Investigation on energy consumption for thermal comfort with respect to plan layout of residential apartment buildings in Dhaka

Abstract

This research focused on the study of electricity consumption to achieve thermal comfort, in apartments of tropical Dhaka, the capital of Bangladesh. As approximately 45% of the total population of Dhaka constitutes the middle income and upper-middle income groups, electricity consumption by this group is a critical factor in the national energy balance. According to recent reports, the electricity consumption in the residential sector has almost doubled in six years. While domestic electricity consumption is considered in three sectors; for lighting, for cooling and for household appliances, this research focuses only on the consumption for cooling. During the warm months (March-October), ventilation and air movement is vital for thermal comfort in the tropics, and electrical cooling appliances are commonly used for the purpose. Thermal comfort in Dhaka was found to be particularly related to air movement; therefore, this factor was focused in the study, especially indoor air movement. As plan layout is seen to affect air movement, its typology was therefore targeted for analysis in this research. Field survey was conducted on apartments of floor area between 93m2 to 148.7 m2 (1000-1600sft), selected on a random sampling method, representative of target middle and upper-middle income group, and located in planned residential areas. A questionnaire survey determined the specifications of electrical appliances used for cooling along with running hours, as indicative of the comfort situation of the inhabitants. Scaled drawings of plan layout were also collected, to understand the spatial quality in terms of “open type” and “cellular type” layout, and related air movement to compare with the measured variables and responses. It was the contention of this study, that there should be a critical analysis of plan layouts in mid-rise apartment buildings, to determine whether there is a relationship between energy consumption and related plan layouts. Analysis of the findings from the survey and the questionnaire responses reveal that, plan layout has a significant impact on electricity consumption needed for thermal comfort.