Commonwealth Edison v. Illinois Commerce Commission ( 2010 )


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  •                          Nos. 2-08-0959, 2-08-1037, 2-08-1137,
    1-08-3008, 1-08-3030, 1-08-3054, 1-08-3313 cons. Filed: 9-30-10
    _________________________________________________________________________________
    IN THE
    APPELLATE COURT OF ILLINOIS
    SECOND DISTRICT
    _________________________________________________________________________________
    COMMONWEALTH EDISON COMPANY,                      )   On Petition for Administrative Review
    )   from the Illinois Commerce Commission.
    Petitioner,                               )
    )
    v.                                                )   No. 07--0566
    )
    ILLINOIS COMMERCE COMMISSION;                     )
    THE PEOPLE OF THE STATE OF ILLINOIS )
    ex rel. LISA MADIGAN, THE ATTORNEY )
    GENERAL; AARP; AARP ILLINOIS;                     )
    BLUESTAR ENERGY SERVICES, INC.;                   )
    BUILDING OWNERS AND MANAGERS                      )
    ASSOCIATION OF CHICAGO; CHICAGO )
    TRANSIT AUTHORITY; CITIZENS                       )
    UTILITY BOARD; CHRYSLER, LLC;                     )
    THE CITY OF CHICAGO; THE                          )
    COMMERCIAL GROUP (styled as such                  )
    collectively from the following petitioners: Best )
    Buy Company, Inc.; J.C. Penney Corporation, )
    Inc.; Macy's, Inc.; Walmart Stores, Inc.);        )
    CONSTELLATION ENERGY                              )
    COMMODITIES GROUP, INC.;                          )
    CONSTELLATION NEWENERGY, INC.;                    )
    UNITED STATES DEPARTMENT OF                       )
    ENERGY; INTERNATIONAL                             )
    BROTHERHOOD OF ELECTRICAL                         )
    WORKERS LOCAL UNION NO. 15,                       )
    AFL-CIO; ILLINOIS INDUSTRIAL                      )
    ENERGY CONSUMERS, a/k/a IIEC                     )
    (styled as such collectively from the following )
    petitioners: Abbott Laboratories, Inc.;           )
    Arcelormittal USA; Caterpillar, Inc.: Citgo,      )
    Inc.; Corn Products International, Inc.;          )
    Daimler Chrysler Corporation; Enbridge            )
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    Energy, LP; Exxonmobil; Ford Motor Company;)
    Merchandise Mart; Sterling Steel Company,         )
    LLC; Thermal Chicago Cooling, Inc.; Citco Inc.;)
    General Iron Industries, Inc.); NORTHEAST )
    ILLINOIS REGIONAL COMMUTER                        )
    RAILROAD CORPORATION, d/b/a Metra; )
    NUCOR STEEL KANKAKEE, INC.; THE                   )
    KROGER COMPANY; THE COALITION                     )
    TO REQUEST EQUITABLE ALLOCATION )
    OF COSTS TOGETHER, a/k/a "REACT"                  )
    (styled as such collectively from the following )
    petitioners: A. Finkl and Sons Company; Alsip )
    Paper Condominium Association; Aux Sable          )
    Liquid Products, LP; The City of Chicago;         )
    Commerce Energy, Inc.; Flint Hills Resources, )
    LLC; Integrys Energy Services, Inc.;              )
    Metropolitan Water Reclamation District of        )
    Greater Chicago; PDV Midwest Refining, LLC; )
    United Airlines, Inc.; Wells Manufacturing, Inc.);)
    RETAIL ENERGY SUPPLY ASSOCIATION, )
    a/k/a "RESA" (styled as such collectively from )
    the following petitioners: Commerce Energy, )
    Inc.; Consolidated Edison Solutions, Inc.;        )
    Direct Energy Services, LLC; Gexa Energy;         )
    Hess Corporation; Intergrys Energy Services, )
    Inc.; Liberty Power Corporation; Reliant Energy)
    Retail Services, LLC; Sempra Energy Solutions; )
    Strategic Energy, LLC; Suez Energy Resources )
    NA, Inc.; US Energy Savings Corporation);         )
    and UNIVERSITY OF ILLINOIS,                       )
    )
    Respondents.                              )
    ______________________________________________________________________________
    THE PEOPLE OF THE STATE OF                    )    On Petition for Administrative Review
    ILLINOIS ex rel. LISA MADIGAN, THE            )    from the Illinois Commerce Commission.
