Summary of the First Meeting of the 

Working Group on Low-Voltage Dry-Type Distribution Transformers 

of the Energy Efficiency and Renewable Energy Advisory Committee 

September 28, 2011 

Richard W. Parker, Facilitator 

Note: This meeting summary has been prepared for the convenience of the Working Group. It has 

not been approved by the Working Group and should not be construed or taken to represent the official 

position of the Working Group or any member as to what transpired at the meeting. 

 The Working Group on Low-Voltage Dry-Type Distribution Transformers (“LV Group”) held its first 

meeting on Sept. 28 in DOE Conference Room 8E-089. A list of attendees is attached as Annex A. 

Rules of Procedure and Meeting Schedule Agreed 

 After a brief discussion the Group adopted substantially the same rules of procedure as had been 

adopted by the Medium Voltage group on Sept. 16 (Annex B). The group also agreed on a timetable for 

future meetings set forth in Annex C. 

 The group then heard from Mr. Nardotti of Navigant Consulting concerning the updated preliminary 

results of the DOE Engineering Analysis of low-voltage dry-type transformers. He explained the 

analytical method used in crafting the Engineering Analysis, in terms that closely mirror the methods used 

in the Medium Voltage Engineering Analysis. That explanation was provided in greater detail in the 

Meeting Summary for the MV Working Group, Sept. 15-16 meeting, and is incorporated by reference 

here. 

Data Centers 

 One participant asked whether the engineering analysis took account of the unique design features 

and constraints facing manufacturers of transformers for data centers. Mr. Nardotti replied that no special 

allowance had been made for data center transformers in the engineering analysis thus far. The facilitator 

explained that setting a special standard for such transformers would require a showing that transformers 

for data centers are physically and/or operationally distinct from other transformers in the same 

equipment class, and that these differences can be specified with sufficient clarity and precision as to 

prevent circumvention. Other participants asked for more information on the volume of sales in this 

category. After further discussion, the Working Group agreed to form a sub-group led by Onyx Electric 

to develop recommendations concerning the feasibility of a separate energy-efficiency standard for data 

centers and, as appropriate, to make a proposal on what such a standard should be. 

Low-kVA Units 

 Another industry participant noted that his company had asked for a special standard for 15 kVA 

three-phase transformers, and for 750 and 1000 kvA transformers, because these very small (or relatively 

large) transformers at the extreme ends of the equipment class raise difficulties and costs not captured in 

the .75 scaling rule, which applies well enough to the middle range. Mr. Nardotti explained that it would 

be difficult at this stage to create a new representative unit for these outliers. Other participants noted that 

it might be feasible to create a special standard for these kVA ranges if technically justified. 

Temperature Rise 

 There was an extensive discussion arising from the observation that at higher efficiencies units would 

operate cooler than the temperature rise built into the design specification for those units, and that an 

appropriate corrective factor would need to be applied. An industry participant noted that this seemed like 
2

a test procedure issue rather than a standards issue. Mr. Parker asked if Mr. Patzner would explain this 

issue in short memo to the group. 

Symmetric Core

Mr. Nardotti reported that DOE had not been able to gather enough manufacturing data to model 

symmetric core designs. Such designs had not been formally screened out from any consideration, but 

due to lack of data they had not been modeled in the engineering analysis. Mr. Cymbalsky noted that 

symmetric core transformers are still covered products, and are still subject to efficiency standards that 

apply to their equipment class. 

Principles of standard setting 

In response to industry concerns that raising efficiency standards for a 35 percent load assumption 

might force consumers to choose designs that are less efficient at higher loads, a public interest advocate 

noted that it is intrinsic to setting nationwide standards that some customers do not benefit while other 

(presumably the large majority) do benefit. It is generally impossible, in practice, to find or set a standard 

that makes everyone better off. 

 An industry participant reinforced the need for higher standards in the low-voltage space by pointing 

out that such transformers are unique in that their purchaser typically bears the cost of the transformer, but 

is not the user of the product and therefore gets none of the energy-saving benefits [which accrue to users 

of the building/facility]. 

