Completion of a full building modernization for the U.S. General Accounting Office (GAO) included the replacement and/or upgrade of all mechanical and electrical systems. The GAO is housed in a seven story, 1.2 million square foot building comprised of general office space with executive suites, computer rooms, a cafeteria and dining room, parking garage, and video teleconference rooms. Five of the seven floors in the GAO building were completely renovated with new HVAC, plumbing, fire protection, lighting, power distribution, and telecommunications systems. A new variable air volume HVAC system, utilizing direct digital control, fan powered terminal units with hot water reheat at the perimeter, provides state of the art temperature control while minimizing energy costs. Ductwork sizes are minimized by the low temperature (“chill air”) medium pressure supply air of the primary air distribution and plenum return air via return air lighting fixtures. The building’s computer needs are served by an isolated power distribution system which includes network substations, isolation transformers and computer grade branch wiring. The modernized floor is now capable of supporting the high-density computer loads associated with today’s office environment. New lighting systems and plumbing systems were completely replaced throughout the modernized floors.