    ATTORNEY GENERAL,                             )
    )
    Petitioner,                            )
    )
    v.                                            )    No. 07--0566
    )
    ILLINOIS COMMERCE COMMISSION;                 )
    COMMONWEALTH EDISON COMPANY;                  )
    -2-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    AARP; AARP ILLINOIS; BLUESTAR                     )
    ENERGY SERVICES, INC.; BUILDING                   )
    OWNERS AND MANAGERS ASSOCIATION)
    OF CHICAGO; CHICAGO TRANSIT                       )
    AUTHORITY; CITIZENS UTILITY BOARD; )
    CHRYSLER, LLC; THE CITY OF CHICAGO;)
    THE COMMERCIAL GROUP (styled as such )
    collectively from the following petitioners: Best )
    Buy Company, Inc.; J.C. Penney Corporation, )
    Inc.; Macy's, Inc.; Walmart Stores, Inc.);        )
    CONSTELLATION ENERGY                              )
    COMMODITIES GROUP, INC.;                          )
    CONSTELLATION NEWENERGY, INC.;                    )
    UNITED STATES DEPARTMENT OF                       )
    ENERGY; INTERNATIONAL                             )
    BROTHERHOOD OF ELECTRICAL                         )
    WORKERS LOCAL UNION NO. 15,                       )
    AFL-CIO; ILLINOIS INDUSTRIAL                      )
    ENERGY CONSUMERS, a/k/a IIEC                      )
    (styled as such collectively from the following )
    petitioners: Abbott Laboratories, Inc.;           )
    Arcelormittal USA; Caterpillar, Inc.; Citgo,      )
    Inc.; Corn Products International, Inc.; Daimler )
    Chrysler Corporation; Enbridge Energy, LP;        )
    Exxonmobil; Ford Motor Company;                   )
    Merchandise Mart; Sterling Steel Company,         )
    LLC; Thermal Chicago Cooling, Inc.; Citco, Inc;)
    General Iron Industries, Inc.); NORTHEAST )
    ILLINOIS REGIONAL COMMUTER                        )
    RAILROAD CORPORATION, d/b/a Metra; )
    NUCOR STEEL KANKAKEE, INC.; THE                   )
    KROGER COMPANY; THE COALITION                     )
    TO REQUEST EQUITABLE ALLOCATION )
    OF COSTS TOGETHER, a/k/a "REACT"                  )
    (styled as such collectively from the following )
    petitioners: A. Finkl and Sons Company;           )
    Alsip Paper Condominium Association;              )
    Aux Sable Liquid Products, LP;                    )
    The City of Chicago; Commerce Energy, Inc.; )
    Flint Hills Resources, LLC; Integrys              )
    Energy Services, Inc.; Metropolitan Water         )
    Reclamation District of Greater Chicago; PDV )
    Midwest Refining, LLC; United Airlines,           )
    Inc.; Wells Manufacturing, Inc.);                 )
    -3-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    RETAIL ENERGY SUPPLY ASSOCIATION, )
    a/k/a "RESA" (styled as such collectively from )
    the following petitioners: Commerce Energy, )
    Inc.; Consolidated Edison Solutions, Inc.;     )
    Direct Energy Services, LLC; Gexa Energy;      )
    Hess Corporation; Intergrys Energy Services, )
    Inc.; Liberty Power Corporation; Reliant Energy)
    Retail Services, LLC; Sempra Energy Solutions; )
    Strategic Energy, LLC; Suez Energy Resources )
    NA, Inc.; US Energy Savings Corporation);      )
    and UNIVERSITY OF                              )
    ILLINOIS,                                      )
    )
    Respondents.                           )
    ______________________________________________________________________________
    CITIZENS UTILITY BOARD,                        )    On Petition for Administrative Review
    )    from the Illinois Commerce Commission.
