Healthy Environments

Dec. 1, 2006
Over the years, schools have had to deal with various indoor air quality (IAQ) issues: Reduced ventilation requirements and tightened building envelopes.

Over the years, schools have had to deal with various indoor air quality (IAQ) issues:

  • Reduced ventilation requirements and tightened building envelopes.

  • Custodians manually bypassing computerized HVAC systems or blocking fresh-air intakes.

  • Propped-open classroom doors.

  • Crowded classrooms.

  • Incorrectly installed pipe insulation and omitted vapor barriers on walls below windows, which led to mold growth in ceiling tiles and vinyl wall coverings.

  • Manufacturers' materials produced pollutants, such as mercury vapors, from aging synthetic gym floors.

Fifteen years ago, Stillwater (Minn.) High School was ahead of its time in focusing on IAQ. An environmental hygienist recommended changes; some were doable, but budget constraints prevented others. The district considered radon pits below the floor slab with vents extended upward through the roof and charcoal filters in each variable-air-volume ventilation box, but bids were rejected as too expensive. Vinyl floor tile was recommended, but teachers wanted carpet.

Forest Elementary School in Crystal, Minn., was replaced with a new building in 2005 because of mold and asbestos. The goal of the new facility was to eliminate the “triggers” that aggravate asthma and other respiratory conditions. The facility was designed to minimize moisture and humidity, remove dust and particles, reduce use of porous materials, circulate air more efficiently, and maximize energy conservation.

Precautions during construction prevented construction dust from seeping into the mechanical systems. In addition, a seminar helped educate construction workers on the importance of precautions such as maintaining walkoff mats; segmenting areas during painting and work that generates dust; preventing the spread of dust with negative air units that have HEPA filters; cleaning and vacuuming daily to prevent the spread of dust; storing materials in wrapped and clean areas; protecting construction from the elements; and adhering to manufacturer recommendations for product storage, handling and installation.

One unique concept used in the facility was a displacement ventilation system. It supplies fresh air to each classroom at floor level through low-velocity supply diffusers. The cooler supply air “displaces” warmer room air to create a zone of fresh, cool air at the occupied level. As air rises, heat and contaminants produced by activities and occupants are removed through ceiling vents. The used air is not re-circulated as with conventional ventilating systems. This system requires fewer ducts above the ceiling, and low air velocity keeps mechanical noise at minimum.

Remember, IAQ can be affected by:

  • Materials and systems.

  • Designs and specifications.

  • Flawed installation and carelessness during construction.

  • Occupants and activities.

  • Inadequate maintenance and operations.

Rydeen, FAIA, is an architect/facility planning specialist and former president of Armstrong, Torseth, Skold & Rydeen, Inc. (ATS&R), Minneapolis. He can be reached at [email protected].

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