DOE/EA-XXXX

ENVIRONMENTAL ASSESSMENT FOR PROPOSED ENERGY

CONSERVATION STANDARDS FOR COMMERCIAL

UNITARY AIR CONDITIONERS AND HEAT PUMPS

July 2004

U.S. Department of Energy

Assistant Secretary

Office of Energy Efficiency & Renewable Energy

Building Technologies Program

Appliances and Commercial Equipment Standards

Washington, DC 20585
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ENVIRONMENTAL ASSESSMENT FOR COMMERCIAL UNITARY AIR

CONDITIONERS AND HEAT PUMPS

TABLE OF CONTENTS

1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EA-1

2.0 METHODOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EA-1

3.0 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EA-2
a

 For more information on NEMS, please refer to the U.S. Department of Energy, Energy Information Administration

documentation. A useful summary is National Energy Modeling System: An Overview 2000, DOE/EIA-0581(2000),

March, 2000. DOE/EIA approves use of the name NEMS to describe only an official version of the model without any

modification to code or data. Because this analysis entails some minor code modifications and the model is run under

various policy scenarios that are variations on DOE/EIA assumptions, we refer to it as NEMS-BT (BT is DOE’s Building

Technologies Program). NEMS-BT was previously called NEMS-BRS.

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ENVIRONMENTAL ASSESSMENT FOR COMMERCIAL UNITARY AIR

CONDITIONERS AND HEAT PUMPS

1.0 INTRODUCTION

The Department will assess the impacts of proposed commercial unitary air conditioner

standard levels on certain environmental indicators using a variant of the U.S.DOE/Energy

Information Administration (EIA)’s National Energy Modelling System (NEMS)a

. DOE/EIA

uses NEMS to produce the 2003 Annual Energy Outlook (AEO2003).

1

 The Department will use

a variant known as NEMS-BT to provide key inputs to the analysis. Results of the

environmental analysis are similar to those provided in AEO2003.

The Department intends the environmental assessment to provide emissions results to

policymakers and interveners, and to fulfill requirements that the environmental effects of all

new Federal rules be properly quantified and considered. The environmental analysis considers

two pollutants, sulfur dioxide (SO2) and nitrogen oxides (NOx), as well as carbon emissions. The

only form of carbon tracked by NEMS-BT is carbon dioxide (CO2), so the carbon discussed in

this report is only in the form of CO2. For each of the standard levels, the Department will

calculate total emissions using NEMS-BT, with external analysis used as needed.

The Department will conduct the environmental assessment as a policy deviation from

the AEO2003, using the same basic set of assumptions. For example, the emissions

characteristics of an electricity generating plant will be exactly those used in AEO2003. The

NEMS reference case and alternative growth scenarios are as described in the utility impact

analysis (Chapter 13 of the Technical Support Document).

2.0 METHODOLOGY

The NEMS-BT tracks carbon emissions using a detailed carbon module; this gives good

results because of its broad coverage of all sectors and inclusion of interactive effects. Past

experience with carbon results from NEMS suggests that the NEMS-generated emissions

estimates are somewhat lower than estimates based on simple average factors. One of the

reasons for this divergence is that NEMS tends to predict that conservation displaces renewable

generating capacity in the later years of its forecast. On the whole, NEMS-BT provides carbon
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emissions results of reasonable accuracy, at a level consistent with other published Federal

results.

The NEMS-BT model reports the two airborne pollutant emissions that DOE has

reported in past analyses, SO2 and NOx. The Clean Air Act Amendments of 1990 set an SO2

emissions cap on all power generation. The attainment of this target, however, is flexible among

generators through the use of emissions allowances and tradable permits. The NEMS-BT model

includes a module for SO2 allowance trading and delivers a forecast of SO2 allowance prices. 

Accurate simulation of SO2 trading tends to imply that physical emissions effects will be zero, as

long as emissions are at the ceiling. This fact has caused considerable confusion in the past. 

However, there is an SO2 benefit from conservation in the form of a lower allowance price as a

result of additional allowances from this rule, and, if it is big enough to be calculable by NEMSBT, DOE will report this value. The NEMS-BT model also has an algorithm for estimating NOx

emissions from power generation. Two recent regulatory actions proposed by the EPA regarding

regulations and guidelines for best available retrofit technology determinations and the reduction

of interstate transport of fine particulate matter and ozone are tending towards further NOx

reductions and likely to an eventual emissions cap on nation-wide NOx. 69 FR 25184 (May 5,

2004) and 69 FR 32684 (June 10, 2004). As with SO2 emissions, a cap on NOx emissions will

likely result in no physical emissions effects from equipment efficiency standards. However,

there is an NOx benefit from conservation in the form of a lower allowance price as a result of

additional allowances from this rule, and, if it is big enough to be calculable by NEMS-BT, DOE

will report this value. 

3.0 RESULTS

The results for the environmental analysis are similar to a complete NEMS run, as

published in the AEO2003. These include power sector emissions for SO2, NOx, and carbon, and

SO2 prices, in five-year forecasted increments extrapolated to the year 2035. The Department

reports the outcome of the analysis for each trial standard level as a deviation from the AEO2003

reference cases.
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1. U.S. Department of Energy-Energy Information Administration, Annual Energy Outlook

2003, January 2003. Washington, DC. Report No. DOE/EIA-0383(2003).

REFERENCES