Efficiency Level Characteristics - Compressed Air Systems

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

No LOW Efficiency Base Case Scenario
1 Few compressed air systems have ever been assessed for system energy efficiency
2 Maintenance is limited to what is required to support operations
3 Compressors are independently controlled; energy use of partly loaded compressor(s) not known
4 System pressure profile, supply/demand balance, and storage, not optimized
5 Leaks are greater than 35%, and there are no plans to fix them
6 There is widespread inappropriate use of compressed air
7 Motors of all sizes are routinely rewound multiple times instead of replaced

No MEDIUM Efficiency Base Case Scenario
1 ~15% of compressed air systems have been assessed for system energy efficiency
2 Maintenance is a routine part of operations and includes some preventative actions
3 Compressor control is coordinated and a single trim compressor operates efficiently
4 Variable speed drives are proposed as a solution for flow control
5 Leaks are > 20%, but < 35% and are fixed periodically
6 There is widespread inappropriate use of compressed air
7 Motors > 37 kW are typically rewound multiple times, while smaller motors may be replaced

No HIGH Efficiency Base Case Scenario  
1 ~30% compressed air systems have been assessed for system energy efficiency
2 Both routine and predictive maintenance are commonly practiced
3 Compressor controls and storage are used to efficiently match supply to demand
4 System pressure profile from supply to end use has been optimized
5 Leaks < 20%; Leaks management is ongoing
6 Inappropriate end use of compressed air has been minimized
7 Most facilities have a written rewind/replace policy that prohibits rewinding smaller motors (typ <37 kW)