    Petitioner,                            )
    )
    v.                                             )    No. 07--0566
    )
    ILLINOIS COMMERCE COMMISSION;                  )
    COMMONWEALTH EDISON COMPANY; )
    THE PEOPLE OF THE STATE OF ILLINOIS )
    ex rel. LISA MADIGAN, THE                      )
    ATTORNEY GENERAL; AARP;                        )
    AARP ILLINOIS; BLUESTAR ENERGY                 )
    SERVICES, INC.; BUILDING OWNERS                )
    AND MANAGERS ASSOCIATION OF                    )
    CHICAGO; CHICAGO TRANSIT                       )
    AUTHORITY; CHRYSLER LLC; THE CITY )
    OF CHICAGO; THE COMMERCIAL                     )
    GROUP (styled as such collectively from the    )
    following petitioners: Best Buy Company, Inc.; )
    J.C. Penney Corporation, Inc.; Macy's, Inc.;   )
    Walmart Stores, Inc.);                         )
    CONSTELLATION ENERGY                           )
    COMMODITIES GROUP, INC.;                       )
    CONSTELLATION NEWENERGY, INC.;                 )
    UNITED STATES DEPARTMENT OF                    )
    ENERGY; INTERNATIONAL                          )
    BROTHERHOOD OF ELECTRICAL                      )
    WORKERS LOCAL UNION NO. 15,                    )
    -4-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    AFL-CIO; ILLINOIS INDUSTRIAL                      )
    ENERGY CONSUMERS, a/k/a IIEC                      )
    (styled as such collectively from the following )
    petitioners: Abbott Laboratories, Inc.;           )
    Arcelormittal USA; Caterpillar, Inc.; Citgo,      )
    Inc.; Corn Products International, Inc.;          )
    Daimler Chrysler Corporation; Enbridge            )
    Energy, LP; Exxonmobil; Ford Motor                )
    Company; Merchandise Mart; Sterling Steel         )
    Company, LLC; Thermal Chicago Cooling,            )
    Inc.; Citco Inc.; General Iron Industries, Inc.); )
    NORTHEAST ILLINOIS REGIONAL                       )
    COMMUTER RAILROAD CORPORATION, )
    d/b/a Metra; NUCOR STEEL KANKAKEE, )
    INC.; THE KROGER COMPANY; THE                     )
    COALITION TO REQUEST EQUITABLE                    )
    ALLOCATION OF COSTS TOGETHER,                     )
    a/k/a "REACT" (styled as such collectively       )
    from the following petitioners: A. Finkl          )
    and Sons Company; Alsip Paper Condominium )
    Association; Aux Sable Liquid Products. LP; )
    The City of Chicago; Commerce Energy, Inc.; )
    Flint Hills Resources, LLC; Integrys Energy       )
    Services, Inc.; Metropolitan Water                )
    Reclamation District of Greater Chicago; PDV )
    Midwest Refining, LLC; United Airlines, Inc.; )
    Wells Manufacturing, Inc.); RETAIL                )
    ENERGY SUPPLY ASSOCIATION,                        )
    a/k/a "RESA" (styled as such collectively from )
    the following petitioners: Commerce Energy, )
    Inc.; Consolidated Edison Solutions, Inc.;        )
    Direct Energy Services, LLC; Gexa Energy;         )
    Hess Corporation; Intergrys Energy Services, )
    Inc.; Liberty Power Corporation; Reliant Energy)
    Retail Services, LLC; Sempra Energy Solutions; )
    Strategic Energy, LLC; Suez Energy Resources )
    NA, Inc.; US Energy Savings Corporation);         )
    and UNIVERSITY OF ILLINOIS,                       )
    )
    Respondents.                              )
    ______________________________________________________________________________
    THE BUILDING OWNERS AND          )                 On Petition for Administrative Review
    MANAGERS ASSOCIATION OF CHICAGO, )                 from the Illinois Commerce Commission.
