The impacts of demographic transition on embodied energy consumption and typology of residential buildings: the case study of Tehran’s Region 5

Abstract

Changes in the structural characteristics of the population, such as age structure, household size, and number of households indicate shifts in the population age structure, moving from the younger towards the older populations and result in the reduction of household size. Former extended families have turned into a nuclear and even one-person household. Shifts in household status, both household composition, and household size lead to the formation of a new housing typology. It can affect the type, number, and floor area of ​​residential units as well as the amount of embodied energy used in the wet zones (kitchen, bathroom, and toilet), which are fixed, inflexible and costly areas of a residential unit. This study attempts to investigate the effect of demographic transition on the housing typology and embodied energy consumption of wet zones. The research is based on a case study: first, the changes in the population characteristics were examined by referring to the data published by the statistics Center of Iran. Then a field survey of residential buildings was started, to identify the number of floors, and the number of residential units. Then interviews with 15 developers have be conducted to investigate the significant changes in the housing typology and the common plan of the area. The common plan of residential units was then examined to assess the floor areas of wet zones and to compare their ratios to dry zones. In the next step, the amount of materials and embodied energy in each wet zone were calculated. The analysis of the reports by the statistics Center of Iran on the case study showed an age transition from the younger to the older, a decrease in the household size, and a change in the housing typology in the case study. The interview with developers and field survey on 831 land plots indicated three periods of changes in the housing typology in the case study between 1987 and 2018. During each period, in each plot of land, more residential units with fewer floor areas were built and the amount of embodied energy used by the wet zones increased.