Reduction of energy consumption by AC due to air tightness and ventilation strategy in residences in hot and humid climates

This paper proposes strategies for reducing energy consumption for cooling in residences in hot and humid climates. Based on the results of fieldwork measurements and questionnaire surveys, a simulation of indoor thermal environments in consideration of air conditioner operation was carried out, in order to evaluate energy consumption by air conditioners. This simulation program takes into account both heat and moisture transfer in building materials. In order to simplify the calculation and due to lack of measurement of ventilation volumes, the ventilation volumes are assumed as constant values depending on open or closed windows. The combined effects of building air-tightness and the opening time of windows for ventilation were examined. Making an entire building airtight results in a small reduction in energy consumption, as the air-conditioned area increases. Meanwhile, simply making an air-conditioned room airtight is more effective for reducing cooling energy consumption. Irrespective of this, nighttime ventilation of non-air-conditioned spaces is quite effective in reducing sensible cooling load. Thus, introduction of not only a high degree of insulation but also air-tightness along with well controlled ventilation is required to achieve energy savings in hot and humid climates.