Search Results (140)

Earth-based materials are promising candidates for balancing thermal performance, hygrothermal regulation, and environmental sustainability. The objective of this study is to evaluate and compare the hygrothermal behavior of two earthen materials, structural cob and lightweight insulating earth, against conventional reference concrete, taking into account not only their insulating properties but also their ability to regulate coupled heat and moisture transfers. Experimental tests show a significantly higher hygroscopic buffering capacity for earth-based materials, with an MBV of 2.23 g/(m²∙%RH) for the structural material and 1.21 g/(m²∙%RH) for the insulation material, compared to less than 0.5 g/(m²∙%RH) for concrete. The sorption isotherms confirm distinct water storage behaviors, with an average sensitivity to relative humidity of 10.47% for the insulation material, compared to 3.8% for concrete and 2.25% for the structural material, in addition to an average reduction of 26% in the adsorption capacity between 23 °C and 45 °C for both earthen materials. Coupled heat–moisture simulations in COMSOL quantitatively demonstrate the hygrothermal superiority of bio-based materials over conventional concrete, as concrete promotes interstitial moisture accumulation due to its low vapor permeability. The parametric sensitivity analysis highlights the effect of hygrothermal properties, where diffusivity controls transport kinetics and sorption governs water storage, while thermal conductivity modulates the spatial redistribution of thermo-hygric fields. The next and final step made it possible to link the phenomena observed at the material scale to the actual energy performance of the building, confirming the potential of the double-wall cob + lightweight earth system to reduce heating and cooling requirements and maintain stable indoor comfort, where the annual heating demand is reduced by approximately 24% compared to the conventional prototype. Full article

This article presents a multi-criteria comparative analysis of modern wall partitions in light-frame technology, with a focus on highly energy-efficient modular construction. The motivation for this research stems from the critical need to optimize building thermal insulation materials to minimize heat loss, while simultaneously ensuring low structural weight, rapid assembly, and hygrothermal safety in prefabricated systems. The aim of this study is to identify the most advantageous insulating materials and structural configurations by evaluating their thermal transmittance, moisture behavior, thermal dynamics, and fire resistance. The analysis encompassed four structural variants paired with seven types of advanced and conventional insulation materials. This comprehensive matrix allowed for the development of 28 computational models. Simulations were carried out for severe winter climatic conditions in Poland, utilizing the Ubakus software and conforming to the PN-EN ISO 13788, PN-EN ISO 6946, PN-EN 12524, and DIN 4108-3 standards. The simulations assumed strict steady-state boundary conditions for a 90-day condensation period, with an external profile of −14 °C/80% RH and an internal climate of 20 °C/50% RH. The evaluation focused on key physical and energy parameters, including the heat transfer coefficient (U-value), condensation risk, diffusion resistance, thermal phase shift, and partition weight. Quantitative findings reveal that the ventilated system with resol foam insulation (variant 4d) yielded the best overall performance, achieving a U-value of 0.089 W/(m²·K) W/(m²·K). The results confirm that the strategic selection of high-performance thermal insulation materials, coupled with structural thermal bridge mitigation, significantly enhances the energy efficiency, thermal stability, and moisture resistance of lightweight enclosures, establishing a comprehensive comparative framework for optimizing modular building envelopes. Full article

This paper addresses the important issue of the proper management and protection of subterranean monuments. It concerns the analysis and decoding of the microclimate that is created in heritage structures, which are structures located beneath the soil or carved into rock. The aim of this study is to understand the hygrothermal processes occurring in the mass of underground structural elements, such as evaporation, condensation, water content, and heat fluxes, based on the principles of building physics. The methodology used is the following: a systematic literature review on the topic, an overview of the factors affecting the microclimate, the assessment methodology, and the simulation tools used to decode and evaluate microclimate in subterranean heritage structures; a discussion of the current gaps; and finally, a proposal for future directions for research. A review of the literature reveals that researchers worldwide have employed similar methodologies to approach this complex issue. Recordings and analyses of the microclimate inside underground monuments lead to decision-making and the formulation of actions for optimal preservation. Due to the large number of parameters involved in microclimate analysis, computer software for numerical simulation has been used in many cases. Following the review of the relevant literature in the field of study, a critical discussion concludes by proposing directions for future research on this important topic. Basic results of this research identify current gaps, problems, and limitations. These include technical and practical issues or gaps concerning lack of data for material properties and weather conditions. Another significant limitation arises from the complexity of physical interactions, as well as from the human factor, which involves the proper use of the simulation program and the correct interpretation of the calculation results. This study demonstrates that the microclimate of subterranean heritage structures is the result of complex interactions between climate, geology, architectural design, material properties, and human use. Across different geographical and cultural contexts, subterranean monuments exhibit distinct microclimatic behaviors. The comparative analysis of case studies highlights that while subterranean environments generally benefit from thermal stability, they remain highly vulnerable to moisture dynamics, ventilation changes, and external climatic coupling. Hence, there is a necessity for context-specific approaches rather than generalized conservation solutions. Decoding subterranean microclimates requires a multidisciplinary framework that combines environmental monitoring, material indicators, architectural analysis, and numerical modeling. Full article