 

 Industry concerns with DOE analysis 

One industry noted that he had done a comparison of his own engineering analysis with the DOE 

analysis for both medium-voltage dry type and low-voltage (DL 8) and had found “fairly broad” (on the 

order of 60 to 70 percent) and unexplained discrepancies in both cases. He thought the analysis was 

pretty well thought out, but that there might be some discrepancies in assumptions made about such 

things as markups. Another observer likewise noted certain discrepancies between his results and DOE’s 

and opined that the difference might be explained by the “destruction factor.” Mr. Parker suggested that 

interested industry participants form a working group to work with Navigant on reconciling their analysis 

with DOE’s, with the caveat that the focus should be on identifying any major discrepancies that might 

significantly bias the final results. An industry participant noted that because much of the data is 

proprietary, industry participants would be more inclined to share that information with DOE than with 

each other. So it was agreed that the sub-group would establish their own internal procedures for sharing 

information and protecting confidentiality while attempting to reconcile the DOE price-efficiency 

analysis with their own company-specific analysis. 

Lunch Break

 

 After lunch, Mr. Gordon of the DOE General Counsel’s office gave a presentation on the 

responsibilities of the group under the Federal Advisory Committee Act. 

 There was extensive discussion about how to deal with the fact that a number of smaller 

manufacturers of low-voltage transformers may not have had time or staff to participate in the negotiating 

group though their interests are significantly affected. Mr. Caskey of NEMA offered to poll his members 

so as to ascertain whether there was interest among his members in either presenting to the Working 

Group or providing independent feedback on DOE analysis for the group’s consideration. 

 Ms. Coughlin of LBNL led the participants through the methodology underlying the Life-Cycle Cost 

(LCC) and National Impacts Analysis (NIA). With certain differences noted below, the methodology for 

Low Voltage transformer LCC/NIA analysis is substantially the same as with Medium-Voltage Dry Type 
3

Transformers and is summarized in the meeting summary for the Sept. 15-16 meeting of the MV Group. 

The same is true of Mr. Gordon’s presentation. Both these explanations are incorporated by reference 

herein. 

 

Evaluation Rates 

 One factor unique to LV transformers, as noted by Ms. Coughlin, is that very few LV purchasers 

evaluate losses or customize design. Nearly all purchase transformers “off the shelf” on the basis of 

lowest first cost and/or some other design parameter such as noise, heat or space. 

Load Factors 

 Ms Coughlin reported that the assumed load factor is determined by calculating the average load 

factor associated with the range of buildings and building types in which LV transformers will be 

installed. Ms Coughlin emphasized that the calculated average load factor is not necessarily the load 

factor specified in the test procedure. The test procedure load is 35%, whereas the average observed 

RMS load in the field is about 22 percent. One industry participant cited a study by the Cadmus Group 

which reported that the average loading of LV transformers in commercial buildings is about 16.6 percent 

and that his own company’s data suggested a loading factor closer to 12 percent, that most transformers 

for commercial buildings are over-sized due to fire codes, and that the load factors are likely to further 

decline over time as lights, appliances and electronic equipment become more energy efficient. 

 Another industry observer pointed out that building codes require over-sized transformers because 

they are based on square footage, number of outlets, and assumptions about power use per outlet that are 

very conservative because they are designed to reduce risk of fires. Yet appliances, lights, etc. are getting 

steadily more efficient. So median load factors are unlikely to increase in the low-voltage market. On the 

other hand, as a government participant observed, more people are using computers, which tends to 

increase energy use. In any case, the DOE policy is to rely on EIA or AEO data for forecasts about 

electricity demand and load growth. 

Material Prices 

 Ms. Coughlin also explained that material prices are drawn from 2006, 2008 and 2010 data, with 

2010 being the base case, and 2006 and 2008 providing the lower and upper bound, respectively. OPS 

calculates an optimal set of designs at each efficiency level for a wide range of A and B factors, and that 

due to the complexity of the optimization algorithm, there is a “limit as to how much we can do to 

investigate the sensitivity of this part of the analysis to changes in materials prices.” 

Key Result: Flat Curves 

 Ms. Coughlin observed that one key conclusion from the Engineering and LCC Analysis is that the 

price-efficiency curve appears fairly flat through about CSL 4, meaning that significant gains in 

efficiency appear achievable with small increases to first cost of low-voltage transformers. 

 An industry participant observed that his company is making and selling transformers at substantially 

higher prices than reflected in the southeast boundary of the price-efficiency scatterplots, even though 

most purchasers are assumed not to evaluate on the basis of A and B factors. One industry observer 

opined that the likely reason was that building owners are buying higher-cost units for other nonefficiency attributes, such as lowering air conditioning costs by reducing heat, or because the unit is 

serving an LEED building, or the buyer (such as a K-12 school) is voluntarily buying to a higher 

standard. 

