Accurate implementation of hygric material properties is critical for reliable hygrothermal simulations. The extensive round robin “Empirical validation of HAM models based on a dedicated HB-CB experiment” underscores a correct implementation of the hygric material properties is crucial for a reliable prediction of the hygrothermal responses in the hygroscopic range. To isolate the impact of different implementation approaches on simulation accuracy, this research explores various implementation methods for moisture transfer properties, addressing variability stemming from experimental constraints and data processing uncertainties. By analyzing simulated hygrothermal responses, it evaluates the effects of these approaches on predictive accuracy within the hygroscopic range and underscores the importance of accounting for their impact in the over-hygroscopic range.

The pore structure of porous building materials, which often covers a wide range (from nanometers to millimeters), plays a crucial role in the material functional properties. This study provides a comprehensive pore structure characterization of ceramic brick, a widely used building facade material, through multiscale and multimodal imaging techniques. To address the inherent conflict between imaging resolution and field of view, an “image chain” of seven three-dimensional greyscale image sets is acquired via X-ray Computed Tomography and X-ray Microscopy, with voxel sizes progressively increasing from nano¬meters to micrometers. Furthermore, a novel bootstrapping-based method is introduced to integrate statistical data from the image chain, enabling a complete pore structure characterization across the full range of scales. Following the image acquisition and processing, the single-scale pore networks are extracted using the maximal ball method. Key statistical information from these partial pore structure representations is systematically analyzed, distinguished, and then integrated. The pro-posed integration approach identifies the most reliable single-scale pore networks across the full pore size spectrum, achieving a total porosity of 32.5 %, which closely matches the experimentally measured value of 32.6 %. Considering the computational cost, preliminary validation on a relatively small full-scale pore network demonstrates reasonable predictions on hygric properties, while larger pore networks are currently being developed and simulated for further validation.

The energy-efficient renovation of Hungary’s heritage buildings poses significant challenges due to the limited availability of reliable thermal and hygrothermal data for historical masonry materials. This study addresses these challenges by integrating laboratory-measured material properties into advanced thermal and hygrothermal simulations of wall-slab connections. The research focuses on historically common slab types in Hungary and modern configurations, providing insights into the energy performance of these critical structural elements.

Material properties were determined through extensive laboratory testing, ensuring high accuracy for the simulation inputs. Thermal conductivity, thermal diffusivity, volumetric heat capacity, and moisture-related properties were measured using standardized laboratory methods. These properties, derived from both traditional Hungarian bricks and modern masonry materials, formed the basis for the geometric modeling and simulations. Three-dimensional geometric models of the most common conventional slab structures as Prussian-, Monier-, Horcsik-, Bohn- and E-beam slab were created and used in simulations performed with Comsol Multiphysics finite element software.

Steady-state thermal simulations adhered to ISO 10211:2017 standards, with boundary conditions designed to reflect realistic thermal environments. Coupled heat and moisture transport simulations, conducted in accordance with the EN 15026:2022 standard, incorporated latent heat fluxes and the moisture behavior of materials, offering a more comprehensive understanding of thermal bridges and their impact on energy performance. This dual approach allowed for the evaluation of heat losses, linear thermal transmittance, and temperature factors, which are critical in assessing the durability and hygrothermal resilience of wall-slab connections.

The study emphasizes the importance of precise material characterization in achieving reliable simulation results. Traditional slab structures, built 100–150 years ago without modern insulation or thermal and moisture considerations, exhibit significant challenges. By integrating detailed laboratory data into the simulations, this research highlights how historical materials perform under contemporary energy standards and identifies potential avenues for energy-efficient renovations.

The results of the simulations guide the development of optimal renovation strategies, particularly layering designs that balance durability with thermal performance. While significant heat losses and thermal bridges were identified in historical configurations, the research underscores the potential for mitigating these issues through targeted interventions informed by simulation data.

This study provides a comprehensive framework for integrating material-specific data into energy performance analyses. It offers architects and engineers practical tools for preserving the architectural integrity of heritage buildings while aligning renovations with modern energy efficiency standards. The methodology also serves as a foundation for future research on historical masonry materials and their role in sustainable building practices.

