Use of smart thermostat data to investigate harmful exposure to heat in Calgary, Canada

With the increase in temperatures and extreme heat events, developing a better strategy to assess and quantify heat exposure indoors is crucial. Although people spend most of their time indoors, most studies and alert systems focus on outdoor temperatures. The growing adoption of smart thermostats in home heating, ventilation, and air conditioning (HVAC) systems offers an opportunity to study the relationship between indoor and outdoor temperatures. The present study uses indoor smart thermostats and weather station data to investigate heat exposure metrics for indoor and outdoor temperatures. We also analyzed the percentage of time indoor temperatures are within the ASHARE acceptability limit. We found that houses spend around 5% of the time above the ASHRAE limit and that indoor heat exposure metrics are higher than outdoor metrics, meaning greater harmful exposure to human health during extreme events like heatwaves.