MALTA, N.Y. — The Building Performance Institute Inc. (BPI) announced that 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 published as an American National Standards Institute (ANSI) standard.

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 will increase homeowners’ confidence in energy savings projected by simulation software used by home performance contractors for homes that undergo energy efficiency retrofits,” said Larry Zarker, CEO, BPI. “By using actual utility bills to measure pre-retrofit energy consumption, this approach sets realistic boundaries on savings predictions. This is truly a groundbreaking standard for the home performance industry.”

“As the first standard of its kind available to home performance contractors, BPI-2400 establishes a critical rule-set for validating the energy use and savings predictions produced by energy simulation tools,” said Courtney Moriarta, chair, BPI’s Standards Technical Committee. “This will enable contractors and program administrators alike to proceed with greater confidence that predicted savings estimates will be realized in actual post-improvement fuel use.”

For more information on BPI’s Delta Standard, visit

Publication date: 11/5/2012