    -5-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    )
    Petitioner,                                  )
    )
    v.                                                  )   No. 07--0566
    ILLINOIS COMMERCE COMMISSION;                       )
    COMMONWEALTH EDISON COMPANY;                        )
    THE PEOPLE OF THE STATE OF ILLINOIS                 )
    ex rel. LISA MADIGAN, THE ATTORNEY                  )
    GENERAL; AARP; AARP ILLINOIS;                       )
    BLUESTAR ENERGY SERVICES, INC.;                     )
    CHICAGO TRANSIT AUTHORITY;                          )
    CITIZENS UTILITY BOARD; CHRYSLER,                   )
    THE CITY OF CHICAGO; THE                            )
    COMMERCIAL GROUP (styled as such                    )
    collectively from the following petitioners: Best   )
    Buy Company, Inc.; J.C. Penney Corporation,         )
    Inc.; Macy's, Inc.; Walmart Stores, Inc.);          )
    CONSTELLATION ENERGY                                )
    COMMODITIES GROUP, INC.;                            )
    CONSTELLATION NEWENERGY, INC.;                      )
    UNITED STATES DEPARTMENT OF                         )
    ENERGY; INTERNATIONAL                               )
    BROTHERHOOD OF ELECTRICAL                           )
    WORKERS LOCAL UNION NO. 15,                         )
    AFL-CIO; ILLINOIS INDUSTRIAL                        )
    ENERGY CONSUMERS, a/k/a IIEC                        )
    (styled as such collectively from the following     )
    petitioners: Abbott Laboratories, Inc.;             )
    Arcelormittal USA; Caterpillar, Inc.; Citgo,        )
    Inc.; Corn Products International, Inc.;            )
    Daimler Chrysler Corporation; Enbridge              )
    Energy, LP; Exxonmobil; Ford Motor                  )
    Company; Merchandise Mart; Sterling Steel           )
    Company, LLC; Thermal Chicago Cooling,              )
    Inc.; Citco Inc.; General Iron Industries, Inc.);   )
    NORTHEAST ILLINOIS REGIONAL                         )
    COMMUTER RAILROAD CORPORATION,                      )
    d/b/a Metra; NUCOR STEEL KANKAKEE,                  )
    INC.; THE KROGER COMPANY;                           )
    THE COALITION TO REQUEST                            )
    EQUITABLE ALLOCATION OF COSTS                       )
    TOGETHER, a/ka/ "REACT" (styled as such             )
    collectively from the following petitioners;        )
    A. Finkl and Sons Company; Alsip Paper              )
    -6-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    Condominium Association; Aux Sable Liquid )
    Products, LP; The City of Chicago; Commerce )
    Energy, Inc.; Flint Hills Resources, LLC;      )
    Integrys Energy Services, Inc.; Metropolitan   )
    Water Reclamation District of Greater Chicago; )
    PDV Midwest Refining, LLC; United Airlines, )
    Inc.; Wells Manufacturing, Inc.);              )
    RETAIL ENERGY SUPPLY ASSOCIATION, )
    a/k/a "RESA" (styled as such collectively from )
    the following petitioners: Commerce Energy, )
    Inc.; Consolidated Edison Solutions, Inc.;     )
    Direct Energy Services, LLC; Gexa Energy;      )
    Hess Corporation; Intergrys Energy Services, )
    Inc.; Liberty Power Corporation; Reliant Energy)
    Retail Services, LLC; Sempra Energy Solutions; )
    Strategic Energy, LLC; Suez Energy Resources )
    NA, Inc.; US Energy Savings Corporation);      )
    and UNIVERSITY OF ILLINOIS,                    )
    )
    Respondents.                           )
    ______________________________________________________________________________
    ABBOTT LABORATORIES, INC.;          )              On Petition for Administrative Review
    ARCELORMITTAL USA; CATERPILLAR      )              from the Illinois Commerce Commission.
