ASHRAE Standard 90.1 Performance Based Compliance (Section 12 and Appendix G)

Performance Based Energy Codes

Commercial building energy codes typically include two types of approaches for demonstrating compliance; prescriptive and performance paths.

ASHRAE Standard 90.1 includes two performance path options: the Energy Cost Budget (ECB) method found in Section 12 and the Performance Rating Method (PRM), commonly referred to by its location in the Standard, Appendix G. These methods provide flexibility by allowing a designer to "trade off" by not meeting some prescriptive requirements if the impact can be offset by exceeding other prescriptive requirements. By using a performance path, owners and designers can optimize their design and construction to reduce the overall cost of construction. This is demonstrated using computer simulation to compare a proposed building design to a reference building design commonly referred to as a baseline.

The main differences between the ECB and PRM approaches in Standard 90.1 are the characteristics of the baseline building design.

ECB

The baseline is essentially a clone of the proposed design with most of the building components adjusted to “just meet” current prescriptive requirements.
A building is deemed in compliance with ECB when the annual energy cost of the proposed design is no greater than the annual energy cost of the baseline building design. This approach is referred to as a dependent baseline.

Appendix G

Appendix G uses an independent baseline where the characteristics of the baseline design are based on standard practice, meaning credit is available not only for exceeding prescriptive requirements in the code, but also for exceeding standard practice that is not regulated by the code. For example, in Appendix G credit is available for strategies not credited in ECB such as optimized window area and orientation, selection of more efficient HVAC and service water heating equipment type, right sizing HVAC equipment, efficient use of thermal mass, etc.
Appendix G uses a stable baseline approach with efficiency levels set at values that are not intended to be updated with each new addition of the code. Instead, the proposed building energy performance needs to exceed that of the baseline by an amount commensurate with the code year being evaluated.

Tools

The following suite of tools makes it simpler for architects, builders, designers, and contractors to demonstrate compliance to the code official using the performance path. The tools also simplify review for building officials, plan checkers, and inspectors by allowing them to more quickly determine if a building project meets the code.

Compliance Form — This spreadsheet-based form meets the documentation requirements of Standards 90.1-2016, 2019, and 2022 Energy Cost Budget Method and Performance Rating Method. It helps the modeler establish simulation inputs for the baseline/budget and proposed design models and includes a submittal checklist to ensure that all necessary supporting documentation is included in the submittal. It standardizes submittal documentations and simplifies submittal reviews by code officials and administrators of above code program implementers.

For questions about use or customization of the form please contact the Building Energy Codes Help Desk.

Compliance Form Companion Tool — This Companion Tool is designed to be used in conjunction with the DOE/PNNL ASHRAE Standard 90.1 Performance Based Compliance Form (i.e., Compliance Form). The process is that submitters first fill out the Compliance Form and import the data entered into the Compliance Form into this tool to perform additional/custom calculations. Code officials and Rating Authorities can select in-built calculations to be performed. Examples of in-built additional/custom calculations include but are not limited to determining performance in alternative metrics such as site energy or source energy and determining savings end use. Please see the "Instructions for AHJs and RAs" tab in the Companion Tool for a complete list. AHJs/RAs can add as many tabs as desired in order to perform additional calculations relevant to their program.

Review Manual — The ASHRAE 90.1 Energy Cost Budget and Performance Rating Method Submittal Review Manual (the Manual) is a comprehensive reference for reviewing modeling-based submittals. The Manual is a companion to the DOE/PNNL 90.1 ASHRAE Standard Performance Based Compliance Form and supports 2016, 2019, and 2022 editions of ANSI/ASHRAE Standard 90.1. The forms can be downloaded from this website.

The Review Manual includes the following:

The review checks to verify that the proposed design reported in the Compliance Form reflects design documents; that the configuration of the baseline/budget model is established correctly, that the baseline/budget and proposed design is modeled as reported, that the simulation is error-free, and that the compliance outcome is established correctly;
Checks to verify compliance with the mandatory requirements of 90.1 relevant to the simulation inputs;
Examples and common mistakes;
The methodology for prioritizing the review;
Simulation reports for common BEM tools annotated with tips on performing specific checks.

