MALTA, N.Y. — The Building Performance Institute Inc. (BPI) has announced that ANSI/BPI-2400-S-2012: Standard Practice for the Standardized Qualification of Whole-House Energy Savings Predictions by Calibration to Energy Use History, also known as the "Delta Standard," has been updated and the revised portions of the standard are now available for public comment through June 7, 2015.

The Delta Standard specifies a process for the calculation of standardized predicted savings: the difference (delta) between the modeled energy usage before and after an upgrade using approved building energy use simulation software. The process uses actual home energy bills to predict savings, and provides a set of standardized operating conditions to be used in the final calculation of predicted savings. The standard applies to existing detached single-family dwellings and townhouses that meet the specific criteria detailed in the scope.

The Delta Standard was developed by a working group created by BPI’s Standards Technical Committee (STC) and comprised of subject matter experts representing a variety of interest categories and geographical locations. Recent revisions to the standard provide incremental improvements in clarity and utility.

ANSI/BPI-2400-S-2012 is currently undergoing a round of American National Standards Institute (ANSI) review, which includes a public comment period as defined under BPI’s standards development process. Comments on the revised portions of the standard are being solicited from stakeholders and the general public.

To view the standard, visit

Comments may be submitted to

Publication date: 5/18/2015

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