    INC.; CORN PRODUCTS                 )
    INTERNATIONAL, INC.; DAIMLER        )
    CHRYSLER CORPORATION; ENBRIDGE      )
    ENERGY, LP; EXXONMOBIL; FORD        )
    COMPANY; MERCHANDISE MART;          )
    STERLING STEEL COMPANY, LLC;        )
    THERMAL CHICAGO COOLING, INC.;      )
    CITCO, INC.; GENERAL IRON           )
    INDUSTRIES, INC.,                   )
    )
    Petitioners,                )
    )
    v.                                  )              No. 07--0566
    )
    ILLINOIS COMMERCE COMMISSION;       )
    COMMONWEALTH EDISON COMPANY; )
    THE PEOPLE OF THE STATE OF ILLINOIS )
    ex rel. LISA MADIGAN, THE ATTORNEY )
    GENERAL; AARP; AARP ILLINOIS;       )
    BLUESTAR ENERGY SERVICES, INC.;     )
    -7-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    BUILDING OWNERS AND MANAGERS                      )
    ASSOCIATION OF CHICAGO; CHICAGO )
    TRANSIT AUTHORITY; CITIZENS                       )
    UTILITY BOARD; CHRYSLER, LLC; THE )
    CITY OF CHICAGO; THE COMMERCIAL )
    COMMERCIAL GROUP (styled as such                  )
    collectively from the following petitioners: Best )
    Buy Company, Inc.; J.C. Penney Corporation, )
    Inc.; Macy's, Inc.; Walmart Stores, Inc.);        )
    CONSTELLATION ENERGY                              )
    COMMODITIES GROUP, INC.;                          )
    CONSTELLATION NEWENERGY, INC.;                    )
    UNITED STATES DEPARTMENT OF                       )
    ENERGY; INTERNATIONAL                             )
    BROTHERHOOD OF ELECTRICAL                         )
    WORKERS LOCAL UNION NO. 15,                       )
    AFL-CIO; NORTHEAST ILLINOIS                       )
    REGIONAL COMMUTER RAILROAD                        )
    CORPORATION, d/b/a Metra; NUCOR                   )
    STEEL KANKAKEE, INC.; THE KROGER )
    COMPANY; THE COALITION TO                         )
    REQUEST EQUITABLE ALLOCATION                      )
    OF COSTS TOGETHER, a/k/a "REACT"                  )
    styled as such collectively from the following )
    petitioners; A. Finkl and Sons Company;           )
    Alsip Paper Condominium Association;              )
    Aux Sable Liquid Products, LP; The City           )
    of Chicago; Commerce Energy, Inc.;                )
    Flint Hills Resources, LLC; Integrys Energy       )
    Services, Inc.; Metropolitan Water                )
    Reclamation District of Greater Chicago;          )
    PDV Midwest Refining, LLC; United Airlines, )
    Inc.; Wells Manufacturing, Inc.);                 )
    RETAIL ENERGY SUPPLY ASSOCIATION, )
    a/k/a "RESA" (styled as such collectively from )
    the following petitioners: Commerce Energy, )
    Inc.; Consolidated Edison Solutions, Inc.;        )
    Direct Energy Services, LLC; Gexa Energy;         )
    Hess Corporation; Intergrys Energy Services, )
    Inc.; Liberty Power Corporation; Reliant Energy)
    Retail Services, LLC; Sempra Energy Solutions; )
    Strategic Energy, LLC; Suez Energy Resources )
    NA, Inc.; US Energy Savings Corporation);         )
    and UNIVERSITY OF ILLINOIS,                       )
    -8-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    )
    Respondents.                     )
    ______________________________________________________________________________
    JUSTICE BURKE delivered the opinion of the court:
    Commonwealth Edison Company (ComEd) is a public utility company that distributes
    electricity to consumers in northern Illinois. ComEd petitioned the Illinois Commerce Commission
    (Commission) to restructure and alter the rates ComEd charges, seeking a $360 million increase.
