Heat: warm air going back to the air handlerCold air along the floor voidPower: grid, UPS, busway, racksChilled water: chiller to coilA data hall in section. Every watt the servers draw leaves as heat: the floor void feeds 24 °C air through the perforated tiles, the servers warm it by 12 K, and the air handler hands the heat to 7 °C chilled water that a chiller (5 kW of cooling per kW of electricity) sends outside. Move across the figure to change the load per rack; the needle reads PUE, the grid draw divided by the server draw, from a model with those assumptions plus fan power that follows the cube of airflow and a UPS that loses 3.5 % of what it carries.