Heating and cooling energy consumption of buildings accounts for a large portion of global energy use and is significantly affected by the air conditioning system in the buildings. In order to predict the energy performance of buildings, various energy simulation engines have been developed and recently applied to the BIM data of buildings. However, due to the interoperability between them, estimating heating and cooling energy at the design stage of the air conditioning system, in collaboration with the building model, still lacks of efficiency and accuracy. In this paper a highly efficient design framework with enhancement of interoperability that enables the designing of a variable refrigerant flow (VRF) type air conditioning system in BIM environments and to analyze its energy behavior is proposed. The framework covers i) computing the energy load of a building, ii) designing a VRF system that includes equipment selection, layout and piping, and iii) predicting energy consumption by the system with consideration of the building's thermal properties and annual weather conditions. The novelty of the proposed approach lies in the fact that the layout and piping for air conditioning system are enabled inside a BIM environment to maximize interoperability. We implemented the framework as an add-in program to the commercial BIM software and present its accuracy in comparison with the reference data provided by ASHARE.
