During minor renovations in the basement, engineers discovered major deterioration of City Hall's basic infrastructure, including rotted and cracked trusses holding up the roof, as well as inadequate life-safety and mechanical systems. In response, the City launched a large-scale project to stabilize and preserve the historic building, bringing it up to 21st-century standards.
The City Hall rehabilitation project included the upgrade of life-safety systems throughout the building, including a new fire alarm and smoke detection system and a new sprinkler system; a new energy efficient heating, ventilation, and air conditioning system; and the structural repair of the east wing. The electrical service supplying the building was also dramatically improved through the construction of a new electrical substation, the replacement of electrical distribution panels, and the installation of electrical branch wiring. Sustainable design features were incorporated throughout the project, reducing City Hall's energy footprint.
In addition, with the generous contributions of private funders, the City was able to conserve and document its rich art and archeological collections, including the City Council Chamber ceiling and historic mural series by Taber Sears.
The 2010-2015 City Hall Rehabilitation was supported in part by Benjamin Moore, Charina Endowment Fund, Drake Design Associates, Gilder Foundation, Leon Levy Foundation, Mayor's Fund to Advance New York City, Municipal Art Society, Oscar de la Renta, Arthur Ross Foundation, May and Samuel Rudin Family Foundation, and Tishman Speyer Properties.