Guidelines for Verifying Savings from Commissioning Existing Buildings

The purpose of these guidelines is to provide standardized methods that may be used within existing building commissioning (EBCx) projects to calculate and verify energy savings. It also provides a framework for EBCx service providers to select a method based on a project’s goals, resources, and constraints. This guideline defines the technical requirements and analysis procedures for each method, defines common terminology, identifies useful tools, and provides examples. It addresses common savings risks and describes the methods’ relationships to formal measurement & verification (M&V) protocols such as IPMVP and ASHRAE Guideline 14.

The verification methods are designed to be integrated with and augment the EBCx process and therefore minimize additional costs. This guideline establishes standardized verification methodologies, terminology, and procedures in order to address project objectives such as:

  • Clarifying savings verification concepts and procedures, eliminating confusion concerning verified versus calculated savings
  • Establishing common and flexible methodologies appropriate to verify EBCx savings given the project’s specific resources and constraints
  • Increasing confidence in each EBCx project’s reported savings.
  • Reducing costs of reviewing EBCx calculations, data, and results, which vary in quality and rigor from project to project, thereby improving the cost effectiveness of both individual projects and energy efficiency programs
  • Helping new entrants into the field of EBCx
  • Providing a means for owners and program managers to verify and quantify the persistence of savings

Verification Methods Covered

The Guidelines cover four key methods for verifying savings (listed below), providing practical guidance for their application. Additionally there is guidance around how to select the appropriate method for a given project, how each method aligns with formal IPMVP and ASHRAE M&V guidelines, and general information on how M&V fits into the EBCx process.

Method 1: Engineering Calculations with Field Verification describes how engineering calculations used to estimate savings prior to implementation are subsequently used to verify actual savings. It also describes how post-installation measurements used are used to improve the savings estimates.

Method 2: System or Equipment Energy Measurement characterizes the system or equipment energy use by its load and schedule components so that each component is measured separately. The primary impact of the EBCx measures on each component is used to determine post-installation measurements.

Method 3: Energy Models Using Interval Data describes a verification method in which empirical models of baseline energy use and key independent variables are used to verify savings. It can be used to verify total savings in a whole building or in building subsystems.

Method 4: Calibrated Simulation describes the use of whole-building simulation software to develop and calibrate a building model that correctly reproduces the baseline energy use of a building and its subsystems.


Development of The Guidelines for Verifying Savings from Commissioning Existing Buildings was primarily funded through the California Energy Commission’s Public Interest Energy Research (PIER) program, with additional funding from the California Commissioning Collaborative. Content was developed by Quantum Energy Services & Technology, PECI, and Architectural Energy Corporation, and was reviewed by an industry Technical Advisory Group (TAG).