Microprocessor techniques for energy conservation in computer rooms

Computers, particularly large ones used by finance bodies and government, are heavy users of electricity both to power the computer and to provide the environment recommended by the computer manufacturer. The power used by the environmental control equipment can be higher than that used by the computer itself. Both capital costs and running costs are high. Some cooling plants consume of the order of a megawatt of power. Recently, very expensive systems have been developed to recover waste heat from computers for use elsewhere in buildings either for hot water supplies or for space heating. This approach can only be easily applied to new custom designed installations, whereas in future most computers will be installed in existing buildings. Most heat is available from such systems in the summer when the demand is at a minimum. At best they are a palliative for an energy design which is wrong in concept. This article advocates an integrated approach to the total computer system design where all the factors, including energy consumption, are considered from the outset and their interactions considered. A working example is described designed on these principles which uses a fresh air ventilation system controlled by a microprocessor. Other advantages include automatic condition monitoring of the equipment, improved security and fire protection. The microprocessor-based environment controller is an order of magnitude cheaper, both in capital and running costs, than conventional designs. There is no evidence to suggest that it is less effective, because the computer installations concerned show higher than average reliability.