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Title: Moisture Risk in Unvented Attics Due to Air Leakage Paths

IBACOS completed an initial analysis of moisture damage potential in an unvented attic insulated with closed-cell spray polyurethane foam. To complete this analysis, the research team collected field data, used computational fluid dynamics to quantify the airflow rates through individual airflow (crack) paths, simulated hourly flow rates through the leakage paths with CONTAM software, correlated the CONTAM flow rates with indoor humidity ratios from Building Energy Optimization software, and used Warme und Feuchte instationar Pro two-dimensional modeling to determine the moisture content of the building materials surrounding the cracks. Given the number of simplifying assumptions and numerical models associated with this analysis, the results indicate that localized damage due to high moisture content of the roof sheathing is possible under very low airflow rates. Reducing the number of assumptions and approximations through field studies and laboratory experiments would be valuable to understand the real-world moisture damage potential in unvented attics.
Authors:
;
Publication Date:
OSTI Identifier:
1164104
Report Number(s):
DOE/GO-102014-4526
KNDJ-0-40341-04
DOE Contract Number:
AC36-08GO28308
Resource Type:
Technical Report
Resource Relation:
Related Information: Work performed by IBACOS, Inc., Pittsburgh, Pennsylvania
Research Org:
National Renewable Energy Laboratory (NREL), Golden, CO.
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy Building Technologies Office
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; RESIDENTIAL BUILDINGS; HUMIDITY; BUILDINGS RESIDENTIAL; RESIDENTIAL BUILDINGS; IBACOS; BUILDING AMERICA; CATHEDRALIZED ATTICS; UNVENTED ATTICS; HYGROTHERMAL ANALYSIS; MOISTURE RISK; CLOSED-CELL SPRAY FOAM INSULATION; ATTIC VENTILATION; ATTIC AIRFLOW PATHS (CRACKS); ATTIC AIR LEAKAGE; MOISTURE IN UNVENTED ATTICS; WATER VAPOR FLOW RATE; CONDENSATION; HUMIDITY; CONTAM; WUFI; BEOPT; CFD ANALYSIS; COLD CLIMATE; Buildings