American Council for an Energy-Efficient Economy

Appliance Standards Awareness Project

Natural Resources Defense Council

October 18, 2013

Ms. Brenda Edwards

U.S. Department of Energy

Building Technologies Office, Mailstop EE-2J

1000 Independence Ave SW

Washington DC 20585-0121

RE: Docket Number EERE-2013-BT-STD-0030/RIN 1904-AD01: Framework Document for 

Commercial Packaged Boilers

Dear Ms. Edwards:

This letter comprises the comments of the American Council for an Energy-Efficient Economy (ACEEE), 

Appliance Standards Awareness Project (ASAP), and Natural Resources Defense Council (NRDC) on the 

framework document for commercial packaged boilers. 78 Fed. Reg. 54197 (September 3, 2013). We 

thank DOE for the opportunity to participate in and contribute to the development of amended 

standards for commercial packaged boilers.

Below we first describe what we believe to be the most important issue at this stage of the 

rulemaking—the test procedure and efficiency metric—and then provide our responses to selected 

items for which DOE has requested comments.

Test Procedure and Efficiency Metric

As discussed in more detail below, we find it imperative that DOE adopt a better metric than the single 

steady-state, peak-load efficiency prescribed by BTS-2000. As outlined in our responses to Items 3.1, 

3.3, and 3.4, this metric massively understates the efficiency difference between condensing and noncondensing boilers in well-designed systems. In turn, this difference makes it hard for designers to show 

savings for clients that would justify the incremental costs of condensing systems. Perhaps as important, 

it has made it very difficult for utilities and other efficiency program operators to design and show the 

value of incentive programs for condensing systems, despite the fact that these systems would very 

likely achieve cost-effective energy savings in the field. 

Items on Which DOE Seeks Comments:

2-2 Extending Coverage to Electric Commercial Packaged Boilers

On the one hand, from a source energy standpoint, all electric resistance boilers are inefficient. At the 

same time, from a site energy standpoint, consider a 90% efficient, 300 kW electric boiler (1 million 

Btu/hr). Unless it was located outdoors, at full load the boiler would create a sizeable nuisance by 
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dissipating 100,000 Btu/hr inside a boiler room—enough heat to satisfy the load of a pretty large house 

on a pretty cold day. Under the circumstances, and given the cost of electricity, manufacturers have 

some incentive to do a reasonable job of minimizing losses by insulating fairly well. DOE might want to 

consider regulating electric boilers like certain large commercial water heaters: by simply requiring that 

the jacket insulation meet a high performance level. This may be appropriate to the extent that electric 

boilers are simple vessels and do not share the fire tube, water tube, or other specialized heat transfer 

approaches generally used in fossil-fuel boilers.

2-3 Standby and Off Mode

Standby and off mode power can consume a significant amount of energy, although this energy use will 

generally be a very small fraction of the total energy use of a commercial boiler. As DOE explores 

potential standards for standby and off mode, it will be important to consider how boilers are 

controlled, including safety devices and connections to building automation systems. It will also be 

important to understand how “boiler trains” (multiple, staged sets of boilers connected to the same 

heat distribution system) are controlled, and to determine whether potential standards for standby and 

off mode could inhibit innovations that would save much more gas or oil than the amount of electricity 

saved. 

3-1 Test Procedures

The current test procedure, which is based on BTS-2000, is simply obsolete, since it obscures the huge 

annual energy savings potential of condensing boilers in commercial building applications. For historical 

reasons, BTS-2000 measures efficiency at peak load, using a minimum 100oF temperature rise between 

the boiler inlet and outlet, and requiring 180oF outlet temperature. BTS-2000 is a steady-state test that 

shows roughly a 10 point difference in efficiency between the best non-condensing equipment and very 

good condensing equipment, because it does not consider that the condensing unit can operate at much 

greater efficiency at part load, if the system design allows water to return to the boiler at condensing 

temperatures (<140oF) when loads allow. Durkin showed that replacement of non-condensing 

commercial packaged boilers with well-regulated condensing boiler systems in 10 schools in the 

Midwest saved an average of 49%, with a 3.5 year payback at $1.00/therm.1

Because BTS-2000 hides the efficiency savings potential of condensing systems, utility incentive 

programs and consulting engineers run into huge problems trying to justify the first cost of condensing 

boiler systems. At a minimum, for all boilers with modulating burners (including high/low fire), the 

rating method must incorporate some part-load efficiency measure. We suggest that an appropriate 

measure might be steady-state at the lowest return water temperature the boiler can sustain under its 

warranty, perhaps with some reasonable lower limit on temperature and upper limit on capacity 

(perhaps 2.5 – 5.0 MMBtu/hr).

3-3 Fair Comparisons of Efficiency Across Boiler Models

As described above (Item 3-1), BTS-2000 is misleading if it is used to estimate the potential energy 

savings of condensing boilers relative to non-condensing boilers. It is functionally obsolete and should 

not continue to be used, unless a measure of part-load efficiency is incorporated.

