||Improvement of large-scale building performance index in the Asian tropics based on the actual conditions : Case study in Vietnam
アジア蒸暑地域におけるビル環境性能評価基準の実態に基づいた適正化 : ベトナムにおけるケーススタディ
Nguyen, Dong Giang
Considering current situation in developed countries, the importance of energy efficient building in tropical countries in Asia increases because it is going to consume up to 40% of total energy use. The main factor influencing the building energy efficiency is building envelope, mechanical system and human factor. In addition, the indoor environment quality (IEQ) is other important factor because it affects the human health and productivity. Therefore, the evaluation framework for building efficiency has been gaining interest in tropical cities, particularly Vietnam. The framework can be categorized into two types; the first one is building code by local government and the second one is a voluntary based green building assessment tool. However, these frameworks are inappropriate for local climate and culture, due to less knowledge in building envelope design, efficient mechanical system (ME) operation and lack of concern on human factor. Furthermore, most of established frameworks follow the western concept and there is limited data on actual building condition and operation. Hence, to improve existing evaluation framework, this research aims to observe actual condition and operation of large-scale building in Vietnam, in terms of IEQ and energy performance. The IEQ result shows poor indoors air temperature and humidity condition during working hour when the air conditioning system is actually in operation. On the psychometric chart derived from ASHRAE standard 55, the data from perimeter zone are outside comfortable zone due to fluctuated operative temperature and poor air tightness of building envelope. This finding indicates a large possibility of improvement on buildings IEQ. Regarding human sensation, the thermal sensation vote (TSV) shows interesting results that distinguish from developed countries. The thermal acceptability shows over 60% acceptance despite of 40% recognition of coldness in summer season. This open possibility of relaxation for criteria of thermal comfort in air-conditioned space. In term of energy efficiency, the electricity consumption has strong relationship with outdoor temperature and the peak is observed in summer season. In winter season, the electricity consumption does not show an increase despite of indoor temperature show lower value than the standard comfort criteria. Furthermore, based on the simulation study, the result shows meaningful difference between the actual condition case and the case within other green building standard. The EUI show better condition on the actual condition case, mainly due to the excessive internal heat generation and air-tightness. The internal heat generations in the actual condition case are less and the air leaking intensity via building envelope is higher. These findings suggest that it is relatively easy to conserve energy, even if the countermeasure is not efficient. In conclusion, based on this comprehensive study on the building evaluation framework, the current frameworks are inappropriate for local climate and culture. Additionally, the parameter inputs based on actual condition case can be set as a good building benchmark for the improvement of the local evaluation framework for building efficiency.
首都大学東京, 2017-03-25, 博士（工学）