Wisconsin Public Power Inc. (WPPI) intended to double their available building square footage while at the same time completely renovate the existing building and keeping the original exterior envelope intact. WPPI aggressively pursued energy efficiency and installed a geothermal heat pump system and many other energy efficiency measures such as daylighting controls, a dedicated outdoor air system with heat recovery, demand-controlled ventilation, and a geothermal hot water heating system. Sustainable Engineering Group provided full commissioning from design phase through first year of operation. The WPPI office building has achieved LEED Gold certification. Sustainable Engineering Group is providing Measurement and Verification and ENERGY STAR® certification services for the building to ensure continuing energy efficiency.