Hygrothermal Behavior Research Articles

Effect of varying the hydrothermal characteristics of concrete on the hygrothermal behaviour of a wall

Resumo Simulações computacionais higrotérmicas consideram trocas transientes e simultâneas de calor e umidade entre os elementos construtivos e o ambiente, sendo uma ferramenta importante de apoio ao projeto e à avaliação de desempenho de edifícios. Essas simulações requerem como dados de entrada a descrição do elemento construtivo, as condições ambientais às quais ele está exposto e as características higrotérmicas dos materiais. Este artigo apresenta uma análise exploratória dos resultados da simulação higrotérmica de uma parede de concreto variando-se as características higrotérmicas do material. As condições ambientais internas foram obtidas utilizando o EnergyPlus™ e a simulação higrotérmica foi feita no WUFI® Pro, com pós-processamento no WUFI® Bio para avaliar o risco de ocorrência de fungos emboloradores. Houve diferenças significativas no comportamento higrotérmico das paredes em função da variação das características higrotérmicas dos materiais, sobretudo para o tipo de concreto cuja função de transporte capilar mostrou-se diferente dos demais. Os resultados indicam a importância de analisar as características e funções higrotérmicas para simulações higrotérmicas e a necessidade de sua determinação experimental para os materiais de construção brasileiros.

Hygrothermal behavior of hemp concrete and conventional concrete: a comparative analysis

This study presents an in-depth comparative analysis of the hygrothermal behavior of hemp concrete and conventional concrete, with a focus on their energy-saving potential and moisture regulation capabilities. Through detailed numerical simulations, the research examines how these two materials perform under identical climatic conditions, highlighting key differences in their ability to retain heat and manage moisture. The results reveal that hemp concrete provides up to 80% less thermal energy dissipation through building walls compared to conventional concrete, making it a far superior material for thermal insulation. In addition, hemp concrete exhibits improved moisture regulation, which not only enhances indoor comfort but also promotes healthier living environments by preventing excessive humidity. The study emphasizes hemp concrete's potential in significantly reducing energy consumption in buildings, thus promoting its application in sustainable construction. While hemp concrete lacks the mechanical strength required for load-bearing applications, its numerous environmental benefits, cost-effectiveness, and suitability for non-structural components make it an attractive choice for eco-friendly construction projects. This research also paves the way for future exploration of innovative uses for hemp-based materials in green building practices.

Influence of non-linear diffusion controlled phenomena on the sorption capability of PEO-Salt-SiO2 composite electrolyte: A study on property optimization

The present research, reports the hygrothermal behavior of poly [ethylene oxide] (PEO) based composite film (500 and1000 μm) containing NH4I and KBr (5–20 wt%) as the mobile phase and non-reactive silica (15 wt%) as the filler. These are termed as PK/NSiO2-series for solvent sorbed and (PK/NSiO2)NS for non-swelled film. The novelty of the research lies in the analyses of non-Fickian solvent diffusion trait of films using python programming. The presence of ions and its variable polarizable nature is found to influence the number density of bonded and free solvent content along with the extend of cross linkage. Introduction of silica is found to enhance the ionic conductivity (about one order higher) of the film irrespective of the type of charge carrier owing to the improved dispersion within the matrix. Non-Fickian diffusion is found to influence the ionic conductivity of P2K20SiO2 (10−5Scm−1 to 10−2 Scm−1) minimizing the degradation to 0.2 %ΔC/1000 h (>1 %ΔC/1000 h, tested for 2000 h) compared to P2N20NSiO2. In contrast, ion migration in P2NSiO2 is guided by Rice and Roth model and being more polarizable ions, the mobility is significant which maximizes the conductivity to ∼10−1 Scm−1. Microstructural study shows heterogenous nucleation to be more pronounced upon addition of silica filler wherein the homogeneity, inter fibrillar interaction and grain growth of spherulites is higher. This tends to extend amorphous regions thereby propagating the ion migration path. The influence of sorption process is studied in terms of electrochemical impedance, dielectric analyses and long term cyclability (20,000 h) in terms of loss tangent.

