This article is reprinted with permission using excerpts from “Personal Computers and Computer Terminals in Commercial Buildings,” a brief written by Eugene Burns at the Energy Information Administration for the U.S. Department of Energy.Over the past 10 to 15 years, the use of personal computers (PCs) has risen dramatically. The energy consumed by PCs and other types of office equipment has become a significant component of electricity consumption in commercial buildings – 13 percent (98 billion kWh) of all electricity consumed in 1995. The Energy Information Administration’s 1999 Annual Energy Outlook forecasts that, for the next two decades, electricity consumption for office equipment (3.2 percent annually) will grow more than twice as fast as electricity use as a whole (1.4 percent annually).PCs and Terminals in 1995In 1995, an estimated 43 million PCs and computer terminals were used in commercial buildings. More than half of the 4.6 million buildings in the United States had at least one PC or computer terminal. On average, there were 571 PCs and computer terminals per thousand employees, and 732 PCs and computer terminals per million square feet of floorspace.Nearly half (21.2 million) of all PCs and computer terminals were located in office buildings. Those buildings contained four PCs and computer terminals for every five employees (797 per thousand employees). Among office buildings, the larger buildings (over 50,000 square feet) contained 13.3 million PCs and computer terminals, and 833 per thousand workers.Educational buildings also had a large number of PCs and computer terminals (8 million). Here, there were 847 PCs and computer terminals per thousand employees – the highest ratio for any commercial building activity. However, that ratio does not include students, and so it excludes a large number of potential users. In 1995, the total seating capacity of educational buildings was 85 million. If the PC-to-employee ratio were recalculated with even a fraction of the number of seats added to the number of employees, the ratio of PCs and computer terminals to thousand users would be much higher.Changes Between 1992 and 1995In three years, the number of PCs and computer terminals used in commercial buildings increased by 45 percent, from 29.8 million in 1992 to 43 million in 1995. Growth rates were considerably higher among the types of buildings that had relatively fewer PCs and computer terminals in 1992. The number of PCs and computer terminals used in mercantile and service buildings increased by 62 percent from 1992 to 1995. The number used in healthcare buildings more than doubled, from 1.1 million to 2.5 million. Sharp increases (from 89 to 146 percent) also occurred in assembly, lodging, food sales, and food service buildings. Growth rates were lower – but still over 30 percent – for office and educational buildings, the two types of buildings that already had substantial numbers of PCs and computer terminals in 1992.PCs are a relatively recent technology, and surveys are capturing this technology as it penetrates the commercial buildings sector. Office and educational buildings adopted the technology earlier but, as PC applications grew, PCs and computer terminals became important in other types of buildings as well. How far will this technology penetrate? At what point will the market become saturated? In office buildings, the number of PCs and computer terminals is already approaching one per person. One per person would seem to be the natural saturation point (for office buildings at least). However, use of multiple PCs, or both a PC and a computer terminal, is not uncommon. Future data collections might answer these questions.For more information about this and other energy-related topics, visit the Energy Information Administration at the U.S. Department of Energy website (www.eia.doe.gov).