    ComEd calculated its revenue requirement using 2006 as an historical "test year" and included certain
    new distribution assets, referred to as "plant."        These consolidated appeals arise from the
    Commission's order granting an increase of about $274 million.
    ComEd appeals the order, arguing that the Commission did not grant ComEd full recovery
    of prudent and reasonable costs of certain employees' salaries and wages. ComEd further asserts that,
    if we rule against it on issues raised by the other parties, it would be denied the benefit of a bargain
    that it struck with the Commission's staff (Staff). During the proceedings, ComEd and the Staff
    recommended that the Commission resolve certain issues in ComEd's favor and, in exchange, ComEd
    would waive inclusion of certain capital additions in its rate base. ComEd argues that it would be
    manifestly unfair to modify the agreement without allowing ComEd to add those capital additions to
    its rate base.
    The Illinois Industrial Energy Consumers (IIEC), which includes Abbott Laboratories, Inc.,
    and other large electricity consumers, intervened in the proceedings, to challenge the proposed rate
    increase. On appeal, IIEC argues that the Commission erred in allowing for post-test-year plant
    additions in the rate base without also recognizing a setoff for post-test-year changes in accumulated
    depreciation in the existing plant. IIEC argues that the order unlawfully inflates ComEd's rate base,
    -9-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    violates test-year requirements as set forth in case law and the Commission's own rules, and
    misapprehends the Commission's duty to decide a case exclusively on the record before it, regardless
    of how the Commission decided the same issue in the past.
    The Attorney General (AG) and the Citizens Utility Board (CUB) intervened separately to
    protect the rights of consumers to "just and reasonable" rates as prescribed by the Public Utilities Act
    (Act) (220 ILCS 5/1--101 et seq. (West 2006)). AG and CUB also filed notices of appeal, appearing
    collectively as the "Government and Residential Consumer Petitioners" (GC Petitioners). GC
    Petitioners echo IIEC's argument that the Commission erred in not accounting for the post-test-year
    changes in accumulated depreciation of the existing plant. GC Petitioners also challenge the
    Commission's approval of "Rider SMP," which ComEd proposed to immediately recoup the costs
    of modernizing its delivery system toward a "smart grid," including a new technology called advanced
    metering infrastructure (AMI) that would allow meter reader and supervisor positions to be phased
    out.
    The Building Owners and Managers Association of Chicago (BOMA) also intervened. On
    appeal, BOMA alleges that the Commission's order subjects nonresidential space-heating customers
    to unreasonable rate increases and discriminatory treatment in violation of the Act. BOMA asks this
    court to order the Commission to provide rate relief to the nonresidential space-heating customers.
    We hold that (1) the Commission heard substantial evidence to support excluding from
    ComEd's recoverable operating expenses 25% of certain labor costs for employees who performed
    both utility work and merger-related work; (2) the Commission erred in not accounting for the
    increased accumulated depreciation of the existing plant during the post-test-year period; (3) the
    Commission erred in implementing Rider SMP, because the rider violates the rule against single-issue
    -10-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    ratemaking; and (4) the Commission did not err in rejecting BOMA's proposal to apply different
    delivery rates to nonresidential space-heating customers.
    JURISDICTION
    The Commission entered its final order on September 10, 2008. On October 15, 2008, the
    Commission denied BOMA's application for rehearing but granted rehearing on two issues raised by
    ComEd. Two days later, ComEd filed a petition for review in the Appellate Court, Second District
    (appeal No. 2--08--0959).
