UW researchers develop warning system for extreme indoor temperatures

CTV News

17-07-2025

The recent stretch of extreme heat doesn't just pose life-threatening conditions outside, but inside too.
It has University of Waterloo researchers developing ways to identify regions across North America that are most at risk.
No laws exist in Canada for cooling buildings and rental units, so the team is creating a warning system to alert vulnerable populations who may not be aware that their home has gotten too hot.
'The threshold that we used was 26 degrees. So when your home is at that temperature for a prolonged period of time, that can be dangerous to your health,' said PhD student Irfhana Zakir Hussain.
The data was collected between 2015 and 2024. The team from UW's Ubiquitous Health Technology Lab (UbiLab) gathered the information from smart thermostats with Wi-Fi to automatically control heating and cooling settings. They then used machine-learning algorithms to accurately track indoor temperatures to determine households with life-threatening conditions.
They set out to find this information after noticing a gap when it comes to how public health agencies have historically approached extreme heat – focusing largely on outdoor temperatures.
'Unfortunately, that lacks insight on what's actually happening inside homes across Canada,' said Plinio Morita, a public health sciences associate professor.
uw researchers
This image shows household heatwave predictions. (CTV News/Spencer Turcotte)
The team says during heat waves, a building, home or rental unit with no air conditioning continues to accumulate heat due to the insulation that keeps us warm in the winter.
'That prevents the heat from leaving the house during the night,' said Morita.
That's where their warning system comes in thanks to the dashboard they hope to make online and public.
'I'm trying to build a system that can predict and map the climate related-health risks that we're dealing with,' said Zakir Hussain. 'How many people are going to be calling the ambulance? How many people are going to the emergency department because of the heat?'
She says the dashboard can help pinpoint a pattern of heat-related problems in particular neighbourhoods, like with older populations.
'As people get older, they also lose the ability to sense the temperature changes in their houses,' said Morita. 'The purpose of our project is to develop tools that we can notify people whenever these extreme heat events are happening and when their houses are getting too hot.'
Once an alert identifies vulnerable households, authorities could know where to implement both immediate and long-term measures. These interventions include establishing cooling strategies by distributing fans, for example, in addition to deploying emergency health services.
With not every dwelling equipped with a thermostat, people at risk may not know they need to get out of that hotspot and seek relief.
It's something they hope municipalities and governments can help with.
'The idea is if we can get this information out to them before they need to plan their budgets or allocate resources, they can use this information to make sure that everyone in the city is equally safe during these heat waves,' said Zakir Hussain.
In the long-term, the team hopes this data will lead to subsidies for smart thermostats and investments in green infrastructure to help reduce these heat risks.