Project Report

Negative Technical Degradation Factors Supplement to Persistence Studies

Prepared for: CADMAC Persistence Subcommittee
Prepared by Proctor Engineering Group
Contributors: John Proctor and G. Peterson

Executive Summary & Introduction

The Statewide Measure Performance Studies (Persistence 1 -- PEG 1996 & Persistence 2 -- PEG 1998) were sponsored by the California DSM Measurement Advisory Committee (CADMAC), Persistence Subcommittee to examine the relative technical degradation of demand side management (DSM) measures compared to standard efficiency equipment. In the original studies, existing information was synthesized into an engineering analysis of technical degradation factors (TDFs). The TDFs are yearly multipliers.

By applying these multipliers to first year savings, the savings in subsequent years are estimated. Specifically, the TDF is defined as: "A scalar to account for time and use related change in the energy savings of a high efficiency measure or practice relative to a standard efficiency measure or practice." (CADMAC 12/17/97) By CADMAC directive, negative degradation rates (TDF>1.0) were set equal to one (1.00) in the original studies.

In this supplemental report, the four negative TDFs from the first two studies are estimated. The four technologies covered and references to the original report are given in Table ES-1.

Table ES-1 Measures with Negative TDF Estimates
Efficiency Measure	Original Report	Section #
Air Conditioners D/X - Residential	Persistence 1	2.1
Residential Refrigerators	Persistence 1	2.3
Process adjustable speed drives -- waste water pumps	Persistence 2	2.3
Agricultural Pumps	Persistence 2	2.7

Air Conditioners D/X - Residential. Residential direct expansion air conditioners have larger coil face areas. These were determined to foul at the same rate as conventional equipment. The same level of air-side fouling results in less efficiency degradation for the efficient unit. A TDF was calculated based on the analysis presented in Persistence 1.

Residential Refrigerators . PEG determined that compressor and fan motor efficiency improvements were the main approaches to higher refrigerator efficiency. These strategies were deemed to result in no absolute technical degradation. Negative relative degradation was found because of cabinet insulation degradation. A TDF was calculated based on the analysis presented in Persistence 1.

Process adjustable speed drives -- waste water pumps. A TDF of one is estimated for this measure based on adjustable speed drives with pumps of diversified time in service ages.

Agricultural Pumps . The baseline and efficient measures are the same pump. The abrasive qualities of well water significantly degrade the efficiency of agricultural pumps over time. In the Persistence 2 report, PEG analyzed a pump test dataset to derive a time in service versus efficiency curve. A TDF was calculated based on this analysis.

TDF Summary Table

Technical degradation factors (TDFs) were estimated for each measure. These estimates are displayed in Table ES-2.

Table ES-2 Summary of TDFs
YEAR	Resid DX AC	Resid Refrig	ASD Process Pumping	Ag Pumps
1*	1.00	1.00	1.00	1.00
2	1.00	1.04	1.00	1.00
3	1.01	1.06	1.00	1.00
4	1.01	1.07	1.00	1.00
5	1.02	1.08	1.00	1.00
6	1.02	1.08	1.00	1.01
7	1.03	1.09	1.00	1.01
8	1.03	1.09	1.00	1.01
9	1.04	1.09	1.00	1.01
10	1.04	1.09	1.00	1.01
11	1.05	1.10	1.00	1.01
12	1.05	1.10	1.00	1.01
13	1.06	1.10	1.00	1.01
14	1.07	1.10	1.00	1.02
15	1.07	1.10	1.00	1.02
16	1.08	1.10	1.00	1.02
17	1.09	1.10	1.00	1.02
18	1.09	1.10	1.00	1.02
19	1.10	1.10	1.00	1.02
20	1.10	1.10	1.00	1.02

* First year savings are one (1.00) by definition. The TDF modifies the first year savings for subsequent years.

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