The BIM to BEM approach (CYPETHERM procedure) proposed aims at reducing time for the energy model creation compared to current practice, as well as at increasing the accuracy of the models. As most of the building data needed for the energy simulations are already included into BIM models, using BIMs as a data source for the generation of BEMs represents a unique opportunity to increase the effectiveness and the energy efficiency of renovations and move towards the BIM-SPEED goal of 30% time-reduction and 60% energy savings.

The ‘BIM-to-BEM Procedure’ implemented as part of BIM-SPEED project is developed to:

• Exploit the data available from a BIM avoiding starting the BEM creation from scratch
• Reduce time and costs for the BEM creation compared to current practice
• Increase the level of accuracy of energy models to achieve the optimal design of renovation projects

The BEM model can be used to evaluate the following BIMSpeed Energy KPIs:

• OPED: Operational Primary Energy Demand
• TED: Total Energy Demand
• TEC: Total Energy Consumption

• Overcoming the main bottlenecks of the BIM-to-BEM current process
• Reducing time for the BIM-to-BEM process by 40%
• Developing a set of BEM creation tools for both a “simple box” approach and a full BIM–BEM approach
• Increasing the level of accuracy of energy models to achieve the optimal design of renovation projects

The main limitation comes from the BIM model used to start the process and the information included that may be not sufficient or not properly set.

Existing guidelines provide instructions to ensure the creation of proper IFC files. Some of the requirements are, as a first example:

• proper orientation of the building with respect to the real North;
• proper classification of the building element functions (internal, external, in contact with ground);
• proper union of the building elements
• all internal locals of the building must belong to a given space. Not empty areas should be left unmapped
• no internal locals of the building can belong simultaneously to 2 spaces (spaces should not overlap);
• external shadowing buildings are modelled as mass blocks (exported as IfcBuildingElementProxy);
• for locals with different internal heights, auxiliary floor surfaces should be used;
• dealing with residential building, each individual dwelling should be considered as a single zone with no further partitions.

Another limitation is that the procedure at the moment do not retrieves HVAC and other thermal zones data from the BIM, but they must be set up directly within the BEM tool.

• BIMSPEED Deliverable 3.1 - Analysis of BIM-to-BEM critical parameters and recommendations to solve the current bottlenecks
• BIMSPEED Deliverable 3.2 - A set of support tools and standardized procedures for BEM creation
• BIMSPEED Deliverable 4.1 - Baseline and Use Cases for BIM-based renovation projects and KPIs for EEB renovation

Data Sheets and Standards: 

• ISO 6946, ISO 10077-1 and ISO 13370: for the calculation of the thermal transmittance
• ISO 14683: for the calculation of the linear thermal transmittance of thermal bridges
• ISO 13789: for the calculation of the heat transfer coefficient
• ISO 10456: material properties

• BS: BIM SPEED
• BEM: Building Energy Model
• BIM: Building Information Modelling
• GIS: Geographical Information System
• HVAC: Heating, Ventilation and Air Conditioning system
• IFC: Industry Foundation Classes