How Can We Have Healthier Kids and Teachers in the Classroom?
Anyone who has ever worked in a classroom knows that they are the perfect breeding ground for illnesses. Most classrooms are often too hot or too cold (sometimes in the same day), and drafty, with millions of viral and bacterial organisms swirling around the teachers and kids. It is no wonder there are so many student sick days throughout the year.
When Healthy Energy Resources began designing a classroom unit ventilator, the primary issue was one of energy savings. But as we got deeper into re-engineering a system that would save energy, we asked ourselves the question– can we engineer for healthier kids and teachers? Our engineering team was already aware of the integration of short wave Ultraviolet (UVGI: Ultraviolet Germicidal Irradiation) technology in HVAC systems in biology laboratories and medical facilities. Because of UVC’s proven sterilization properties, Healthy Energy Resources decided to incorporate this beneficial technology into the Aristotle-Air system design to eliminate airborne viruses and bacteria in the classroom. Today, the unit goes beyond neutralizing microbes– this new UVC component additionally converts Volatile Organic Compounds (VOCs) in the air into harmless carbon dioxide and water vapor.
Every Aristotle-Air unit has a built-in Advanced Monolithic Absorptive photocatalytic (PCO) cell that incorporates proprietary absorption media and a titanium dioxide (TiO2) photo catalyst. This PCO cell utilizes a high-intensity UVC lamp operating at 254 nm. Here’s how it works– as the heated air passes through the Aristotle-Air unit, the activated carbon matrix captures and holds airborne microbes in place. The UVC light shining on this matrix causes a photocatalytic reaction that sterilizes the viral and bacterial microbes and converts the VOCs into CO2 and H2O. The result is indoor air quality that is comparable to a hospital laboratory.
Can we have healthier classrooms? The answer is yes, with Aristotle-Air.
Technical Note: The contaminants that pollute the indoor environment are almost entirely based upon organic or carbon-based compounds. These compounds break down when exposed to high-intensity UV at 240 to 280 nm. This short-wave ultraviolet light can destroy living microorganisms and break down organic material found in indoor air. These low-pressure lamps emit about 86% of their light at 254 nanometers (nm) which coincides with the germicidal effectiveness curve (C. von Sonntag et al., 1992).
The Effects of Elevated CO2 Levels
When replacing old classroom unit ventilators, we have often found intake dampers stuck in the closed position. When this occurs, the only fresh air the unit can provide is from the air leaking around the damper. This lack of fresh air produces excessively high levels of CO2 over the course of the school day. This affects the learning environment. Recent studies have shown that increases in indoor CO2 concentrations were associated with statistically significant and meaningful reductions in nine different metrics of decision-making performance. At 2,500 ppm CO2, compared to 600 ppm, performance was significantly reduced with percentile ranks for some performance metrics decreasing to levels associated with marginal or dysfunctional performance*.
ASHRAE recommends that CO2 levels do not exceed 1000 ppm in a classroom. Fresh air is usually is around 400 ppm, but an improperly ventilated classroom with 25 to 30 students producing CO2 constantly can bring levels into an unhealthy zone. To counteract this, Aristotle Air units have built-in CO2 sensors to insure a preset optimum level of carbon dioxide will be maintained throughout the day (800 ppm). This is achieved by simply delivering more fresh air into the room to dilute classroom air when levels are near the preset limit. During the evening, or anytime the room is scheduled to be unoccupied, the Aristotle Air unit re-circulates only indoor air to minimize energy usage.
*Technical Note: (See Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making Performance, Usha Satish, Mark J. Mendell, Krishnamurthy, Shekhar, Toshifumi Hotchi, Douglas Sullivan, Siegfried Streufert and William J. Fisk, NIEHS, September 2012).