Smart buildings were sold on a simple promise: connect a building’s systems, from HVAC to elevators to access control, and you get lower operating costs, predictive maintenance, and a better experience for everyone inside. That promise is real, and it is why the global smart building market is projected to nearly double to 121 billion dollars by 2026, according to research from MarketsandMarkets. What gets less attention is the tradeoff that comes with all that connectivity, one that a growing number of security researchers say most facility owners have not fully reckoned with.