 

1 Durkin, T.H. 2006. Boiler System Efficiency. ASHRAE Journal, July, pp. 51-57. 
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3-4 Alternative Test Methods

We have great respect for the efforts made to develop an alternative rating method in ASHRAE SSPC 

155. However, a case has been made that for the relatively small volumes of some product classes that 

are sold in the market, the testing burden is greater than the potential benefits. We believe that 

incorporating an appropriate part-load test for modulating and condensing boilers can and must be 

done now. For the future, the work on AEDMs done by the ASRAC working group should empower 

industry to both reduce testing burden and provide better information to its customers, so they can 

waste less money and energy.

5-3 Equipment Classes

DOE notes in the framework document that if the outcome of the proposed determination of coverage 

confirms DOE’s authority to cover natural draft commercial packaged boilers, DOE would create 

separate equipment classes for natural draft boilers. We are unaware of significant differences in utility, 

and encourage DOE to evaluate whether there is a specific utility of natural draft boilers in certain 

applications that would warrant separate equipment classes.

5-4 Technology Options

Increasingly, boilers (including moderate-sized commercial boilers) and their components (such as 

burners) are traded internationally. This has two implications:

 As for all other rulemakings, DOE’s screening must be based on an international evaluation of 

technologies applied in products available in Europe, East Asia, and other competitive markets. 

These technologies, such as burners, are readily available as components for U.S.

manufacturers, too.

 To the extent that U.S. standards lag behind those of competitor countries, our manufacturers 

suffer vulnerability to loss of market to offshore competitors hardened by market discipline in 

their home markets, and lose the ability to compete abroad.

8-1 Distribution Channels

For packaged boilers, as for much other specialized mechanical equipment, the role of the 

“manufacturer’s representative” is critical. These firms typically sell products from many manufacturers, 

usually not with overlapping product lines. They sell for the manufacturer, but we believe that they 

generally do not actually buy and hold equipment, in contrast to wholesalers. It is of concern because 

this channel, which may be a significant part of many kinds of specialty equipment (not just HVAC) is 

extremely important in many sectors, but somehow missed completely in this effort to set up the 

analysis.

9-1 Energy Consumption

Thermal Efficiency by itself may not be well correlated with annual energy use because it measures only 

peak load. Since loads vary seasonally and since most boilers are said to be oversized, it is likely that few 

boilers (except in boiler trains) ever operate at full load for significant periods of time. We suggest that 

DOE adapt the “prototype buildings” simulation approach used to support ASHRAE 90.1 analyses, 

running representative buildings through hourly simulations. 
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9-3 Field Data

For field monitoring data, we suggest outreach to MNCEE, CEE, and NEEP. The latter two are regional 

efficiency organizations. Natural Resources Canada (Martin Thomas) may also be a resource.

9-8 Rebound Effect

For reasons identified by the manufacturers at the DOE Public Meeting on October 1, there is no reason 

to expect significant “rebound”, that is, additional energy consumption when a more-efficient 

commercial packaged boiler replaces a less-efficient one.

10-4, 10-5 Installation, Maintenance and Repair Costs

We believe that condensing and non-condensing equipment may differ in terms of installation, 

maintenance and repair costs, but possibly in counterintuitive ways. For example, for some fraction of 

packaged commercial boiler replacements, substituting a condensing boiler (or boiler train) may reduce

both installation and maintenance costs. This might well be true, for example, if the efficiency upgrade 

allowed abandoning a masonry chimney that otherwise requires repointing and annual inspection.

The 2011 ASHRAE Handbook, Chapter 37 (Owning and Operating Costs) notes some newer on-line 

resources for estimating these factors. In informal analyses based on earlier data, Sachs found that the 

distribution of maintenance cost frequencies was very asymmetric, looking Poisson or lognormal. This is 

not unsurprising (the fraction of buildings with very, very, high O&M costs, including energy, is small), 

but suggests caution in the distributions assumed in the Monte Carlo analysis.

10-6 Equipment Lifetimes

The 2011 ASHRAE Handbook, Chapter 37 (Owning and Operating Costs) notes some newer on-line 

resources for estimating expected service life for various equipment classes, but also stresses the 

uncertainties involved in estimates based on equipment designs and manufacturing processes that may 

have changed substantially.

Conclusion

We appreciate the opportunity to contribute thoughts at this framework stage of the rulemaking for 

commercial packaged boilers, and look forward to the future steps in the process. At this time, the most 

important issue to us is shifting to a rating method that incorporates a good part-load efficiency 

estimate, because the present BTS-2000 hides the efficiencies achievable in the field by well-designed 

and well-controlled condensing systems. 

Thank you for your consideration.

Sincerely,
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Harvey Sachs, Ph.D

Senior Fellow

American Council for an Energy-Efficient Economy

Joanna Mauer

Technical Advocacy Coordinator

Appliance Standards Awareness Project

Meg Waltner

Manager, Building Energy Policy

Natural Resources Defense Council