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In building design, several approaches have been proposed for coupling computational fluid dynamics (CFD) and energy simulation (ES) to perform analyses of thermal environments. The unsteady analysis of thermal environments within buildings containing offices and colonnade spaces is difficult to perform using an ES that represents the space with a single mass point, owing to excessive predictive heat loss; therefore, CFD has typically been used instead. Although it is possible to divide the space into zones using ES, it leads to excessive predicted heat loss and the prediction of heat movement due to the influence of strong air currents, such as those associated with air conditioners. This behavior is observed because these zones are not detailed mesh divisions. To solve these problems, we proposed a method for calculating the ratio of heat contribution to zones that were pre-divided using CFD followed by the distribution of the total thermal load calculated by ES. In this study, we proposed a method for coupling ES and CFD, which enabled the unsteady analysis of a thermal environment in a large space and verified its accuracy.

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Airtight construction and high‐performance thermal insulation materials are commonly considered important building features to enhance indoor thermal comfort while reducing thermal load. However, when water vapor is generated in such airtight indoor spaces, it cannot be discharged to the outside, causing interstitial condensation and subsequent intrusion of moisture into the walls. Hygroscopic building materials such as cellulose fiber insulation (CFI), characterized by high water capacity, are a potential countermeasure against such condensation. In this study, the humidity control performance of external walls containing CFI was evaluated using data measured inside a demonstration house and calculated by numerical simulations based on thermodynamic chemical potential theory. The changes in moisture adsorption and desorption were then evaluated for different wall constructions and different climate conditions using a parameter sensitivity analysis. Finally, the effective application of CFI to prevent interstitial condensation was confirmed by comparing different wall compositions.

In this paper, the thermal performance of a sunspace attached to a house with a central air conditioning system was experimentally investigated. The house with a south-facing sunspace is located in Miyazaki, Japan, where heating is required in winter. In order to reduce the heating energy in winter, the hot air from the attached sunspace is sent to the central air conditioning room, from where it is then distributed and stored throughout the house by way of air circulation. Only when the temperature in the sunspace exceeds 24 • C is the hot air in the sunspace sent to the central air conditioning room. The air circulation between the attached sunspace and central air conditioning room is 500 m 3 /h. The temperature of the attached sunspace and each room were measured. The results showed that a house with a sunspace can save about 12.2% of energy compared to a house without a sunspace.