50 United Nations Plaza

Originally constructed between 1934 and 1936, the Federal Building at 50 United Nations Plaza in San Francisco is recognized on the official National Register of Historic Places as well as the California Register as a national landmark. WSP USA performed a full systems redesign of the buildings MEP, fire protection, lighting and sustainability systems, with a reliance on natural ventilation and passive cooling wherever possible.



  • San Francisco, California, USA


  • General Services Administration

Project Status

  • Completed in 2013

Modernizing a Landmark

The renovation was the first in the building’s 77-year history. In addition to a full systems update, the project also included roof replacement and refurbishment of existing historic wood windows, restoration of historically significant interiors and central courtyard, and a redesign of the office interiors. A new 14,000-square-foot green roof helps to reduce storm water runoff and to lower heating and cooling costs.

Our engineers reviewed the existing steam piping and asbestos-containing insulation, located throughout the entire building. We assisted the team in developing recommendations for best practices abatement. Our solution allowed for the pipes and insulation to remain and resulted in only minor impacts to the building’s historic fabric wall coverings, saving the project the high cost of new piping installation.

Building Analysis for Sustainable Outcomes

As a result of building analyses including bulk air flow modeling and computation fluid dynamics, it was determined that the interior layout and workstation partition heights were a key factor in the assessment of natural ventilation performance. Given the limited cooling capacity provided by natural ventilation, differences in temperature and ventilation were studies against a range of factors. It was determined a hybrid condenser water system using high temperature chillers would minimize energy use of the overall system while achieving comfortable conditions within the building.

Additional energy modeling services performed by out built ecology team showed projected energy savings beyond ASHRAE 92.1-2007 baseline. Included in this was the assertion that all existing windows be replaced with laminated glass to improve the building’s overall shading coefficient. The glass tinting was optimized to greatly minimize solar gain while retaining maximum daylighting capabilities.

While the project was originally only pursuing LEED Gold, it ultimately achieved LEED Platinum certification.