Non-optimal indoor temperatures measured in informal dwellings during cold months in Johannesburg, South Africa: implications in a changing climate

Background: Exposure to non-optimal temperatures is associated with adverse health outcomes. Low-income communities living in informal housing (colloquially called shacks) are vulnerable to the negative health outcomes associated with non-optimal temperatures given the characteristics of their dwellings. Objective: The study aimed to measure wintertime temperatures in shacks in Bekkersdal, West Rand District Municipality (South Africa). Methods: iButtons were installed in 10 shacks for 13 days to measure temperature at 10-min intervals. Ambient outdoor temperature data were collected for the same period as the dwelling temperature campaign from the nearest automatic weather station operated by the South African Weather Service. A questionnaire was administered to 127 shack residents to determine household socio-demographics (participant age/gender; number living in dwelling; and length of stay in dwelling) and dwelling characteristics (type of wall/floor; presence/absence of insulation; energy used for heating). Results: Indoor temperatures ranged between 3 °C–33 °C (mean: 13 °C, median 12 °C). Daily mean indoor temperatures for all shacks combined were below the World Health Organization threshold for minimum indoor temperature of 18 °C for 94 % of the study duration. Indoor temperature increased as outdoor temperatures increased and this association was statistically significant (R = 0.98, p < 0.001). The majority of shacks (n = 108, 85 %) were made from corrugated iron sheeting and had no insulation hence the strong correlation between indoor and outdoor temperatures. Conclusions: The poor insulation of shacks exposes residents to cold outdoor temperatures. Thus, people living in shacks are vulnerable to the adverse health effects associated with extreme cold. Guidance on how to create thermally efficient shacks with insulation is recommended as a temporary solution. However, the main goal should be to replace shacks with adequate formal, low-cost housing, which the government should provide.