Study on changes in micro-climatic parameters and domestic energy consumption influenced by changes in urban morphology in Hatirjheel area, Dhaka.

Abstract

Although there are several control measures for morphological changes in urban residential areas, it’s seldom followed or maintained because of the growing community demand. Hence, once planned residential areas transforms into an unplanned state in relation to their physical layout and distribution of non-residential function. These morphological changes may affect the urban microclimate in either positive or negative way and that might affect the urban energy consumption in return. Therefore, it is paramount that these effects should be observed, because these changes and effects might lead to a situation where we may need to re-evaluate morphological changes to aid or counter its effects on urban microclimate and energy consumption.

To understand the influence of changed morphology on microclimate and energy consumption of an urban domestic area of Dhaka, Mohanagar Housing has been selected since this residential area underwent a large scale morphological changes in the resent years through the renovation work of Hatirjheel Lake and two periods (2007 and 2017) were observed, which are pre and post renovation respectively. The effect of renewed morphological changes (lake, roads adjacent to the lake, boundary wall, bridges, overpasses etc.) on the Micro-climatic parameters (temperature, mean radiant temperature, relative humidity and wind speed) and domestic energy consumption (electricity billing data) has been observed.

Analysis shows that, there is an obvious influence of the urban morphological changes on the Micro-climatic parameters and domestic energy consumption. Specifically, for this research area, with the change of 1°C in temperature due to the morphological changes, the rate of change of energy consumption is 17.67%. The Air Temperature increases and the RH is dramatically lowered due to the excessive heat gain at day and inadequate heat release at night from the pavements, roads and overpass near the Hatirjheel Lake. The malfunction of advection of humidity and inversion layer effect also plays a major role in this scenario throughout the day and night alike. Additionally, newly erected non porous wall and overpass too close to the water body created a barrier in between the water body (Hatirjheel Lake) and the residential (Mohanagar Housing) area, which obstructs the advection of humidity and wind flow. It is further perceived that although the morphological parameters of that area is changed as a whole, individual micro-domain samples are showing unique role to this due to their individual micro-domain parameters. Specially, the open area and the built area largely contributes to the change of micro-domain attributes.