In this study, simulations of a scale model of an unfurnished rectangular room with an absorbing ceiling using an energy-based geometrical acoustic model and a phased geometrical acoustic model are compared to measurements. This room can represent a typical classroom or office. This comparison concluded that the phased model can capture more details of the sound field, particularly at low frequencies. For accurate predictions, precise surface descriptions are needed for the phased GA method, which are not always available. The main drawback of the phased model is a longer calculation time.