Questioning the Efficiency of HVACs

 

Heating, ventilation, and air conditioning systems -- or HVACs -- are often held as a panacea for combatting indoor air pollution, so much so that their presence in office buildings is standardized. While HVACs do effectively reduce the levels of volatile organic compounds (VOCs) present in the air they filter when the systems are properly maintained, a study conducted by the Public Interest Energy Research Program found that 43% of HVACs installed in buildings today fail to reach ventilation standards put in place by the American Society of Heating, Refrigerating, and Conditioning Engineers (ASHRAE) (Bennet et al., 2011).  The use of the word “standard” is a bit of a stretch here, as these requirements are entirely voluntary. They pertain only to how a building is designed with little to do with how it actually functions. Owing to this lax stance, criterions for ventilation are seldom enforced, in large part because ASHRAE’s standards must first be adopted and then incorporated into a state’s building code. With seldom to no legal status to keep companies honest, HVACs receive little attention and often fall into disrepair.

According to a study conducted by the Environmental Protection Agency (EPA), which aimed to illuminate factors contributing to faulty HVAC systems, several easily remedied factors are to blame here. However, measures put in place to reduce spending more often than not lead to inaction. Many of the ventilation units used in office buildings, which market themselves as energy efficient, operate intermittently throughout the day in response to air conditioning needs. When consistent airflow is repeatedly interrupted for extended periods of time, the window in which ventilation rates are not met provide ample time for VOCs to accumulate in the workplace (Henning & Schleibinger, 1999).

An accompanying consideration that can corrupt the efficiency of HVACs is improper installation and placement. Due to the complexity of safely ventilating such a massive space as a multi story commercial space, positioning of building vents and exhausts are often overlooked. When the two are placed in too close of a proximity to one another, air saturated with VOCs intended to leave the building can be reabsorbed by the air supply vents and subsequently pumped back inside. On a more acute level, efforts to minimize heating and cooling costs by reducing the amount of outdoor air flow into the building can further exacerbate these conditions.

While all of these active processes have a hand in reducing indoor air quality, perhaps the mostly costly oversight when it comes to the efficacy of HVACs is simply neglect. When filters are not replaced regularly within these systems, certain microbes that produce both formaldehyde and acetone are capable of growing in large quantities on the filters themselves. Unbeknownst to the occupants of the building, the very ventilation systems intended to purify its air are actually contributing to its toxification.

Considering commercial office buildings account for nearly 20 percent of the country’s total energy expenditure and house an even larger portion of its population, indoor air quality is deservedly an extremely important area of focus (Bennet et al., 2011). The various unavoidable shortcomings of HVACs shed light on the reality that these systems are ultimately just reactionary measures to problems that need dealing with directly. If preventative measures are taken to avoid tainting the air in the first place, massive HVAC systems become superfluous. Why filter air when you can purify it? 


Sources:

1. Deborah Bennett, Deborah, Xiangmei Wu, and Amber Trout. "Indoor Environmental Quality and Heating, Ventilating, and Air Conditioning Survey of Small and Medium Size Commercial Buildings ." California Energy Commission (2011): 110-76. Public Interest Energy Program . Web. 1 July 2017.    

2. Rüden, Henning , and Hans Schleibinger. "Air filters from HVAC systems as possible source of volatile organic compounds (VOC) – laboratory and field assays." Atmospheric Environment 33.28 (1999): n. pag. ScienceDirect . Web. 1 July 2017.

3. "Ventilation and Air Quality in Offices ." National Service Center for Environmental Publication (1990): n. pag. Environmental Protection Agency . Web. 1 July 2017.