Gateway Tower is a multi-story medium rise office building in Pasadena, California. FSI was contracted to audit the energy usage and implement energy cost reduction strategies that would provide a three year or less payback. The facility’s HVAC system consisted of a boiler and chiller system on the roof with air handlers. FSI installed an energy management system, retrofitted the existing zone control to variable air volume and optimized chiller. Energy savings were identified at over $100,000 per year for a cost of about $300,000 for a three year payback.