In　order　to　gain　a　good　understanding　of　residential　building　energy　consumption　in　China,　a　case　study　about　occupants＇　use　of　electricity　for　lighting,　appliances　and　room　air　conditioners　was　carried　out　in　44　identical　apartments　in　Beijing.　Additionally,　two　apartments　with　significantly　different　energy　consumption　levels　were　chosen　for　a　detailed　study　about　the　impact　of　occupants＇　daily　behavior　in　using　lighting,　appliances　and　room　air　conditioners.　The　results　of　this　study　demonstrate　the　important　contribution　of　occupant　behavior　to　the　significant　variation　of　electricity　consumption　among　residential　buildings.　The　detailed　measurement　of　occupant　behavior　showed　a　potential　in　better　understanding　how　energy　is　consumed　in　buildings　and　relevant　information　gathered　from　this　process　can　help　occupants　change　their　behavior　for　energy　saving.