Investigation of the proposed solar-driven moisture phenomenon in asphalt shingle roofs
Abstract
We report that unvented, sealed or conditioned attics are an energy efficiency measure to reduce the thermal load of the home and decrease the space conditioning energy consumption. This retrofit is usually done by using spray polyurethane foam underneath the roof sheathing and on the gables and soffits of an attic to provide a thermal and air barrier. Unvented attics perform well from this perspective but from a moisture perspective sometimes the unvented attic homes have high interior humidity or moisture damage to the roof. As homes become more air tight and energy efficient, an understanding of the hygrothermal dynamics of the home become more important. One proposed reason for high unvented attic humidity has been that moisture can come through the asphalt shingle roof system and increase the moisture content of the roof sheathing and attic air. This has been called solar driven moisture. Oak Ridge National Laboratory (ORNL) investigated this proposed phenomenon by examining the physical properties of a roof and the physics required for the phenomenon. Results showed that there are not favorable conditions for solar driven moisture to occur. ORNL also conducted an experimental study on an unvented attic home and compared the humidity below themore »
- Authors:
-
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Publication Date:
- Research Org.:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Org.:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE)
- OSTI Identifier:
- 1260070
- Grant/Contract Number:
- AC05-00OR22725
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Journal of Building Physics
- Additional Journal Information:
- Journal Name: Journal of Building Physics; Journal ID: ISSN 1744-2591
- Publisher:
- SAGE
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; Attic; Solar; Driven; Moisture; Sealed; Unvented; Asphalt; Shingle; Hygrothermal
Citation Formats
Boudreaux, Philip, Pallin, Simon, and Jackson, Roderick. Investigation of the proposed solar-driven moisture phenomenon in asphalt shingle roofs. United States: N. p., 2016.
Web. doi:10.1177/1744259115624183.
Boudreaux, Philip, Pallin, Simon, & Jackson, Roderick. Investigation of the proposed solar-driven moisture phenomenon in asphalt shingle roofs. United States. https://doi.org/10.1177/1744259115624183
Boudreaux, Philip, Pallin, Simon, and Jackson, Roderick. Tue .
"Investigation of the proposed solar-driven moisture phenomenon in asphalt shingle roofs". United States. https://doi.org/10.1177/1744259115624183. https://www.osti.gov/servlets/purl/1260070.
@article{osti_1260070,
title = {Investigation of the proposed solar-driven moisture phenomenon in asphalt shingle roofs},
author = {Boudreaux, Philip and Pallin, Simon and Jackson, Roderick},
abstractNote = {We report that unvented, sealed or conditioned attics are an energy efficiency measure to reduce the thermal load of the home and decrease the space conditioning energy consumption. This retrofit is usually done by using spray polyurethane foam underneath the roof sheathing and on the gables and soffits of an attic to provide a thermal and air barrier. Unvented attics perform well from this perspective but from a moisture perspective sometimes the unvented attic homes have high interior humidity or moisture damage to the roof. As homes become more air tight and energy efficient, an understanding of the hygrothermal dynamics of the home become more important. One proposed reason for high unvented attic humidity has been that moisture can come through the asphalt shingle roof system and increase the moisture content of the roof sheathing and attic air. This has been called solar driven moisture. Oak Ridge National Laboratory (ORNL) investigated this proposed phenomenon by examining the physical properties of a roof and the physics required for the phenomenon. Results showed that there are not favorable conditions for solar driven moisture to occur. ORNL also conducted an experimental study on an unvented attic home and compared the humidity below the roof sheathing before and after a vapor impermeable underlayment was installed. There was no statistically significant difference in absolute humidity before and after the vapor barrier was installed. Finally, the outcome of the theoretical and experimental study both suggest that solar driven moisture does not occur in any significant amount.},
doi = {10.1177/1744259115624183},
journal = {Journal of Building Physics},
number = ,
volume = ,
place = {United States},
year = {Tue Jan 19 00:00:00 EST 2016},
month = {Tue Jan 19 00:00:00 EST 2016}
}