Influence of climates and materials on the moisture buffering in office buildings: a comprehensive numerical study in China

Fang, Jinzhong; Zhang, Huibo; Ren, Peng; He, Bao‐Jie; Tang, Mingfang; Feng, Chi

doi:10.1007/s11356-021-16684-3

Cited by 10 publications

(3 citation statements)

References 57 publications

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“…This function is particularly important in the context of climate change [14,[89][90][91][92][93], which has been shown to result in greater fluctuations in temperature and humidity [94][95][96][97][98][99][100][101]. This aspect is significant for maintaining thermal comfort in historical buildings [102][103][104][105] and for enhancing energy efficiency in new constructions [106][107][108][109][110][111].…”

Section: Analysis Of the Thermophysical Performance Of Rammed Earth W...mentioning

confidence: 99%

Thermophysical Characteristics of Clay for Efficient Rammed Earth Wall Construction

Petcu,

Dobrescu,

Dragomir

et al. 2023

Materials

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This case study focuses on twelve compacted clay soil samples to understand their fundamental physical and thermal properties. For each sample, the density, thermal conductivity, thermal diffusivity, specific heat, and drying shrinkage were assessed. The identification and characterisation of the materials were also carried out by positioning them into the ternary diagram based on the percentage of sand, silt, and clay. These properties are definitive for the performance characteristics of materials used in rammed earth wall construction. The aim is to provide information for better knowledge and prediction regarding the dynamic heat flow in rammed earth walls. Experimental results show a relatively wide range of values for each property, reflecting the diverse properties of the sampled clays. The thermophysical characteristics of the 12 types of earth analysed showed correlations with reports in the literature in terms of density (1490–2150 kg/m3), porosity (23.22–39.99%), specific heat capacity (701–999 J/kgK), and thermal conductivity (0.523–1.209 W/mK), which indicates them as materials suitable for use in the construction of rammed earth walls. Using test data, a dynamic assessment of heat flow through simulated rammed earth walls was performed. For a better understanding of the results obtained, they were compared with results obtained for simulations where the building element would be made of concrete, i.e., a mineral wool core composite. Thus, heat flux at the wall surface and mass flux, respectively, during the 16 years of operation showed similar evolution for all 12 types of clay material analysed, with small variations explained by differences in thermophysical characteristics specific to each type of S1–S12 earth. In the case of walls made from clay material, there is a stabilisation in the evolution of the water content phenomenon by the 5th year of simulation. This contrasts with walls made of concrete, where the characteristic water content appears to evolve continuously over the 16-year period. Therefore, it can be said that in the case of the construction elements of existing buildings, which have already gone through a sufficient period for the maturation of the materials in their construction elements, the rammed earth wall quickly develops a moisture buffer function. In the case of simulating a mineral wool core composite wall, it cannot perform as a temperature or humidity buffer, exhibiting an enthalpy exchange with indoor air that is only 4% of that of the rammed earth walls; consequently, it does not play a significant role in regulating indoor comfort conditions. Overall, there is confirmation of the temperature and moisture buffering capabilities of rammed earth walls during both warm and cold periods of the year, which is consistent with other reports in the literature. The findings of this research provide a better insight into clay as a material for rammed earth walls for more efficient design and construction, offering potential improvements regarding indoor comfort, energy efficiency, and sustainability. The data also provides useful information in the fields of architecture and civil engineering regarding the use of clay as an eco-friendly building material. The results emphasise the importance of thoroughly understanding the thermophysical properties of clay to ensure the efficiency of rammed earth construction.

