This paper presents the findings of a questionnaire survey on usage of air-conditioners and windows among selected households in apartment houses in Johor Bahru City, Malaysia and compares the results with those in terraced houses surveyed previously. The frequency of respondents who open their windows during the nighttime in apartment houses was higher by 20% than that in terraced houses. However, this did not directly contribute to reduce the use of air-conditioners in apartment houses. It is especially important to find out the means to reduce both numbers and use of air-conditioners directly in order to help achieve energy-saving objectives in Malaysian residential areas.