This publication and accompanying CD-ROM "Decision support tool" provide information to help clients obtain an understanding of building services to satisfy functional needs in buildings. It will enable a client to specify the type of environment it wants rather than a particular building services solution. The guide will help the client and the professional design team ask the right questions, and arrive at reasoned answers, to identify the most appropriate and cost-effective solutions to the client's business needs. It will also be of use to experienced professionals in architecture, design and construction in that it will provide information on building services in straightforward, non-technical language. The guide will also enable an audit trail to be established which directly links to the original needs of the business to the actual operation of the building services. The main aim of this publication is to avoid unmanageable complexity and an excessive dependency on technology and management. It helps give control tasks to the occupants and to cut waste, especially energy.