Since Busch Stadium began improvements soon after it opened in 2006, the ballpark reduced energy use by 23% (down to 161.2 kBtu per square-foot from 211.8 after normalizing for weather). That’s a savings of about $150,000 annually. Part of the savings are due to a 2011 energy audit that resulted in the replacing more than 1,000 traditional spotlights and floodlights with LED lamps to cut lighting power demand in several areas by 90%, the implementation of a ventilation control scheme in electrical rooms to eliminate the year-round use of the equivalent of a 100-ton air conditioner, and the installation of small cooling systems for the scoreboard control room and video coaching room to substitute for huge HVAC units meant for larger areas. Additionally, a new heat exchanger was installed to recover heat waste and reduce the amount of heat that must be generated by the stadium.