This paper presents several correlation based models to be used for estimation of the energy performance of vapor compression screw chillers. They were developed using a detail thermodynamic model, contained in the ASHRAE Toolkit-I, for (1) identification of chiller parameters along with data from the manufacturer's catalogue and (2) simulation of the energy performance of screw chillers. The new models were compared with those currently used for centrifugal chillers. The energy performance of screw chillers from two different manufacturers was also compared.