Contaminant Control in High-Performance Buildings

Objectives: 

1. To better understand how strategies to achieve resilient buildings will impact chemical reactions, rates, and concentrations of high-priority indoor air contaminants. 
2. To develop test methods and building control strategies to reduce chemical levels in low-energy buildings, and to enable their integration into product development, building design and retrofit guidance, standards, codes, and emissions labeling programs.
    

What is the new technical idea?
NIST is developing the measurement science required to support strategies that maintain or improve indoor air quality (IAQ) in high-performance buildings. Changes that are being made in the design, operation and furnishing of buildings to save energy and promote resilience have the potential to alter the indoor environment and to adversely affect the health and productivity of building occupants.

What is the research plan? 
Test methods, guides, and control strategies.  Chemical Assessment of Air Cleaning Technologies.  Air cleaning devices have increased in popularity over the last few years due to concerns about wildfire smoke and indoor airborne infectious aerosols.  A wide variety of technologies have entered the marketplace with a range of claims about proficiency and impact on indoor air quality.  Some of these electronic air cleaning devices have the potential to create unintentional byproducts that may impact the indoor chemistry.  Currently there are no test standards and minimal peer reviewed published data that address the chemical removal effectiveness and byproduct production of air cleaning technologies. NIST is facilitating an international effort of over 20 industry, academic, governmental and experts within ASTM workgroup WK81750 to develop a draft test standard for portable air cleaners through the D22.05 subcommittee.  The initial draft was balloted in July 2023. NIST will work with closely with industry representatives to ensure feedback on this test method is appropriately addressed and get a final approved method incorporated into other organization standards.  NIST is leading the process for the revision and renewal of multiple indoor air related ASTM standards. NIST will work to initiate and facilitate a new guide on the application of chemical ionization mass spectrometry (CIMS) in the indoor space.  

Wildland Urban Interface (WUI).  With the proliferation of wildfires impacting the indoor environment, appropriate methods to reduce the long-term impact of fire related chemicals indoors is lacking. The effectiveness of wiping, vacuuming, rug cleaning, and other methods at reducing the reservoir of WUI delivered chemicals needs to be determined. The NIST manufactured house has been exposed to a series of smoke events related to controlled burns.  Chemicals related to the burns have coated the interior of the house.  The effectiveness of a variety of cleaning activities will be assessed over a period of months using a PTR-Tof-MS. 
 

Understanding Indoor Air Chemistry.  Indoor Air Analytical Challenges.  The use of advanced analytical equipment is rapidly expanding in the indoor air field.  This equipment includes Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-Tof-MS).  PRT-ToF-MS allows part per trillion detection of airborne chemicals at second time resolution. Historically used in the lower concentration outdoor air field, NIST has identified complications when using the equipment in the indoor environment.  Specifically, the combination of PTR-Tof-MS combined with gas chronography has shown that signals once attributed to a single chemical may include contributions from multiple chemicals and chemical fragments.  The impact of this complication can be highly dependent on the instrument operational settings.  In addition, NIST seeks to extend the use of Chemical Ionization methods (other than PTR) to the analysis of PFAS in indoor air.  NIST will investigate the performance of a PTR-Tof-MS under varying operating conditions and chemicals.  NIST will prepare a journal article highlighting varying instrument performance after coordinating with up to five other institutions. 

Chemical Assessment of Surface and Air (CASA) Experiment. In spring 2022, NIST hosted a large field investigation with 12 collaborative institutions at the NIST Net-Zero Energy Residential Test Facility to better understand fundamental chemical reactions that occur in indoor air. A large amount of data remains to be analyzed and published. Over $3.5 million dollars of equipment was used to analyze indoor air during CASA.  This equipment produced nearly 600 GB of data.  There are over 12 collaborative institutions who will each be seeking to address varying research questions from this data in the coming years. In FY25 NIST will focus on analyzing data and producing peer reviewed journal articles relating to two subject areas: 1) Chemistry in NZERTF ventilation systems; and 2) Modeling particle distribution throughout the NZERTF.  In addition, NIST expects to contribute as co-authors on up to five other CASA journal articles to be published in FY25.