In 2018, the Toronto District School Board (TDSB) staff estimated the cost of air conditioning all its schools at roughly $400 million — so, nearly $500 million in 2025 dollars — plus millions more in annual maintenance and electricity bills. It described the task as “virtually impossible.” Last week, the Hamilton Wentworth District School Board (HWDSB) staff pegged the cost to air condition its own schools at $200 million, while describing the job as only “relatively impossible.”