Modern buildings are just boxes full of air. Air that's being moved around by various forces. Air that's full of water, air that's cool, air that's warm, air that smells funny. Architects tend to focus on visual and tactile aspects of space and shove the air problem over to the mechanical engineers. This division of labor is necessary, but there's no guarantee that the left hand of the building designer can keep track of the right hand of the environmental engineer.
In most circumstances, our boxes of air are okay. The engineer relies on thermostats, the architect signs over important parts of the building for air distribution networks, and the client is mostly happy. Sometimes, the mechanical engineer confuses the current project with a previous project and makes assumptions that turn out to be wrong. The architect makes this mistake also. Efficiency, more than comfort, suffers.