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Office space represents a major environment where work is accomplished in the United States and around the world. Data from the Commercial Buildings Energy Consumption Survey indicates that there were 5.6 million commercial buildings in the United States in 2012 (the most recent year for which data are available), spanning 87.4 billion ft² of floorspace (see Figure 1.3) [13, 14]. The typical space allocation per employee is 130–150 ft², although some lower‐end industries (e.g. retail) allocate less and some higher‐end industries (e.g. law firms) allocate more.

TABLE 1.9 Top Subway and Rapid Transit Systems in the United States

System	Annual Ridership (2018) (M)	Avg. Weekday Ridership (K)	Stations (Approx.)
1.	New York City Subway	2629	8765	470
2.	Washington Metro	226	764	90
3.	Chicago “L”	226	720	145
4.	MBTA, Boston	156	510	50
5.	BART, Bay Area Rapid Transit	126	417	46
6.	SEPTA Philadelphia	94	328	75
7.	PATH NJ/NY	92	310	13
8.	MARTA, Atlanta	65	206	38

FIGURE 1.3 Inventory of US buildings.

Observers call out the need for tens of Tbps per square kilometer for traffic volume density. Using the data just cited, the requirement would be 3 connections per 100 ft² (a VoIP connection, a LAN data connection, and a wireless connection) – this equates to 1 per 33 ft². Conference rooms typically have higher concentration, say 20 connections in a 400 ft² conference room, or 1 per 20 ft²; this motivates the need for space optimization and tools to address occupancy (for example, using occupancy sensors under desks, utilization sensors in meeting rooms, and comfort sensors in rooms and desk areas). Figure 1.4 depicts a heuristic model for office and conference room space allocations and costs. Requirements span voice, video, data, and IoT applications. It is expected that the number of IoT sensors will increase with time for smart lighting, smart building, and other automation functions. Thus, it would not be a stretch to reach a point in the near future, where a density of 1 connection per 10 ft² is required for office environments.

FIGURE 1.4 Heuristic model for office space allocation.