Reliability of energy performance evaluations through different BIM and BEM models

With the adoption of the EPBD recast in 2010 (Directive 2010/31/EU), EU Member States faced new tough challenges, foremost among them, moving towards new and retrofitted nearly- zero energy buildings by 2020 (2018 in the case of Public buildings). For this reason, along with the widespread availability of Building Information Modeling (BIM) technologies, many relevant problems arose in transforming the Building Information Model into the Building Energy Models (BEM). In the last few years, various software have been developed to translate geometrical and technological information into an energy model that helps designers in analyzing thermal performance and predicting buildings energy consumption. Even though software are getting more and more powerful and user-friendly, large discrepancies occur between results obtained with different BEM programs. The goal of the present research is to evaluate the effective accuracy and reliability of energy simulations performed with some state of the art BIM and BEM software and to outline a best practice for these types of simulation. The research has been carried out through a case study: a primary school building located in northern Italy. The BIM model of the building has been exported into Green Building Studio to analyze the energy performance, which has been compared to the results achieved with a semi-stationary calculation method, according to UNI TR 11300:2014 and with a dynamic simulations in Energy Plus well-known software. For the software considered, interoperability weaknesses and strengths have been found and results compared. Later the key influencing factors have been detected in order to validate the accuracy of the energy performance evaluation.