A BIM-compatible framework to assess the thermal and optical performance of envelope systems

The building envelope, as the interface between the indoor and outdoor environments, plays a key role in determining building energy efficiency, as well as indoor thermal and visual comfort. A reliable performance evaluation of envelope systems requires information about the thermal and optical properties of the envelope system. The determination, processing and management of this information, particularly in the case of architecturally special buildings is challenging. This makes it harder to include performance considerations in the design and construction process of buildings. To decrease the complexity induced by the lack of communication standards between architecture software and simulation engines, Building Information Modelling is currently more and more used. Some methodologies have been developed that successfully convert Industry Foundation Classes (IFC) to EnergyPlus or Modellica. However, a detailed modelling of window coupled with the possibility to use ray-tracing engines as Radiance has not yet been included in any BIM platform. In this study, a new framework is presented in order to reliably evaluate the performance of envelope systems from Building Information Modelling (BIM). Therefore assisting in the design of energy buildings and optimizing the cost of such projects. The methodology complies with the Industry Foundation Classes format's specifications, in order to represent the energy, daylighting and comfort performance of envelope systems. The framework is based on the Black-Box model [1] and the Three-Phase Method [2], which use standardized and measurable optical and thermal properties as inputs. This paper will describe the methodologies and main IFC components used to generate and share automatically the simulation model inputs. A library has been developed to generate Radiance and Fener format input files.