单项选择题 Asmallbusinesscurrentlyhasaserverroomwithalargecoolingsystemthatisappropriateforitssize.Thelocationoftheserverroomisthetoplevelofabuilding.Theserverroomisfilledwithincandescentlightingthatneedstocontinuouslystayonforsecuritypurposes.WhichofthefollowingwouldbetheMOSTcost-effectivewayforthecompanytoreducetheserverroomsenergyfootprint？（）