LEED Certfication
What’s Whole Building Energy Simulation for LEED?
LEED Green Building Certification System requires a building project to demonstrate an improvement of at least 5% for new construction, 3% for major renovations, or 2% for core and shell projects in the proposed building performance rating compared with the baseline building performance rating. Baseline building performance is calculated according to ASHRAE Standard 90.1–2010, Appendix G, using a simulation model. Building projects must meet the minimum percentage savings in order to be eligible for LEED certification.
Benefits of Energy Modeling
Working with a building performance team comprising building energy modeling professionals early in the project can help a project team explore a panoply of design parameters and alternatives that might not otherwise be considered, including passive design elements such as building orientation, size of facility, function of the design, geometry/shape, building envelope materiality, window-to-wall ratio, shading and daylighting, among other elements.
Incorporating these features, as well as heating, ventilating and air conditioning (HVAC) strategies, into an early-stage design energy model can optimize whole-building performance and aid in meeting project energy goals. This approach can also reduce redesign time and costs that could otherwise arise when incorporating energy modeling later in the project.
What are the best practices for using energy modeling and simulation applications in LEED certification?
- Choose the right application There are many energy modeling and simulation applications available in the market, each with different features, capabilities, and limitations. Some of the most popular ones include eQUEST, EnergyPlus, IES VE, TRNSYS, and DesignBuilder. Depending on your project scope, complexity, and objectives, you should choose the application that best suits your needs and preferences. You should consider factors such as the level of detail, accuracy, flexibility, user-friendliness, compatibility, and support of the application. You should also check the LEED reference guides and the US Department of Energy website for the list of approved applications and their validation status.
- Define the scope and objectives Before you start using energy modeling and simulation applications, you should define the scope and objectives of your project and your energy analysis. You should identify the LEED categories and credits that you are targeting, such as energy and atmosphere, indoor environmental quality, water efficiency, and materials and resources. You should also determine the baseline and proposed scenarios that you want to compare, and the performance metrics and indicators that you want to measure, such as energy use intensity, carbon dioxide emissions, thermal comfort, and life cycle cost. By defining the scope and objectives, you can focus your energy analysis on the relevant aspects and avoid unnecessary or redundant work.
- Follow the standards and guidelines To ensure the quality and consistency of your energy analysis, you should follow the standards and guidelines that are applicable to your project and your LEED certification. Some of the most common standards and guidelines include ASHRAE 90.1, ASHRAE 62.1, ASHRAE 55, and LEED v4.1. These standards and guidelines provide the specifications, assumptions, methods, and procedures for conducting energy analysis and modeling. They also define the minimum requirements and criteria for achieving certain levels of performance and certification. By following the standards and guidelines, you can ensure that your energy analysis is credible, reliable, and compliant with the LEED requirements.
- Use appropriate data and inputs The accuracy and validity of your energy analysis depend largely on the data and inputs that you use for your energy modeling and simulation applications. You should use appropriate data and inputs that reflect the actual or expected conditions and characteristics of your project site, building, systems, and occupants. You should avoid using default or generic data and inputs that may not be representative or realistic for your project. You should also verify and validate your data and inputs by comparing them with the available sources, such as site surveys, building plans, equipment specifications, utility bills, weather data, and benchmarks.
- Perform sensitivity and uncertainty analysis Energy modeling and simulation applications are not perfect and may have some limitations, uncertainties, and errors. Therefore, you should perform sensitivity and uncertainty analysis to evaluate the impact and significance of these factors on your energy analysis results and conclusions. Sensitivity analysis is the process of changing one or more parameters or variables in your energy model and observing how the results change. Uncertainty analysis is the process of quantifying the range and probability of the results based on the uncertainties and errors in your data and inputs. By performing sensitivity and uncertainty analysis, you can identify the most influential and uncertain factors in your energy analysis, and adjust your model or inputs accordingly.
- Document and communicate the results The final and most important step of using energy modeling and simulation applications in LEED certification is to document and communicate the results of your energy analysis. You should prepare a clear, concise, and comprehensive report that summarizes the methods, assumptions, data, inputs, outputs, and conclusions of your energy analysis. You should also include the relevant graphs, tables, charts, and diagrams that illustrate and support your results. You should follow the LEED documentation requirements and templates, and submit your report to the LEED review team for verification and approval. You should also communicate your results to your project stakeholders, such as clients, architects, engineers, contractors, and occupants, and explain how your results inform and influence your design decisions and strategies.