Introduction

Energy managers are the secret warriors of the twenty-first century. Together they comprise a vital phalanx of the collective army whose essential role is to defend the world from destruction by climate change. For the most part unseen and unnoticed by the public, they toil in buildings everywhere, from hospitals to hotels, factories to data centres, from office blocks to leisure centres. After all, the energy used in buildings forms about 40 per cent of all energy used and 36 per cent of the world's CO₂ emissions.