The benefits of BIM such as effective decision making, improved analysis, easier access to information and simpler green building certification provide an optimised solution for sustainable design and construction. This study proposes an IFC-based framework within an integrated BIM and sustainable data model for the design stage of the building project life cycle. We present the green building assessment tool (GBAT), which implements the proposed model and aids the design team in the generation of documentation necessary for obtaining green building certification. It extracts the necessary data from BIM models for calculating the green rating and provides feedback for further evaluation. A sample project is run and a green rating score table for the BREEAM materials category is obtained for validation of the model. This tool serves as a proof of concept that green data relevant for BREEAM certification can be automatically processed and used to inform the design. (C) 2016 Elsevier B.V. All rights reserved.