Project Report

Prepared for California Statewide Persistence Subcommittee, CADMAC
Report dated: April 1, 1996
Prepared by Proctor Engineering Group
Contributor: M. Blasnik, J. Proctor, Z. Katsnelson

Executive Summary

The first stage involved performing an exhaustive search for existing information from published and unpublished sources and synthesizing this information into an engineering analysis of technical degradation rates. The second stage of the project involved developing research plans for assessing relative technical degradation for those measures where substantial uncertainty was found in stage one. This report provides the findings from both stages of the project.

Prior interim technical memos summarizing the work in each stage of the project were reviewed by the CADMAC subcommittee and this final report incorporates much of the feedback from project review meetings as well as formal comments submitted by some of the concerned parties.

Stage 1 - Degradation Analysis Findings

As expected, existing data on performance changes over time were very limited. However, PEG was able to utilize the information that was available to develop a systematic engineering analysis of technical degradation for each measure. The goal of the engineering analysis was to identify, understand, and quantify the underlying mechanisms of technical degradation for each measure. PEG utilized this approach to estimate degradation rates and/or identify key uncertainties for each of the measures. The results of this analysis are summarized in Table 1.

The engineering analysis found that relative degradation is very unlikely for ten of the thirteen measures. Indeed, some measures (residential air conditioners and refrigerators) are likely to degrade less than their standard efficiency counterparts, resulting in increasing savings over time, or "negative" degradation. In one case, HID lighting, a small and quantifiable degradation was found. In three cases (occupancy sensors, optical reflectors, and adjustable speed drives), the potential degradation mechanisms were considered related to measure retention and further investigation would be best performed via retention studies. In two cases (commercial package air conditioners and oversized evaporative cooled condensers), the first stage analysis found that potentially significant relative technical degradation could occur and therefore research plans were developed to collect additional information.

While few measures were found to suffer from relative degradation, many measures are likely to experience absolute degradation (i.e. decreases in efficiency over time). In particular: air conditioners, refrigerators, fryers, and insulation may all suffer from absolute technical degradation. However, this degradation tends to lead to stable or increasing savings over time relative to the standard measure.

Stage 2 - Research Plans

The air conditioner plan involves two stages. In the first stage, laboratory testing will be used to simulate a variety of heat exchanger fouling scenarios and measure performance impacts. This testing may find that no relative degradation will occur, and the research will be complete. If the testing indicates that a small amount of relative degradation may occur, then the involved parties may be able to agree to default estimates of degradation factors, avoiding more costly research.

If the testing indicates that large relative degradation may occur, then a model which relates measurable fouling parameters to system efficiency will be developed and field testing will be used to collect data needed to quantify the relative degradation rate.

The evaporative cooled condenser plan involves a relatively large number of brief site visits to characterize the population and typical field conditions (including a visual assessment of fouling/scaling) with more intensive site testing and modeling of a selected sub-sample of these sites. A combination of test data, population characteristics, and engineering simulations will be used to quantify relative degradation. Installation, Operation, Maintenance and Retention Issues

The performance and useful life of most efficient and baseline measures depends upon installation, operation, and maintenance (O&M) practices. The influences of these factors were included within this study to the extent that they were found to affect relative changes in measure performance over time. The scope of this study involved examining how performance may change over time after a measure is installed. Therefore, installation problems are only accounted for to the extent that they may lead to continuing performance changes over time. The immediate impacts of any initial installation defects are assumed to be accounted for in first year impact studies.

In most cases, the efficient and baseline measures are very similar and no relative degradation from installation or O&M practices should occur if they receive comparable attention. In some cases, the efficient measure is believed to be more tolerant of poor practices. In the case of reflectors, maintenance issues may affect light output, but not energy savings. For occupancy detectors, dust build-up may lead to occupants changing control settings or over-riding the system. For adjustable speed drives, operators may over-ride the system or adjust settings which compromise savings. For each of these three measures, the CADMAC subcommittee determined that these issues should be addressed through retention studies. For the two measures which need additional research, maintenance practices were identified as a key factor in degradation and are incorporated within the research plan.

Conclusions and Next Steps

The project results are quite encouraging. The analytical approach developed and employed in this study has proven to be quite successful in providing strong conclusions concerning relative technical degradation rates, even though empirical data were limited. Because of this success, the CADMAC subcommittee requested that PEG review lists of additional measures in order to assess the likely time and effort needed to perform a similar analysis on some of the major remaining measures.

Many opportunities were found for leveraging the results of this project to help assess degradation rates. For example, some of the measures which would benefit from this study include other HID lighting applications, residential freezers, many other commercial gas cooking appliances, and insulation measures in all sectors. In addition, the current findings could be used to assess future year design variations in the measures covered.

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