxic substances emitted from building materials and furnishings degrade IAQ. This off-gassing, as it is known, is a by-product of such pervasive materials as paint, varnishes, carpet, flooring, insulation, adhesives, and particleboard. The harmful volatile organic compounds (VOCs) that are emitted from these materials can have adverse short- and long-term health effects. One of the easiest and most cost-effective approaches to improving IAQ is eliminating individual sources of pollution. It has become common practice today in the design of health care facilities to utilize natural materials-linoleum flooring, cotton insulation, undyed wool carpet, among others-as well as products with low or no VOCs. Additionally, more and more hospitals are switching to nontoxic cleaning products.

The need to vent

While source control is a straightforward first step toward improving IAQ, ensuring proper ventilation is an obvious, if not more formidable, task. Several recent health care projects make enhanced ventilation a design priority. At Dell Children's Medical Center of Central Texas in Austin, Ohio-based architecture firm Karlsberger brought the outside in by incorporating six courtyards-all open to the sky, and all but one enclosed on all sides by building walls-that serve as air intakes for the hospital's innovative mechanical system.

 

The courtyards, most of which are accessible, serve as air intakes for the building. Photo © John Durant Photography

 

 

Replete with flora representing the various ecosystems found within central Texas, as well as numerous water features, the courtyards-referred to as the "lungs" of the building-provide the interiors with clean, oxygenated air from an extremely controlled environment. "In the old children's hospital, they complained that they could detect a faint smell of lawn-mower exhaust in the operating room when the lawn was being mowed," recalls Joe Kuspan, AIA, principal at Karlsberger. The new arrangement avoids such scenarios: Within the courtyards, a couple of which are inaccessible, there is no lawn maintenance (the few small patches of grass are artificial), or trucks pulling into a loading dock spewing fumes. Throughout the hospital campus-located on a former municipal airport site-smoking is prohibited, and this is strictly enforced in the courtyards that are open to patients, visitors, and staff for physical therapy activities and outdoor dining.

Locating the air intakes at these courtyards provides other advantages as well. With Texas's sweltering summer days, taking air in from the roof, as is typically done, would mean filling the building with super-heated air. Instead, the roof is equipped with heat-recovery units located at the upper elevation of the courtyards, above a series of stacked air handlers, which are distributed on each floor. Rather than utilizing a single, consolidated, rooftop air-handling unit-which can be as large as a transit bus and typically pushes air down through shafts over long distances-Karlsberger "right-sized" these individual air handlers for specific zones of the hospital, each having varying needs. "While some parts of a hospital are like an office building," Kuspan explains, "other parts, such as the operating rooms, have very stringent air requirements." By reducing the distance air travels through ducts, the chances of picking up dirt and other particles along the way were lessened, and maintenance made easier. The setup was also well-suited for establishing smoke zones, a fire-safety requirement for hospitals.