The reliability of hygrothermal models depends on the quality of their inputs. Conventionally, thermal and moisture properties are treated as temperature-independent, yet previous studies have shown that many of these properties are temperature-dependent. This paper investigates the impact of using temperature-dependent material properties on hygrothermal simulation results compared to standard temperature-independent properties at the building envelope level. A representative exterior wood-frame wall assembly is modelled with constant material properties, including water vapour permeability, sorption isotherm, and water absorption coefficient corresponding to values measured at 3 °C, 21 °C, and 45 °C, as well as a case in which the properties vary with temperature. The variation in hygrothermal response is evaluated under several scenarios, including different climates (Toronto and Vancouver, Canada), cladding types (fibre cement and stucco), sheathing materials (oriented strand board (OSB) and plywood), and with and without rain-penetration load. Results indicate that the variation attributed to temperature-dependent material properties was greater for Vancouver than for Toronto and increased with rain penetration. In particular, the choice of cladding seemed to have a greater impact than the choice of sheathing material, with stucco showing greater differences than fibre cement. Overall, however, the temperature at which material properties are defined has a minimal impact on hygrothermal simulation results and wall performance assessments, with maximum hourly differences in sheathing moisture content (MC) differences ranging from 1.18 to 4.32 wt% without rain penetration. These findings demonstrate that the use of temperature-dependent material properties does not have a significant impact on the hygrothermal simulation results or the performance assessment of exterior wood-frame wall assemblies. Full article

Fungal decay fundamentally alters moisture transport in wood through complex bio-physical coupling mechanisms that remain poorly understood. Brown-rot fungi such as Coniophora puteana (Schumach.: Fr.) P. Karst. degrade wood through chelator-mediated Fenton (CMF) chemistry, producing hydroxyl radicals that depolymerise cellulose and hemicellulose before significant mass loss. This diffusion-dependent process requires elevated moisture content and leads to structural degradation. However, existing models fail to capture the interaction between boundary-driven fungal colonization, decay-induced property changes, and multi-phase multi-Fickian moisture redistribution, particularly the separate evolution of bound- and free-water phases during decay. Here, we present a transport-response bio-hygrothermal finite element model that couples boundary-driven Monod-type fungal colonization kinetics with multi-phase moisture transport (free water, bound water, vapor) in decaying wood. Although fungal biomass evolution is simulated via a reaction–diffusion equation, decay progression is not derived from biomass–substrate interaction but prescribed independently as an experimentally informed input. The model incorporates decay-modified sorption isotherms, permeability evolution, and boundary-driven biomass influx, along with associated moisture transport, into the governing equations. The model is validated against low-field nuclear magnetic resonance (LF-NMR) measurements of C. puteana decay in Scots pine over 35 days. The model successfully reproduces the experimentally observed moisture evolution: a peak free-water content of 50%–70% during weeks 1–2, followed by a progressive decline, while bound water remains remarkably constant despite advancing decay. Monte Carlo uncertainty quantification demonstrates hierarchical parameter control: bound water is governed solely by thermodynamic factors, while free water responds to interacting biological and physical processes. Time-resolved correlation analysis shows a fundamental transition from colonization-dominated (weeks 1–2) to transport-dominated (weeks 3–5) moisture control, quantitatively explaining the experimentally observed shift from accumulation to depletion. This transport-response framework for analyzing moisture behavior under externally defined decay progression establishes quantitative parameter hierarchies that may inform the development of future substrate-coupled bio-hygrothermal models. Full article

