The update, “Informative Annex E: Alternative Asset‐Based Savings Calculation with Insufficient Energy Use Data” (BPI-2400 Annex E for short) is available for public comment until Tuesday, Jan. 16.

The Delta Standard specifies the requirements and process for the calculation of standardized predicted savings using approved building energy-simulation software.

This standard specifies a process to calibrate the model to the actual energy use of the home, using an approved building energy-simulation software tool and actual energy bills. It provides a set of criteria for use in the final calculation of standardized estimated savings that may be considered in compliance with this standard.

The Delta Standard is referenced in the Home Owner Managing Energy Savings (HOMES) energy efficiency rebate program, part of the Inflation Reduction Act (IRA). BPI has updated the standard to provide more flexibility to contractors while maintaining consistent and conservative savings estimations.

Like all BPI standards, the Delta Standard was developed by a working group of subject-matter experts who represent a wide variety of interest categories and geographic locations. BPI’s Data and Modeling Standards Technical Committee (DM-STC) convened a new working group to create this latest update.

BPI-2400 Annex E was approved by the DM-STC for public review and is currently undergoing a public comment period as defined under BPI’s standards development process. Comments on BPI-2400 Annex E are being solicited from stakeholders and the general public. The full Delta Standard will undergo review and revision by the DM-STC in 2024.

To view the standard, visit: Standards Under Review. Comments may be submitted to standards@bpi.org by January 16.