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The concept of autonomous humidity control material (AHCM) is inspired by phase change material. AHCM is a new type of functional sorbent material. It can adsorb/release sufficient water vapor at the target relative humidity level and autonomously maintain the indoor relative humidity at a set value/range without external intervention, which cannot be achieved by conventional sorbents (e.g., zeolite, silica gel, etc.). In this study, a novel metal-organic framework (MOF) based AHCM is prepared, and its application for energy-efficient indoor moisture control has been investigated. The new MOF-AHCM has an S-shaped water vapor isotherm, large porosity, and high moisture adsorption capacity. The trigger points for adsorption and desorption occur at 60 % and 40 % RH, respectively. It means MOF-AHCM can autonomously regulate the indoor relative humidity to fall within 40%–60 % RH, which fits the thermal comfort range recommended by ASHRAE well. The physicochemical and hygrothermal characteristics of the synthesized MOF-ACHM have been assessed. Full-scale chamber tests were carried out to verify the humidity control ability of the new material. The experimental results show that MOF-AHCM can significantly mitigate indoor humidity fluctuation and regulate the humidity level within the target range autonomously. Furthermore, numerical simulation has been performed to investigate the impact of MOF-AHCM on building energy consumption in different moisture regions globally, namely, arid, semiarid, dry, moist, and wet areas. The results reveal that MOF-AHCM has an excellent humidity control capacity and can reduce the latent cooling demand of HVAC systems in most climates, especially in arid, semiarid, dry, and moist areas. • A new MOF-based autonomous humidity control material was prepared. • MOF-AHCM has an exceptional moisture buffering capacity in the range of 40%–60 % RH. • MOF-AHCM can autonomously regulate indoor RH within the thermal comfort range. • MOF-AHCM can reduce the latent cooling demand of HVAC systems in most climates. [ABSTRACT FROM AUTHOR]

Moisture buffer value (MBV) is a critical parameter for assessing hygroscopic material's ability to moderate indoor humidity variation. The original MBV theory is strictly valid only for a semi-infinite (or "very thick") material. When the material is thinner than semi-infinite, the material's thickness will affect its moisture buffering ability. The existing MBV theory is inapplicable. This study proposed a new numerical method to calculate a material's MBV at different thicknesses. The proposed model is simple and efficient. The relation between a material's MBV and thickness and the optimal thickness can be obtained without extensive experimental measurement. What's more, the material's adsorption and desorption isotherms, as well as the material's hysteresis loop and scanning isotherms, are incorporated in the proposed model, making it applicable to advanced desiccant materials like Metal-Organic Frameworks (MOFs). MIL-100(Fe), one of the most promising MOF candidates for indoor humidity control, was used to validate the newly developed model. MBVs of MIL-100(Fe) samples with different thicknesses were measured, and the experimental data closely matched the simulated results. Finally, a building energy consumption simulation model was developed based on the proposed numerical model. A MOF panel with its optimal thickness was placed in the BESTEST typical office room located in Copenhagen. The results show that MOF can reduce about 30 % of the energy consumption of air conditioning in a purely passive way. • A new method to calculate the MBV of hygroscopic materials at different thicknesses. • Both the ad/desorption isotherms and hysteresis loop of the material are considered. • A building energy simulation model was developed based on the new MBV model. • The optimal thickness and energy-saving potential of a MOF panel were investigated. [ABSTRACT FROM AUTHOR]

Providing a high-quality indoor environment with appropriate indoor humidity levels for residential buildings is essential for good physical and mental health, occupant comfort, and long-term building performance. The role of moisture recovery in indoor humidity levels in cold climates has long been the subject of controversy; scholars have debated whether it ameliorates the problem of "too dry" air or causes a new problem of "too humid" air. The current study examines a method using moisture balance equations integrated with moisture recovery to analyse moisture recovery's effect in cold climates. A virtual single-family house in Oslo, Norway, was used to demonstrate the impact of moisture recovery on humidity levels in the kitchen, bathroom, bedroom and living room. The results show that moisture recovery has varying influences on indoor humidity depending on the intensity of moisture recovery, moisture production and ventilation. The indoor moisture production and humidity levels were validated against large-scale field measurements in residential buildings. For the virtual single-family house, the optimal moisture recovery effectiveness is about 50–60% with a 2-min interval, as the "too dry" air (RH<20%) issue is eliminated while the risk of "too humid" air (RH>80%) is not exacerbated. This work also identifies the possibility of controlling or optimising indoor humidity by altering the energy recovery system's moisture recovery effectiveness. Furthermore, the study's findings can be used to optimise thermal comfort or assess epidemiological risk in terms of the impact of indoor humidity. • One of the first studies to reveal the impact of different moisture recovery on indoor humidity. • The moisture production and indoor RH levels are validated against field measurements. • Optimal moisture recovery efficiency to reduce extreme RH was investigated. • Identify the possibility of controlling or optimising indoor humidity with moisture recovery. [ABSTRACT FROM AUTHOR]

Buildings are large consumers of energy in all countries. In regions with harsh climatic conditions, a substantial share of energy goes to heat and cool buildings. This heating and air-conditioning load can be reduced through many means; notable among them is the proper design and selection of building envelope and its components.The proper use of thermal insulation in buildings does not only contribute in reducing the required air-conditioning system size but also in reducing the annual energy cost. Additionally, it helps in extending the periods of thermal comfort without reliance on mechanical air-conditioning especially during inter-seasons periods. The magnitude of energy savings as a result of using thermal insulation vary according to the building type, the climatic conditions at which the building is located as well as the type of the insulating material used. The question now in the minds of many building owners is no longer should insulation be used but rather which type, how, and how much.The objective of this paper is to present an overview of the basic principles of thermal insulation and to survey the most commonly used building insulation materials, their performance characteristics and proper applications. [Copyright &y& Elsevier]