| Abstract |
Commercial buildings in the U.S. have more than 67-billion square feet of floor space and consume about 17 quads of primary energy per year, or about 17 percent of all U.S. energy consumption. TIAX carried out a study for the U.S. Department of Energy, Office of Building Technology (DOE/BT), to evaluate the energy saving potential of controls and diagnostics for commercial buildings through improved operation of energy-consuming building systems such as HVAC, lighting, and larger refrigeration systems. In the context of this study, controls are the hardware and software used to control indoor conditions to provide a safe, comfortable and productive environment for the building occupants. Diagnostics use measurements of building systems and equipment to evaluate their functionality and detect sub par performance, i.e., by comparing expected performance to actual performance. Both controls and diagnostics can operate at the central, system, equipment, or room level. Almost all commercial buildings have at least very basic on-off control functionality to provide lighting, e.g., lamp fixtures controlled by light switches or a circuit breaker, and heating, e.g., a furnace controlled by a thermostat. In addition, many commercial buildings have time-based controls to turn on and off lighting and vary space conditioning at specified times of day, particularly when buildings are unoccupied. Over the past 25 years, direct digital controls (DDC) using software-based controllers have come to market, driven by dramatic increases in computing power and the concurrent miniaturization and cost decrease of computing power. This has greatly increased the flexibility and potential sophistication of building controls while decreasing their implementation cost, a trend that continues with current movement toward control communications over enterprise networks. |