ASHRAE Standard 90.1 Adopter Toolkit Navigator provides recommendations for organizing effective and efficient submittal review of projects that follow ASHRAE 90.1 Section 12 and Appendix G, and includes links to the tools and resources available to jurisdictions and beyond-code programs including the following:

Recommended Minimum Energy Modeler Qualifications including work experience, professional credentials and completed trainings
Recommended Minimum Submittal Reviewer Qualifications including work experience, professional credentials and completed trainings
Third Party Submittal Reviewer Scope of Work is a template that may be used by jurisdictions and rating authorities who chose to engage external consultants for performing submittal review of projects documenting compliance with ASHRAE Standard 90.1 using Energy Cost Budget Method (Section 12) or Performance Rating Method (Appendix G). The template provides an overview of third party review process, suggested tasks and deliverables

Technical Support Document to Facilitate Adoption of ASHRAE Standard 90.1 Performance Rating Method (PRM). This report describes solutions to ensure the adoption of PRM includes the proper calculation of energy consumption, energy demand and energy cost savings when comparing a proposed design to the current code. The calculations described in this technical support document are automated in the ASHRAE Standard 90.1 Performance Based Compliance Form and the Compliance Form Companion Tool described above.

Performance-Based Code Compliance: A Roadmap to Establishing Quality Control and Quality Assurance Infrastructure. This report was completed as part of a research project to identify and present options to overcome implementation challenges associated with performance based paths in commercial energy codes. It provides short, medium and long-term recommendations for streamlining implementation and ensuring consistency in outcomes. It incorporates input from over 70 stakeholders representing jurisdictions, rating authorities, developers of relevant standards and organizations.

Performance Rating Method Reference Manuals (PRM RM) [2010, 2016 , 2019, and 2022]. These documents are intended to be a reference manual for the Appendix G PRM of Standard 90.1. The PRM can be used to demonstrate conformity with the standard and to rate the energy efficiency of commercial and high-rise residential buildings with designs that exceed the requirements of Standard 90.1. The procedures and processes described in this manual are designed to provide consistency and accuracy by filling in gaps and providing additional details needed by users of the PRM. PNNL has created PRM RMs for Standard 90.1 2010, 2016 , 2019, and 2022.

Training webinar recordings available! BECP hosted two webinars on forms for performance-based code compliance:

Performance-based Compliance Documentation for ASHRAE 90.1 Section 12 and Appendix G — September 29,2020. Learn more

Performance-based Compliance for Submittal Reviewers — December 8, 2020. Learn more

HVAC System Performance

Total System Performance Ratio (TSPR). TSPR is an approach for rating the efficiency of the entire HVAC system. Unlike a component based prescriptive approach, a system efficiency approach accounts for the interactions between the different components of a system. However, unlike whole-building performance it does not allow tradeoffs between different building systems (i.e., HVAC, lighting, envelope). TSPR evaluates the resources required for an HVAC system to fulfill the function for which it is intended—meeting building sensible and latent loads. TSPR in its most basic form, is calculated as the ratio of the sum of a building’s annual heating and cooling loads to the sum of the annual energy used for the whole HVAC system including heating, cooling, fans, pumps, heat rejection, and energy recovery.

As demonstrated by simplified energy modeling, the TSPR of a proposed building design must be greater than the TSPR of a baseline building design to comply. The baseline system configuration used to represent energy use can be customized to meet any desired level of performance. Washington State’s new energy code uses cycling air source heat pumps with a DOAS with heat recovery as the baseline system (WSEC 2018). The denominator representing energy use can be customized to meet any policy goal. Site energy use, source energy, energy cost, and CO2 emissions are all valid metrics. Washington State uses carbon emissions in the denominator to promote the states policy goal of zero carbon emissions from buildings. A tool has been created by PNNL to implement Washington State's new TSPR requirement.

The technical brief provides an additional heating, ventilation, and air conditioning (HVAC) System Performance (HSP) path that goes beyond the prescriptive energy code. It provides a comprehensive performance-based approach for HVAC system evaluation and analysis. The approach develops a Total System Performance Ratio (TSPR) to compare proposed, target, and reference HVAC systems.

The technical support documentation (TSD) provides background on development of mechanical system performance factors for use in the HSP for ASHRAE Standard 90.1-2022. It provides documentation of HVAC system input parameters and simplified HVAC measure modeling approaches.

Other TSPR Resources

Service Water Heating System Performance Approach

This technical brief provides an additional Service Water Heating (SWH) System Performance path that goes beyond the prescriptive energy code by outlining a comprehensive performance-based approach for SWH system evaluation and analysis.