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The Design Process and BEM

Building energy modeling can be used throughout the design process for a new building or when considering updates to existing buildings. It can also be used later in the life-cycle of a building related to comparing actual operation of the building with the predicted operation. ASHRAE Standard 209 titled "Energy Simulation Aided Design for Buildings Except Low-Rise Residential Buildings" is a critical document in how to apply building energy modeling. It describes a methodology to apply building energy modeling to the design and was created to define reliable and consistent procedures that advance the use of timely energy modeling to quantify the impact of design decisions at the point in time which they are made. The standard includes different "Modeling Cycles" for different stages of using building energy modeling during the life-cycle of the building:

  • Modeling Cycle #1 -- Simple Box Modeling
  • Modeling Cycle #2 -- Conceptual Design Modeling
  • Modeling Cycle #3 -- Load Reduction Modeling
  • Modeling Cycle #4 -- HVAC System Selection Modeling
  • Modeling Cycle #5 -- Design Refinement
  • Modeling Cycle #6 -- Design Integration and Optimization
  • Modeling Cycle #7 -- Energy Simulated-Aided Value Engineering
  • Modeling Cycle #8 -- As-Designed Energy Performance
  • Modeling Cycle #9 -- Change Orders
  • Modeling Cycle #10 -- As-Built Energy Performance
  • Modeling Cycle #11 -- Postoccupancy Energy Comparison

In addition, it has information about how to integrate climate and site analysis, benchmarking, energy charrettes (a meeting of the stakeholders to discuss goals and design strategies) and the energy performance goals of the owners project requirements into the design process when using building energy modeling.