The aim of the present paper is to analyze a building optimization and control (BOC) algorithm which is implemented in the existing building energy management system (BEMS) of the Saint George Hospital in Chania, Greece. The developed algorithm consists of predicted models for outdoor/indoor air temperature using artificial neural networks, multi-step optimization using genetic algorithms and Real Time control using fuzzy techniques. The algorithm is developed in Matlab (TM) environment and is implemented to the existing BEMS of the Hospital, using a specialized web-based energy management and control system (Web-EMCS). The implementation of the BOC algorithm is realized by developing a ".net assembly" code, which interconnects the Web-EMCS with the existing conventional hospital's BEMS, without the need of Matlab (TM). The annual primary energy efficiency achieved is almost 36%. (C) 2014 Elsevier B.V. All rights reserved.