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The heating, ventilating, and air conditioning system is critical in any building, and is responsible for up to 40 percent of the total energy consumed by a typical commercial building. Proper operation of the system is essential both to energy efficiency and comfort for tenants and/or customers. Improper operation can lead to unnecessary energy consumption, tenant complaints, poor indoor air quality, and even environmental damage.
Most HVAC systems can be retrofitted to improve reliability, reduce energy consumption, and meet new environmental standards. The first two concerns are the most common reasons for HVAC system retrofits, but environmental concerns should be considered as a part of any change.
New developments in control systems, variable-speed drives, and other equipment provide additional incentives for system retrofits. Changing codes and standards also are factors to be considered when evaluating a possible HVAC system retrofit.
As equipment ages, it has a tendency to break down more frequently. The age at which breakdowns occur will vary with the type of equipment in the building, but increased maintenance costs and/or frequency of breakdowns are major clues that the equipment needs to be modernized. Direct replacement of the equipment is the simplest approach, but may not be the best choice in every case.
Instead, managers can consider re-fitting parts of an older or inefficient system. For example, pneumatic temperature-control systems are widely used because of their simplicity but require continual maintenance and calibration. New, computerized, direct digital control (DDC) systems provide more precise control and greater reliability, along with better energy efficiency. In addition, the information capability of these systems can improve the productivity of the maintenance staff, a side benefit of a retrofit that was designed to save energy.
Energy efficiency is the most common reason for retrofitting an HVAC system. One option for the air-distribution system is to convert dual-duct, multi-zone, or constant volume systems to a variable volume system. This may require damper installation, duct-work modifications, and fan changes. The older variable-volume systems can have outlet dampers or inlet guide-vanes replaced with variable speed drives for improved savings.
The chilled-water system can be converted to a primary/secondary system that uses variable water flow for the secondary system, which feeds the chilled water coils that allow the system to provide cooling without utilizing the chiller.
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