Field tests, model validation and performance of a CO2 commercial refrigeration plant integrated with HVAC system

•Results from field measurements of a fully instrumented integrated CO2 booster system in a supermarket in northern Italy are given and analyzed.•A comprehensive model of the refrigeration system, display cabinets, cold rooms and refrigerating unit is presented and successfully validated.•Different levels of integration between the actual CO2 system and the HVAC are compared.•Conversion to a standalone solution, covering full space heating, air-conditioning and DHW requests is feasible and gets slight energy savings. A fully instrumented CO2 trans-critical booster system with parallel compression, in operation in a small size supermarket in northern Italy, made available measured data that allowed monitoring its performance. The entire refrigeration system of the supermarket, i.e. the Commercial Refrigerating Unit, the refrigerated display cabinets and cold rooms, have been modeled in TRNSYS with in-house types for all components. The comparison with the field data available from monitoring the plant allowed to thoroughly calibrate the model, spanning the operation conditions of a whole year. The validated model is a reliable and powerful tool, usable to predict the plant performance in several conditions and to evaluate the feasibility and effectiveness of the integration with DHW/HVAC systems. Measurements and simulations show that, at mild climate conditions, it is possible and effective to fully provide HVAC and refrigeration duties with a single all-in-one unit properly designed and operated.