were used to shift the weight of the mast to the columns below. Mechanical features The New York Times Building has a cogeneration plant, which can provide 40 percent of the building's energy requirements. It is variously cited as being capable of or . The plant is in a mechanical room on the top floor of the podium, at the far eastern end. The cogeneration plant is powered by two natural gas-fired engines. The New York Times Building is also connected to the main New York City power grid, which serves as a backup power source. Because of a disagreement with Consolidated Edison (Con Ed), the cogeneration plant is not connected to the grid. The plant runs at 85 or 89 percent efficiency. Heat is generated as a byproduct of the cogeneration plant's operation and is used to provide hot water. The recovered hot water is used in the building's perimeter heating system during the winter, while it is fed into the building's chillers during the summer. The New York Times Building contains a single-stage absorption chiller that is capable of . The building also has five electric centrifugal chillers of each, which serve the building's central chilled-water plant. The air from the chillers is delivered from chillers at . It travels to an underfloor air distribution system under each of the Times stories and to the ceilings of the top 21 stories. The steam for heating the building itself is purchased from Con Ed rather than being generated on-site, since the architects determined on-site heat generation to be more expensive. The cellar and the podium's roof contain air handling units with steam coils that take low-pressure steam. There are over 18,000 lighting fixtures in the offices, all of which can be dimmed. The electrical ballast in each fixture contains a computer chip, which adjusts the lighting based on natural light levels and on whether the office is occupied. There are also automatic shades, which change automatically based on the sun's position, sunlight glare, and interior heat gain. The shades can also be manually overridden. The movable shades reduce energy consumption by about 13 percent and reduce solar heat gain by 30 percent in the Times portion of the building. The upper stories have two data closets and two electric closets each. In addition, the building has emergency generators throughout. Interior There are 32 elevators total: 24 for passengers and