Air Cleaning in Practice: Improving IAQ and Saving Energy in Schools, Part 2 of 2

Picking off from our last post

There is a need to provide “fresh air” into K-12 classrooms and Purafil with FGI’s current filtration technology can be used to capture and remove most, if not all, harmful air contaminants. Air in classrooms should contain only extremely low levels of airborne contaminants (particulate – both nonviable and viable – and chemical) that can affect student health and result in poor attendance or low academic achievement. The following types of airborne contaminants have significance with regards to human health and well-being.

  1. Respirable Particles is airborne matter smaller than 2.5 microns that have the potential to cause allergic reactions, skin irritation, coughing, sneezing, respiratory difficulties and circulatory system problems. They can, however, be removed with the proper choice and application of particulate filters.
  1. Irritant Gases include, but are not restricted to, volatile organic compounds (VOCs), formaldehyde, ozone, PCBs, body odors, and bioeffluents that can be causes of discomfort and poor health outcomes. These contaminants and many others can be removed using Purafil’s gas-phase air filtration media, filters, and air cleaning systems.
  1. Viable Particles (or infectious microbes) can cause bacterial and viral respiratory tract infections, particularly from cold-causing rhinoviruses, and are associated with a majority of asthma attacks in both children and adults. Many of these infectious agents can be removed with the appropriate particulate filters. 

Professors Pawel Wargocki and David P. Wyon of the International Center for Indoor Environment and Energy at the Technical University of Denmark have shown how air filtration can remove respirable particles from classroom air as part of a research project funded by the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE). Chris Muller of Purafil, Inc. and Gerald Lamping, former Director of IAQ at the North East Independent School District in San Antonio, Texas have shown how gas-phase (or dry-scrubbing) air filtration can remove irritant and odorous gases from classrooms as part of applying the IAQ Procedure of ASHRAE’s Standard 62.1-2016: Ventilation for Acceptable Indoor Air Quality.

Parham Azimi and Brent Stephens, Ph.D. from the Department of Civil, Architectural and Environmental Engineering at Illinois Institute of Technology have shown how air filtration can reduce the risk of infection from the influenza virus at lower annual costs than the injection of high levels of outside air for dilution. They found that the relative risk of being infected by the flu virus inside a space can be lowered by either higher outdoor air ventilation rates (dilution) or by higher levels of recirculation with air cleaning. The annual costs for each method were calculated and a lowest cost break point was for a filter with a minimum efficiency reporting value (MERV) of 13 as verified by ASHRAE Standard 52.2-2012: Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size.

Kathleen Ward Brown, John D. Spengler and others from Environmental Health & Engineering Inc. and the Harvard School of Public Health, respectively, assessed the effectiveness of commercially available air filters to reduce the levels of asthma and allergy triggers in indoor environments. Their analysis found that an ASHRAE MERV 12-13 air filter can effectively lower the indoor concentrations of asthma triggers and allergens by more than 50% when installed in a central HVAC system. Other studies throughout the world have demonstrated that improved filtration and air cleaning (FAC) practices are successful in reducing indoor levels of potentially harmful particulate and chemical contaminants – especially ozone which is a primary asthma trigger in both children and adults.

The U.S. Green Building Council (USGBC) Leadership in Energy and Environmental Design (LEED) and the Collaborative for High Performance Schools (CHPS) Building Rating Systems are requiring air filters in HVAC systems to be MERV 13 or higher and ASHRAE Standards 62.1 and 189.1 require gas-phase air filtration of the outdoor air before use as ventilation air if it is known to exceed the EPA’s NAAQS criteria in that location. European researchers have studied the outside air in various locations and concluded that both the outdoor AND indoor air need additional filtration and air cleaning as part of an overall scheme for ventilation in a schools. In recent years, the European Ventilation Standard EN 13779: Ventilation for non-residential buildings. Performance requirements for ventilation and room-conditioning systems, has listed the types of air cleaning devices that are required to achieve one of four levels of IAQ with three grades of outside air.



When used in schools, the IAQ Procedure of ASHRAE Standard 62.1-2016 is an HVAC design option that focuses on direct control of harmful contaminants in the air through the use of filtration and air cleaning. It does not have the shortcomings of other design approaches that oftentimes assumes that the outdoor air being used for ventilation is of better quality than the air inside a building. The IAQ Procedure provides improved indoor air quality as well the potential to reduce the amount of energy spent on conditioning outdoor air. This makes it a powerful tool for design engineers to assure that taxpayer dollars are not being wasted on excessive energy use and for school boards and school administrators to provide a comfortable and healthy learning environment for all grade levels.

Due to increasing momentum for more sustainable, greener building design with the concurrent demands for increased energy efficiency and IAQ, interest in this HVAC design method is growing. Properly applied, the IAQ Procedure can provide for considerable up-front capital cost savings, HVAC-related operational energy savings, and significant improvements to IAQ. All this to the benefit of students and faculty alike.

Whereas other HVAC design approaches focus primarily on assuring acceptable indoor air quality by keeping CO2 levels below specific design criteria, the IAQ Procedure provides a way to reduce HVAC system operating costs while still providing a healthy learning environment. It provides a direct solution for reducing and controlling contaminants to specified acceptable levels through filtration and air cleaning.

Although the IAQ Procedure can be applied for many different applications, the most common, and those with the greatest potential for capital cost savings and operational cost reductions, involve new construction and renovation. It provides a design approach in which the building and its ventilation system are designed to achieve an IAQ target level to the benefit of all.

While the use of this technique can provide compelling savings in equipment capacity and operating costs, the widespread usage of the practice has been limited because of more rigorous engineering and commissioning requirements and the lack of documented energy usage results. And because more attention now being given to the quality of outdoor ventilation air, the interest in filtration and gaseous air cleaning applications has been revitalized through the activities of organizations such as ASHRAE and the USGBC. If one has to apply enhanced air cleaning to comply with LEED, the use of the IAQ Procedure could pay for upgrades to the air cleaning system AND provide for a reduction in overall HVAC operating costs.

Being able to achieve IAQ goals while reducing energy consumption is one of the more valuable aspects of using Standard 62.1 which is now allowed for use on LEED projects. With most public schools and many private schools now being mandated to achieve LEED certification, the IAQ Procedure provides a direct path towards achieving multiple LEED points for Indoor Environmental Quality, Design Innovation, Energy Conservation, and other categories.

By meeting the requirements of the IAQ Procedure, one is allowed to take credit – in the form of a reduction of the outside air intake rate(s) – for the application of validated air cleaning technologies that result in indoor contaminant concentrations equal to or lower than those achieved using other design approaches. The IAQ Procedure has been and continues to be successfully used in schools to lower outdoor air intake rates thereby reducing the up-front capital costs for HVAC equipment, lowering HVAC system energy requirements, and most importantly, improving IAQ.

In times when energy conservation and sustainability are at the forefront of many peoples’ minds, the IAQ Procedure should be considered as a proven option to achieve these goals. editedoffice-cubicles-with-lightRemoval of harmful contaminants from the air we breathe inside of buildings is paramount to protecting the health and well-being of building occupants. However, it becomes even more critical in schools for the protection of a still developing and more vulnerable population where poor IAQ has been linked to absenteeism, lack of adequate progress at each grade level, and reductions in standardized test scores.

Reach out to Purafil to see how they can help you achieve IAQ goals and LEED certification by visiting:  Contact Purafil Support

By Chris Muller, Director of Technical Services at Purafil  – Filtration Group



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