Analysis of Passive cooling and heating potential in Vietnam using Graphical Method and Typical Meteorological Year weather file

摘要

This paper studies the potential to improve thermal comfort in Vietnam thanks to passivestrategies. First, a thermal comfort zone for the Vietnamese is proposed by using the PMV-PPDheat balance model of Fanger and the effects of adaptive mechanism of the people living intropical hot humid region. Then, the comfort zone is enlarged using the algorithms proposed bythe authors to calculate the effects of the passive heating and cooling strategies. TypicalMeteorological Year (TMY) weather data are used for graphically printing of hourlyenvironmental parameters on the psychrometric chart and for climate analysis, subsequently. Thelimitation and the scope of this method are also specified. Results of this study show that in allclimatic zones of Vietnam, natural ventilation is an efficient cooling solution, low-cost and easy toapply. Thermal comfort improvement of natural ventilation strategy varies with the climatic zones,increasing from 17.1% in Hanoi, 21% in Danang to 31.4% in Hochiminh city. Meanwhile, passivesolar heating is not really effective since winter in Vietnam is usually not too cold and thecapacity of the passive solar collector system is usually limited. Direct evaporative cooling alsohas a great cooling effect compared with that of natural ventilation, but significant humidityaugmentation in the air in hot and humid conditions may be inappropriate. Seasonal analysisreveals that natural ventilation gives higher performance than other methods and is particularlyeffective in mild seasons. During 12 months in Hanoi, the analysis clearly shows significantcontribution of natural ventilation in the period from April to October during which comfortperiod achieved might vary from 30% to 81%. The combination of all passive strategiesconsiderably improves thermal comfort: 22.6%, 31.7% and 47.6% of total time in Hanoi, Danangand Hochiminh city, respectively. Finally, the findings of this study indicate that conventionalheating and cooling methods are also needed during extreme weather conditions in summer andwinter, especially in Hanoi.