The use of solid timber for building construction is regulated - amongst others - by various standards regarding the physical properties of wood. In this long-term monitoring project of an office building in Austria, the relationship between the currently required theoretical target for heat transmission based on national code and the actual state of the construction is derived. The transient hygrothermal behavior of its exterior walls as well as of the different space-enclosing surfaces made of cross laminated timber (CLT) is being monitored and analyzed on the basis of everyday conditions. The focus of this paper is on the transmission heat loss through the nine-layer CLT construction which does not have any additional insulation layers. The results after one year of monitoring indicate a measured U-value that is lower than the one calculated according to current code. Particular attention was paid to the selection of the data in order to achieve the most accurate results possible. This shows the importance of sensor positioning, monitoring of moisture content and fairly long, undisturbed test periods with significant temperature differences between inside and outside. This paper therefore serves two purposes: It supports the proposal for a reduction in the current coefficient of thermal conductivity for CLT, and provides helpful information for future monitoring projects in order to further examine our findings.     «

The use of solid timber for building construction is regulated - amongst others - by various standards regarding the physical properties of wood. In this long-term monitoring project of an office building in Austria, the relationship between the currently required theoretical target for heat transmission based on national code and the actual state of the construction is derived. The transient hygrothermal behavior of its exterior walls as well as of the different space-enclosing surfaces made of...     »