The San Diego Unified School District will install individual air-conditioning units in 2,000 of its hottest classrooms. The San Diego Union-Tribune says the $9 million needed for the upgrades will come from the Proposition Z bond proposal approved by voters last year. Superintendent Bill Kowba says it will take 18 to 24 months to determine which classrooms are eligible for the air-conditioning units and then complete the installations. The district intends to spend $534 million over the next 20 years on air-conditioning needs in its schools. The projects just approved are meant to provide quicker relief to campuses with the greatest need.