<P> In February 2006, the Professional Bull Riders hosted a Built Ford Tough Series bull riding event at this venue . Chris Shivers won this event with a total score of 181.5 points (out of a possible 200) on two bulls, including an impressive 93.75 (out of 100) points on Taylor Made bucking bull, Smokeless Wardance, in the short - go round . During the long - go round, the roof was closed, but during the short - go, the roof was opened . </P> <P> The stadium has hosted Monster Energy Supercross rounds from 1999 to 2015 . Monster Jam came to Chase Field every year in late January about two weeks after Monster Energy Supercross . Both events moved to the University of Phoenix Stadium in 2016 . </P> <P> Chase Field's roof is opened or closed depending on the game - time temperature . When the decision is made to close the roof, it is left open for as long as possible before game time in order to keep the grass growing . Even when the roof is closed, the park's windows allow enough sunlight to play in true daylight without overheating the stadium . </P> <P> The roof, which takes just 41⁄2 minutes to open or close at a cost of $2--$3, is closed three hours before game time using two 200 - horsepower motors triggered from a control room in the upper deck above left - center field . A massive HVAC system then drops the temperature inside the park 30 ° by the time the gates open . The cooling system, which has the power equivalent of cooling 2,500 homes of 2,000 square feet, uses chilled water and is part of the same system that serves more than 30 buildings in downtown Phoenix . The cooling plant is located in a separate building right outside the ballpark . Originally, the HVAC system didn't work above row 25 of the upper level, exposing fans in the higher rows to the full force of the often - oppressive heat typical of Arizona summers . Recent changes keep virtually all of the facility in air - conditioned comfort . </P>

When do they close the roof at chase field