486 ITU‐T's Technical Reports and Specifications 7.2.7 Routers Routers provided connectivity to the external world of Internet Service Providers. The picture shows this connection to an ISP. Some basic routing may be needed within the building based on the requirement assessment to provide network isolation (also called subnets) between various departments occupying the building. This is also termed Layer 3 switching. 7.3 Building Control Systems While there are a large number of different possibilities, the list below provides examples of common \"smart\" control features which integrate with the different physical systems to ensure that all the systems act together in an optimized and efficient fashion – thereby improving efficiency and reducing cost. Building Automation System (BAS) – HVAC & Energy Management Lighting Control System Fire & Life Safety Control Systems Access Control Video Surveillance Systems Parking Guidance and Management Systems Integrated Building Management System 7.3.1 Building Automation – Smart HVAC Systems Typically, when one refers to a Building Automation System (BAS), it refers to the various components of the HVAC control system. HVAC equipment is one of the most complex aspects of a building since it has many components ranging from chillers, boilers, air handlers, fan coil units, associated electrical and mechanical systems just to mention a few. While an HVAC system has one primary goal – to keep the occupants of the building comfortable it also is the single most consumer of energy in a building – over 60% of a building load. Hence, the balance of what can be done to ensure it meets the comfort and wellbeing of its occupants while minimizing energy use is the key to a good BAS. This means that many parameters need to be measured, analysed and then appropriate action or control need to be performed. For example indoor environmental parameters such as occupancy, temperature, humidity, noise, air quality, ventilation and outdoor environmental parameters such as outdoor temperature, solar radiation and other weather variable. All of these and more concurrently optimizing the operations of the HVAC system to minimize energy use. The large number of variables and components in an HVAC system necessitates extensive automation and system integration. For example, in a smart building the HVAC system may have the ability to sequence chillers, pumps, boilers automatically based on the different conditions and constraints including but not limited to run time, time of day, occupancy and other similar parameters. 7.3.2 Smart Lighting Control Lighting is a critical aspect to any building. It is both aesthetic as well as practical. Buildings need to provide sufficient lighting to enable their occupants to work perform their tasks effectively. Finally, lighting typically consumes approximately 20 % of a building’s energy load.