Assessing the Effect of Cool Roofs on Health Using Smartwatches

Increasing heat exposure from climate change is causing and exacerbating heat-related illnesses in millions worldwide - particularly in low resource settings. June 2024 was the 13th consecutive hottest month on record globally - shattering previous records. Heat exposure can instigate and worsen numerous health conditions. Adaptation is essential for protecting people from increasing heat exposure. The built environment, especially homes, are ideal for deploying interventions to reduce heat exposure and accelerate adaptation efforts. However, evidence is currently lacking on a global scale - generated through empirical studies - guiding the uptake of interventions to reduce indoor heat stress in low resource settings.

Sunlight-reflecting cool roof coatings passively reduce indoor temperatures and lower energy use, offering protection to home occupants from extreme heat. Continuous monitoring of health and wellbeing using smartwatches can provide insight into important parameters such as heart rate, sleep and physical activity - which are all affected by heat. Using smartwatches, the investigators will also continuously measure health and wellbeing outcomes during the day and night. The investigators will conduct a global multi-centre study to investigate the effects of cool-roof use on heart rate, sleep and physical activity in four urban climate hotspots - Ouagadougou, Burkina Faso (sub-Saharan Africa), Ahmedabad, India (Asia), Niue (Oceania), and Sonora, Mexico (Latin America). These sites represent hotspots where people experience a triple burden from heat exposure, chronic health issues and vulnerable housing conditions (slums, informal settlements and low socioeconomic housing). They also exhibit diversity in climate profiles, housing typology, level of socioeconomic development, population density and rates of urbanisation.

This trial will quantify whether cool roofs are an effective passive home cooling intervention with beneficial health effects for vulnerable populations in four locations. Findings will inform global policy responses on scaling cool roof implementation to protect people from increasing heat exposure driven by climate change.