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Section: Analysis Of the Thermophysical Performance Of Rammed Earth W...mentioning

confidence: 99%

Thermophysical Characteristics of Clay for Efficient Rammed Earth Wall Construction

Petcu,

Dobrescu,

Dragomir

et al. 2023

Materials

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“…Thin-layer materials are used in many scenarios, from standard building materials such as wall panels to desiccant coatings for air conditioning systems [8,9]. Results from a recent study investigating the influence of material parameters on moisture buffering in office buildings in Chinese cities from Harbin to Kunming shows that material thickness significantly impacts the energy used on dehumidification and in some cities humidification [10]. In some cases, knowing the range of thickness, where a material is used as optimally as possible, can also prove beneficial economically, since many of these novel materials are harder to come by than standard building materials and, thus more expensive to acquire.…”

Section: Introductionmentioning

confidence: 99%

Moisture buffer value for hygroscopic materials with different thickness

Rasmussen,

Qin

2023

J. Phys.: Conf. Ser.

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Moisture buffering is the capacity of hygroscopic building materials or adsorbents to mitigate the humidity fluctuations in the indoor environment through the adsorption/desorption phenomenon. NORDTEST proposed the moisture buffer value to quantitively characterize the moisture buffering capacity of porous materials. Materials with high moisture buffer values have a higher ability to passively control indoor humidity conditions and thus reduce building energy consumption and improve indoor thermal comfort. However, the ideal moisture buffer value theory is based on the assumption that the thickness of the studied materials should exceed the penetration depth of that material. This assumption significantly limits the application of moisture buffer value theory to thin-layer materials, such as textiles, desiccant coating, wallpaper, wood wall panels, etc, which represent a large proportion of moisture buffering in the built environment. In this study, we developed a new numerical model to calculate moisture buffer values for hygroscopic materials with different thicknesses. Experimental measurements were also carried out to validate the solutions. The moisture buffer value of a new kind of desiccant (metal-organic frameworks) under different thicknesses were measured by climatic chamber tests. Simulated results showed agreement with both the measurements and theory. The results indicate that the new moisture buffer value model can be used to find the optimal thickness of desiccant coating or hygroscopic materials for autonomous indoor humidity control.

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“…They can absorb moisture from the indoor environment when humidity gets higher, and release it when the air gets drier [20]. This type of behaviour is particularly studied for spaces that are subjected to the effects of intermittent sources of indoor moisture, such as spaces with temporary human occupation e.g., bedrooms, offices and public spaces [21]- [24]. Indeed, when we breathe and sweat, we release water vapor, thus contributing to indoor moisture levels.…”

Section: Introductionmentioning

confidence: 99%

Re-thinking Indoor Humidity Control Strategies: The potential of additive manufacturing with low-carbon, super hygroscopic materials.

Posani,

Voney,

Odaglia

et al. 2023

Preprint

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Indoor humidity plays a major role in our comfort and well-being. For this reason, mechanical systems are often used to regulate indoor humidity levels, a choice that can entail relevant embodied and operational carbon emissions. This study offers an alternative solution: using materials that naturally buffer moisture to passively regulate indoor humidity levels. In this work, a geopolymer composite incorporating industrial waste is implemented via a binder jet 3D-printing technology. The combination of the super hygroscopic nature of the material and optimal geometry allows for an effective reduction of embodied emissions and unlocks an unprecedented potential for passive regulation of indoor humidity. Results show that the adoption of 3D-printed geopolymer-based tiles can improve the annual indoor hygrometric conditions by up to 90% in a library hosting 15 people: a passive performance that is inconceivable to obtain with conventional building materials and manufacturing methods. The 3D-printing technology allows for optimal usage of material and consequent lower embodied emissions. In the case study considered, the environmental impact of using 3D-printed tiles emerges to be lower than adopting a conventional dehumidification system to actively achieve equivalent indoor hygrometric comfort levels over a 15-year time span. The outcomes of this study pave the way towards merging super hygroscopic low carbon materials with the advanced manufacturing technique of binder jetting in order to regulate indoor humidity levels and reduce indoor environments' dependency on mechanical systems.

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Influence of climates and materials on the moisture buffering in office buildings: a comprehensive numerical study in China

Cited by 10 publications

References 57 publications

Thermophysical Characteristics of Clay for Efficient Rammed Earth Wall Construction

Thermophysical Characteristics of Clay for Efficient Rammed Earth Wall Construction

Moisture buffer value for hygroscopic materials with different thickness

Re-thinking Indoor Humidity Control Strategies: The potential of additive manufacturing with low-carbon, super hygroscopic materials.

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