Variations in the hygrothermal properties of several wood-based building products

Abstract

With the advent of high power personal computers, hygrothermal computer models have become powerful tools for building physicists and building practitioners alike. Researchers active in the field of hygrothermal analyses have developed many such models in recent years (Hens, 1996; Trechsel, 2001). All these models require a set of very reliable inputs to yield meaningful results. Among these inputs include the properties of the building materials. The most commonly used properties today are those from an International Energy Agency Annex (Kumaran, 1996). As building materials evolve there is a need for continuous updating of the information on their hygrothermal properties. At the Institute for Research in Construction two recently concluded projects have generated detailed information on the hygrothermal properties of more than 70 building products that are currently used in Canada and the United States of America (Kumaran et al. 2002a, Kumaran et al. 2002b). One of these projects (Kumaran et al. 2002a) was specifically looking at the ranges of the properties shown by contemporary products in North America. The products chosen included wood and wood based materials, bricks, mortar, stucco and building membranes. This paper reports only the information on wood-based products such as oriented strand board (OSB), plywood, wood fibreboard and wood siding. The properties that have been measured in both projects include: thermal conductivity equilibrium moisture content water vapour permeance water absorption coefficient moisture diffusivity and air permeance

Hygrothermal performance of highly insulated wood frame walls with air leakage: field measurements and simulations

“…The A w -values for softwood range from 10-16 g /m 2 s 1/2 in the longitudinal direction and 1-7 g /m 2 s 1/2 in the transverse direction (Glass and Zelinka, 2010). The A w -values for the panel surface of OSB range from 1.1 to 3.3 g /m 2 s 1/2 (Kumaran, Lackey, Normandin, Tariku, van Reenen, 2003).…”

“…The test method used to determine the liquid water diffusivity of OSB products (Kumaran et al, 2003) may involve the edge wood of the OSB sample. Since the edge wood is biased with longitudinal grains, the resulting diffusivity values are not necessarily applicable to the panel face in a sheathing application.…”

“…Once the calibrations of temperature and humidity were optimized, further correction of the model data was achieved through modifying the material parameters of the OSB sheathing. The OSB material properties of moisture storage function (MSF) and water vapour diffusion resistance (WVDR) factor were obtained from the National Research Council of Canada report NRCC-46090 (Kumaran et al, 2003).…”

“…These ranges of OSB material properties were used to define several OSB material definitions within the WUFI® material database to examine the effect of these properties on OSB moisture content. Separate material definitions were created to encompass the data range using low, average, and high values from the MSF and the WVDR factor datasets reported by NRCC-46090 (Kumaran et al, 2003).…”

Faanyagok hővezetési tulajdonságainak változása a termikus kezelés hatására

“…Az építési célra használt faanyagok rostra merőleges irányban 0,12-0,15 W•m -1 •K -1 hővezetési tényezővel rendelkeznek, míg rostirányban az érték ennek akár kétszerese is lehet. Mivel a különböző épületekben jelentős mennyiségű faanyag lehet jelen, fontos tudni a különböző fatermékek, faanyagok hőtani tulajdonságait is (TenWolde et al 1988, Kumaran et al 2003. A faanyag hővezetési tulajdonságainak és azok más tulajdonságoktól való függésének ismerete elsősorban hőszigetelés, szárítás, plasztifikálás, ragasztás témakörökben fontos, illetve olyan esetekben, amikor a faanyag hőellenállása fontos tényező (Kol 2009, Kol et al 2010.…”