Indoor Air Quality for Schools and How to Plan for a Safer School EnvironmentArticle | 01.07.2021
The December 16, 2020, Wednesdays with Wightman Town Hall session featured guest panelist Douglas Lafever, president of Upgrade-Evolve Consulting, who discussed indoor air quality in the education setting.
Douglas has 30 years of experience in multidisciplinary engineering including aviation, manufacturing, and building design. Included in this is 15 years specifically working in building automation programming, a field in which he holds certifications from seven automations manufacturers. During his career, he has designed over $50 million in energy efficiency retrofits and upgrades for a variety of clients. In 2011, Douglas was recognized as a Legend in Energy by the Association of Energy Engineers for contributions to the industry.
Indoor air quality refers to the quality of air as it relates to the health and comfort of the people who spend time inside a structure. Generally, much attention is paid to outdoor air quality, when in fact, indoor air is typically two to five times more polluted. This issue of indoor air quality becomes even more important when you consider that the average person spends 90% of their life indoors.
Regulations and guidelines
Two primary organizations in the U.S. have the greatest influence over indoor air quality standards: the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) and the U.S. Building Green Council, which has enhanced many of the ASHRAE guidelines. Both organizations have, in recent years, increased recommended levels for fresh air levels and reductions on indoor pollutant levels. In fact, codes have changes more in the past two decades than the 80 years prior.
Existing methods to manage indoor air quality
Currently, three main methods are used to improve air quality in many schools. First, is MERV (Minimum Efficiency Reporting Value) filtration. Most schools operate at a MERV 8 filtration level, trapping pollutants down to 3 microns, such as dust mites, some volatile organic compounds (VOCs), mold, and plastic dust.
Second, heat recovery technology is used to retain moisture in buildings during the winter, and thus improve the comfort and healthfulness of indoor air. Heat recovery technology traps H20 molecules and recirculates them. Most schools are not yet using this newer technology. It is still being refined but is a viable technology for schools to explore.
A third tool to manage indoor air quality is carbon dioxide detection. By continuously measuring carbon dioxide levels, it can be determined how much fresh air to bring in for the optimal benefit of building occupants, thus allowing the air handling system to adjust to immediate conditions. This is critical because carbon dioxide levels are one of the key indicators of air quality. Acceptable levels of carbon dioxide have been set at 1200 parts per million (ppm). However, studies show that the cognitive functioning of students is better at 800 ppm.
During the pandemic, ASHRAE recommendations have been to flood buildings with as much fresh air from outdoors as possible to lower the carbon dioxide levels. This action helps reduce the indoor air viral load.
In a study published in Environmental Health Perspectives by Joseph Allen, director of the Healthy Buildings program at Harvard University, it was shown that students’ cognitive abilities improved by 101% when moved from an environment where carbon dioxide levels were 1200 ppm or higher to spaces where levels were reduced to 800 ppm.
Other studies show that indoor air pollution can be long-term contributors to heart disease and can compromise immune systems. Again, more fresh air can mitigate these factors.
Other ways to improve indoor air quality
Several newer methods and guidelines are available to help schools improve air quality within their facilities.
- Proprietary indoor air cleaners – These systems can handle both indoor air pollution and outdoor air pollution brought into the building. Currently, they are not included in many commercial HVAC system because the technology is so new.
- Increasing MERV filtration rates – By increasing to MERV 11 from MERV 8, schools can make a tremendous move forward. Students benefit from reduce VOCs, allergens, and other urban pollutants. This year, ASHRAE recommended that schools move to MERV 15. This can be a challenge for many schools since existing HVAC systems cannot be easily retrofitted to achieve this level. However, most systems can be modified to achieve MERV 11. It was noted that by increasing filtration rates, there is more air resistance. This can increase energy usage costs and may require modifications to existing equipment.
- Bipolar ionization – This process releases charged atoms that then bind to pollutants, allowing them to be collected and removed from the indoor air. This method also helps to sterilize the air from bacteria and viruses.
- Ultraviolet light – We know that UV-C rays from sunlight can sterilize the air by killing bacteria and viruses. When applying this concept correctly to indoor air quality, UV elements can be added to air handling systems to sanitize the air as is done in hospitals and laboratories. An application engineer can help a school apply this technology correctly and get the most out of the product.
Common practices schools can implement to improve air quality during the pandemic
- Adding room air cleaners and room humidifiers – These are effective but can cost up to $800 per room. Daily cleaning and upkeep of these systems is required to maintain their effectiveness and safety. They also contribute to the noise level in classrooms.
- Duct cleaning – This is always a good choice for air handling systems with external insulation.
- Cleaning and disinfecting internal components of air handlers – This low-cost activity is recommended annually in the summer.
- Improving filtration module in the air handler – By upgrading the filter racks and sealing them properly, schools can reasonably move from MERV 8 to MERV 11 filtration.
- Adding electronic air cleaning systems – These technologies reduce bacterial and viral transmission and can be one of the lowest cost options. However, there is a lot of noise in the market so working with a trained professional to determine the best system for your situation is important.
In closing, Douglas’ three guiding principles for improved air quality are chasing energy reduction to improve overall indoor air quality and reduce operating costs, cleaning return air grills and supply diffusers, and accurate design of air cleaning systems along with careful attention to installation and maintenance of these systems.
A copy of the slide presentation is featured below.
The next Town Hall meeting on Wednesday, January 20, will cover Michigan contract law. The playback of the December 16 Town Hall is below.