The objective of the annex 34 was to develop HVAC fault detection and diagnosis tools, which are closed to commercial products. The approach was to design a number of different computer based demonstration systems that could be interfaced to HVAC processes in buildings. By monitoring the operation of these demonstration systems, researchers were able to test a variety of fault detection and diagnosis methods and technique in a real environment, find possible shortcomings and obtain new ideas for further development. Over fifty partners participated in the 30 demonstrations that were completed. The program of research which involved research engineers from 11 countries was completed in under 4 years.