LB-17-C009 — Case Study of Chiller Selection for the Retrofit of a Large Building Cooling System

This paper describes the chiller selection design and procurement process for a large municipal office building. The retrofit project was carried out according to specifications used to govern chiller selections ASHRAE 90.1 “Minimum Requirements for Chillers” and the ASHRAE “Chiller Life Expectancy”. For efficiency, the ASHRAE 90.1-2004, Section 6.2.1, “Mechanical Equipment Efficiency” standard is used. The integrated part load value (IPLV) is addressed using AHRI Standard 550/590. The large municipal office building operates four chillers that provide the cooling as well as heat recovery for the office building. Two 1100 ton (3869 kW) chillers are approaching the end of their useful lives and thus being replaced. Both have a full load efficiency of 22.7 EER with an IPLV of 19.13 EER and 18.13 EER, respectively. The Building Management System (BMS) archived trend data analysis for a two-year period and an energy simulation model was used to analyze the cooling load for the building. This analysis was used to see if, more efficient, lower capacity chillers would be sufficient for the replacements. It was determined that the new chillers can be downsized up to 800 tons each (2814 kW). A life-cycle cost analysis was performed to showing that up to $52K in energy costs can be saved be retrofitting the existing chillers.