This article explains upgrades to an 1970s-era office building complex in Montreal consisting of three office towers and a hotel. A 330 ton (1160 kW) heat pump was installed, as well as an innovative system to recover heat from computers, the lighting system and occupants. There was an initial investment of $3,390,000 with a simple payback of 6.4 years. Energy efficiency grants amounted to $1,144,000, for a simple payback of 4.2 years.