[PDF] Field Study Of Thermal Performance Of Exterior Steel Frame Walls eBook

Author : J. R. Sasaki
Publisher : Division of Building Research, National Research Council
Page : 30 pages
File Size : 47,34 MB
Release : 1971
Category : Exterior walls
ISBN :

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Steel studs have been used quite successfully in the construction of interior walls and are now being offered as an alternative to wood studs in exterior wall construction. A major consideration in the acceptance of such a wall is its thermal performance in cold weather. Central Mortgage and Housing Corporation, who are responsible for accepting building materials for construction financed by their loans, requested the assistance of the Division of Building Research in evaluating the thermal performance of steel-stud walls for exterior use. To provide this assistance and to develop information that will be of use to the designers of steel-stud walls, the Division initiated a laboratory investigation to determine the thermal performance of a number of idealized steel-stud walls. The results of this investigation are given in this note.

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Page : 66 pages
File Size : 40,73 MB
Release : 1994
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ISBN :

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In wall construction, highly conductive members spaced along the wall, which allow higher heat transfer than that through less conductive areas, are referred to as thermal bridges. Thermal bridges in walls tend to increase heat loss and, under certain adverse conditions, can cause dust streaking (''ghosting'') on interior walls over studs due to temperature differentials, as well as condensation in and on walls. Although such adverse conditions can be easily avoided by proper thermal design of wall systems, these effects have not been well understood and thermal data has been lacking. Therefore, the present study was initiated to provide (1) a better understanding of the thermal behavior of steel-framed walls, (2) a set of R-values for typical wall constructions, and (3) information that could be used to develop improved methods of predicting R-values. An improved method for estimating R-value would allow an equitable comparison of thermal performance with other construction types and materials. This would increase the number of alternative materials for walls available to designers, thus allowing them to choose the optimum choice for construction. Twenty-three wall samples were tested in a calibrated hot box (ASTM C9761) to measure the thermal performance of steel-framed wall systems. The tests included an array of stud frame configurations, exterior sheathing and fiberglass batt insulations. Other studies have not included the use of insulating sheathing, which reduces the extent of the thermal bridges and improves total thermal performance. The purpose of the project was to provide measured R-values for commonly used steel-framed wall configurations and to improve R-value estimating methods. Test results were compared to R-value estimates using the parallel path method, the isothermal planes method and the ASHRAE Zone method. The comparison showed that the known procedures do not fully account for the three-dimensional effects created by steel framing in a wall.