Here’s Why Science Matters When it Comes to Increasing Credibility for the Duct Cleaning Industry

Posted on 04/28/2023

In 2019 NADCA embarked on a scientific journey to understand energy efficiencies associated with HVAC system cleaning. Our ‘Energy Study’ began in Vermont, a region with a temperate Northeast climate. But for a legitimate study to really understand the effects of duct cleaning on energy use – a study that would eventually be peer-reviewed and published – scientific data needed to be gathered from multiple climate zones. This led to three additional studies in the sub-tropical Southeast climate of Mississippi, the arid mountain West of Colorado, and the temperate Mediterranean climate of Pavia, Italy. Each of the studies in varying climates and regions was intended to compare the performance and energy consumption before, during, and after cleaning of HVAC systems serving similar occupied spaces.

The studies are a significant part of NADCA’s mission to gather scientific evidence to bring validation to the HVAC system cleaning industry. But science isn’t just important for NADCA. Scientific data informs decision-making at all levels, from personal choices to public policy, so by using science-backed information, we can make better-informed decisions about our health, the environment, and many other critical issues. In other words, by collecting, analyzing, and interpreting data, researchers and scientists can test hypotheses, develop theories, and draw conclusions. 

NADCA’s Scientific Advisor, Dr. Mark Hernandez, PhD, a professor with the College of Engineering and Applied Science at the University of Colorado at Boulder, a professional civil engineer, and an expert on the characterization and control of bioaerosols, has been overseeing the studies since their conception. The forward-thinking researcher placed air quality sensors in all the occupied spaces being used in the study, creating the opportunity to collect additional data to prove that cleaning of HVAC systems can also lead to better indoor air quality (IAQ).

But why? While understanding energy use before, during, and after duct cleaning is important, why not use the same studies to learn more about the occupied space? After all, indoor air quality monitoring technology has come a long way, and is more affordable than ever. 

Dr. Hernandez and the team set out to determine the magnitude of indoor particulate matter (PM) exposure reduction in response to HVAC system cleaning. They also wanted to learn how long the benefit of PM reduction would last, whether air ducts would continue to act as a significant PM reservoir following cleaning, and how the total and biological fractions of airborne PM might react in occupied spaces.

We spend 90% of our time indoors, and it’s a fact that millions of tiny particulates exist in occupied spaces, whether hotels, office buildings, manufacturing facilities, hospitals, universities, or homes; and with monitoring devices so affordable and scientifically accurate, it made sense to expand that study to include IAQ measurements.

Let’s talk a little about those microparticles, also called dust or airborne particulate matter. PMs are measured in sizes, such as PM10 and PM2.5. PM10 includes things like dust, pollen, and mold, while PM2.5 includes combustion particles, organic compounds, metals, and so on, which are even smaller. 

According to the American Lung Association, each day humans breathe in just over 2,000 gallons of air — enough to almost fill a normal-sized swimming pool. That's a lot of air! Our lungs work hard. Even when we rest, our lungs are diligently transporting oxygen into the bloodstream and moving carbon dioxide out. They're part of a serious business run by an intricate structure of organs and tissues — aka, the respiratory system. And when it comes to the human respiratory system, PM10 particles reach the upper airways and trachea (and can be eliminated by sneezing or simple nose blowing), but PM2.5 actually enter the lungs, and the even smaller PM1 particles go further to infiltrate the lung alveoli and cardiovascular system.

Anecdotally, we know that air duct cleaning, when done properly, can greatly improve indoor air quality and save energy. We intuitively know that air duct cleaning removes and reduces dust accumulation in both the HVAC system AND the occupied space. We intuitively know that reduced dust exposure improves indoor air quality. But we must prove it, and we’re working to do just that! 

Final results of NADCA’s ongoing energy study and exposure assessments will come soon enough. And when it comes to validating and building credibility for our industry, it’s a step in the right direction for sure.