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Contaminant Control in High-Performance Buildings

Summary

Net-zero energy strategies have the potential to significantly impact the indoor air quality of buildings. This project is designed to better understand how strategies to achieve net-zero energy and sustainable buildings will impact the concentrations of high-priority indoor air contaminants and to support the development of effective low-energy solutions that also improve the health of indoor environments. Specific project outcomes include creating a formaldehyde reference material for wood product emissions testing, developing a test method to validate real-time formaldehyde monitors used   in emission testing, assessing the accuracy of an exposure model used by regulatory agencies, and creating updated research methods for determining volatile organic compound (VOC)  and semi-volatile organic compound (SVOC) emission parameters from building materials into applicable ASTM standards for use by rating organizations and industry.

Description

Using NIST's small chamber test facility, researchers are assessing the performance of a prototype reference material to improve the measurement of volatile organic compound emissions from building products.
Using NIST's small chamber test facility, researchers are assessing the performance of a prototype reference material to improve the measurement of volatile organic compound emissions from building products.

Objective - To develop test methods, reference materials, and control strategies to ensure low contaminant levels in low-energy buildings, and to enable their integration into product development, building design and retrofit guidance, standards, codes, and building material 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 sustainability (e.g., envelope insulation and tightening, alternative ventilation approaches, and installation of “green” building materials) have the potential to alter the indoor environment and to adversely affect the health and productivity of building occupants.

Formaldehyde Reference Material.  
The use of building materials with low volatile organic compound (VOC) emissions may allow energy savings by lowering outdoor air ventilation requirements. Many sustainable building programs require or otherwise promote low emitting materials and furnishings. To support improved labeling of low VOC products, NIST is developing formaldehyde reference materials with known contaminant emissions profiles to ensure accurate determination of product emission rates. The reference materials will provide more confidence in materials and furnishings emission ratings systems that are used in specifications of low-energy and high-performance buildings.  In addition, the reference materials may provide a less expensive method to meet formaldehyde emission regulations.

Formaldehyde Emission Testing.  
In 2019, the United States Environmental Protection Agency (EPA) fully implemented the Formaldehyde Emission Standards for Composite Wood Products rule that sets formaldehyde emission standards for hardwood plywood, medium density fiberboard, and particle board products.  Current emission testing to meet this rule requires resource-intensive manual sampling and analysis.  New innovative, real-time methods are available that could make analysis faster and less error prone.  However, prior to regulatory adoption of real-time formaldehyde instruments a new consensus test method must be established.  NIST is leading the development of a new ASTM method for real-time formaldehyde emission testing using the NIST formaldehyde reference material as a calibration source.  

Assessing Exposure Models.  
The Frank R. Lautenberg Chemical Safety for the 21st Century Act which amends the Toxic Substances Control Act (TSCA), instructs the EPA to conduct risk-based chemical assessments.  The EPA uses the Indoor Environmental Concentrations in Buildings with Conditioned and Unconditioned Zones (IECCU) model to assess indoor exposure to SVOC chemicals.  However, the long-term accuracy of this model has never been verified.  NIST is leading an effort to evaluate this model in predicting long term (five-year) flame retardant concentrations in the Net-Zero Energy Residential Test Facility (NZERTF).

SVOCs.
Currently, some industry groups are proposing that building products be evaluated via a risk-based emission approach rather than a content-based approach.  Content based evaluations list the chemical contents of a product. Risk based approaches measure the emission of a chemical from a product, determine the transport to an occupant and the relative risk to that occupant.  Although there are existing standards to measure VOC emissions from some building materials, there is currently a lack of consensus standards that allow accurate quantification of SVOC emissions from building materials that are needed for SVOC exposure modeling.  In addition, there are existing ASTM standards that quantify both VOC and SVOC emissions that need to be updated.  NIST is leading the process for the revision and renewal of multiple emission-related ASTM standards.   

What is the research plan?
Formaldehyde Reference Material
.  
For VOCs and formaldehyde, the most effective and energy efficient control strategy is to reduce emissions from building products and materials. NIST has been developing a formaldehyde reference material to improve the reliability and reduce the uncertainty of emissions testing. These reference materials will allow manufacturers and designers to more accurately estimate indoor contaminant levels associated with different product choices and support existing and future product labeling programs. In FY20, NIST will work to address formaldehyde reference material production challenges with new approaches and designs.

Formaldehyde Emission Testing.  
NIST will work with ASTM colleagues to develop an approach that will allow for the calibration and testing for chemicals that may interfere with the formaldehyde signal when real-time formaldehyde monitors are used in emission testing.  The approach then will be tested using the NIST small chamber system.  Finally, a draft of the method will be written for review and input from the ASTM committee and other stakeholders. 
Assessing Exposure Models.  NIST will measure the concentrations of tris (1-chloro-2-propyl) phosphate (TCPP) in the NZERTF.  Five years of TCPP concentrations will be compared to IECCU emission models of the NZERTF.  The IECCU model will account for the varying weather, infiltration, and HVAC operation.  Infiltration and HVAC operation will be determined using a calibrated, coupled EnergyPlus/CONTAM model.  Finally, a journal paper will be published summarizing the performance of the IECCU model.  

SVOCs and Standards.  
Control strategies for SVOCs in the indoor environment are largely non-existent.  There are several new analytical approaches that have been developed to measure SVOC emission parameters.  NIST is leading an effort to support the development of consensus ASTM standards based on these new analytical approaches.  In addition, NIST will participate in an interlaboratory study to measure VOC and SVOC emissions from SPF in an effort to validate ASTM D8142.

Major Accomplishments

Outcomes:

  • The further development of the toluene reference film. Packaging challenges were addressed to move the material closer to production phase.
  • Exposure scenarios were developed in conjunction with ASTM and the California Department of Public Health (CDPH) to assist in evaluating acceptable VOC emission rates in building products.
  • In-duct electrostatic precipitator (ESP) experiments showed that these devices are ineffective at removing nanoparticles (3-10 nm) and revealed the propensity of these devices to emit significant levels of ozone.

Impact of Standards and Tools:

  • Reference VOC source developed which is to serve as a NIST Standard Reference Material.
Created October 31, 2011, Updated October 16, 2019