ITU‐T's Technical Reports and Specifications 471 continues to be widely adopted in the market due to the fast expansion of mobile, cloud, grid and big data applications and networks connectivity benefits. 4 Other aspects 4.1 Operating costs and occupant comfort A major objective of an intelligent building is to provide a building which can be operated at a lower cost, (i.e., to cut the unnecessary expenditure of energy when it is of no benefit e.g., do not heat or light areas when they are not occupied) and ensure that the systems are there to evaluate costs and to quickly respond to occupants' needs and maintain occupant comfort. 4.2 Tenants' satisfaction The investment and efforts to make a building intelligent are ultimately all part of a marketing campaign by landlords and developers to ensure that the building becomes a \"desirable\" facility. This is only one small part of the overall thrust of developing a new building where the architect will endeavour to make it as appealing as possible, the engineers will endeavour to make it as comfortable as possible and the interior designers will take great care in ensuring that the \"form\" of the interior design makes people want to work in that environment. The function provided by the engineers and implementers will augment that capability, thus for example, attractive features can be added as in putting lights on the building which would change with the season, or with the time of day, or, with the weather, or with the extent to which the building is occupied meaning that the building when fully occupied may be coloured red or when the building is empty may be coloured blue. With the widespread development of smart telephones with enormous capabilities the opportunities further exist that tenants or guests may be able to download suitable information for their own smart phones to ensure that their particular interests e.g., calling of an elevator or modifying their work space environment can easily be achieved by requesting different lighting levels, background music, or room temperatures. Fire alarm or other emergency information can be clearly defined in messages sent to the smart phones of all tenants. Instantaneous electrical utilization or billing can be monitored. With time of day pricing instantaneous monitoring of electricity meters or sub metering becomes crucial to maintaining close control on overall costs. 4.3 Maintenance One of the key issues related to any intelligent building is that on‐going maintenance of the facility is absolutely critical to maintaining the benefits of building intelligence. While most intelligent buildings will operate using less energy and water, equipment throughout the building needs constant maintenance to ensure that optimal performance is maintained. The key is also to ensure that sensors are cleaned and calibrated on a regular schedule. Poorly performing sensors can be one of the main reasons that an investment in building intelligence does not result in reductions in energy and water usage.