Hygrothermal performance of multilayer wall assemblies incorporating starch/beet pulp in France

This work focuses on the investigation of the hygrothermal performance of four different wall insulation assemblies including starch/beet pulp composite for an office in France under two climatic conditions. Subsequently, a comparative performance analysis is made on all studied assemblies by substituting the Starch/beet pulp composite with hemp concrete (HC). For each design, the overall energy performance, total water content, drying rate and condensation risk were evaluated through hygrothermal simulations using the WUFI® Plus software and mold growth risk assessment was conducted with WUFI®Bio software. Results showed that insulation assemblies based on Starch/Beet pulp exhibited a slightly improved effectiveness in potential energy savings and higher dryness rate while having a higher condensation risk, a lower dynamic thermal performance, and a higher susceptibility to mold growth risk. Moreover, insulation assemblies based on Starch/Beet pulp demonstrated better hygrothermal performance under Nancy’s climate compared to that of Marseille. Wall assemblies based on hemp concrete reduced total energy consumption by up to 35 % in Nancy’s climate and 24.9 % in Marseille’s climate. In comparison, starch/beet pulp concrete achieved reductions of up to 37.5 % and 26 % respectively. However, the mold growth risk for starch/beet pulp was 1.2–7.2 times higher than for hemp concrete. In Marseille’s climate, this risk was 2.3–8.9 times higher for starch/beet pulp and 4.7–17.8 times higher for hemp concrete compared to Nancy’s climate. The findings from these room-scale studies enhance the understanding of the hygrothermal behavior of the Starch/Beet pulp bio-composite material by comparing its performance, under the same conditions, to that of the well-studied hemp concrete material in the literature. Additionally, these studies provide greater insight into the impact of water on the overall energy consumption, service performance of a building and health hazards. Finally, this research also tackles the challenges of integrating innovative materials into the established construction industry.

Hygrothermal risk assessment tool for brick walls in a changing climate

Due to the heritage value of historical buildings, external facades can often not be modified. Therefore, in heritage buildings interior insulation is often considered when undergoing an energy renovation. However, interior retrofitting drastically changes the hygrothermal behaviour of a wall and can potentially cause moisture-related problems. Besides an interior retrofit, a changing climate might also trigger some of these damage mechanisms as parameters such as temperature and precipitation will change over time. Hygrothermal models can provide relevant insights into the risk of deterioration associated with these damage phenomena. However, these Heat, Air and Moisture (HAM) tools are commercially available but rarely used in the building industry to study deterioration risks. Translating research into practical tools and guidelines is a challenge across the whole field of building renovation. This paper aims to tackle that challenge, by means of creating a hygrothermal risk assessment tool based on 48,384 HAM-simulations for the climate of Brussels, Belgium. Seven different performance criteria are addressed and discussed: freeze-thaw damage, mould growth, wood rot, corrosion, moisture accumulation, salt efflorescence and bio-colonisation. Subsequent to a sensitivity analysis, the study further explains how these results can be translated into practice, providing building practitioners the most suitable insights and recommendations. The development of an interactive web tool to assess hygrothermal risks is demonstrated and its use and benefits are further elaborated.

Integration of moisture transfer through walls into an urban climate model and application to the medieval city centre of Cahors (France)

Moisture transfer is a key phenomenon for simulating the energy balance of the walls of historical buildings as it has an impact on indoor and outdoor comfort, energy consumption and the durability of the walls. It is therefore essential to consider moisture transfer through walls when simulating old city centres, in order to properly assess the impact of different retrofit solutions on building and city energy balances. However, urban climate models neglect this phenomenon. The objective of this paper is to integrate the coupled mass and heat transfers into the urban climate model Town Energy Balance (TEB). A specially designed numerical method for solving hygrothermal transfers at the urban scale is updated and the hygrothermal transfer through walls is integrated using an IMplicit/EXplicit (IMEX) discretization scheme with large spatiotemporal scales. The reliability of this modified version of TEB for representing a historical district is verified by comparing the simulated results with in-situ measurements in a building of the medieval city centre of Cahors (France). The comparison is carried out for several points in the wall and for indoor conditions, running from June to December 2021. The integration of the moisture transfers through the walls greatly improves the moisture estimation inside the building. This new version of the model gives a good representation of the hygrothermal behaviour of a historical building and could therefore be used to compare several renovation scenarios for the medieval centre of Cahors, with regard to durability, energy and microclimatic issues.

