Analysis of natural ventilation effect for an office building considering moisture absorption by materials

Natural ventilation of buildings is becoming one of the major design approaches for sustainable buildings all over the world; however, the control strategies of vents or windows have not been well established especially when applied to hot and humid climate such as the Asian summer. In humid weather natural ventilation accelerates the absorption of water vapor by books, papers, materials used for furniture and furnishing, etc. This effect may increase the air-conditioning load when ventilation is performed intermittently in an air-conditioned building. Therefore it is important to determine ventilation control strategies on how and when vents or windows should be open and closed. For this analysis the authors developed a simulation code that can calculate air-conditioning load and room conditions by taking both natural ventilation and moisture flow analysis into account. In the present paper how much the vent schedules and quantities of moisture absorbing materials affects air-conditioning loads and room thermal conditions is evaluated and investigated. The results show that the natural ventilation controlled by temperature plus humidity ratio during nighttime is the best scenario among the considered scenarios, but enthalpy based control is not adequate contrary to expectation. Air-conditioning load is reduced by 37% in comparison to that for the no ventilation scenario.