Improving Energy Efficiency for the United States Postal Service

USPS case study

Problem

The United States Postal Service (USPS) sought to reduce its overall energy consumption and lower costs throughout numerous facilities. Their goal: to achieve a 30% reduction in energy use by 2015. Since air compressors are a major source of energy consumption within its facilities, the USPS contacted Compressed Air Systems (CAS) to assess the entire system of a Southwest Florida processing and distribution center.

After conducting a comprehensive air study using data loggers, flow meters, and pressure transducers, CAS technicians discovered that this USPS site utilized six air compressors operating at pressures up to 145 psi. In addition to operating above their capacity, these compressors seemed to work against each other rather than as one stable unit.

A CAS ultrasonic leak detector found over 40 leaks in the air system, further contributing to the substantial energy inefficiency of the site.

Solution

CAS determined that this USPS facility needed a modernized control system to properly regulate its air compressors. Without regulation, compressors can run longer than needed—wasting energy in the process. Our technicians installed a Kaeser Sigma Air Controller to ensure the six compressors would operate in unison. Once the new controller was in place and the system leaks were repaired, it was determined that the site would benefit from a variable speed compressor.

Result

Compressed Air Systems Award USPSThe new controller helped the compressors operate at lower capacities, saving the USPS over $7,000 yearly in energy costs. A new variable speed compressor was also installed in the facility, reducing energy usage from 180 HP (six units) down to 50 HP (one unit); the new compressor saved USPS another $8,000 yearly in kilowatt usage.

The repaired air leaks resulted in an additional yearly savings of $5,000. Partnering with CAS enabled the USPS to save over $20,000 a year in energy costs—not including the savings netted from lowered maintenance costs.

Due to significant improvements in their facility’s energy efficiency, the USPS was presented with a Con Edison award to commemorate this accomplishment. With other facilities following suit, the USPS will assuredly meet and exceed their energy reduction goals.