What constitutes a single structure? What if multiple buildings are connected via hallways, common spaces, etc?

EPA’s national energy performance rating system is based on a statistical analysis of individual buildings, not campuses of buildings. A series of buildings situated closely together as a plaza or campus, even if sharing a common heating or cooling source, is NOT considered a single structure, it is considered a campus of buildings. In this type of arrangement it is necessary to separately meter the energy consumption for each building, and pursue separate energy performance ratings and ENERGY STAR labels. This type of sub-metering is a more effective management strategy as it will help you isolate problems and target the most efficient upgrade opportunities. Moreover, sub-metering will also provide you with a much more accurate energy performance rating, given that the rating system is based on data from single structure buildings.

Buildings that have multiple towers connected by common concourse levels and/or hallways may present a different situation. In these types of buildings, if there are common areas that cannot truly be divided or separated among the towers, then EPA will consider this to be a single structure. The following are several examples:

• An office building has three stories of common space including an atrium, a cafeteria, and seamless connections between two towers. This IS considered a complete and indivisible connection, and the building may be treated as a single structure for the purposes of the ENERGY STAR even though it may appear as two above ground towers.
• An office complex consists of two buildings connected by an outdoor (covered) walkway. This IS NOT considered a complete and indivisible connection, and energy use in these buildings must be separately metered. An energy performance rating and the ENERGY STAR must be pursued separately for each structure.
• An office complex consists of three buildings connected by underground walkways “tunnels” that allow workers to move between the buildings without being exposed to the outside weather. This IS NOT considered a complete and indivisible connection, and energy use in these buildings must be separately metered. An energy performance rating and the ENERGY STAR must be pursued separately for each structure.