Facility Energy Analysis

Description:

The BIM Use of Facility Energy Analysis is a process in the facility design phase which one or more building energy simulation programs use a properly adjusted BIM model to conduct energy assessments for the current building design. The core goal of this BIM use is to inspect building energy standard compatibility and seek opportunities to optimize proposed design to reduce structure's life-cycle costs.

Potential Value:

  • Save time and costs by obtaining building and system information automatically from BIM model instead of inputting data manually
  • Improve building energy prediction accuracy by auto-determining building information such as geometries, volumes precisely from BIM model
  • Help with building energy code verification
  • Optimize building design for better building performance efficiency and reduce building life-cycle cost

Resources Required:

  • Building Energy Simulation and Analysis Software(s)
  • Well-adjusted Building 3D-BIM Model
  • Detailed Local Weather Data
  • National/Local Building Energy Standards (e.g. ASHRAE Standard 90.1)

Team Competencies Required:

  • Knowledge of basic building energy systems
  • Knowledge of compatible building energy standard
  • Knowledge and experience of building system design
  • Ability to manipulate, navigate, and review a 3D Model
  • Ability to assess a model through engineering analysis tools

Selected Resources:

  • ASHRAE. 2009. ASHRE Handbook-Fundamentals. Atlanta. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.
  • Crawley. D. B., Hand, J. W., et, 2008. Contrasting the capabilities of building energy performance simulation program. Building and Environment 43 (2008) 661-673.
  • Bazjanac. V. 2008. IFC BIM-Based Methodology for Semi-Automated Building Energy Performance Simulation. Proceedings of CIB-W78 25th International Conferenceon Information Technology in Construction.
  • Stumpf. A., Kim. H., Jenicek. E. 2009. Early Design Energy Analysis Using BIMS (Building Information Models). 2009 Construction Research Congress. ASCE.
  • Cho. Y. K., Alaskar. S., and Bode.T.A. 2010. BIM-Integrated Sustainable Material and Renewable Energy Simulation. 2010 Construction Research Congress. ASCE.

Additional Information:

This BIM Use can be further divided into two categories based on different levels of modeling details and implementation phases: Building Energy Analysis during Conceptual Design and Detailed Building Energy Analysis in the late Design. A quick energy analysis by using a simple BIM model during early design stage could help select best building orientations and configurations to improve building load and energy consumption profiles. Detailed BIM energy analysis is typically done in late design phase by using more powerful energy simulation tools, most of which are currently capable of behaving an hourly building load, system and plant energy simulation with economic analysis based on building location and local utility rates, and supporting BIM model files as inputs.

Before a BIM model is used for energy analysis, the responsible party (mechanical engineers or energy analysts) should review the model and make proper adjustments if the BIM model is not ready for simulation. The reviewing work includes checking model integrity and ensuring all parameters needed are not missed. Simulation tools also need to be determined before energy analysis, if single simulation program cannot satisfy all purposes (e.g. not all simulation tools are able to deal with renewable energy systems or on-site power generation, while others may lack of economic analysis), more than one software should be used jointly to accomplish energy analysis task.

Frequently, a reference building energy model also needs to be established to check if the current building design reaches the targeted energy performance goals set by national or local codes. A more significant amount of work is required to build a reference model on the basis of existing BIM model: building geometric parameters will remain the same while exterior walls, windows, and roof materials are changed based on the standard requirements as well as HVAC equipment and lighting facilities, etc., regardless what are really used in the actual design. The reference building BIM model will then be input to the simulation tools for energy assessment and the results are compared with actual building BIM model's prediction to examine whether the design agrees with the energy code.

If the targeted energy performance is not achieved, a design revision should be made and recorded into the initial BIM model. Energy analysis to the new version of building BIM model will be performed repeatedly until the energy goals are satisfied.