460 ITU‐T's Technical Reports and Specifications \"Smart\" buildings should take advantage of dynamics, characteristics of building shell and HVAC system, automation, communications, and data analysis technologies in order to operate in the most cost‐effective manner1. Clearly, these definitions are not very different. Additionally, these definitions require an understanding of the building's systems and their abilities to interact with each other. 1.2 The fourth utility Traditionally building structures, all around the world, are built in accordance with similar principles in which individual specifications and typically vendors, devise and implement operational components of the building in a manner, which is often described as \"the three utilities.\" In traditional buildings, these three utilities are electrical, mechanical and plumbing, which are integrated with the base building. In such traditional constructions, the tenants become responsible with respect to a variety of different plans to implement their \"tenant improvements\" which are fed from the three utilities, which have been integrated with the building. Notably, communications are traditionally omitted from the base building services and it is the responsibility of the base building utility providers to install any communication services necessary for the provision of those utilities. As examples, the reader should consider elevators, which clearly include significant communications requirements dedicated to the elevator, and which are an independent installation used exclusively for this one application. The communications requirements for the heating, ventilating and air conditioning (HVAC) mechanical systems, monitoring of electrical usage and potentially other systems are equally repetitive, isolated and not able to promote or address the abilities for these systems to become a true basis for any form of intelligence. The thesis of intelligent buildings, therefore, is that base building systems shall be designed in a manner which permits their intercommunication and which also allows for communication between the building and individual tenant. The benefits are not always the same for each group of interested parties, nor are all the benefits evident when not all buildings include all the same features. This report has described some buildings in which such systems have been employed and which have, in most cases, functioned successfully for a number of years, allowing for many parties to enjoy some of the benefits. Consider some of the following examples of the benefits and opportunities which these intercommunications, or intelligence, can provide. 1.3 Access control and security systems The access control system should be integrated with the fire system, lighting system and the HVAC system. With these forms of integration, the system \"intelligence\" can allow a user to enter the building and the information that this user has presented in terms of his credentials will be signalled to a number of independent systems. As a result, when the user approaches his/her workspace, the lighting, HVAC controls (and potentially other systems) can each have been adjusted to meet that user's preferences. In the hotel industry, for example, empty rooms are normally not ventilated or lit so as to reduce energy usage. When the room is \"rented\", the necessary adjustments can be made long before the new occupant reaches his/her temporary front door. ____________________ 1 ASHRAE, The American Society for Heating, Refrigerating and Air‐Conditioning Engineers as part of their Technical Committee 7.5 (http://tc75.ashraetcs.org/)