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Existing buildings account for 40% of total green gas emission in the atmosphere [1,2] . Historic and heritage buildings are part of this building stock, and the need for improving their energy performance, despite the derogations for officially protected ones, is supported for achieving the European 2020 Energy Strategy aims [3] . However, when dealing with these buildings, not only are the intervention measures constrained by possible architectural preservation requirements, but also the preparatory building diagnosis itself: only non-destructive and non-invasive monitoring techniques are, reasonably, allowed. Therefore, during onsite energy auditing, ad-hoc monitoring protocols should be adopted. In this study, an indirect non-invasive envelope monitoring, for evaluating brick masonry hygrothermal behavior, has been proposed and applied in a heritage building in Antwerp (Belgium). The suggested method is aimed at onsite evaluating the thermal performance of buildings traditional masonry and at quantifying the extent of its alteration due to the moisture distribution variation. Areas detected as wet during iterative passive infrared thermography and environmental monitoring, showed thermal transmittance values more than three times higher than the dry ones on the same masonry surface. [ABSTRACT FROM AUTHOR]

Mould growth on building materials is a complex phenomenon involving various causes environmental conditions including temperature and relative humidity, nutrients, exposure time. Environmental conditions and nutrient are closely related to physical properties of building materials. Thus, the appropriate selection of building materials is very important for prevention of adverse health effects due to mould growth. The aim of this study is to determine the influence of the hygric properties of interior finishing materials on the mould growth. This paper presents the results of mould growth risk evaluation with variation of hygric properties of interior finishing materials using hygrothermal and bio-hygrothermal simulation approaches. An experimental study was conducted to characterize the hygric properties of wallpapers which are used mainly as interior finishing material in residential buildings. Six types of wallpapers and two type of hygric properties (water vapour transmission property and moisture storage function) were selected for the study. WUFI Plus was selected for a whole building hygrothermal simulation. The results from the hygrothermal simulation were used for the assessment of mould growth risk using a biohygrothermal calculation model, WUFI-Bio. The simulation results show the clear correlation between the mould growth rates and the hygric properties of wallpapers. [ABSTRACT FROM AUTHOR]

Bio-based building materials such as hemp concrete have been used successfully in building construction due to their thermal and environmental properties. Since they are also hygroscopic, modeling their hygrothermal behavior is also relevant for appropriate building design. In this work, heat and moisture transfer is investigated numerically by accounting for hysteresis and phase change effects. Input physical properties and their dependency on temperature and moisture content were determined by laboratory experiments. To validate the model, two extended cyclical adsorption/desorption experiments were first performed on an instrumented hemp concrete sample. One of the tests was conducted according to the Nordtest protocol. In the third experiment, a hemp concrete wall was monitored under various boundary conditions. The comparison of numerical results with experimental data gave satisfactory results for all the experiments, regarding mean moisture variation, local temperature and relative humidity variations. Lastly, we conclude on the use of a hysteresis model for hygroscopic materials. [ABSTRACT FROM AUTHOR]

• Hygrothermal material properties of bio-based insulators were determined. • Bio-based materials provide high thermal resistance and water vapour permeability. • Properties of bio-based thermal insulations are comparable with conventional materials. Hygrothermal performance of buildings is one key element to the sustainable design, health, and comfort of the indoor environment. Building sustainability depends on all associated lifespan stages, from building design and material production to demounting and waste management. Many building materials are unsustainable in terms of their environmental impacts. One approach to reduce environmental impacts associated with buildings is the development and application of bio-based building materials. The aim of this study was to determine the hygrothermal properties of bio-based thermal insulators that promote energy efficiency and contribute in decreasing environmental impacts of buildings. Here, the hygrothermal properties of eight new peat-, recycled paper-, wood shaving-, and feather-based insulation materials were assessed. Measurements of these material properties will improve understanding of the energy efficiency, permeability, and sustainability of new buildings, building retrofits, or both. Data on these new materials will provide the necessary parameters to develop a hygrothermal dynamic numerical model. The studied bio-based materials appear to provide sufficient hygrothermal performance, which is comparable with conventional insulation materials with minimum embodied energy. [ABSTRACT FROM AUTHOR]

• Effects of driving forces on hygroscopic conditions are investigated. • Indoor humidity showed different degrees and tendencies according to moisture driving forces. • Humidity ratios differed by 0.01%–38.78% according to driving forces. • The EMPD model can produce differences of 4.4%–51.2% in thermal loads. To more accurately evaluate the indoor hygrothermal environment of a building, control the indoor temperature and humidity, evaluate the thermal comfort of occupants, and select the capacity of the heating, ventilation, and air conditioning (HVAC) system, moisture transfer from and into architectural materials should be considered. However, the most widely used commercialized software ignores the moisture effect from envelopes or adopts a simplified model based on the difference in humidity ratios between hygroscopic materials and interior zone air. In this study, the effects of the driving forces of hygrothermal models were identified and quantified. The calculated results show that the indoor humidity changes differed when the moisture effect by moisture adsorption and desorption was considered in the models. Because the simplified effective moisture penetration depth (EMPD) model uses differences in the humidity ratio as a driving force, the calculated results of the indoor humidity ratio exhibit relatively constant tendencies. However, the thermodynamic chemical potential model corresponds to a detailed heat, air, and moisture transfer (HAM) model that uses the water potential as a driving force; this model can consider the moisture effect based on temperature and humidity changes. Therefore, the humidity ratios calculated using the detailed thermodynamic HAM model show differences of 0.01%–38.78%, and the difference in relative humidity between building materials and indoor air becomes smaller; these results are comparable to those of the simplified model. Finally, the adoption of a simplified model can result in differences in the sensible heat load of 4.4%–13.8% and latent heat load of 16.1%–51.2%. Thus, this study confirmed that a coupled HAM model, which uses the water potential as a driving force, can be employed to accurately simulate the hygrothermal behavior of building envelopes. [ABSTRACT FROM AUTHOR]

