As a design decision-making tool, energy modeling is best initiated at the Conceptual Design phase and carried through 100% of Construction Documents. The model should be used as an integrated design tool for making decisions and assessing the life cycle cost of various options.  Integrated design is essential – each decision should aid in optimization of the design in the context of all other decisions. According to the USGBC, the goals of the energy model are to “reduce demand, harvest free energy, increase efficiency, recover waste energy.”    

Note:  LEED version 2.2, EAc1: Optimize Energy Performance uses the Building Performance Method.  LEED v. 2.1 used the Energy Cost Budget (ECB) method.  The difference is that, with the version 2.2 method, you can change the schedules to look at efficiency, and baselines can be simulated for each building orientation, then averaged to calculate the baseline building performance. Process loads are included. ECB required that the budget building be modeled with the same orientation as the proposed building.  When viewing other project's energy models, note which version of LEED was used.

• Include energy modeling requirements in the RFP for Engineers, or hire a consultant (who would work closely with the Engineers) specifically to create the energy model. See Model Language for Energy Modeling Scope of Services.
• In the RFP, require that multiple parametric runs be performed and that results be evaluated for incorporation into the design. Appendix G of ASHRAE requires a total of five energy simulation runs to demonstrate compliance – 1 proposed design (models the building as designed) and 4 baseline simulations with modified orientations.

• Using the recommended and appropriate software, create a preliminary baseline building model based on ASHRAE 90.1-2004 (code minimum) for benchmarking. Use the Building Performance Rating Method in Appendix G of ASHRAE/IESNA Standard 90.1-2004 (without amendments). It must comply with the mandatory provisions (Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4) in Standard 90.1-2004 (without amendments). The model is to be used as a tool to inform design decisions, so it will transform as the process proceeds.
• All associated energy costs must be included. The baseline must comply with ASHRAE Appendix G. The default process load for the baseline is 25% of the total energy cost. This baseline model should establish basic load calculation parameters using the conceptual design.
• Identify energy requirements based on the programmatic needs and project goals.
• Consider renewable energy possibilities, such as ground source heat pumps, building wind turbines, or photovoltaics, using initial life cycle costing. Investigate rebates and grants for financial support for renewable systems.
• Orientation: Optimize the form and orientation of the building in order to take advantage of passive heating or cooling. Model four orientations. Include non-regulated load with square footage.
• HVAC: Determine the overall HVAC strategy. Use passive strategies to reduce the HVAC load. Consider renewable energy strategies, such as photovoltaics, ground source heat pumps, or wind turbines. Consider solar hot water heating. Consider cogeneration.
• Daylighting: Evaluate the design for daylight opportunities.

• At the beginning and end of each phase, have the person responsible for the energy model provide a summary report.
• Create a preliminary energy model parametric run with up to three variations on the building envelope or systems. For all runs, use the Performance Rating Method as outlined in LEED-NC EAc1: Optimize Energy Performance to compare the Proposed Building Performance to the Baseline Building Performance. See Energy Modeling Templates. The model is to be used as a tool to inform design decisions, so it will transform as the process proceeds.
• HVAC: Using the preliminary energy model and life cycle costing as a basis, refine the the overall HVAC strategy, considering alternative design solutions. Consider renewable energy strategies, such as photovoltaics, ground source heat pumps, or building wind turbines. Consider solar hot water heating. Locate mechanical areas to reduce distribution pressure drop. Consider cogeneration. Compare the preliminary energy model results against the baseline building/code minimum.
• Daylighting: Evaluate the design for daylight opportunities and calculate daylight factors. Establish lighting power density goals.
• Process Load: The default process load for the baseline is 25% of the total energy cost.
• SD Review : The Client and project team should review the energy model results in relation to the project goals.Work with the Commissioning Agent during the review.

• At the beginning and end of each phase, have the person responsible for the energy model provide a summary report.
• Create an additional parametric run with at least three 'minor' variations on system options during the Design Development phase. Update the model to reflect any changes to orientation or massing. Minor variations correspond to globe variable changes, or system component changes only. See Energy Modeling Templates.
• Determine appropriate sizing of systems (tonnage), U and R values, internal shading, cfm/person, etc.
• HVAC: If applicable, consider variable frequency drives. In addition to renewable energy sources, also consider heat and ventilation air recovery systems, valance units or chilled beams, condensing boilers, etc. See Technologies & Products for more information.
• Envelope: Use the energy model to optimize the R-value of the insulation. Architect – If applicable, specify an EnergyStar roof. Specify envelope and glazing performance requirements.
• Lighting: Reduce electric lighting and use daylighting as much as possible. Specify high efficacy lighting and efficient ballasts. Specify lighting control strategies for each space based on the energy model, such as occupancy and daylight sensors.
• Design and modify scheduling.
• The Client and project team should review the energy model results in relation to the project’s sustainability goals and refine the design accordingly. Work with the Commissioning Agent during the review.

• At the beginning and end of each phase, have the person responsible for the energy model provide a summary report.
• 90% CD:  Assess the model and systems design. The Client and project team should review the energy model results in relation to the project’s sustainability goals.Work with the Commissioning Agent during the review.
• 100% CD: Assessment of final design. In the CD phase, after the design is finalized, provide energy modeling services to document EAc1: Optimize Energy Performance, per LEED-NC version 2.2. requirements.  A final summary report of the building’s performance should be prepared in accordance with LEED-NC EAc1 requirements. See Energy Modeling Templates.
• Write the Measurement and Verification plan for building operations to verify the building is performing as designed.

• Document the Energy Model per the requirements of LEED-NC EAc1: Optimize Energy Performance. See Energy Modeling Templates.

• Address USGBC audit questions after the initial review, if required.
• Provide the client with an electronic and printed copy of the energy model.