PNNL

If a paper envelope gets wet, the contents may be ruined.

It’s similar for a building’s “envelope”—essentially the space between the inside of a structure and the outside, including walls, doors, and windows.

Researchers from Pacific Northwest National Laboratory (PNNL), the University of Minnesota (U of M), and Oak Ridge National Laboratory (ORNL) have been exploring better ways to test moisture in and around the envelope, particularly walls.

According to the report titled Decarbonizing the U.S. Economy by 2050: A National Blueprint for the Building Sector, a 50 percent reduction of energy use intensity (EUI) compared to 2005 levels is required by 2050 to decarbonize the nation’s building stock. This refers to the large volume of building envelopes that need to be retrofitted in a relatively short time frame. Additionally, a particular barrier to reaching the EUI goal was identified in the report as “substandard building conditions.” Part of that barrier pertains to the challenge of keeping envelope materials dry and mold-free, and subsequently improving long-term energy efficiency, comfort, and structural integrity.

In an effort to address this challenge, DOE’s Building Technologies Office awarded PNNL, U of M, and ORNL funding to complete a three-year project to compare a range of residential wall retrofit systems that prioritized affordability, durability, and energy savings potential. Sixteen different wall assemblies were constructed and tested for these three metrics at the U of M’s Cloquet Residential Research Facility, which Fatih Evren, currently a research engineer in PNNL’s Electricity Infrastructure and Buildings Division, helped manage.

“About 60 percent of buildings in the nation were constructed before the advent of modern building energy codes. To improve the efficiency and comfort of these structures, we need to find ways to optimize installation of beneficial envelope technologies, assure performance, and limit costs,” Evren said.

Project outcomes earn international recognition

Evren served as lead author for a paper based on the PNNL-led research that focused on improving moisture content measurement techniques to guide wall system designs.

Acknowledging the technical advances captured in the paper, the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE), an international organization, recognized Evren and colleagues with a Best Technical Paper Award, which was presented at the ASHRAE annual conference in Indianapolis in June. 

“It was a great experience to receive the award and realize that this work is setting the stage for significant gains in efficiency,” Evren said.

Keeping the envelope dry

The paper, “Data Acquisition System Selection and Calibration of Resistive Moisture Content Measurements for Large-Scale Field Studies in Cold Climate Residential Building Envelope Performance,” was published in ASHRAE Transactions. The paper outlined the researchers’ overall approach, as well as fabrication and calibration methodologies for a combination of custom-made moisture pin sensors and a multi-purpose data acquisition system.

Evren said the proposed methodology, which has been shown to be more accurate than existing approaches, certainly benefits the wall system design process. But it’s also not out of the realm of possibility that the technique could be adopted as a long-term moisture monitoring method for home and building owners.

In addition to Evren, journal paper authors included Pat Huelman and Garrett Mosiman from the U of M and Antonio Aldykiewicz Jr. and Andre Desjarlais of ORNL.

“We are so excited to have Fatih get to share his skillset as an exceptional experimental research engineer with a broader audience through receiving this award from ASHRAE. Congratulations to Fatih and the team for developing a new approach to the ever-more-important moisture content measurements,” said Cheryn Metzger, residential program manager at PNNL.