Thermography measurements and latent heat documentation of Norwegian spruce (Picea abies) exposed to dynamic indoor climate

Abstract

Hygroscopic materials hold the potential to reduce ventilation loads in a building by damping the peak fluctuations of the indoor relative humidity. Of particular interest is the moisture buffer capacity of wooden surfaces. This paper investigates, the response of Norwegian spruce (Picea abies) samples to changes of indoor relative humidity as well as the corresponding latent heat release during moisture buffering. A climate chamber was used to subject samples to dynamic air humidity. Thermographic techniques and thermocouples were employed to measure surface temperature on the exposed surface of the spruce sample (permeable case), while a covered control sample was used as reference (impermeable case). The moisture uptake was logged synchronously by weighting cells. The results show that the surface temperature of spruce increased by 2.1 °C during moisture uptake, while only by 0.9 °C in the control sample. This finding has implications for direct energy savings when wooden surfaces are used indoors. In addition, thermography is evaluated as an appropriate measurement method for documenting latent heat release.