By Alex Harris

This article originally appeared in the Miami Herald.

Recently installed air-conditioning units at 2840-2842 NW 10th Avenue in Miami, Florida. Federal housing doesn’t require air-conditioning, but Miami-Dade County is funding new A/C units for hundreds of public housing apartments.
Jose A. Iglesias jiglesias@elnuevoherald.com

It’s no secret that summer in Miami is hellishly hot. But a new study found that it’s particularly rough for low and middle-income residents.

A newly published University of Miami study found that on some of the warmest days of the year, it’s actually hotter inside some people’s homes than outside — dangerously hot.

The study, published in the journal One Earth, offers the most comprehensive look yet at the problems of extreme heat inside homes in Miami-Dade, which handles its scorching temperatures differently than other places around the nation. In other cities where researchers have looked into indoor temperatures in the summer, the main question was whether the home had air conditioning or not.

“Everyone in Miami has AC,” said Lynée Turek-Hankins, lead author of the study and a post-doctoral fellow at Dartmouth College. “The question is does it work and can you afford to use it?”

Turek and her team worked with Catalyst Miami, a nonprofit, to find 57 houses across the county where they placed smart sensors that automatically measured heat and humidity over the summer and fall of 2022. More than 80% of the people in those homes had household incomes of less than $60,000 a year, and the majority were Black or Hispanic.

“Unfortunately, we found widespread issues,” she said.

Researchers tested their heat and humidity sensors in a University of Miami lab before deploying them to 57 homes all across Miami-Dade County.
Lynée Turek Contributed to the Herald

The majority of the homes reported issues with the heat. Most of the homes had working AC units, but plenty of households just couldn’t afford to run them or repair them if they broke.

One of the hottest homes they surveyed belonged to a college-educated woman with a middle-income job, who lived with her mother and her teenage daughter. The AC broke early on in the study, and fixing it was just too expensive, so the family baked in the heat.

“On paper, they might look like a pretty average family, but the costs were so prohibitive they didn’t turn their AC on all summer,” Turek-Hankins said. “Even if you own your home and can decide what to do with it, the repairs are so expensive you can’t do anything about it.”

To cope with high energy bills, many of the families researchers surveyed said they cut costs elsewhere, including skimping out on food, medicine and car repairs. One participant said they took out a high-interest payday loan to cover the costs, and another stopped going to physical therapy.

In a normal home budget, energy is supposed to take up around 6% of monthly expenses. Anything more than that is considered “energy burdened.” At least 10 of the homes the team surveyed spent more than 10% of their monthly income on their power bills, including some homes that didn’t even run their AC during the hottest months of the year.

“It was breathtaking, honestly,” said Turek-Hankins.

In one home, she said, the AC was broken, so the family left the doors and windows open all summer long to try and bring in some airflow. In another, the AC unit was too small to handle the home, so no matter how high the family cranked it — sending their bill skyrocketing — the house never felt comfortably cool.

One of the participants in the study did not have a functioning AC system, so residents left the doors and windows open all summer to try and stay cool. Researchers installed a sensor, visible in the reflection, to measure how warm it got inside the home.
Lynée Turek Contributed to the Herald

Miami-Dade has already gotten hotter in the last sixty years, and if climate change continues unchecked its likely to keep getting worse.

Miami-Dade County's hottest days are becoming more common

There are more days per year with temperatures above 90 degrees now than in 1960.

During the five-month study, there were a few times when the temperatures inside some of the homes were so hot that researchers were moved to call the residents and warn them that it was unsafe inside their homes.

Those usually occurred in homes that either didn’t have a functioning AC or had structural issues with keeping the home cool, like leaky windows and doors, which made up a small group of the study. The far larger group was the people who had functioning AC but couldn’t afford to run it.

That’s actually good news, Turek-Hankins said, because it means some of the solutions the county and federal government were already using to try to help people beat the heat will probably work.

“I feel like we actually have a lot of the solutions already,” she said.

The federal government helps low-income people with their power bill through the LIHEAP program, and Miami-Dade funds a program that helps low-income homeowners make energy-efficient upgrades to their homes, like adding insulation or upgrading to a more efficient AC. The county is also on a mission to install air conditioning in every public housing unit in the county.

This new study suggests that to solve the extreme heat problem in Miami-Dade, residents will need more help in all of those categories. “A one-size-fits-all strategy isn’t going to work for everybody,” Turek-Hankins said. “It doesn’t matter how much money you give someone for their bill if the AC isn’t working, of if you give them a brand new AC unit but they can’t afford to run it.”