Improving the energy efficiency of historic field stone masonry buildings often requires internal insulation, as external insulation is frequently restricted by heritage and architectural constraints. Internal insulation, however, alters the hygrothermal behavior of massive masonry walls and may increase moisture-related risks. This study assesses the hygrothermal performance of an internally insulated historic field stone masonry wall under past and projected future climatic conditions using long-term transient simulations. Coupled heat and moisture transfer simulations were performed with the DELPHIN software for an uninsulated reference wall and an internally insulated configuration. The analyses accounted for wind-driven rain, masonry heterogeneity, and variations in inner core composition. Past conditions were represented by a continuous 20-year measured climate dataset, while future conditions were evaluated using regional late-century climate projections (RCP2.6 and RCP8.5). Hygrothermal performance was evaluated based on moisture mass density, freeze–thaw exposure, and mold-relevant temperature–relative humidity conditions at predefined evaluation points within the wall. The results show that moisture accumulation develops gradually and cannot be reliably captured by short simulation periods. Internal insulation redistributes moisture-related risks within the wall rather than fundamentally altering the seasonal moisture regime. Freeze–thaw exposure occurs under all investigated climates, while mold-relevant humidity conditions persist at interior-adjacent locations. The findings demonstrate the importance of multi-year hygrothermal analyses when assessing moisture-related risks in internally insulated historic masonry walls. Full article

This study investigated energy-efficient renovation strategies for traditional Thai wooden houses through constructing a demo building and computational assessments. The study addresses the challenges posed by climate change and increasing comfort demands, which have led to increasing use of air conditioning in these historically significant structures. A demo building, designed to replicate a traditional Thai house, was constructed, featuring two rooms: one insulated with magnesium-bonded Typha boards and the other uninsulated. The effectiveness of the insulation was evaluated through hygrothermal simulations and real-time temperature and humidity measurements. The frequently occurring problem of missing measurement data was solved by approximately determining unknown variables through iterative adjustment and comparison of simulation results with measured data. The results indicate that the Typha-insulated room maintained a stable indoor climate, with significantly lower energy consumption from air conditioning than the uninsulated room. Since the air conditioning system was insufficiently powerful in the uninsulated room, it is not possible to quantify the energy savings precisely using measurement technology. However, subsequent hygrothermal simulations enabled a comparative assessment of the energy-saving potential of various measures. Depending on insulation measures and manner of room use, savings of 75–80% could be achieved. Such computational and practical studies can contribute to the preservation of historic buildings. Full article

This paper introduces the dynamic hygrothermal performances of existing walls in humid climates using the EN ISO 15026 procedure. Water content, mould formation and freezing risk were investigated considering rock wool (RW) and expanded polystyrene (EPS) allocated at different points of two typologies of existing walls requiring renovation. Results show that RW is recommended for insulation on the external side, whereas EPS is more suitable for the internal side. A freezing risk occurs in massive walls insulated internally with RW in severe winter climates. Mould formation appears in the initial phases on the renovated side, driven by the built-in humidity of the new layers. Wall thermal transmittance shows large fluctuations, especially in lightweight structures renovated with EPS, reaching an increase of over 22% at the beginning of the heating period, driven by EPS water content peaks of 1.9 kg/m² in cold climates when installed on the external side, achieved in a stabilized regime and independently from the wall’s technical solution. Outcomes confirm transient hygrothermal analysis as the recommended approach to evaluate the component behaviour over a long-term projection, facilitating sizing in the design phase and ensuring compliance with regulations for retrofitted elements. Full article

The Jiangsu Provincial Judicial Commissioner’s Office, a significant official yamen and regional judicial-administrative center during the Ming and Qing dynasties, exemplifies one of the rare remaining instances of official architecture in Suzhou. Notwithstanding its historical continuity, the thermal and hygrothermal performance of its high and large historical building areas is unable to meet modern thermal comfort standards. Due to the concept of heritage conservation, “restoring the original state”, changing the thermal properties of the building envelope is difficult. Therefore, this study adopts a combined simulation method using DesignBuilder and Fluent to explore the potential to improve the indoor thermal climate by optimizing the HVAC air supply system. Various situations with differing supply air angles, velocities, and outlet configurations are assessed, utilizing temperature fields, velocity fields, and PMV-PPD indices as the primary evaluation criteria. The study’s findings demonstrate that air supply configurations have a substantial impact on the distribution of comfortable zones. The judicious selection of supply angles, velocities, and outlet arrangements can effectively mitigate vertical temperature stratification and enhance thermal comfort in the primary activity areas. The results offer technical guidance for optimizing HVAC operations in high and large historical buildings while preserving their original architectural characteristics. Full article

