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The study investigated the hygrothermal performance and risk of fungal growth in a phenolic foam system with a closed cell structure and a diffusion-open and capillary active lime-cork based insulating plaster, for internal retrofitting purposes. The setup comprised two 40-feet (12.2 m) insulated reefer container with controlled indoor climate, reconfigured with 24 holes (1 × 2 m each) containing solid masonry walls with embedded wooden elements on the interior side. Focus was on the conditions in the masonry/insulation interface and embedded wooden elements, and the performance of the two systems were compared to three diffusion-open insulation systems and one diffusion-tight. The effect of exterior hydrophobisation was also investigated. Relative humidity and temperature were measured in several locations in the test walls over 2½ years, and the risk of fungal growth was evaluated by on-site measurements and the VTT mould-growth model. The findings indicate that internally insulated walls with bare brick exterior surfaces performed poorly with high risk of fungal growth. The effect of exterior hydrophobisation was found to vary with the orientation and the installed insulation system, with a generally positive effect on walls facing south-west but limited effect for north-east. Furthermore, the more diffusion-tight insulation systems were found to perform better in combination with exterior hydrophobisation than the highly diffusion-open systems. The lime-cork insulating plaster showed high relative humidity and risk of moisture-induced problems. The on-site fungal tests showed no growth in the masonry/insulation interface inside the two insulation systems, probably due to high initial pH-value.

The objective of this study was to test whether compliance with the current Danish best practice recommendations concerning design of the cold attic space will prevent damaging moisture levels. The project was performed as a full-scale experimental setup in the cool temperate climate of Denmark. The setup comprised 18 north-facing attic spaces with varying ventilation principles and varying infiltration scenarios. The relative humidity and temperature were measured in attic spaces, indoor and outdoor, for almost 3 years. The hygrothermal performance of the attics was evaluated by post-processing and comparing the data with predicted mould growth risk and with visual observations of mould growth. The results showed that following the recommended passive ventilation strategies made the hygrothermal performance in attics with diffusion-open roofing underlay worse. In addition, increasing vapour diffusion tightness of the roofing underlay made the hygrothermal performance of the cold attic spaces under the eaves worse, except for attics with passive ventilation but without infiltration. The hygrothermal performance of the attics with diffusion-tight roofing underlay was poor when combining infiltration and the assessed ventilation strategy. The performance of the same attic without infiltration showed that some degree of ventilation was needed. External roof insulation did not significantly improve the hygrothermal performance of the attic.