Publication outlining the results of research into the applicability of condition monitoring techniques to the maintenance of building services. Notes the drawbacks of breakdown maintenance and time- based maintenance and states that condition based maintenance (CBM) has the potential to reduce costs and increased the effectiveness of maintenance in a number of building services applications. Considers in some detail the use of Building Energy Management Systems (BEMS) as CBM tools. Focuses on BEMS applications expected to yield the most widespread benefit, the primary areas being filters and heat exchange processes. Notes in addition the use of a BEMS to monitor the overall vibration level of a fan.