The focus of this paper is on the large-format wooden panel painting Maundy Thursday Altarpiece from Southern Germany. Its wooden support and paint layer were severely damaged due to high climatic fluctuations, above all dryness. The aim of the research project was to develop a low-risk, conservatively acceptable procedure for controlled in situ humidification. In an interdisciplinary approach, a practical monitoring concept on-site was linked to art technology analyses, surface monitoring, hygrothermal simulations, and climate chamber tests. Based on the results, an individual climate corridor for controlled humidification of the case study was developed with the help of an enclosure and implemented in two gradual moistening phases. The combination of conservative support, measurement technology, and digital assessment allowed a controlled approach to a conservation optimum without other active interventions in the original material. The results highlight the need for object-specific strategies and humidity corridors at the interface between conservation, climate adaptation, and sustainability. A deviation from museum standard recommendations (depending on the guidelines 40–60% rH) shows the special challenges of monument preservation. Full article

The strengthening performance of carbon-fiber-reinforced polymer (CFRP) in concrete structures primarily depends on the CFRP–concrete interfacial bond behavior. For CFRP-strengthened circular reinforced concrete (RC) pipe piles in marine environments, the interfacial bond behavior is susceptible to hygrothermal conditions. In this study, cylindrical concrete specimens were designed and subjected to pull-off tests to evaluate the CFRP–concrete interfacial performance under simulated marine environmental attacks (3 days in a 50 °C salt spray followed by 4 days of seawater immersion). The deterioration mechanism and failure modes of the CFRP–concrete bond behavior in such environments were analyzed, and relationship equations describing the interfacial bond degradation were proposed and validated. Test results indicated that the CFRP–concrete bond strength at circular interfaces is approximately 21% lower than that at planar interfaces. Under hygrothermal marine conditions, the average CFRP–concrete bond strength remained relatively stable in the early stages due to the competing effects of epoxy plasticization and post-curing, while variability increased significantly in later stages. For test specimens in Group A without concrete surface grinding before CFRP wrapping, an initial bond strength of 1.5 MPa was exhibited, while, for test specimens in Group B, with surface grinding, the initial bond strength started at 2.0 MPa. Both groups experienced a significant CFRP–concrete bond strength reduction of 0.4 MPa after the first wet–dry cycle, with the subsequent average strength stabilizing near initial values. Notably, Group B achieved a peak strength of 3.88 MPa at 84 days, attributed to surface grinding, which enhanced bond strength by 33% and delayed bond failure. The overall stable average strength resulted from averaging high-strength and degraded points. A bond degradation model based on averaged strength reduction was proposed: demonstrating a strength loss of 27%–36% after 98 days of accelerated marine environmental exposure. The proposed equations describing the interfacial bond degradation on a circular concrete surface predict well the flexural capacity of CFRP-wrapped RC beams under similar environmental conditions, where the calculated flexural capacity is 0.8 times the experimental value, confirming the model’s conservative and safe design applicability. Full article

As an eco-friendly natural building material, rammed earth possesses outstanding hygrothermal performance, which plays a vital role in achieving the goals of sustainable architecture. However, most existing simulations assume constant hygrothermal parameters, resulting in considerable discrepancies between predicted and actual energy performance and consequently underestimating the true passive regulatory potential of rammed earth. To enhance the accuracy of energy consumption predictions in rammed earth buildings, this study integrates experimental measurements with dynamic simulations and experimentally determines both the constant and non-constant hygrothermal parameters of rammed earth. By integrating experimental and simulation approaches, this study reveals a strong positive linear correlation between the thermal conductivity of rammed earth and its moisture content (R² = 0.9919), increasing from 0.77 W/(m·K) to 1.38 W/(m·K) as moisture content rises from 0% to 14%, whereas the moisture resistance factor decreases exponentially with increasing relative humidity (RH). Subsequently, the two sets of hygrothermal parameters were implemented in the WUFI-Plus simulation platform to conduct annual dynamic simulations across five representative Chinese climate zones (Harbin, Beijing, Nanjing, Guangzhou, and Dali), systematically comparing the performance differences between the “non-constant” and “constant” parameter models. The results show that the non-constant parameter model effectively captures the dynamic hygrothermal regulation of rammed earth, exhibiting superior passive performance. It predicts substantially lower building energy loads, with heating energy reductions most pronounced in Harbin and Beijing (16.9% and 15.5%) and cooling energy reductions most significant in Guangzhou and Nanjing (15.8% and 15.2%). This study confirms that accurately accounting for the dynamic hygrothermal coupling process is fundamental to reliably evaluating the performance of hygroscopic materials such as rammed earth, providing a robust scientific basis for promoting energy-efficient, low-carbon, and climate-responsive sustainable building design. Full article

