Iconic hotels, casinos, office towers are the largest energy hogs in the U.S.

The nation’s largest iconic buildings such as Detroit’s Renaissance Center and Chicago’s Willis Tower consume more electricity than many small cities, according to a study by Oregon Generators, a provider of generator installation and electrical services.

Detroit’s Renaissance Center, a 5.5 million sf structure that houses the Detroit Marriott hotel, multiple office towers, and retail spaces that operate around the clock, tops the list of buildings with the highest energy demand with over 190 million kWh per year. The electric bill for that facility is estimated to be nearly $27 million annually. Chicago’s Willis Tower comes in second with 153.5 million kWh annually, costing $18.3 million.

The top factors for high consumption are climate control, lighting, and constant activity. These factors create intensive usage in public-facing buildings and usage patterns that prioritize comfort and convenience over efficiency. Total square footage and operation schedules matter more than height in creating energy demand.

Hotels, casinos, and office buildings have the highest rates of consumption, due to their nature of 24/7 operations and climate-controlled environments that serve thousands of people daily. “The real eye-opener is how building function trumps building height when it comes to energy consumption,” says Corey Gilgan, Owner of Oregon Generators. “A shorter casino can easily outpace a taller office building in terms of raw power usage. Hotels are energy-intensive by nature because they never really shut down. You've got lighting, heating, cooling, elevators, and guest services running 24/7.”

The study encourages property managers to audit their energy use and plan for sustainability.