Developing an Integrated Part Load Value for Chillers of Office Buildings in Hong Kong

Abstract Integrated Part Load Value (IPLV) has been adopted worldwide as a simple metric for regulating and evaluating chiller performance. There is no exception for Hong Kong. However, the weighting factors and working temperatures for the derivation of IPLV were developed for the US. They may not be appropriate for use in other countries/regions with different operating conditions. Europe and China therefore have developed their own formula but the formulation is based on simulations and details cannot be found in literature. This study adopts a carefully-designed methodology to develop a Hong Kong specific IPLV. The development was based on actual operating characteristics of 20 Grade A office buildings in Hong Kong. Representativeness of the 20 office buildings was verified by statistical analysis. Through in-situ measurements and site surveys, hour-by-hour operating data of the studied buildings were collected. Monte Carlo analysis and ASHRAE's bin method were employed to examine the massive volume of operating data. Regression analysis was employed to formulate the Hong Kong specific IPLV. The formulated IPLV was validated. It gives the highest weighting to 75% capacity (0.682), followed in descending order are 50% capacity (0.257), 25% capacity (0.049) and 100% capacity (0.012). In determining the working temperatures, a mathematical model to enable quick estimation of entering condenser water temperature for water-cooled chillers was developed. The results and methodology adopted in this study will be useful for reference of manufacturers, policy makers and researchers in searching for a reliable metric for performance evaluation of chillers should simulation is not practical.

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