Hygrothermal performance of timber-framed walls in Turkey – Long-term monitoring

The increasing energy consumption emphasizes the urgency of sustainable building practices. Worldwide, there is a tendency towards local, natural, durable, and recyclable materials like timber. Furthermore, timber's excellent thermal insulation and natural hygroscopic properties enable it to efficiently regulate indoor humidity levels, ensuring stability and comfort. In Turkey, timber construction declined significantly in the 20th century due to the shift towards vertical reinforced concrete, however, recent years have witnessed a renewed interest driven by earthquake concerns and global inclination. Despite this resurgence, timber construction practices are still limited, and the hygrothermal performance of exterior walls in both restoring traditional timber buildings and constructing new ones is often disregarded. Furthermore, there is a lack of scientific research in this area. Understanding the hygrothermal behaviour of these structures is essential for meeting modern energy efficiency standards. This study evaluates the hygrothermal performance of prevalent practices in timber-framed constructions in Turkey. Long-term monitoring in a full-scale test cabin exposed to real climatic effects provides insights. Findings indicate the exterior plywood sheathing on the North-west facing walls being more susceptible to moisture, particularly when the indoor relative humidity is elevated. South-east facing walls are better at drying, but air barrier membrane slows down drying. Timber cladding with ventilated cavity offers improved protection but its high exposure to rainfall in North-west, and solar radiation in South-east, implies potential performance degradation over time. Installing suitable vapour retarders and additional exterior thermal insulation particularly to the North-west facing walls could possibly reduce risks associated with moisture, as well as preventing thermal bridges.

A Review—Durability, Mechanical and Hygrothermal Behavior of Building Materials Incorporating Biomass

The growing importance of environmental efficiency in reducing carbon emissions has prompted scientists around the world to intensify their efforts to prevent the destructive effects of a changing climate and a warming planet. Global carbon emissions rose by more than 40% in 2021, leading to significant variations in the planet’s weather patterns. Nevertheless, a significant proportion of natural resources continue to be exploited. To prepare for this challenge, it is essential to implement a sustainable approach in the construction industry. Biobased materials are made primarily from renewable raw materials like hemp, straw, miscanthus, and jute. These new materials provide excellent thermal and acoustic performance and make optimum use of local natural resources such as agricultural waste. Nowadays, cement is one of the most important construction materials. In an attempt to meet this exciting challenge, biobased materials with low-carbon binders are one of the proposed solutions to create a more insulating and less polluting material. The aim of this review is to investigate and to analyze the impact of the incorporation of different types of biobased materials on the mechanical, thermal, and hygric performance of a mix using different types of binder.

Effect of Different Types of Paint on the Hygrothermal Behavior of Facade-Rendering Mortars in Brazil

Effect of Different Types of Paint on the Hygrothermal Behavior of Facade-Rendering Mortars in Brazil

Safe Insulation from the Inside as a Solution to the Energy and Climate Crisis

Along with rapid climate changes, issues related to energy efficiency and efficient use of energy are becoming more and more relevant in the EU. One of the energy-consuming sectors is buildings, which are responsible for about 40% of the EU final energy consumption and 36% of CO2 emissions. In addition to this, the current energy crisis has acutely raised the issue of energy poverty. Therefore, one of the ways to fight with energy poverty and high energy consumption in buildings is insulation from the inside. However, warming from the inside is risky due to hygrothermal processes and mold risks. This study assesses the hygrothermal performance of masonry walls with 9 interior insulation systems exposed to different external conditions in the climate chambers. Masonry walls were tested in a steady cycle, a dynamic cycle, a dynamic cycle with rain and a steady cycle as drying. Also, an identical simulation of the hygrothermal process was carried out in the DELPHIN software to compare results of both testing methods. Both vapor-open and vaportight systems were chosen as insulation systems. Results show that the hygrothermal behavior of vapor-open and vapor-tight insulation systems are different under different test cycles regarding different vapor diffusion resistance of materials. Mathematical simulations results are different from the climate chamber simulations, because of the change in material humidity, that are changing during climate chambers simulations. From this it can be concluded that mathematical simulations do not give a complete vision of hydrothermal processes, because they are dynamic, but in modeling the properties of materials are defined. The study provides valuable data on hygrothermal processes in different wall insulation systems from the inside.

