Benjamin Egner

Many industrial manufacturing facilities utilize energy savings initiatives in a segmented manner, installing energy savings projects based on simple ROI per individual project or initiative. Most manufacturing facilities are process/product driven. When investments are made in areas that will improve production output, energy efficiency in rarely considered.
This case study is for an industrial plastics manufacturer that utilizes a blow-molding process to produce completed plastic bottles. The process was experiencing issues with molds “sweating” due to humidity in the manufacturing space. This caused production slowdowns and excessive scrap rates. The manufacturing area is air-conditioned with chilled water air rotation units. A second process chilled water system provides the cooling water for the molds. The process chilled water system is fed from an open tank and provided constant flow rates at all times.

Taking a systematic approach to solving the issues between the manufacturing space and the molds, resulted in a project that resolved the humidity issues by controlling both the process chilled water and the manufacturing environment. Outdoor air duct was installed on the existing air handlers to utilized enthalpy-based economization. The process chilled water system was flow balanced, installing VFDs on chilled water pumps, running the pumps in a staged parallel configuration and making the system variable flow based on temperatures. The cooling tower pumps and fans are controlled with a wet-bulb based logic maximizing temperature control and efficiency.

These “combined” energy efficiency initiatives were utilized to help fund a solution for the facility. The production output has increased, and scrap rates have reduced to minimal levels. The energy initiatives were calculated to produce an annual avoidance of 84.0 kW, 1,656,384 kWh, and $119,260 in operating cost. The total investment was $411,000 for the project, showing a 3.45 yr. simple payback. Post project M&V showed an actual annual reduction of 137.8 kW, 2,263,227 kwh, and $162,951 operating cost reduction for a 2.51 yr. simple payback. The Chicago based manufacturer was eligible for the ComEd rebate program. The actual incentive received from the utility company was $271,587.24 for the verified kWh reduction. This resulted in a Net project cost of $139,413 for a payback of 0.86 yrs.

These energy savings were achieved by in depth balancing and commission of the chilled water and HVAC systems to accomplish and exceed the estimated energy savings.