Building automation serves the overall functionality of buildings in their usage. The ATV DIN 18386 "Building Automation" from the VOB/Part C establishes the general contractual conditions applicable to the execution of building automation systems concerning materials, execution, main and ancillary services, as well as billing. It applies to systems for measuring, controlling, regulating, and directing technical facilities. The ATV was technically revised by the DVA in 2015, adapted to the latest developments in construction, such as guidelines for room automation, and partially restructured. The commentary on the new ATV DIN 18386 addresses the changes and provides practical guidance for implementation on the construction site.