The Integrated Project Delivery (IPD) in integration with Building Information Modelling/Management (BIM) is an optimal approach for delivering construction projects. This is, however fraught with complications, due to the inability of current cost management practices to determine fair risk/reward ratio in IPD arrangements. Previous research has established the advantages of Earned Value Management-based (EVM) method for risk/reward sharing, as well as, how Activity Based Costing (ABC) method can facilitate automating the sharing process. This study proposes an innovative approach to exploit the capabilities of these techniques coupled with BIM in automating/optimising the process of IPD risk/reward sharing. This includes providing mathematical equations for risk/reward sharing and developing a model that strengthens IPD parties' relationships. The process is enhanced through developing an EVM-Web grid that enables the participants to easily track their costs on computers and mobile devices. To demonstrate the applicability and validity of the proposed model, it is applied on a real-life case and displays promising results in terms of flexibility in allocating risk/reward for varying scenarios.