An energy-saving building, designed in its shape and volumes to flow with the urban and environmental context. The front wall to the north is closed to protect from the cold winds and the traffic of the freeway. Two inner courtyards in the middle allow act as a daylighting system, allowing natural light to provide effective internal illumination on every floor of the building and contributing to energy saving. The 4C building hosts the offices of the Ministry of Environmental Protection of China, created to implement multilateral environmental agreements.