On-site measurement and evaluations of indoor thermal environment in low-cost dwellings of urban Kampung district

Abstract

This paper reported results of a field measurement and questionnaire survey regarding the indoor thermal conditions of 17 low-cost dwellings located in a typical unplanned urban residential district ‘Kampung’ in Surakarta City, Indonesia. The surveyed dwellings were selected to grasp the indoor thermal features of various conditions, including the building materials, area, occupants' behaviours, and household economic level. The observed time series variations of the indoor air temperature showed significant diversity among the 17 dwellings. The decrement factor f, which refers to the ratio of the averaged daily amplitude of the indoor temperature to that of the outdoor temperature, showed a strong linear correlation with the parameter Q, i.e. the heat capacity of a building envelope per unit interior volume, regardless of the occupants' behavioural conditions. In addition, a statistical test using Spearman's rank correlation indicated that both Q and the floor area per interior volume have significant correlations with the percentiles of indoor air temperatures. Furthermore, estimated thermal comfort index PMVs suggested that most of the activity times in all of the surveyed dwellings were classified as out of thermally neutral conditions, i.e. they were slightly warm, warm, or hot. In contrast, the time fraction for the thermally neutral range of PMVs lower than 0.5 varied for the sleeping period among the dwellings, from 7% to 55%, owing to the parameter Q, as dwellings with low Q values tend to have a longer time period in the neutral range. These findings imply that the parameter Q and interior geometry of a dwelling can be utilized to establish countermeasures for vulnerable dwellings having a heat risk in Kampung districts.