Before the first shovel of dirt is removed from a prospective building site, the owner wants to know something very basic: what’s the payback over time?
I developed a continuing education course on energy modeling for Building Design + Construction University exploring how to increase project value and how to identify the most viable energy strategies for a project. It details why it is important to conduct energy modeling during early design, and how to conduct quick payback and net present value analyses.
Energy typically represents 30% of a commercial office building’s operating cost. Energy modeling can provide direction to the building team and generate consensus around an energy-efficient design that saves time and money over the life of the building.
Building the Model
Energy modeling as a process allows project stakeholders to understand the predicted energy use/energy cost of a building before it is actually built.
It’s essential to create an energy model and cost profile early in the design process to capture the most benefit. Team may use lightweight tools and resources, such as energy use intensity data, Department of Energy commercial benchmark model data, online photovoltaic and solar thermal sizing tools, and guidance published by ASHRAE, Core Performance, and other energy codes.
The most successful energy strategy has three attributes:
- It should push the boundaries of the owner’s and project team’s aspirations while demonstrating successful payback over time
- It should have the backing of all project stakeholders
- It should align with the project’s overall sustainability goal
The 9 Steps to Effective SD-Level Energy Modeling
In order to create a highly effective energy strategy, the building team and the owner must first determine if the energy strategy for the project should include any predetermined energy goals, such as a specific energy savings target for utility incentives or code compliance, green building certification, or the owner’s marketing strategy. The process can then be broken down into nine steps:
- Create the project’s energy use profile. Creating the energy use profile will highlight where the building’s highest energy impact areas are.
- Identify energy conservation measures (ECMs) for the major end uses. Review the energy profile to identify the project’s two or three major end uses, which may vary depending on the building program.
- Calculate the savings for each ECM. Use spreadsheet calculations of energy modeling to determine the energy savings for each ECM.
- Create ECM packages. Using energy-cost savings and level-of-effort and cost-to-implement ECMs, designate each EM as “low-hanging” or “advanced.”
- Conduct the payback analysis for each package. Obtain first cost information for each measure, and calculate life cycle payback for each low-hanging and advanced package.
- Present your findings to the entire team. Publish a finding report with your recommended energy goal and ECM packages. Include your findings on energy cost savings and payback periods. List any points for energy savings in LEED, Green Globes, or other rating systems.
- Finalize your energy strategy to meet the project’s energy goal. Conduct a mini-charrette with the entire team (including the owner, if possible) to finalize the project’s energy goal and strategy.
- Incorporate your recommended strategies in the project design. Publish the final strategy memo showing the list of agreed-upon ECMs and the cumulative energy savings. Also indicate if the project energy goal is achievable, along with the expected payback in years.
- Complete your compliance modeling. At 50% CDs or at the end of the construction drawings stage, use the project documents to complete the compliance modeling for the project to achieve the project’s energy goal.
Please click here to read the course I wrote that includes a more detailed explanation of energy modeling and the nine steps in the process. Readers may earn one AIA HSW Learning Unit after reading the course and successfully completing a quiz.
Have you used energy modeling in your building projects? Did energy modeling save you time and money? Please share your experiences in the comment box below.
Thulasi Narayan is a Senior Green Building Consultant, LEED® AP, in Paladino’s Seattle Office