Saratoga Springs, NY: The Building Performance Institute, Inc. (BPI) is inviting public input on a revised draft of BPI 2100, Home Performance Related Data Transfer (HPXML Transfer Standard). Following review of comments received during the initial public comment period, BPI's Data and Modeling Standards Technical Committee (DM-STC) has approved the release of an updated draft of Version 5.0 for a second 45-day public comment period. 

HPXML is a data transfer protocol that enables the exchange of information between software systems using an open, technology-neutral solution developed through BPI's ANSI-accredited standards development process. The standard is maintained through a consensus-based approach that emphasizes openness, transparency, and stakeholder participation. 

The HPXML Transfer Standard was developed by BPI's HPXML Working Group, which reports to the DM-STC. The standard helps improve data collection efficiency, reduce costs, and facilitate the transfer of residential energy efficiency data across a broad range of programs and industries. 

Following review of comments received during the first public comment period, several updates were approved for inclusion in HPXML Version 5.0. Because these revisions include substantive changes, the draft is being released for a second public review in accordance with BPI's ANSI-accredited standards development procedures. 

The updated Version 5.0 draft includes the following changes: 

• Add CoolRoof element and ”white” color choice to support additional roof and wall characteristic data. Clarify the definition of the CoolRoof element to reflect that cool roof designations are determined by local programs and requirements. 
• ​Add WaterFixture/Location element to improve the representation of water fixture placement. 
• Correct WaterHeatingSystem/HPWHOperatingMode data restriction by changing it from a pattern to an enumeration, improving data validation consistency. 
• Require Units for all UnitAndValue pairs to ensure values are always accompanied by their associated units.* 

*This change is considered technically breaking because files containing values without associated units will no longer validate. However, the work group determined that values without units are not meaningful and such files were already effectively invalid. 

Many programs currently utilize HPXML, including: 

• Arizona Public Service 
• Austin Energy 
• Efficiency Vermont 
• NYSERDA 
• Pacific Gas & Electric 
• Pearl Certification 
• PSEG Long Island 
• Salt River Project 
• San Diego Gas & Electric 
• SoCalGas 
• Southern California Edison 
• United Illuminating 

The HPXML Data Transfer Standard, also referred to as a schema, follows the Semantic Versioning 2.0 specification. Version numbers follow a Major.Minor.Patch format (e.g., 2.3.0). 

Version 5.0 represents a major update to the HPXML standard and incorporates both new functionality and schema improvements developed through stakeholder input and public review. 

A complete list of changes to the HPXML standard can be found in the HPXML Version 5.0 Release Candidate 2 documentation and associated GitHub repository. 

HPXML Version 5.0 draft: https://github.com/hpxmlwg/hpxml/releases/tag/v5.0-rc2 

To submit comments on HPXML, please download the BPI Standards Comment Form.   

Completed forms must be submitted to standards@bpi.org by July 30, 2026 in order for comments to be considered by the DM-STC.