LCC Analysis 

 Ms. Coughlin noted that although the engineering charts often display a range of prices for units sold 

at any given efficiency level, the DOE Life-Cycle Cost (LCC) model would select only the most efficient 
4

units (units on the lower boundary of the price-efficiency curve at each EL) for purposes of calculating 

Life Cycle Cost and National Impact Analysis. 

 She then reviewed the method for deriving National Energy Savings and Net Present Value. 

 

Sensitivity Analysis (done by participants) 

Some participants expressed an interest in being able to do their own analysis using the DOE models. 

Ms. Coughlin replied that they could do this by downloading the spreadsheets from the DOE website, 

inputting the relevant assumptions, and running the “Crystal Ball” Monte Carlo analysis, which they 

could purchase from Crystal Ball (or use on trial for two weeks without charge). However, an advocate 

responded that in his experience Crystal Ball is not something they can run, so the Working Group might 

have to come up with some scenarios that they would ask the consultants to run. 

 Ms Coughlin offered to circulate a list of sensitivities that are done as part of the standard analysis, 

but noted that they are also listed in Chapter 8 of the TSD. 

The Problem of Low kVA units 

One industry participant noted that for covered products at the low kVA end of DL 7 (15, 30, 45 

kVA), manufacturers have a technical option of building either ventilated transformers (covered) or 

sealed transformers (statutorily exempt). If the standard for ventilated transformers in these kVA ranges 

is made too high, the market may simply shift to sealed transformers. Another industry participant noted 

that the statutory term “sealed transformers” referred to sealed gas-filled transformers, not encapsulated 

transformers (see Sec. 35(b) in EPACT 2005). The facilitator suggested that the industry participants 

work with DOE counsel to investigate that issue and report back to the working group. 

The perverse consequence of current test procedures 

 Ms. Coughlin noted that actual loadings are typically much lower than test procedure loading, which 

means that transformers designed to meet the test procedure will be geared to significantly reducing load 

losses, which will mean higher no-load losses than is optimal for the actual loading profile on that 

transformer, and less efficiency in the field than would be the case if test procedures more accurately 

reflected actual load conditions. 

Trial Standard Levels (TSLs) 

After some discussion, the Working Group agreed on the following TSLs: (1) max tech, (2) 

maximum net present value (which is usually associated with minimum life cycle cost; (3) maximum 

energy savings with a non-negative LCC. There was general conceptual agreement that an interesting 

point of inflection might be the most efficient unit which preserves a capability to meet the standard using 

more than one type of core steel, and perhaps a separate TSL set at the level that preserves significant 

competition among steel suppliers in the market. Defining these points proved difficult, in practice, 

however. 

 Participants concluded that it would not be advisable on anti-trust grounds for steel suppliers and 

transformer manufacturers to talk among themselves about where such TSLs might be established, but 

that suppliers might work separately with Navigant to inform that decision.1

 There was discussion of 

possibly examining how weight would increase with efficiency at different ELs with the idea of deriving 

 

1 This notwithstanding that the facilitator reported the results of his conversation with an official in the Anti-trust 

Division of the Department of Justice, which clarified that the Justice Department does not have an objection with 

private parties discussing efficiency levels and likely impacts of such levels on prices if the purpose is to avoid anticompetitive outcomes from standard-setting. 
5

a TSL from that, but the analysts concluded that this would not be practical. An industry participant 

proposed a TSL set at the level of minimum, but non-zero, job impact. However, a DOE representative 

noted that job impacts are calculated in DOE analyses, but are not normally used to define TSLs. There 

was agreement on allowing DOE staff to define “gap-filling” TSLs to ensure analysis of points along the 

spectrum of ELs where there are no previously-defined TSLs. 

The meeting concluded with agreement in principle on the following TSLs, understanding that further 

consultations would be required to clarify the 4th and 5th TSLs. 

 Max Tech, (Complete) 

 Max Net Present Value, (Complete) 

 Maximum Energy Savings With Positive Life Cycle Cost, Baseline (No Standard Standard), 

(Complete) 

 Highest Energy Savings With Multiple Core Material Suppliers, 

 Highest Energy Savings With Multiple Competitive Core Material Suppliers, 

 Some Aspect Of Annual Electricity Bill Savings (E.g., 30% Or 50%) 

 Gap Fill As Necessary. 

Conclusion 

 

Participants concluded by agreeing to work with DOE consultants in validating the data, refining the 

analysis, and proposing the diversity of supply and competitiveness inflection points for the various 

Design Lines. The meeting adjourned at 4:44 pm.