This ESTCP project was a joint effort between energy simulation and energy auditing experts at the National Renewable Energy Laboratory (NREL) and software developers from commercialization partner concept3D. This team integrated NREL’s formal auditing methodology with existing concept3D software technologies to create a single, tablet-based tool called simuwatt™ Energy Auditor, which concept3D now offers as a commercial product. The goal of this project was to demonstrate that simuwatt™ could enable an energy auditor to perform American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) level II audits and achieve a 35% cost reduction compared to audits typically procured by the U.S. Department of Defense (DoD) without sacrificing audit quality. The Energy Independence and Security Act (EISA) of 2007 requires DoD to audit 25% of the 1.9 billion square feet (ft2) of covered facilities each year. A simuwatt™ Energy Auditor has the potential to significantly reduce the cost of these audits.

Technology Description

The software integration goal of this project was achieved. Connections between simuwatt™ Energy Auditor and the Building Component Library (BCL) were successful, allowing access to high-quality, standardized energy modeling components. The EnergyPlus simulation engine was used to transfer data collected during the simuwatt™ audit to OpenStudio for detailed energy analysis. Standardized energy efficiency measures from the BCL were used to perform life cycle calculations. Data from this process were presented in an automatically generated, standardized report.

The demonstration occurred in two phases. During the first phase, NREL auditing experts performed energy audits using simuwatt™ at 11 DoD buildings across four sites. NREL auditors recorded the time required to perform a range of audit tasks, estimated audit costs by applying reasonable energy auditor rates to those times, and compared the results to the cost of audits previously procured by DoD. This phase tested simuwatt™’s flexibility to be used across a range of sites and provided data on the cost and quality of simuwatt™ audit reports. The second phase provided a direct head-to-head comparison of the simuwatt™ audit approach with a traditional audit process. In this phase, two teams of auditors with similar qualifications from the same third-party auditing firm audited the same two buildings at Naval Support Activity Monterey. One team used simuwatt™ and the other team used a standard audit process. Neither team was aware of the other’s activities. In both phases, the audits were scored on cost of the audit; the quality and usefulness of the audit report from the perspective of a DoD facility/energy manager; and the comprehensiveness and completeness of the audit report from the perspective of an unbiased energy auditing expert.

Demonstration Results

Phase 1 demonstrations achieved an average cost savings of 53% compared to past DoD audits, exceeding the project’s cost reduction goal of 35%; however, the DoD reviewers gave the reports an average score of 49.9/80 and the third-party energy auditing expert gave the reports an average score of 40.5/80. Review comments by DoD and third-party reviewers indicated that the Phase 1 reports were not as comprehensive as desired, specifically with regard to documenting underlying analysis assumptions. Because the simuwatt™ audit report generation is semi-automated, its content might be improved based on data already collected by simuwatt™. However, there was little time between Phase 1 and Phase 2, and the team was unable to address these issues before Phase 2 started.

In Phase 2, the third-party auditing team used simuwatt™ to successfully complete audits of two buildings and achieved a time savings of 28% compared to the traditional auditing team. This time savings is slightly less than the 35% time savings goal. However, this was the third-party auditor team’s first time using the simuwatt™ Energy Auditor. The team members reported that they believe that their audit, analysis, and reporting times would improve with subsequent use of the tool. The DoD reviewers gave the reports produced by both the simuwatt™ and the traditional auditing teams identical scores of 71/80 in terms of quality and usefulness, which was an improvement from the average score of 49.9/80 given during Phase 1. However, the third-party energy auditing expert gave the Phase 2 reports an average score of 45/80 in terms of completeness and comprehensiveness, similar to the average score of 40.5/80 in Phase 1. As in Phase 1, these scores are expected to increase as improvements are made to the simuwatt™ audit report generation.

Overall, the Phase I and Phase II demonstrations showed that simuwatt™ reduces the time to complete an audit for DoD. The time savings for a first-time user were 28% in the Phase 2 head-to-head test and 53% for experienced auditors with previous simuwatt™ experience in Phase 1. However, the performance goals for report quality were not met during this demonstration. During a reviewer debriefing, the development team explained how calculations are performed and what assumptions are used, improving the reviewers’ opinions of the analysis results; however, this information was not clearly communicated in the reports. Improvements to quality as well as clarification of calculation methods and assumptions in the generated report are anticipated in future versions of simuwatt™.

Implementation Issues

Based on the demonstration results and the expectation that report quality issues are addressed by future software releases, simuwatt™ Energy Auditor shows potential for significant energy audit cost savings. If simuwatt™ is used to audit all DoD buildings over a 4-year period, the estimated DoD-wide savings is approximately $171 million, or an average of $43 million annually. This savings level is substantially larger than the estimated software cost of approximately $1 million annually and indicates that DoD could recognize significant energy audit savings through the use of simuwatt™.

Although the first-time audit cost and the audit report quality were the main focuses of this demonstration, simuwatt™ would provide additional benefits, including:

  • The data collection process is standardized and DoD owns and controls the resulting data. This means that future energy audits, such as those performed every 4 years to comply with the EISA 2007 mandate, would have a significant head start in collecting data. The recurring audits would be updates rather than entirely new investigations. Reusing previous simuwatt™ audit data would reduce the amount of time needed to complete a future audit by an estimated 50%. A 25-year estimate of DoD-wide auditing costs shows that the life cycle cost savings have a net present value of approximately $1.3 billion. This estimate does not include further savings associated with reduced audit review costs resulting from the standardized report format and calculation methods.
  • DoD can compare a portfolio of buildings to find opportunities and economies of scale that may currently go unnoticed.
  • The data can be leveraged for other uses. For example, energy auditors commonly record detailed inventories of equipment, space usage, and building condition. This information could be tied to facility maintenance systems and used to develop operations and maintenance plans.
  • The building energy models could be used to support automated fault detection and diagnostics as well as used to support model-based control strategies.