While calm conditions are supposed in the present testing method for hood capture efficiency in Japan, various disturbances exist in commercial kitchens. In the HVAC design of commercial kitchens, the hood capture efficiency evaluated under moderate disturbances should be utilized. In this study, a survey was conducted to study the actual air disturbance around exhaust hoods, caused by airflow supplied from HVAC openings in electrical commercial kitchens. The results of the survey elucidated the relationship between the type of openings and the intensity of disturbance on the basis of measured airflow data.

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Against the background of global warming and climate change, unprecedented effort is required in the building sector for energy conservation. Energy recovery ventilator (ERV) with carbon dioxide (CO_2) demand-controlled algorithm has potential for contributing to energy saving in buildings and also to indoor air quality (IAQ) control. Concerning the development of ERV with CO_2-DCV system, optimization of CO_2 sensor layout, feedback algorithm and time between CO_2 sensing and air flow rate operation are critically important issues. In this paper, we focus on the field measurement and numerical prediction of time delay of CO_2 sensing from local CO_2 generation point to sensor location. In order to measure the residual life time of CO_2 in a real residential space, instantaneous and point CO_2 generator was originally developed. The residual life time of CO_2 were also numerically analyzed by adopting the ventilation effectiveness concept SVE6 (Scale for ventilation effectiveness No.6) proposed by Kobayashi and Kato et al. In this study, four cases were investigated to estimate the profiles of residual life time of CO_2 in a real residential space. The results were reasonably consistent with CFD predictions. Because SVE6 distribution is an essential IAQ indicator, it can contribute to the development of feedback algorithm of demand-controlled ventilation systems.

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Establishment of zero-energy buildings (ZEBs) and methods for reducing energy consumption and effective use of energy, such as net zero energy, are typically required for the realization of sustainable buildings, and realization of ZEBs is an urgent worldwide demand. Toward meeting this demand, we studied a dynamic insulation (DI) system, which uses ineluctable ventilation airflow effectively. Application of the DI system is distinct from the conventional building practices in the U.K. Majority of the previous practices applied the DI system to wall parts, but not to opening parts such as windows and sashes, which have poor thermal insulation performance. Therefore, we created prototypes of window with the DI system, called the DI window. The DI window consists of three parts: an outside window, air layer, and inside window. We evaluated the thermal insulation performance of the DI window, the risk of condensation on the inside sash surface, and the heat recovery rate and the rate of temperature increase between the inlet and outlet of the window. Further, we performed a heat box test qualitatively and a field test for practical application. As a result of the heat box test, we verified the effect of the DI window on energy-saving rate with increasing ventilation airflow and the positive effect on thermal insulation performance after installing a blind in the air layer. The results of the field test showed improvement of the thermal insulation performance under the condition of a real residential house installed with the DI system. Notably, the DI window with a blind in the air layer demonstrated the best thermal insulation performance in majority of the cases; however, it increased the risk of condensation on the inside sash surface. Therefore, we calculated the tolerance dew point temperature of the inside surface of the window frame for a certain Technical Advisory Committee temperature (-9.4[℃]) in the real condition and the tolerance relative humidity of the indoors of the residential house.

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