This aging, 300,000 square foot, former automotive plant had been unoccupied for several years and its owners were rehabilitating and re-purposing the facility for lease by multiple new industrial tenants. Their mechanical service contractor recognized that the steam boiler was very old and potentially inefficient, and asked BPT for a performance and energy assessment of the heating system. BPT evaluated the heating system and its boiler, and then compared that with alternative systems, including their costs of operation. BPT's assessment included review of the envelope (walls, windows, roof) conditions, the repairs needed for the old boiler and zones that should have individual controls and scheduling. That information was then incorporated into a zone-by-zone load calculation and a simplified energy model to predict operating costs between several heating options. This assessment resulted in our recommendation to relace the boiler with a new heating system that provided individual zone temperature and scheduling control and had exceptional efficiency. The new system was installed and demonstrated dramatic energy savings, even when compared to the previously unoccupied condition! Payback was less than 2 years.