OPTI-visor™ is an add-on control solution that advises a BMS system on optimal speed settings for the operation of HVAC components.

Background

Whirlpool is the world’s largest manufacturer of home appliances with brands such as Whirlpool, Maytag, Jennair and KitchenAid. Management wanted to improve the energy efficiency of a stand-alone central chiller plant at the 584,000 ft2 headquarters in Benton Harbor, Michigan. Armstrong supported the retrofit project with an installation of an OPTI-visor.

Without operating data to draw upon, the efficiency baseline was estimated to be just over 1 kW/ton. This was based on the chiller manufacturer’s published efficiency claims plus a review of system components.

It would later turn out that over 70% of the system operating hours were below 35% capacity. In this zone the chillers were using twice the published efficiency. Based on this is was collectively agreed that the real efficiency baseline closer to 1.8 kW/ton

ON/OFF testing

In the first month, the operators were still gaining trust in the system and didn’t always follow the OPTIvisor recommendations. With digital records operators were able to review operating stats in the time periods when the BAS accepted the recommendations. With approval, system efficiency was tracked for one month of operation with the OPTI-visor alternating on and off. Results showed a 0.5 kW/ton. (27%) efficiency improvement directly attributable to the OPTIVisor optimization strategy.

In all, the project was a great success. Energy consumption has been reduced by 763,000 kwh in year one. Chiller plant efficiency improved by 66%, partly through operation in free cooling mode. Financial results are equally impressive suggesting a simple payback of less than the original estimate of 3 years.

Net Project Cost: $140,000

Energy Savings/Year: $61,532

3 Year Savings: $184,597

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