Abstract: This work studies the thermal behavior of a new construction material: gypsum board containing 45% by weight of phase change materials (PCMs) reinforced with additives. A facility has been designed and built to simulate the hygrothermal conditions of any room or building. The influence of different parameters and variables regarding heat storage in buildings (air temperature, air velocity, material position, and so on) has been studied. The thermal storage capacity of different construction materials with similar use and position in buildings than boards with PCMs – laminated gypsum boards, bricks, etc. – has been evaluated and compared. It has been proved that a 1.5cm-thick board of gypsum with PCMs stores 5 times the thermal energy of a laminated gypsum board, and the same energy as a 12cm-thick brick wall within the comfort temperature range (20–30°C). This work demonstrates the suitability of incorporating PCMs into gypsum boards to increase heat storage capacity and to reduce energy consumption. [Copyright &y& Elsevier]

Abstract: The sustainable world''s economic growth and people''s life improvement greatly depend on the use of alternative products in the architecture and construction, such as industrial wastes conventionally called green materials. For this purpose, hemp concrete is more and more recommended by the eco-builders because hemp is a renewable plant, recyclable and does not degrade within time. It corresponds perfectly to the requirements of high environmental quality buildings. The objective of this article is to study transient hygrothermal behaviour of hemp concrete at whole building level. The physical model is one-dimensional and was implemented into the object-oriented simulation environment SPARK, using the finite difference technique with an implicit scheme. The numerical result showed that the use of hemp concrete wall in buildings can ensure good indoor air quality and energy savings in winter. Besides, the combined effect of moisture buffering with the adequate ventilation strategies increases hemp concrete building performance. Our results also suggest that taking into account the hygrothermal transfer at whole building level with heat and moisture production sources has significant effects on predictions. [Copyright &y& Elsevier]

• A kind of fiber felt/silica aerogel thermal-insulation material was prepared. • The microstructure and hydrophobic properties were characterized. • The moisture absorption rate and water-vapor transmission rate were measured. • The thermal conductivity under different humidity conditions was measured. Building thermal insulation can enhance the thermal environment of buildings, thus decreasing energy consumption. Traditional inorganic insulation materials are easy to absorb moisture so that their insulation performance is reduced significantly when they are used in humid environment. It is of great significance to develop new building insulation materials with low moisture absorption and high thermal insulation. In this paper, sol-gel method and ambient pressure drying were used to prepare polyester fiber felt/silica aerogel composite thermal-insulation material. The hydrophobic properties and the microstructure of the aerogel composites were characterized. Moreover, the water-vapor transmission rate and the moisture absorption rate of the aerogel composites and the fiber felt in various humidity conditions were measured. Transient thermal plane method was applied to the measurement of the thermal conductivity. The thermal conductivity and moisture absorptivity of the polyester fiber felt increased significantly with the increase of ambient humidity. After being composited with silica aerogel, both moisture absorptivity and thermal conductivity decreased significantly and kept small value even in high humidity. The moisture absorption rate of the composites is approximately 1%, and the thermal conductivity is 0.0176–0.0187 W·m−1·K−1. Therefore, the prepared fiber felt/silica aerogel composites could be widely used for building insulation even in humid areas. [ABSTRACT FROM AUTHOR]

• Adhesive used for ETICS provides moisture within the wall and increases moisture transfer resistance. • Simulated temperature and relative humidity profiles agree with the measured ones. • Using bio-based insulation may reduce the condensation risk. • The ventilated cladding system design is of high importance regarding the condensation risk. This work focuses on the hygrothermal behavior of three external thermal insulation systems: one ETICS including EPS insulation and two ventilated cladding systems including either mineral or biobased insulation. These systems were applied on a rendered hollow concrete wall and tested simultaneously between two climatic chambers. Thermocouples, humidity sensors and heat flux sensors allow investigating the hygrothermal behavior of the retrofitted wall at different stages: just after the application of insulations systems, during safe and critical use. The measured data are compared to numerical results obtained by solving a heat and moisture transfer model. Results highlight the key role of adhesive on ETICS, which provides a significant moisture source during the application and forms an additional moisture transfer resistance within the wall. Results on ventilated cladding systems show that using biobased insulation may delay and even prevent the risk of interstitial condensation. The comparison between numerical and experimental results is satisfying for temperature and heat flow density, but underline the sensitivity of relative humidity to the sorption capacity of hygroscopic building materials. In addition, the systems design has a great influence on the condensation risks. [ABSTRACT FROM AUTHOR]