Then, the innards. An efficient PC has an internal design that produces little heat. There are two sides to this. Not only does an energy-efficient computer minimise the transformation of electricity into heat, but production of less heat also ensures that additional cooling costs can be decreased. “There is a lot of heat that is generated and lost during the conversion process from alternate current to direct current,” explains Choudhary.

While power supply in India is AC (220V), the internal power supply unit of a computer requires DC (5v-12v). The conversion from one to the other results in heat and magnetic radiation. The better the PC, the better the conversion rate—i.e. it generates more DC power, less heat. Among the HP products with higher power conversion are the DC-class models such as the ultra slim dc 7800, which has an efficiency of 80 per cent (which means 80 per cent of the AC power is converted to the needed DC current). Other DS-class models have efficiency in the 60-70 per cent range. “A thousand PCs with 80 per cent efficiency can save the equivalent in CO2 emissions generated by the burning of over 4,500 gallons of gasoline,” says Choudhary.

Like most things, the efficiency of computers too are rated. To be acknowledged as environment-responsible products, all products have to be Energy Star compliant or and Restriction of Hazardous Substance (RoHS) compliant. The United States Environment Protection Agency-funded Electronic Product Environmental Assessment Tool (EPEAT) is the standard system for evaluating, certifying and registering green computers, based on its efficiency parameters.

... contd.