The depressed oil economy has sent rental rates in Calgary’s downtown office market spiralling by 17 per cent over the past year, says commercial real estate firm JLL.

Its third-quarter report said the average asking net rent fell $20.75 per square foot, almost half the $40.01 peak of 2007 and 2008, with higher-end space the hardest hit.

“Since the start of oil price decline one year ago September, Class A net asking rents have fallen by 41.7 per cent,” said JLL. “This is largely due to the complete lack of demand in the Class A market and landlords being forced to reduce asking rates to create activity on vacant space.”

The firm said a rise in sublease space — which has grown from 1.7 to 2.7 million square feet — is having a significant impact on rental and vacancy rates. While the rise of sublease space is slowing, it still accounts for almost half of all available space downtown, it said.