Epcor Tower is a 29-storey office tower located in Edmonton, Alberta, Canada. It is located at 53.3° latitude. The design temperature is -34°C (-29°F) in winter and 28°C (82°F) DB/19°C (66°F) WB in summer (annual 62°C or 111°F delta). Various measures are applied to create an energy efficient building in this climate. A high performance envelope is used to minimize the effects of large temperature swings. Energy efficiency is also achieved by providing an outdoor air system with geothermal pre-heating and pre-cooling via earth tubes. Additional energy saving measures include exhaust air heat recovery, winter free cooling, and boiler stack condenser heat recovery. Using the energy saving measures presented, the building is expected to achieve a 41.4% energy use reduction as compared to ASHRAE Standard 90.1.