Mechanical concerns in tall buildings
from http://en.wikipedia.org/wiki/Mechanical_floor "Besides structural support and elevator management, the primary purpose of mechanical floors is heating, ventilation and air-conditioning, and other services. They contain electrical generators, chiller plants, water pumps, and so on. In particular, the problem of bringing and keeping water on the upper floors is an important constraint in the design of skyscrapers. Water is necessary for tenant use, air conditioning, equipment cooling, and basic firefighting through sprinklers (especially important since ground-based firefighting equipment usually cannot reach higher than a dozen floors or so). It is inefficient, and seldom feasible, for water pumps to send water directly to a height of several hundred meters, so intermediate pumps and water tanks are used. The pumps on each group of mechanical floors acts as a relay to the next one up, while the tanks hold water in reserve for normal and emergency use. Usually the pumps have enough power to bypass a level if the pumps there have failed, and send water two levels up. Special care must be taken towards fire safety on mechanical floors that contain generators, compressors and elevator machine rooms, since oil is used as either a fuel or lubricant in those elements. Mechanical floors also contain communication and control systems that service the building and sometimes outbound communications, such as through a large rooftop antenna (which is also physically held in place inside the top-floor mechanical levels). Modern computerized HVAC control systems minimize the problem of equipment distribution among floors, by enabling central remote control." Harry