Experimental analysis of building components with paper and textile waste

The fast growth of building constructions industry and of the universal population is the main cause of increase in global energy consumption. Therefore, the improvement of the building envelope encourages the scientific community to investigate the use of alternative materials that assure indoor comfort conditions and at the same time promote the reduction of energy consumption by adopting energy saving strategies in the manufacturing process. The present research contribution aims to focus on the potential use of innovative building materials developed with waste paper, classified as urban non-hazardous discard component. The use of paper pulp originated from recycled paper and cardboard with the addition of textile fibers from industrial by-products was explored. Here, an effort has been made to realize sustainable insulating panel for internal use, considering different mix design and recycled components in various percentages. The research focuses on hygric, thermal, and physical performances of recycled waste based panels, measuring physical aspects as bulk porosity and bulk density and testing hygrothermal performances as the dry-state thermal conductivity, thermal diffusivity, volumetric heat capacity, and water vapour permeability. Furthermore, in order to assess the hygrothermal behaviour of the building envelope, a numerical simulation, carried out by WUFI® Plus in a Mediterranean context, was developed using as inputs the results collected from the measurement campaign in laboratory.

Numerical investigation on mechanical behavior of 3D orthogonal woven composites in hygrothermal environments

3D orthogonal woven composites (3DOWCs) are increasingly utilized in various engineering applications due to their superior mechanical properties. However, their mechanical properties and damage mechanisms could be significantly influenced by the environmental factors such as temperature and moisture. This study aims to investigate the mechanical behavior of 3DOWCs under hygrothermal conditions through meso-scale finite element (FE) simulations. The proposed FE model is validated using existing experimental results under standard temperature and humidity conditions, and subsequently applied to predict the performance in hygrothermal environments. The effects of temperature, humidity, and loading conditions on the mechanical properties of 3DOWCs are analyzed and the corresponding failure mechanisms are revealed. This study offers significant insights into the hygrothermal behavior of 3DOWCs, thereby facilitating their optimal design and implementation in various engineering applications.

Bio-based innovations in cross-laminated timber (CLT) envelopes: A hygrothermal and life cycle analysis (LCA) study

The purpose of this study is to evaluate the performance of a Cross-Laminated Timber (CLT) building envelope that employs more bio-based materials, in terms of its hygrothermal behavior and environmental impact. The study involved the construction of four wall assemblies, comparing the effects of the installation of a self-adhesive air barrier on the CLT and the choice of insulation: bio-based wood fiber insulation or stone wool insulation. The walls were subjected to static and dynamic tests in a climate chamber, with temperature and relative humidity sensors installed across the walls. Additionally, the life cycle analysis (LCA) of the identical assemblies was calculated using the Ecoinvent 3.5 database.The findings of the study showed that the wood fiber insulation had a lower relative humidity and a temperature similar to the stone wool insulation. The air barrier reduced the transfer of moisture and increased the temperature across the wall. Furthermore, the wood fiber insulation acted as a moisture buffer, thereby delaying the migration of moisture through the envelope. Concerning the LCA, the metal siding had the highest global warming impact, followed by the insulation types. The wood fiber insulation had a similar impact to the stone wool insulation, except for eutrophication, where stone wool had a lower impact. The air barrier had a negligible impact compared to the rest of the envelope but prevented the CLT wall from being fully recycled. The biogenic carbon stored in the CLT and the wood fiber insulation reduced the global warming potential of the walls.

Microclimate-Monitoring: Examining the Indoor Environment of Greek Museums and Historical Buildings in the Face of Climate Change

