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4.3 Single-Zone Systems

This part of the Energy Efficiency Manual presents the energy conservation measures that apply to single-zone air handling systems. Single-zone systems are defined by the fact that they are controlled by a single space thermostat. They may heat or cool, or both. They may have separate heating and cooling coils, or a single coil may perform both functions. The coils may be electric, hydronic, or direct-expansion. Thermostatic control may be proportional or on-off. They may have any means of controlling outside air, humidification, and other functions.

Single-zone systems differ from room conditioning units primarily in size, in having more elaborate duct systems, and perhaps, in having more positive control of outside air intake. Their larger size often makes it economical to make design and component improvements that would not be practical with room conditioning units.

The basic single-zone system is an efficient type. The main opportunities for saving energy with single-zone systems are eliminating unnecessary conditioning and reducing fan energy consumption. In this Subsection, you will learn to exploit energy saving improvements such as temperature setback, thermostatic deadband, multi-speed fans, and variable-air-volume (VAV) fan control.