The 'greening' of data centres has been a descant to the corporate utterances from most of the operators and equipment vendors selling into that industry. Many data centres took the green pledge not only because they affirmed its principles and didn't want to damned by default, but also as they realised that IT in general was receiving more than its fair share of criticism. Not only were data centres using vast amounts of energy to run servers, power control units, cooling and air-conditioning units, but the resultant heat generated was not reused constructively. The attention this brought raised the spectre of regulation, and the data centre sector rapidly realised that it needed to be seen to be acting to address environmental issues to offset any possibility of legislative controls from outside agencies.