As the rising temperatures last week closed dozens of schools in Baltimore and Baltimore County, the lack of air conditioning in old schools became a political issue.

Gov. Larry Hogan blamed city and county school officials for not getting the work done quickly enough. Both school systems, however, say they have kept state officials updated on detailed plans to do so.

The county had 90 schools without air conditioning seven years ago, and now has only eight. There are plans to install air conditioning in all but two of the schools, Lansdowne and Dulaney high schools — by 2021. The school board voted to replace those two schools last year, but the next county executive must decide when and how to do it. The schools had been slated for renovation, but the communities rejected renovations in favor of new schools. In addition, there is no plan in place to install air conditioning to two school centers — one an early education center and one an alternative school — that lack it.

The city has a five-year plan that would add air conditioning to more than 60 schools in the next several years. The city’s progress has been slower because the city government doesn’t have enough money to pay for the projects up front, and then ask for reimbursement from the state. The county has done just that, and the state will gradually pay back about $200 million it owes the county for the project.

Here’s the timetable for both school systems.

Comptroller Peter Franchot has advocated for portable air conditioning units to be placed in schools to provide immediate relief even if it is a temporary solution.

The county decided against using portable units. County Executive Don Mohler said school officials examined the costs and found they would have to spend about $500,000 to $1 million per school to replace wiring to support the increased electric use of the air conditioning units. Mohler said the county decided against installing the units because in many cases they were about to tear down the old schools and replace them with new buildings. Doing the math, Mohler said, it was not responsible use of $8 million to $9 million dollars to put in the portable units to ensure students were cool for several days a year when the heat was high.

Instead, he said, the county tore down the buildings or completely renovated them to put in central air.

The city has gone with portable units for some schools that weren’t slated for extensive renovations or new buildings. But instead of using the typical window units that have a short life and would significantly increase electric bills, the city is purchasing units that attach to the wall and serve as both air conditioning and heating units, said chief of staff Alison Perkins-Cohen. While they are more expensive than traditional window units, she said, they will help resolve the heating problems in schools as well, and they are far cheaper than installing an entirely new HVAC system. At one school, the cost of installing portable units was $1.5 million compared to $6 million or $7 million for a completely new HVAC system.

— Liz Bowie