Many older buildings are energy-efficient compared with average new construction, but can be challenging to bring to a level of higher performance. Consult building science experts to avoid moisture and structural problems, and consult with historic preservationists to make sure that any solutions don’t conflict with historic standards, if relevant. For example, in buildings with load-bearing masonry walls, building scientists tend to want to insulate the exterior, while preservationists may object to changing the appearance of the building. Adding equipment like cooling towers may conflict with a building or neighborhood’s historic character.