Additional Action Needed to Achieve Clean Air & Decarbonization Goals in Commercial Buildings

The EPA’s recently announced Clean Air in Buildings Challenge is a critical step to focus attention on the importance of healthy Indoor Air Quality (IAQ). Now let’s connect the dots between this important EPA initiative and all the good work being done in both the public and private sectors to decarbonize our buildings. We can improve IAQ and reduce building emissions at the same time.

The EPA’s Clean Air in Buildings Challenge Factsheet offers a range of recommendations for improving IAQ including optimizing fresh air ventilation and enhancing air filtration and cleaning to “reduce the risk of airborne viruses and other contaminants indoors.” The EPA acknowledges that the recommendations are a work in progress, and that updates should be expected as the guidance evolves.  

The Factsheet is a good start with room for refinement. One area in need of refinement is the discussion of filtration, which should be expanded to include filters and other forms of air cleaning that address all three types of airborne contaminants: particulate matter, pathogens (including bioaerosols), and gases like formaldehyde, ozone, and carbon dioxide. Emphasizing enhanced filtration and air cleaning before increased outside air ventilation aligns with the latest guidance from the ASHRAE Epidemic Task Force (ETF) and would allow building owners to achieve an important win-win: better IAQ and lower building emissions. As Dr. Joseph Allen from the Harvard T.H. Chan School of Public Health wrote recently in STAT, “Our climate and healthy building goals do not have to be in conflict; it is possible to have energy efficient buildings that provide healthy indoor air.” 

Let’s not miss the opportunity to connect the good work on IAQ being done by the EPA with the sustainability initiatives stemming from Biden’s Executive Order on Catalyzing Clean Energy Industries and Jobs Through Federal Sustainability and a growing number of states and cities and leaders in the private sector. By linking these efforts, we can achieve Sustainable IAQ – better IAQ, more energy efficiently, with improved resilience.  

At the beginning of the pandemic, the ASHRAE ETF recommended maximizing outside air to decrease the risk of airborne transmission. This guidance was consistent with the old paradigm for improving IAQ that relies on energy intensive dilution ventilation to clean indoor air. But as Dr. William Bahnfleth, chair of the ETF, told The Atlantic in September 2021, this early guidance met immediate pushback due to concerns about surging energy use associated with conditioning large volumes of outside air. In November 2021, Johnson Controls and MIT published a study that found increasing outdoor air ventilation rates to dilute the concentrations of infectious aerosol particles indoors, while effective, “is often much more costly than other strategies that provide equivalent particle removal or deactivation.” 

Like many initial responses to the pandemic, the preliminary guidance emphasizing more outside air became the entrenched policy. Not surprisingly, many building owners saw energy costs and carbon emissions increase, even after ASHRAE updated its COVID-19 guidance in January 2021 to address the energy penalty concern by recommending layered filtration, air cleaning, and ventilation strategies.  

The new Core Recommendations for Reducing Airborne Infectious Aerosol Exposure are based on the concept that filtration, air cleaning, and outside air ventilation can be combined flexibly to achieve exposure reduction goals while minimizing associated energy penalties. According to the Core Recommendations for ventilation, filtration, and air cleaning, building operators should use combinations of filters and air cleaners that achieve MERV 13 or better performance for recirculated air, maintain at least required minimum outdoor airflow rates, and select control options, including filters and air cleaners, that provide “desired exposure reduction while minimizing associated energy penalties.”  

The Core Recommendations also state that the effectiveness of filtration, air cleaners, and ventilation can be measured using an equivalent air change per hour (eACH) metric in place of the traditional ACH metric that only focuses on outdoor air and does not account for filtration and air cleaning. 

This updated ASHRAE guidance provides a roadmap to improve IAQ and achieve building decarbonization goals simultaneously.   

The key to achieving Sustainable IAQ is to clean indoor air as much as possible using a Clean First approach that combines filtration and air cleaning for particulate matter, pathogens, and gases and supplements cleaned indoor air with outside air ventilation that meets or exceeds code minimums. This Clean First approach will deliver the IAQ improvements we need without the energy penalty that inhibits progress on decarbonization. Continuous IAQ monitoring and dynamic building controls complete the Clean First framework to ensure IAQ goals are maintained energy efficiently.     

In the words of Dr. Bahnfleth, “The future of really good indoor air quality is going to be alternatives to ventilation, so we don’t have to rely on outside air for everything.”

Read more about Clean First and Sustainable IAQ in our white paper “How to Achieve Sustainable Indoor Air Quality: A Roadmap to Simultaneously Improving Indoor Air Quality & Meeting Building Decarbonization and Climate Resiliency Goals”.