The second floor of the West Wing houses offices for the president's staff, including various assistants, speech writers, and the White House counsel (the president's lawyer). The second floor was added to the West Wing in 1934 by Franklin Roosevelt, expansion of the federal government to manage New Deal programs and later to fight World War 2 made it necessary to have more senior staff members close by.
Solar White House
In 1977, Jimmy Carter had solar panel installed on the roof of the West Wing, on top of the Cabinet Room. These were removed in the Reagan era because of leakage problems, but around 2002 were reinstalled by the second Bush administration, along with new solar collector systems on the Swimming Pool cabana and grounds keeping building.