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: 1) better understand how strategies to achieve net-zero energy and sustainable buildings will impact chemical reactions, rates and concentrations of high-priority indoor air contaminants, 2) support the development of effective low-energy solutions that also improve the health of indoor environments.

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.

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.

Indoor Air Chemistry.
NIST will participate in and provide logistical support to a large field investigation at the NIST Net-Zero Residential Test Facility to better understand fundamental chemical reactions that occur in indoor air. The Chemical Assessment of Surface and Air (CASA) Experiment will bring together a diverse group of chemists, surface scientists, engineers, and modelers from universities around North America to explore the fate of organic compounds. By spiking in labeled reaction precursors, the primary, secondary, tertiary and other products will be able to be tracked using multiple cutting-edge instrumentation. NIST’s analytical contribution to these novel experiments will be to analyze the final reaction product formaldehyde. Among the numerous potential findings from the CASA experiments, this research should demonstrate one of the first apportionment of sources of indoor formaldehyde: primary emissions from building materials versus the end products of indoor airborne reactions.

Standard and Society Support.
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 semi-volatile organic compound (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 from building products need to be updated.

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.

Indoor Air Chemistry.
State of the art, real-time sampling instrumentation from multiple institutions will be placed internally and externally to the NZERTF. Some of the proposed CASA experiments will use labeled chemicals (such as 18O-labelled oxygen as an input to an ozone generator) to allow for tracking of the complex chemical reactions that are expected to occur. NIST will measure real time formaldehyde concentration changes to quantify one end product of the reactions. Other reaction intermediates and end products (like particulate matter) will be quantified by participating teams. Together the collection of instruments and scientists will allow tracking of indoor reaction pathways and rates in a building for the first time. In addition to participating in the experiments, NIST will organize site access; develop IRB, safety training and hazard review protocols for all participants; install upgraded power and instrument housing facilities; and coordinate research activities, meetings and outreach during measurement campaign.

Standard and Society Support.
There are several new analytical approaches that have been developed to measure SVOC emission parameters in indoor environments. 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 in FY2021 to measure VOC and SVOC emissions from SPF to validate ASTM D8142. In addition, NIST is leading the process for the revision and renewal of multiple emission-related ASTM standards. Finally, NIST will play a leading role in shaping the future of the International Society of Indoor Air Quality and Climate (ISIAQ) by serving as the society secretary until 2024.

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.