a privately held collection of manuscripts by poet Rubén Darío. Hayden Library is on Cady Mall in the center of the Tempe campus and is currently under renovation. It opened in 1966 and is the largest library facility at ASU. An expansion in 1989 created the subterranean entrance underneath Hayden Lawn and is attached to the above-ground portion of the original library. There are two floors underneath Hayden Lawn with a landmark known as the "Beacon of Knowledge" rising from the center. The underground library lights the beacon at night. The 2013 Capital Improvement Plan, approved by the Arizona Board of Regents, incorporates a $35 million repurposing and renovation project for Hayden Library. The open air moat area that serves as an outdoor study space will be enclosed to increase indoor space for the library. Along with increasing space and renovating the facility, the front entrance of Hayden Library was rebuilt. Sustainability , ASU was the top institution of higher education in the United States for solar generating capacity. Today, the university generates over 24 megawatts (MW) of electricity from on-campus solar arrays. This is an increase over the June 2012 total of 15.3 MW. ASU has 88 solar photovoltaic (PV) installations containing 81,424 solar panels across four campuses and the ASU Research Park. An additional 29 MWdc solar installation was dedicated at Red Rock, Pinal County, Arizona, in January 2017, bringing the university's solar generating capacity to 50 MWdc. Additionally, six wind turbines installed on the roof of the Julie Ann Wrigley Global Institute of Sustainability building on the Tempe campus have operated since October 2008. Under normal conditions, the six turbines produce enough electricity to power approximately 36 computers. In 2021, ASU researchers installed a passive radiative cooling film to local Tempe bus shelters to cool temperatures during the daytime by radiating heat to space with zero energy use. The film was produced by 3M and cooled shelter temperatures by 4°C. It was one of the first applications of the cooling film in the country. ASU's School of Sustainability was the first school in the United States to introduce degrees in the field of sustainability. ASU's School of Sustainability is part of the Wrigley Global Institute of Sustainability. The School was established in spring 2007 and began enrolling undergraduates in fall 2008. The school offers majors, minors, and a number of certificates in sustainability. ASU is also home