Simulation Research on the Effect of Coupled Heat and Moisture Transfer on the Energy Consumption and Indoor Environment of Public Buildings

Abstract

A building envelope is a multi-layer porous structure. It transfers heat and moisture to balance the indoor and outdoor temperature difference and water vapor partial pressure difference. This is a typical coupled heat and moisture migration process. When the space is filled with moist air, water or ice, it will directly affect the thermal properties of the material. With respect to moisture coming through the wall into the indoor building, it will also affect the indoor environment and the energy consumption due to the formation of latent heat. However, the moisture transfer process in the building envelopes is not taken into account in the current conventional thermal calculation and energy consumption analysis. This paper analyzes the indoor thermal and humidity environment and building energy consumption of typical cities in Harbin, Shenyang, Beijing, Shanghai, and Guangzhou. The results show that it is obvious that the coupled heat and moisture transfer in the building envelopes has an impact on the annual cooling and heating energy consumption, the total energy consumption, and the indoor thermal and humidity environment. The geographical location of buildings ranging from north to south influences the effect of coupled heat and moisture transfer on the annual energy consumption of the building, moving from positive to negative. It is suggested that the additional coefficient of the coupled thermal and moisture method can effectively correct the existing energy consumption calculation results, which do not take the consumption from the coupled heat and moisture in the building envelopes into account.

Moisture Influence on the Thermal Operation of the Late 19th Century Brick Facade, in a Historic Building in the City of Zamora

“…Estimates of energy loss through facade enclosures are made assuming materials are dry. This fact can lead to important mistakes when estimating energy consumption during interventions in buildings with enclosures similar to those studied in this work [5].…”

“…However, this is not only in cultural heritage buildings, but also in those where an intervention to thermally insulate the exterior is not possible, in order to improve the thermal efficiency of the envelope [2,3] When calculations and estimates of energy demand are made due to losses through this type of facade, it is usual to work with the theoretical values contained in the regulations or auxiliary documents, without making specific checks that corroborate its application. Brick is a porous material that can absorb a significant amount of water: from rain, from the ground or from air humidity, and this humidity can cause thermal characteristics to vary considerably, showing a large difference in the dry state to the wet [4][5][6][7][8][9][10]. For this reason, it is necessary to perform an analysis that allows knowing the influence of moisture on the thermal behavior of the walls [11].…”

System Approach in Complex Integral Design Methodology and Its Application in New Zealand

“…The third step in the proposed framework by using BIM contains the incorporation of whole building energy simulation tools, such as DOE-2 or EnergyPlus [101][102][103] and whole building hygrothermal simulation tools, such as WUFI Plus into the design process [104][105][106]. The choice of building simulation programs depends on the personal experience of the designer, available hardware, and the frequency of usage [107].…”

“…The assessment of the risk of surface and interstitial condensation and mould growth should follow the methods described in BS EN ISO 13788 [110]. Consequently, the incorporation of moisture transport mechanisms into the decision process might prevent the underestimation of heating and cooling energy [106]. Research shows that energy consumption by consideration of moisture effects might be significantly higher than by thermal simulation only [111,112].…”

Numerical Investigation on Heat-Transfer and Hydromechanical Performance inside Contaminant-Insensitive Sublimators under a Vacuum Environment for Spacecraft Applications

“…Wang et al used the variable time step finite-difference method to solve the governing equation of the drying process numerically, and studied the sublimation condensation phenomenon in the process of microwave freeze drying [39]. Another category is the establishment of mathematical models for phase-change processes in porous substrate [40][41][42][43][44][45][46]. Farid has established unsteady-state heat conduction equations for phase-change processes such as melting, solidification, microwave thawing, spray-drying, and freeze-drying, and developed two different numerical solutions for sharp interfaces and materials undergoing phase transformation within a certain temperature range [47].In order to solve the nonhomogeneous problem from the moving phase-change interface, Leung et al used a Green function to solve the problem of phase-change heat transfer during thawing of frozen food theoretically [48].…”