Monitoring and moderating extreme indoor temperatures in low-income urban communities

Abstract

Climate change presents significant threats to human health, especially for low-income urban communities in the Global South. Despite numerous studies of heat stress, surprisingly little is known about the temperatures actually encountered by people in their homes, or the benefits of affordable adaptations. This paper examines indoor air temperature measurements gathered from 47 living rooms within eight low-income communities of Accra and Tamale, Ghana. Using multiple temperature indices and a tiered analysis, we evaluate indoor temperature variations linked to roof type, ceiling insulation, presence of fans, and tree shade, for different housing types and locations. Our data reveal indoor temperatures in the range 22.4 °C to 45.9 °C for Accra, and 22.2 °C to 43.0 °C in Tamale. Using dummy regression analysis, we find that tree shade reduces the number of very hot days (>40 °C) and nights (>30 °C) by about 12 and 15 d per year, respectively. Building materials also strongly moderate indoor temperatures but in opposing ways: rooms with traditional mud walls and thatch roofs are on average 4.5 °C cooler than rooms in concrete block houses with uninsulated metal roofs during the day but are 1.5 °C warmer at night; rooms with ceiling insulation are on average 6.9 °C cooler in the day but 1.4 °C warmer at night. We conclude that sub-daily data are necessary for reporting extreme indoor temperatures, and that trade-offs between minimum and maximum temperatures require interventions to be assessed carefully before attempting to counter extreme heat inside homes.

Heat Stress Adaptation within Informal, Low-Income Urban Settlements in Africa

“…Studies from other parts of Africa confirm increased heat exposure within low-income informal settlements. These studies from Accra (Ghana) [23] and Kampala (Uganda) [24] attribute the problem to housing materials and lack of greening.…”

Beating the Heat

“…Unfortunately, people residing in high-density, informal neighborhoods are more exposed to higher ambient temperatures than those residing in affluent neighborhoods (Jacobs et al 2019). Moreover, the research literature is largely silent about temperatures experienced inside the homes and workspaces of low-income communities (Wilby et al 2021) (Figure 2.3). Climate model projections provide useful information about some of these expected global and regional changes but should be interpreted with care because of deep uncertainties, especially at the city and street scale (Box 2.2).…”

“…Even advanced climate models likely underrate the true severity of future urban warming encountered at community, household, and human scales. This is because models typically 1. simulate air temperature and humidity for very large idealized land cover types rather than at street scales; 2. provide climate scenarios for natural or agricultural landscapes-only a few models explicitly represent urban surfaces and, even then, in highly idealized ways (e.g., Zhao et al 2021); 3. ignore local climate changes due to future urbanization and adaptation measures, such as incorporating more green space or reflective roofs (e.g., Oleson, Bonan, and Feddema 2010); 4. correct biases using data from grass covered areas of meteorological compounds (Switanek et al 2017)-whereas asphalt pavements and highly dense urban areas are already warmer and behave differently to rural weather stations; 5. represent climate conditions outdoors rather than inside homes, workplaces, and public spaces (Wilby et al 2021); and 6. neglect potentially harmful synergistic effects such as joint occurrence of heat waves with air pollution episodes (Xu et al 2020).…”

“…that increase indoor temperatures and decrease the ability of residents to cool down (NRDC 2013). A host of other local factors increase their vulnerability to extreme heat, including the prevalence of cooking stoves inside the home, overcrowding, poor ventilation, the absence of greenery and tree shade around the houses, and running businesses in the home (Wilby et al 2021;Martin and Mathema 2009). Many households lack reliable water and electricity supplies-two essential items for keeping cool and hydrated during heat waves.…”

Chronic heat stress in tropical urban informal settlements

“…Yet, extreme heat may still be underestimated in topographically complex and/or data-scarce areas, such as urban informal settlements ( Scott et al., 2017 ; Baruti et al., 2019 ; Banerjee et al, 2021 ), where regional meteorological models may not capture the intricacies of temperature and humidity variation and extremes at a local scale and in situ environmental monitoring is lacking ( Coffel et al., 2018 ; Wang et al., 2019 ). Indoor temperatures are rarely examined in informal settlements (but see Mukhopadhyay et al., 2021 and Wilby et al., 2021 ) and it may be assumed that adaptations, such as the use of air-conditioning, will be practiced ( Biardeau et al., 2019 ), even though mitigation of this kind is expensive and often unavailable to informal settlement households ( Satterthwaite et al., 2020 ). These shortcomings and assumptions likely result in vulnerable populations with limited capacity to adapt being overlooked in broader scale heat stress exposure assessments ( Scovronick et al., 2015 ; Green et al., 2019 ).…”