Ensuring Proper Ventilation In Schools
School IAQ problems can fester unnoticed for years before suddenly claiming the limelight. A recent television news broadcast on NBC-TV Channel 6 in Miami focused on southern Florida's "sickest schools," and school board members interviewed during the broadcast lamented the state of some school buildings in the Miami-Dade School District.
The Miami example is just one of many played out across the United States. In some cases, school boards and parent groups have taken action to correct problems, but in other districts the problems persist and buildings continue to deteriorate as school boards are forced to slash operating budgets.
While those in the HVACR trade cannot help with school budgets, they can help by providing equipment designed to ensure clean and comfortable indoor air. Products that affect building ventilation are one key to ensuring proper IAQ.
IAQ Problems And SolutionsJohn Miles is director of engineering and technical support for Quietside, Whittier, Calif. He identified ductwork and outside air as common culprits behind poor school IAQ.
"The units typically applied in schools are designed to cool the room," he said. "No thought is given to the humidity level inside the classroom. Therefore, in many applications, cold, moist air is directed down metal ductwork, causing condensation and contributing to the growth of mold, fungi, and harmful bacteria, which can then be transported into the air.
Miles offered a solution to this scenario. "To solve this, one of the answers is to look to the ductless products, where the unit is installed in the space to be conditioned," he said. "The other is to look closely at the definition of comfort. Is pure temperature control the answer? Humidity control plays a huge role in keeping the classroom air healthy."
He suggested that ventilation procedures should be examined closely. "The requirement for outside air at 15 cubic feet per minute (cfm) per student is understandable, if excessive," he said. "However, why designate that outside air must be introduced, and then have no standard for filtration or treatment of that air? Can it be reasonably argued that the outside air of a school in any major metropolitan area is acceptable for a student, especially those in an elementary school, to breathe?"
Miles said he would mandate that outside air be handled apart from the conditioning equipment. "This would provide the ability to both temper any excess humidity and also to clean the air at a standard far higher than any used currently," he said.
Bede Wellford, vice president of marketing for Airxchange Inc., Rockland, Mass., said, "IAQ is a multidisciplinary science, and all factors should be considered, including source control and air cleaning. However, in schools, the single most important factor is providing the appropriate outside air for dilution of indoor pollutants, especially airborne human pathogens such as virus and bacteria, as well as pollen, spores, and volatile organic compounds.
"Failing a strong source, such as a pipe break-induced mold bloom, for example, the worst problems arise when there is a reduced (or closed off) outdoor air intake or neglected ventilation system."
Wellford pointed out that maintenance can be a very significant factor, noting systems that once did a fine job of supplying outside air and maintaining temperature control may fall well short today if they have not been maintained.
"In other cases, a system designed for 1,000 students is now faced with twice that number," he said. "The HVAC system must be maintained and updated as necessary to provide every student and teacher with a healthy, productive learning environment."
Robert Van Becelaere, vice president of Engineering for the Ruskin Co., Kansas City, Mo., stated, "School IAQ is a problem because the design of the system does not incorporate controls to measure and control the outside air entering the HVAC system, which is listed as the No. 1 source of poor indoor air quality.
"If the HVAC system does not incorporate the outside air control device, most likely the janitor will close the outside air manual damper to save energy without knowing the consequences of not supplying the ASHRAE-prescribed amount of outside air per person."
Sidebar: Honeywell Conducts IAQ Test Of Minnesota SchoolHoneywell's Commercial Indoor Air Quality group recently performed a test at a middle school in central Minnesota. The test focused on improving indoor air quality and balancing the energy needs usually required for thermal comfort in a classroom environment.
Specifically, supplemental stand-alone air filtration systems were installed and operated in two classrooms. The filtration systems utilize pre-filtration, high-efficiency particle arrestance (HEPA), sorbent media for gases and odors, and ultraviolet (UV) light for bioaerosol control.
The two classrooms with the air filtration systems were then compared to the air quality in two nearby classrooms, which had similar use patterns. Data was collected to make a comparison of the overall air quality in each of the four classroom settings. A range of variables was studied, including temperature, humidity, and air quality. Variables such as large (10 micron) and small (2.5 micron) particulates, total volatile organic compounds (TVOCs), radon, carbon monoxide (CO), and carbon dioxide (CO2) were also studied.
The test was conducted with two goals in mind. The first was to show school systems how they may be able to reduce the amount of outside air being brought in if the school currently meets codes for ventilation rates. For schools that are not in ventilation compliance, the test was designed to show them how to achieve compliance with the use of supplemental air cleaning systems.
This approach utilizes the indoor air quality procedure as prescribed in American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 62. According to Honeywell, this approach can be used if cleaner, more energy-efficient environments can be shown and should be considered whenever the outside air has been deemed unfit or not in compliance with standards for dilution ventilation.
Publication date: 08/02/2004