The preservation of cultural artifacts within museums and historical buildings requires control of microclimatic conditions, and the constantly evolving climate certainly poses a challenge to maintaining recommended conditions. Focused on the Archaeological Museum of Delphi and the Church of Acheiropoietos in Greece, our study evaluates the hygrothermal behavior of these buildings with a specific emphasis on the preservation of cultural heritage objects hosted there. An innovative approach to the real-time analysis of data is utilized, aiming to achieve a timely detection of extreme temperature and humidity levels. A one-year monitoring campaign was carried out to achieve a detailed assessment of the indoor climate in selected museums and historical buildings in Greece. The monitoring campaign was performed using dataloggers that were set to measure and record temperature (T) and relative humidity (RH) values hourly. The results allowed for the detection of extreme temperature and relative humidity values, pinpointing the time period that requires more attention. The museum’s heating, ventilation, and air conditioning (HVAC) systems provide temperature control for visitor comfort, but the temperature still rises in summer, highlighting the impact of external climate factors. The church’s lack of HVAC systems widens the temperature range compared to the museum, but significant hourly fluctuations are not observed, underlining the building’s high thermal mass and inertia. Both buildings demonstrate a significant response to changes in outdoor temperature, emphasizing the need for future adaptation to climate change. The HMRhs and PRD indices indicate minimal microclimate risk in both buildings for temperature and RH, reducing the probability of material damage. The church’s slightly higher HMRhs index values, attributed to relative humidity, increases susceptibility due to sensitive materials. Overall, the study highlights the importance of managing microclimatic conditions in historical buildings and proposes careful adaptations for the protection of cultural heritage.

Hygrothermal behaviour of external thermal insulation composite systems (ETICS) to withstand biological colonisation

ETICS are multilayer building solutions applied to the building external walls to provide an improved thermal performance to the building envelope. However, several questions have been raised concerning the durability of ETICS, namely related to biological colonisation phenomena. Considering the high susceptibility of ETICS to bio-colonisation, the following research questions arise: (i) what is the impact of surface temperature (ST) and surface relative humidity (SRH) fluctuation on mould growth in ETICS facades? (ii) is it possible to predict mould growth on ETICS under fluctuating conditions considering favourable and unfavourable growth conditions? This study aims to investigate the influence of the hygrothermal behaviour of five different ETICS (with thermal mortars and insulation boards) on mould growth. ETICS were exposed for one year at an urban site in Lisbon, Portugal, facing North, during which the ST and the SRH were monitored. Concurrently, numerical simulations were performed to evaluate the hygrothermal behaviour of the ETICS. Three theoretical indices were applied, using numerically and experimentally obtained values of ST and SRH as input to provide an indication of the risk of mould growth. The results were complemented and validated by assessing the bio-colonisation, water performance and aesthetic properties of the ETICS. Index 1 (percentage of time with SRH ≥80%) indicated similar potential of mould growth for all systems. Both index 2 (percentage of time with SRH = 100%) and index 3 (percentage of time with SRH ≥80% and 15 °C ≤ ST ≤ 30 °C) indicated a higher potential of mould growth for the lime-based ETICS and a lower potential for the acrylic-based ETICS with an EPS-based mortar. Moreover, the lime-based system obtained the highest rate of mould growth after one year of outdoor exposure. Therefore, results suggested that indices 2 and 3 are in agreement with field observations and thus can provide an indication on mould growth for the analysed ETICS. Results also showed that an increase of capillary water absorption after ageing to levels higher than 1 kg/m2 after 24 h in direct contact with water can favour mould growth. Thus, the combination of unfavourable microclimatic conditions (SRH <80%; ST < 15 °C or ST > 30 °C) and surface hydrophobicity are fundamental to avoid mould growth on ETICS, regardless of the incorporation of biocide in the finishing coat composition.

Application of Novel Phase Change Material Constructive Solution for Thermal Regulation of Passive Solar Buildings

A comprehensive investigation regarding the hygrothermal behavior of a constructive solution containing phase change materials (PCMs) was performed on a full-scale test cell, divided into two similar compartments. This involved hygrothermal monitoring (indoor air temperature) of the two compartments, in which one had PCM incorporated into the floor mortar. The main goal of this research was to investigate the potential of this kind of solution for overheating mitigation. The numerical study was conducted using EnergyPlus® software (version 9.0), exploring different natural ventilation flow rates to gauge the novel solution’s potential to reduce overheating rates. The results from the monitoring studies revealed prolonged periods of thermal discomfort in both test cells, particularly overheating. However, it was proven that the PCM application in one of the test cells led to a reduction of almost 10 °C in the maximum peak of air temperature. In the simulation analysis, the increase in the ventilation rate led to a linear decrease in the overheating hours of up to one renovation per hour, and then the reductions were attenuated.

