TORONTO -- An Ontario-based pension plan has agreed to buy a half interest in the TransCanada Tower in Calgary for $257.4 million.

H&R Real Estate Investment Trust (TSX:HR.UN) says the property has almost doubled in value in the 15 years since it was built in 2001.

The buyer is HOOPP Realty Inc., a subsidiary of the Healthcare of Ontario Pension Plan (HOOPP), which manages about $64 billion of assets for its members.

The deal is subject to conditions but expected to close in November.

The 38-storey TransCanada Tower houses the headquarters for TransCanada Corp. (TSX:TRP), one of North America's largest pipeline and energy infrastructure companies.