For years, Denver teachers and parents have expressed concerns about hot classrooms when students return to school in August — many to buildings without air conditioning.

It’s no different this year, despite efforts by the district to cool some of its hottest schools. The temperature on the first day of school last week was 98 degrees. As the forecast calls for weather in the mid-90s this week, heat concerns are once again reaching a fever pitch.

“I joke that I don’t teach reptiles, I teach mammals,” said Lisa Yemma, a teacher at Slavens K-8 School. “Thirty middle schoolers in a room, it’s hot.”

On social media, teachers and parents have been sharing photos of thermometers: 90 degrees in a special education classroom. 89 degrees in a second-floor middle school classroom. 88 degrees in an elementary school classroom where the teacher is pregnant.

“Teachers tend to be martyrs,” Yemma said. “We say, ‘This totally sucks, but we’re going to do it anyway because it’s for the kids.’ But at this point, we are risking the health and safety of the kids.”

A group of teachers organized a rally Monday evening outside Denver Public Schools headquarters to protest hot classrooms.

“We demand the district come up with a plan, including concrete steps to fix the problem,” said South High School teacher Elizabeth McMahon, who helped organize the rally.

“That could be moving the school calendar back or budgeting to put [air conditioning] in the remaining schools that don’t have it,” McMahon said by text during school Monday.

Sixty of Denver’s 207 schools don’t have full air conditioning. That’s fewer than in years past. Well aware of the problem, Denver Public Schools asked voters to approve tax increases in 2012 and 2016 for bond measures that the district spent in part on heat mitigation.

In 2012, the district earmarked $22 million for cooling 79 schools that did not have air conditioning. Ruling out installing air conditioning as too expensive, the district experimented with other approaches, including automated nighttime air exchange, which pushes hot air out and pulls cool air in; portable evaporative coolers; and ceiling fans.

Temperature data showed the automated nighttime air exchange systems were the most effective. So in 2016, the district earmarked $44 million for installing the systems in the 79 schools without air conditioning. It earmarked another $21 million for classroom air conditioning at the very hottest schools, as measured by a temperature study done in 2015.

To date, district officials report that 19 schools have gotten air conditioning paid with the 2016 bond money. They include several of the big comprehensive high schools: East, South, Abraham Lincoln, John F. Kennedy, and George Washington.

Another three campuses — Beach Court Elementary, Garden Place Elementary, and the Kepner campus, which is home to a district-run school and two charter schools — are scheduled to get air conditioning next summer, officials said.

For the 57 schools that won’t get air conditioning soon (see the list below), the district has set aside $27 million for things like replacing equipment and improving ventilation to cool those schools, said Mark Ferrandino, the district’s chief operating officer.

It would cost an estimated $200 million to put air conditioning in the 57 schools, Ferrandino said — an option the district may consider if it asks voters for another tax increase in 2020.

Meanwhile, stories of oppressive heat in classrooms abound.

“I got a text of headaches, nosebleeds, and kids saying they were wanting to throw up,” school board member Angela Cobián said at a meeting with district officials on the first day of school.

She asked if there was anything immediate the district could do to support schools, especially those without full-time nurses, as it figures out a long-term solution.

“We’ve been focused on the cooling and how we can get the resources, whether it’s portable cooling or getting [the] facilities [department] into buildings to make sure all the vents are working and everything is moving the air the right way,” Ferrandino said.

Superintendent Susana Cordova added that the district distributes information to schools “on the little things we can do to lower temperatures. Doing things like turning off monitors on computers. Frequently, we let them go to sleep instead of turning them off, and they’re actually putting off heat when they’re on, even when they’re in sleep mode.”

School leaders can also release students early, before the temperature peaks in the afternoon, if they feel classrooms are too hot. At least two schools have already done so.

The teachers who organized Monday’s rally charge that the district is ignoring one possible solution: delaying the start of school. They credit the mid-August start date to “pressure to perform on standardized tests,” including state literacy and math tests that students take in the spring. Schools whose students score poorly can face district or state sanctions.

But district spokesman Will Jones said Denver has started school in mid-August for the past 20 years, which would predate the threat of state sanctions. The district’s calendar is set by a committee that includes parents and teachers, he said.

Among the reasons school starts in August, he said, are a desire to finish the first semester before winter break, minimize the gap between when summer camps end and school begins, and align high school sports schedules with surrounding districts that start in August, too.

He said the district has also heard concerns from parents that starting later would mean high school students have less time to prepare for college entrance exams like the SAT.

Yemma, the teacher at Slavens K-8 School, said she understands some of those reasons. But she argues that if Denver wants to start school in August, it needs the facilities to do so.

“In the future, as the climate gets warmer, this is an issue we do need to solve,” she said.

These campuses do not have full air conditioning:

Beach Court Elementary (scheduled to get air conditioning in 2020)
Garden Place Elementary (scheduled to get air conditioning in 2020)
Kepner campus (scheduled to get air conditioning in 2020)
KIPP Sunshine Peak Academy middle school (scheduled to get air conditioning in 16-room addition)
Asbury Elementary
Ashley Elementary
Former Barrett Elementary, now a program for students with disabilities ages 18 to 21
Bradley International elementary school
Brown International Academy elementary school
Bryant Webster Dual Language ECE-8
Carson Elementary
Cory Elementary
Cowell Elementary
Doull Elementary
Ellis Elementary
Force Elementary
Denison Montessori elementary school
Denver Green School K-8
Denver Language School elementary school
Denver Language School middle school
Denver Online High
Edison Elementary
Fairview Elementary
Godsman Elementary
Goldrick Elementary
Grant Beacon Middle
Gust Elementary
Hallett Academy elementary school
Hamilton Middle
Johnson Elementary
KIPP Denver Collegiate High
Knapp Elementary
Lincoln Elementary
Manual High / McAuliffe Manual middle school
McAuliffe International middle school
McMeen Elementary
Merrill Middle / Creativity Challenge Community elementary school
Montclair School of Academics and Enrichment elementary school
North High / STRIVE Prep Excel
Park Hill Elementary
Polaris Elementary
Rocky Mountain School of Expeditionary Learning K-12
Sabin World Elementary
Skinner Middle
Slavens K-8
Smith Elementary
Steck Elementary
Stedman Elementary
Steele Elementary
Stephen Knight Center for Early Education
STRIVE Prep Sunnyside middle school
Teller Elementary
Thomas Jefferson High
Traylor Academy elementary school
University Park Elementary
University Prep — Arapahoe St. elementary school
University Prep — Steele St. elementary school
Valverde Elementary
West Early College / West Leadership Academy