Abstract This paper presents a methodology for sizing passive thermal energy storage (TES) systems in solaria and greenhouses. Six different configurations are investigated, which encompass the most frequent cases. These configurations are studied with two complementary approaches: frequency response (FR) and finite difference thermal network (FD). FR models are used for sensitivity studies under short periodic design sequences while FD models are used in full-year performance assessments with real weather data. The most relevant performance variables for characterizing TES in solaria and greenhouses were identified in Part 1. In this paper, simulation results of these key variables are presented under varying conditions. A methodology for sizing TES in solaria and greenhouses is presented along with design recommendations. The energy balance equations for six different configurations are included in order to make the methodology applicable to a variety of designs. The methodology is based on a FR model with a simulation design period of five cold sunny days followed by five cold cloudy days; this sequence is representative of the most extreme conditions in a year and thus provides a good basis for the comparative assessment of design improvements.