The Management and Automation of a Commercial building Heating, Ventilation and Air Conditioning (H.V.A.C) System has got enormous benefits from the use of all the available information sources. The modern H.V.A.C using direct digital control methods have provided useful performance data from the building occupants. The untapped data can be cultivated with the help of modern maintenance management databases. This research work has got the integration and application of these fundamental sources of information, using some modern and novel techniques. The cost and scalability of these techniques can be positively influenced by the recent technological advancement in computing power, sensors and databases. The important theme of this research paper is to increase the computational efficiency and practical usefulness of techniques, via some clever approximations.