Metro's underground stations are cooled by chilled water air handling units, or "chillers," not air conditioning. The chiller system is designed to reduce temperatures in stations for customer comfort. Metro’s more than 35 chillers are in freestanding buildings, on rooftops or underground.

In 1995, the historic façade of DC Fire Department Engine Company No. 24 was relocated and integrated into the outer walls of the New Hampshire Ave Chiller Plant. The original firehouse building was constructed in 1911 using Italian Renaissance style. Local architects Luther Leisenring and Charles Gregg designed the neighborhood landmark for use with horse-drawn equipment; however, new motorized equipment was soon assigned to the firehouse. Within one year, Engine Company No. 24 became DC's first fully motorized firefighting company, which represented leading-edge technological advancements for the day.

The site is designated as a historic landmark and the upcoming addition to the structure meets the District of Columbia's Historic Preservation guidelines.