Electricity using equipment such as computers, cell phone chargers, printers, copy machines, televisions, hair dryers, and room refrigerators creates "plug" loads, or electrical loads. In the last decade this has been a significant and rapidly growing portion of a campus electricity profile and a contributor to a growing need for air-conditioning. In the early 1990s Tufts undertook two major retrofits of lighting in Halligan Hall, our electrical engineering building. We advocated for these projects based on their financial savings over time. However, after four years passed and the savings were not seen by the finance department, the energy manager was called to task. With the help of an undergraduate engineering student who combed through department purchasing records, we were able to show that the lighting retrofits had in fact created huge savings. The problem was that these savings had been more than offset by the purchase of over one million dollars worth of electricity-using equipment—including substantial numbers of computers, lab equipment, and even a large electric oven for fabricating computer chips.
This example illustrates not only the ability of building users to cancel out the gains from building infrastructure improvements, it is also an excellent example of the tension that can exist between legitimate educational and research activities and energy and environment goals. The Tufts Climate Initiative invests considerable effort in distinguishing energy use that can be reduced or avoided from energy use that is essential to the central mission of the organization. Strategies for addressing personal action are discussed in chapter 10.
Internal loads in buildings have important energy implications and are a reality of modern life. First, the building load and thus the electrical service for the building is affected by the quantity and type of plug loads in the buildings. Second, the effect of all of these appliances on the building heating and cooling systems can be dramatic since inefficiency from refrigerators, VCRs, computers, and other equipment adds significantly to the internal heat of the building. While these loads can actually reduce the need for heating, using waste heat from equipment is a very expensive and inefficient way to heat a space. More importantly, these heat sources contribute significantly to the need for air-conditioning. Third, plug loads have implications for the size of building systems such as transformer capacity, computer closets, air-conditioning and air-handling loads, and occupant comfort. With the increased demand for cooling described above, these systems can also become overloaded in a domino effect. And lastly, the increasing demand for classrooms that are wired for sound, projection, and video means that there are more heat gains in a building and greater need for air-conditioning. Changing from cathode ray tube computer (CRT) monitors to flat screens can help to alleviate the internal heat in computer-intensive spaces. Flat-screen displays use less electricity, generate less heat, and may allow for the pur chase and operation of a smaller HVAC system for specialized areas such as computer labs.
Buildings also have other equipment that seems to be outside of the domain of facilities, construction, or building occupants. This equipment includes vending machines, washing machines, dryers, refrigerators, stoves, and so on. While this equipment is "essential," it can be a large electricity user and generator of waste heat. For example, Tufts calculated that the electricity used by its 115 vending machines is over 350,000 kWh per year, resulting in 203 tons of carbon dioxide and costing the university $40,000 each year. See chapter 8 for a more complete discussion of vending equipment and some solutions for reducing its energy demand.
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