Jonas Niklewski

Understanding how outdoor exposure affects moisture dynamics in wood is essential for durability assessments and for supporting the use of timber in exterior applications. While several long-term field studies exist, a combination of high-quality weather data and multi-depth moisture measurements, which is needed for model validation, is lacking. This study presents the first numerical validation against an ongoing outdoor experiment on Norway spruce boards ( Picea abies (L.) Karst.), which was designed to address this gap. Surface and core moisture content was measured continuously in boards exposed in different configurations, including sheltered, fully exposed, and double-layer setups. Local weather was recorded at 1-minute resolution. The paper presents the first attempt at modelling the experiments using a simple moisture-transport model driven by measured relative humidity, temperature, and precipitation. In general, the model reproduced the moisture trends and the timing of wetting events across all three configurations. It also captured the relative influence of precipitation when comparing exposed and sheltered boards, although some discrepancies were observed. Core moisture responses were occasionally too rapid, suggesting an overestimated diffusion rate or missing hysteresis effects. The rate of surface drying in the double-layer setup was underestimated, possibly due to the simplified boundary condition. The experiment will continue to generate long-term data to support the development and validation of more advanced hygrothermal models for durability assessment.

Existing factorized methods for timber decay assessment lack spatial resolution and rely on manual assignment of exposure and detailing factors. This study presents a spatially resolved, factorized framework for decay assessment of timber cladding and decking, integrating wind-driven rain modelling via ray-casting, data-driven moisture prediction, automatic geometry-based surface labelling, and dose-response modelling into a single workflow operating on detailed three-dimensional building geometry. The framework was evaluated on a playhouse using hourly climate data from Gothenburg, Sweden. The moisture prediction relies on a metamodel with inputs of daily relative humidity, temperature and precipitation. Decay dose was computed with adjustments for detailing and ground proximity. The metamodel showed robust agreement with the numerical model under varying exposure to precipitation and board thickness. South-facing façades exhibited the highest decay risk with a pronounced vertical gradient, while vertical north-facing surfaces remained largely sheltered. Horizontal decking showed the highest overall risk due to its greater exposure to precipitation and ground proximity. Contact faces and bottom end-grain received substantially elevated doses. Within individual boards, dose varied considerably. The framework automates spatial decay assessment directly from geometry, eliminating manual factor assignment. The pronounced internal dose variation across board faces demonstrates that conventional single-value-per-board methods significantly simplify risk distributions. This information can be used for model validation against full façade systems and to define appropriate limit states for service life assessment.

1. In 2023, building construction and operations accounted for 34% of global CO₂ emissions (United Nations Environment Programme 2025). Among the recommended mitigation strategies is reducing opera...

With increased focus on sustainable building materials and the growing popularity of uncoated wooden cladding, understanding consumer acceptance of aesthetic changes becomes crucial for sustainable architectural choices. This study investigated consumer acceptance of uncoated wooden cladding in Norway, Sweden, and Germany, focusing on personality traits and perceptions. Using an online survey with 3112 participants, the study found that preference for uncoated wooden cladding was similar (around 20%) across the three countries, despite differences in the prevalence of wooden cladding. A natural consequence of weathering of wood exposed outdoors is greying of the surface. The survey presented participants with images of uncoated wooden cladding with varying degrees of grey discolouration. Participants rated the acceptability of these claddings based on their preferences. Acceptance of this discolouration differed by country, Norwegians preferred intermediate-coloured panels, Swedes preferred darker panels, and Germans accepted all panels. Personality traits measured using the Big Five personality inventory and socioeconomic factors influenced preferences. In Norway and Sweden, those accepting the discolouration of uncoated wooden cladding included introverts, highly conscientious individuals, young people, females, and those with tertiary education. Additionally, in Norway and Germany, openness to experience was linked to acceptance, while strong emotional control was significant only in Norway. This study underscores the complexity of consumer preferences for uncoated wooden cladding, demonstrating that personality traits, in conjunction with cultural and demographic variables, jointly influence perception. The findings offer valuable insights for architects, builders, and policymakers seeking to advance sustainable construction practices while optimising consumer satisfaction in the housing sector.

Common solutions for building energy-efficient buildings constitute e.g., double-glazed windows, airtight building envelopes and highly insulated walls. These s