Silicone rubber, primarily composed of polydimethylsiloxane (PDMS) chains, is widely used in sealing materials due to its excellent flexibility and durability. Its performance is significantly affected by environmental conditions, with humid-heat aging being a major factor of degradation. In this study, molecular dynamics simulations were conducted to systematically investigate the effects of water and temperature on PDMS at the molecular scale. The glass transition temperature (T_g) and free volume distribution were analyzed to evaluate the mobility of polymer chains under hydrated conditions. Mechanical simulations (including tensile and compressive deformation) indicate that the combined effect of elevated temperature and moisture significantly accelerates the degradation of rubber properties. Thermal decomposition simulations indicate that, under high-temperature and humid conditions, PDMS main chains gradually break into small molecules, with free radical reactions further promoting the aging process. The results elucidate the molecular mechanisms underlying silicone rubber performance deterioration under the coupled action of water and temperature, providing a theoretical basis for service-life prediction and durability design of sealing materials. Full article

Achieving a decarbonized built environment in Canada requires proven, resilient, and scalable building envelope assemblies. In 2022, building operations accounted for 18% of Canada’s greenhouse gas (GHG) emissions, with space heating responsible for nearly two-thirds of this total. Alongside operational carbon reductions, embodied carbon emissions—stemming from the production and transport of building materials—must be prioritized during the design phase. Without intervention, construction materials could consume up to half of the remaining global 1.5 °C carbon budget by 2050. This paper highlights NRCan’s prototype, low-carbon, prefabricated panels filled with chopped straw and cellulose insulation under the Prefabricated Exterior Energy Retrofit (PEER) research project. The research advances confidence in performance and durability of biogenic materials by conducting controlled experiments, guarded hot box testing, and hygrothermal modelling. These panels present a promising pathway to drastically lower embodied carbon in the built environment. The validated hygrothermal model, accurate to between 3% and 7, enables assessment of hygrothermal performance across Canadian climates, retrofit scenarios and future climate conditions. This work supports the evidence for low-carbon or bio-based materials as a solution for Canada’s built environment. Full article

Lime-based repair mortars, plasters, and renders are widely utilized in the conservation of traditional buildings. Historically, considerable emphasis has been placed on ensuring that new repair mortars are aesthetically compatible with existing historic materials. However, comparatively less focus has been placed on ensuring hygric compatibility, which is critical to maintaining the moisture equilibrium of traditional masonry walls and preventing moisture accumulation caused by repair interventions. The FabTrads project examined the hygrothermal properties of newly fabricated quicklime mortars, prepared with binder-to-aggregate ratios of 1:2 and 1:4, alongside a range of historic lime-based mortars, plasters, and renders, sourced from buildings across Ireland. This paper presents a comparative analysis of their hygric behaviour. Experimental results indicate that the capillary absorption of the fabricated mortars correlates well with their historic counterparts. Both fabricated mortars exhibited vapour diffusion resistance factors within the range of the historic samples, albeit towards the higher end. Hygrothermal simulations of vapour and liquid water transport revealed that the moisture behaviour of the fabricated mortars is largely within the range of performance of their historic counterparts. Relative humidity was slightly elevated for the fabricated mortars in the models concerning vapour transfer. Notwithstanding this, the findings provide a reassuring indication that the hygric performance of fabricated quicklime mortars is comparable with that of traditional lime-based materials, supporting their appropriate use in conservation practices without adversely affecting the moisture dynamics of the building fabric. Full article