Terminal 3 was designed by a consortium of Netherlands Airport Consultants (NACO), UK Architect Foster and Partners, and ARUP. Lighting was designed by UK lighting architects Speirs and Major Associates. The budget for the expansion is US$3.5 billion. Much larger in size and scale than the other two terminals, Terminal 3 was the largest airport terminal-building complex in the world to be built in a single phase, with in total floor area at its opening. It features a main passenger terminal (Terminal 3C) and two satellite concourses (Terminal 3D and Terminal 3E), all of the five floors above ground and two underground, with the letters "A and B" omitted to avoid confusion with the existing Terminals 1 and 2. Only two concourses were initially opened, namely, Terminal 3C dedicated for domestic flights and Terminal 3E for international flights. Terminal 3D officially opened on 18 April 2013. The newly opened concourse is temporarily used solely by Air China for some of its domestic flights.