As a natural, cost-effective, and CO2 storage material, wood has recently gained recognition also in basement constructions. In previous studies by the authors, the hygrothermal behavior of a wooden basement in a reference building in Switzerland was investigated through field measurements and numerical simulations. The measured data were used to analyze the structure's performance under real operating conditions and to validate the numerical model used for evaluating its long-term performance. Results showed that, under normal conditions, wood moisture levels consistently remained below standard-specified limits, indicating minimal risk of wood decay or mold growth. Furthermore, the validated models in WUFI Pro and WUFI 2D were used to conduct risk analyses under critical conditions, evaluating the wooden basement's hygrothermal performance in various scenarios. This paper presents 2D simulations to investigate the impact of gaps created at the joints between insulation layers, which may occur due to improper workmanship or ground pressure, on the hygrothermal performance of wooden basements. Thresholds for gap size and indoor relative humidity are established to ensure satisfactory performance of the construction and to prevent wood decay. The findings of this study offer practical guidelines for the safe use of wood in the basements, helping ensure durability against moisture-related deterioration.

Murals and painted statues in grotto temples are often created on cliff faces or cave surfaces, forming a multi-layered structure composed of rock, earthen plaster (clay), and pigments. Environmental factors such as air temperature, humidity, solar radiation, and rainfall induce significant heat and moisture transfer within these porous materials, leading to possible damage and deterioration (e.g., cracking and flaking) on the surface of these valuable artifacts. However, limited knowledge of the hygrothermal properties of these heritage materials has hindered the understanding of the mural painting material deterioration, as well as the development of preventative conservation methods (to predict and provide early warnings for potential mural deterioration). In this study, laboratory experiments were conducted on earthen plaster samples from the Mogao Caves to investigate their hygrothermal behavior, including isothermal moisture sorption and water vapor permeability (WVP). Six groups of samples were prepared with different soil-to-sand ratios (pure soil and 1:1 mixture) and with the addition of plant fibers (none; hemp, wheat straw or cotton at 2% wt). As a result, significant differences were found in the properties of mural samples based on composition. A higher ratio of sand decreased moisture absorption capabilities, while plant fiber addition increased these properties. Both conditions had a limited influence on water vapor permeability, but the increase by fiber addition is higher. These findings enhance the cognition of mural materials with different components, provide essential data for coupled heat and moisture calculations, and deterioration risk assessment tools, contributing to the preservation of precious mural paintings.

In Canada, over 70% of the buildings were constructed prior to the implementation of the Ontario Building Code of 1975, the first code to include energy requirements. Many of these buildings are reaching the end of their useful life and require building envelope repairs and upgrades where alternatives are to demolish and rebuild, which is less sustainable. Performing a retrofit on the building envelope can improve the buildings air tightness and thermal resistance. While these improvements increase the energy efficiency of the building, it also creates potential for the building envelope to accumulate moisture if the design is not carefully selected. Overcladding a brick building envelope could cause mold growth if the building envelope is not able to adequately dry and if the brick contained high amounts of moisture at the time of installation (such as after a high rain event).

This paper describes the development of a hygrothermal model utilizing in-situ data to assess the performance and suitability four different types of retrofit panels on a brick veneer building envelope. The base building envelope is built to 1950’s specifications to represent thousands of aging brick clad community housing units in Ottawa. In-situ data from four 1.5 m by 3 m tests walls with sensors embedded within the assembly is utilized to develop the hygrothermal model. The brick veneer layer of the wall was built onto load cells to more accurately measure the moisture content within this brick layer. Prior to installing the retrofit panels onto the base construction, the brick veneer underwent multiple rounds of wetting, to introduce an initial moisture load within the brick layer. The drying potential of four proposed retrofit designs is assessed through experimental results and simulation of a hygrothermal model. The retrofit panels tested comprise of a structurally insulated panel (expanded polystyrene sandwiched between two layers of oriented strand board), an expanded polystyrene nailbase panel, a woodfibre nailbase panel, and a sheathingless I-Joint panel filled with blown in cellulose. The sheathingless panel and woodfiber nailbase panel had the least risk of mold growth within the base building and retrofit panel.