Enhancing indoor comfort and building energy efficiency with cross-laminated timber (CLT) in hygrothermal environments

The hygrothermal behavior of a building is important because it directly influences indoor comfort levels and energy consumption. Hence, effective strategies must be implemented to minimize energy consumption while optimizing indoor conditions. This study analyzed indoor hygrothermal environments and energy consumption in scenarios related to passive and active building elements, such as exterior walls and indoor control temperature. A simulation considering hygrothermal behavior in walls and spaces was utilized, and the accuracy of the model was validated via an on-site test. Here, cross-laminated timber (CLT) walls, which have been proposed for their energy-saving potential, were substituted for conventional concrete walls. The application of CLT walls enhances indoor comfort better than concrete walls. Despite using the same CLT material, different wall layer compositions lead to internal moisture accumulation. Hence, it was determined that appropriate wall layer compositions should be selected based on regional climate conditions. Furthermore, although indoor comfort was ensured by varying indoor control temperatures, the energy consumption of the heating and cooling systems increased by up to 81 %. Despite the application of passive elements, an indoor heating temperature of 24 °C achieves an optimal balance between comfort and energy consumption. This temperature ensured a satisfactory indoor comfort level and facilitated a manageable increase in energy consumption. In summary, this study provides nuanced insights into the hygrothermal dynamics of buildings, emphasizing the demand for strategic materials, considering regional climates, and carefully managing indoor temperatures to strike an effective balance between comfort and energy efficiency.

Study of Hygrothermal Behavior of Bio-Sourced Material Treated Ecologically for Improving Thermal Performance of Buildings

Study of Hygrothermal Behavior of Bio-Sourced Material Treated Ecologically for Improving Thermal Performance of Buildings

The impact of lime as a replacement of cement-based mortar, on the water absorption and rain penetration of masonry

Since the 1970s, the rise of cement-based mortars has overtaken the traditional lime mortar in construction. This marks a drastic change from circular traditions of reusing ceramic facade materials to a linear economy with an increased difficulty in the reuse of bricks. Lime mortar joints make the recovery of bricks manageable, while cracks can easily occur during dismantling of cement-based masonry. This has prompted a resurgence in the use of lime mortar especially in historical restoration and renovation. It also presents lower CO2 emissions compared to cement mortar, which is a crucial aspect in an industry responsible for 37% of global CO2 emissions. Lime has the ability to capture up to 90% of its production CO2 through carbonation further emphasizes its environmental advantages. This study investigates the hygrothermal behaviour of a hybrid construction with load-bearing masonry, and an interior lime-hemp insulation. Typically, lime mortar exhibits higher moisture transport and storage characteristics, enhancing masonry waterproofing compared to cement mortar. Eighteen setups are subjected to rain-tightness tests in order to monitor potential water infiltration. During these tests, visual evaluations, weight, and moisture measurements are conducted to monitor moisture absorption and rain infiltration to assess the performance of lime mortar versus cement-mortar. This research contributes to sustainable building practices by promoting the advantages of lime mortar in enhancing material reuse, reducing CO2 emissions, and improving the hygrothermal performance.

Evaluation method for hygrothermal performance of masonry rendering mortars: Assessing moisture and mould growth risk under brazilian climate conditions

The presence of moisture in environments, when it exceeds certain limits and is associated with specific temperature ranges, can promote the growth of mould fungi inside buildings, compromising the health of occupants and leading to other harmful pathological manifestations affecting building performance. In this context, rendering mortars with paint application show significant potential to mitigate moisture ingress into building walls. This study aims to analyse normative trends related to criteria for water absorption by capillarity and resistance to vapour diffusion in masonry rendering mortars in Brazil. Additionally, we sought to identify gaps in existing standards and propose recommendations to enhance the suitability of rendering materials to the diverse climatic conditions found in the country. In this context, the results of the analysis of the hygrothermal behaviour of a wall rendering system are presented in this paper. The analysis, conducted through computational simulations, considered the climatic conditions of select Brazilian cities. Despite advancements in Brazilian standards, there are still gaps in existing norms regarding standardised criteria that allow for better selection of materials with performance compatible with their climatic context. The criteria outlined and the computational simulation method used were relevant in evaluating rendering materials under selected climatic conditions and have the potential to contribute to the development of more effective guidelines for the construction sector in Brazil.