Efficiency Level Characteristics - Fan Systems

In the UNIDO (2010) report covering energy efficiency and cost implications of different measures for fan systems, Low, Medium and High Efficiency base cases are defined with having the following characteristics:

No LOW Efficiency Base Case Scenario
1 Few fan systems have ever been assessed for system energy efficiency
2 Maintenance is limited to what is required to support operations
3 Flow is typically controlled by dampers or bypass
4 Low cost fans types, like radial, are often used even in clean air applications
5 Fans are often located on the dirty side of the process
6 Fans are oversized for the present load
7 Variable speed drives or variable inlet vanes are not commonly used
8 Motors of all sizes are routinely rewound multiple times instead of replaced
9 5% or less of the installed motors are high efficiency--either EPAct or EFF1 equivalent

No MEDIUM Efficiency Base Case Scenario
1 ~30% fan systems representing 60% of the connected fan load have been assessed for system energy efficiency
2 Maintenance is a routine part of operations and includes some preventative actions
3 System operators take steps to avoid controlling flow via dampers or bypass
4 Fans are located on the clean side of the process whenever possible
5 Airfoil or backward curved impellers are used in clean air handling applications
6 Fans are chosen to efficiently serve a given condition
7 Variable speed drives or variable inlet vanes are proposed as a solution for flow control
8 Motors > 37 kW are typically rewound multiple times, while smaller motors may be replaced
9 ~25% of the installed motors are high efficiency--either EPAct or EFF1 equivalent

No HIGH Efficiency Base Case Scenario  
1 ~50% fan systems representing 80% of the connected fan load have been assessed for system energy efficiency
2 Both routine and predictive maintenance are commonly practiced
3 Flow is not controlled by dampers or bypass except in emergencies
4 Variable speed drives are one of several flow control strategies commonly applied to increase system efficiency
5 Fans are located on the clean side of the process whenever possible
6 Fans types are chosen based on the highest efficient type to serve a given condition
7 Fans are selected and procured so that typical process flow and pressure requirements are at or near Best Efficiency Point
8 Most facilities have a written rewind/replace policy that prohibits rewinding smaller motors (typ <45 kW)
9 50% or more of the installed motors are high efficiency--either EPAct or EFF1 equivalent