Methodology and Design of Field Experiments for Monitoring the Hygrothermal Performance of Wood Frame Enclosures

Abstract

Measurement of heat, air and moisture (HAM) phenomena in building assemblies under both controlled conditions and field conditions are difficult to achieve with uniform accuracy and reliability. Care is needed in selecting the measurement sensors and instrumentation to achieve an acceptable degree of accuracy. When the experiments are planned to answer specific questions or to confirm expected responses, the degree of accuracy needed is pre-determined. Proper calibration coupled with appropriate selection of materials can improve the reliability of the measurements, enhance the accuracy achieved, and ensure that the installation has the durability to survive for as long as is needed by the experiment. The field and laboratory experience of the authors in undertaking HAM measurements, particularly those involving transient conditions arising from exposure to real weather, are the basis for the recommendations provided here. The limitations in both undertaking certain measurements and in the interpretation of some data are addressed. The complex of interactions related to the driving forces and changes in material properties prevents experimenters from attributing certain outcomes to particular theoretical assumptions. However, field studies are complementary to carefully executed laboratory studies. As the accuracy of theory increases, there will be an increased need for detailed and accurate field measurements.

Review of in-service moisture and temperature conditions in wood-frame buildings

“…Techniques for measuring moisture in buildings have been reviewed by TenWolde and Courville (1985), James (1988), Derome et al (2001), Straube et al (2002), and Healy (2003). The most commonly used techniques are based on electrical resistance, electrical capacitance, and gravimetric analysis.…”

Inspecciones en la gestión del agua de fachadas ventiladas basadas en la evaluación in situ y pruebas de laboratorio = Insights in the water management characteristics of rear-ventilated façades based on on-site assessment and laboratory testing

“…Gravity is the tendency of water to flow downwards the face of a wall and into the openings that lead inwards and downwards (Bassett, 1996;Straube, 2005) (see a in Fig.1). Note that in horizontal joints of less than 0.5 mm rainwater will not flow through the opening by gravity due to surface tension (Birkeland, 1963).…”

Experimental investigation of the wetting and drying potentials of wood frame walls subjected to vapor diffusion and wind-driven rain loads

“…The sensor layout is similar to Straube et al [34]. The moisture pins are inserted into the mid-thickness (6 mm) of the plywood sheathing and the thermocouple wires are installed on the interior surface of the plywood.…”