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Abstract
A sloped-roof structure, having only one ventilation airspace, is studied in this paper. In this cold-roof system, the underlay foil forms a nonventilated airsace above the thermal insulation, which improves the thermal performance of the roof. The internal moisture loads can be transported by diffusion through the highly vapor-permeable underlay to the ventilation cavity. The sealed underlay system works also as a additional resistance against air leakages. The thermal and moisture performance of the sealed and conventional roofs were studied in field experiments dones in a test building in southern Finland. different roof sections have been studied for three heating seasons. The experiments show that the sealed roofs have as good a moisture performance as conventional roofs. With similar air leakage paths and pressure differences, the sealed underlay systems could decrease the leakage airflow rate by 15% and the total heat losses through the ceiling by 23% when compared to a conventional roof.
A sloped-roof structure, having only one ventilation airspace, is studied in this paper. In this cold-roof system, the underlay foil forms a nonventilated airsace above the thermal insulation, which improves the thermal performance of the roof. The internal moisture loads can be transported by diffusion through the highly vapor-permeable underlay to the ventilation cavity. The sealed underlay system works also as a additional resistance against air leakages. The thermal and moisture performance of the sealed and conventional roofs were studied in field experiments dones in a test building in southern Finland. different roof sections have been studied for three heating seasons. The experiments show that the sealed roofs have as good a moisture performance as conventional roofs. With similar air leakage paths and pressure differences, the sealed underlay systems could decrease the leakage airflow rate by 15% and the total heat losses through the ceiling by 23% when compared to a conventional roof.
Date
12/2001
12/2001
Author(s)
Tuomo Ojanen
Tuomo Ojanen
Page(s)
Keyword(s)
ASHRAE; ORNL; themal performance; moisture performance; cold roof; underlayment; vapor permeable; ventilation;
ASHRAE; ORNL; themal performance; moisture performance; cold roof; underlayment; vapor permeable; ventilation;