Blowing smoke and shocking air particles

As the green building movement expands, so does the awareness of buildings' overall effects on human health and the environment. Although hospitals and their operations have always had a large footprint, only recently have designers, contractors, operators, and even ground-level staff been making decisions in light of this larger awareness, including product life spans, waste streams, occupants' means of transportation, and other far-reaching concepts. Another consideration is air quality, whose footprint covers anything from the insulation inside walls to adjacent properties and into the earth's atmosphere.

Of the different green and sustainable aspects of the Denver Health Pavilion for Women and Children (which has earned LEED-NC v2.1 Silver for new construction and major renovations), its approaches to air quality are perhaps the most innovative. As part of a first-responder hospital, as a facility dedicated to a vulnerable population segment, and as a publicly funded project, the Pavilion for Women and Children addition needed to be ever more aware of its health and environmental effects, including its air-quality footprint.

Aside from using low-emitting interior materials, installing cotton installation (avoiding the particulates from fiberglass fibers), running a strict construction indoor air-quality program, and installing a carbon dioxide monitoring system, the project team also took a close look at both the operating emissions that the building puts into the exterior air and how the building takes in that same air. The team chose to conduct tests on exterior exhaust streams in a wind tunnel and to install a state-of-the-art air filtration system that electrically charges and attracts particles. The combination of the air-filtration system and the design guidelines from the wind testing mitigate, if not totally eliminate, air-quality issues such as operating emissions from Denver Health buildings and surrounding buildings, general community pollution, bioterrorism, and pandemics.

In with the good

Manufactured by Louisville, Colorado-based StrionAir, the filtration system in the facility's air handler combines mechanical filtration, electrostatics, and ionization to achieve infection control along with energy efficiency and relatively low waste (figure 1). The code minimum for healthcare is Minimum Efficiency Reporting Value (MERV) 14, says Jim Lazzeri, principal of Cator, Ruma & Associates, the mechanical and electrical engineers on the project. Because the fibers in the filter media actually attract particles, the Strion filter has a MERV 15 with the same or lower pressure drop as a MERV 14. “You have the potential of catching more stuff without the penalty of using more power to push it through,” Lazzeri explains.

The filter rack in the Denver Health Pavilion for Women and Children's air handler. The filtration system combines mechanical filtration, electrostatics, and ionization. Particles passing through the air handler are charged and attracted to an oppositely charged filter media, which drops the pressure and saves energy in terms of blower motor efficiency. Image courtesy of StrionAir

The facility is a first-response hospital, which means it will have to handle an influx of patients in the event of a bioterrorism act or a disease pandemic. The filtration system can filter anthrax and has recently been shown in a joint Centers for Disease Control and Prevention (CDC) study to filter the avian influenza virus.1 According to the researchers' results, “weak electric fields used to enhance the efficiency of coarse low-pressure–drop filters may be an effective engineering technology for rapidly inactivating and/or destroying pathogenic viral agents in and on fiberglass and other polymeric media.”