    On November 3, 2008, the Commission issued a decision denying all the remaining
    applications for review as well as an amendatory order disposing of ComEd's two issues for
    rehearing. On that date, AG filed a petition for review in the Appellate Court, First District (appeal
    No. 1--08--3008). ComEd filed a second petition for review in the Second District (appeal No. 2--
    08--1037). On November 5, 2008, CUB filed a petition for review in the First District (appeal No.
    1--08--3030). On November 10, 2008, BOMA filed a petition for review in the First District (appeal
    No. 1--08--3054). On December 3, 2008, ComEd filed a third petition for review in the Second
    District (appeal No. 2--08--1137). On December 4, 2008, IIEC filed its petition for review in the
    First District (appeal No. 1--08--3313).
    On January 6, 2009, the supreme court issued a supervisory order directing the First District
    to transfer its appeals in this matter to the Second District for consolidation with ComEd's appeals.
    This court has jurisdiction to consider the appeals pursuant to Supreme Court Rule 335 and section
    10--201(a) of the Act. See 155 Ill. 2d R. 335 (direct review of administrative orders in the appellate
    court); 220 ILCS 5/10--201(a) (West 2008) (appeal allowed within 35 days of rehearing to the
    -11-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    appellate court of any district where the subject matter is situated, and the district first acquiring
    jurisdiction has and retains jurisdiction over all other appeals).
    BACKGROUND
    ComEd delivers electricity to more than 3.7 million retail consumers in northern Illinois.
    Illinois's electric industry underwent certain changes in the late 1990s. In 1997, the General Assembly
    amended the Act by enacting the Electric Service Customer Choice and Rate Relief Law of 1997
    (Rate Relief Law) (220 ILCS 5/16--101 et seq. (West 2006)), which required electric utilities to open
    their formerly legislatively approved monopoly. See 220 ILCS 5/16--103 (West 2006). Utilities were
    required to offer delivery services in addition to existing services, at least until an existing service was
    either abandoned or declared competitive. 220 ILCS 5/16--103 (West 2006). Delivery services are
    "those services provided by the electric utility that are necessary in order for the transmission and
    distribution systems to function so that retail customers located in the electric utility's service area can
    receive electric power and energy from suppliers other than the electric utility." 220 ILCS 5/16--102
    (West 2006).
    The Rate Relief Law caused change at both the retail and wholesale levels. For instance,
    utilities were required to offer delivery services in a nondiscriminatory manner to all customers. In
    response to the new law, ComEd divested itself of its electricity generating assets. See 220 ILCS
    5/16--111(g) (West 2006). ComEd became an "integrated distribution company," also known as a
    "wires company." ComEd's costs now are driven by the requirement that it meet the needs of a
    maximum number of customers, "regardless of the nature of the usage of customers." Generation
    of electricity is no longer a consideration. ComEd's costs as a "wires company" do not vary
    -12-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    appreciably over time, as they did when costs were driven by generating electricity. Commonwealth
    Edison Co. v. Illinois Commerce Comm'n, 
    398 Ill. App. 3d 510
    , 513 (2009) (ComEd).
    The rates for delivering electricity are calculated separately from the rates for the electric
    supply itself. 220 ILCS 5/16--109A, 16--111.5 (West 2008). An electric utility like ComEd is
    entitled to rates that allow it to recover fully its prudent and reasonable costs of service. 220 ILCS
    5/16--108(c) (West 2006) (rates "shall allow the electric utility to recover the costs of providing
    delivery services through its charges").
    A rate case is initiated when a utility files tariffs providing for a rate increase and the
    Commission suspends those tariffs to conduct an investigation and hearing. 220 ILCS 5/9--201
    (West 2006). The Commission may approve, reject, or modify the proposed tariffs. Section 9--
    201(c) of the Act provides that, if the Commission initiates a proceeding concerning the
    appropriateness of a utility's proposed rates, the utility has the burden of proving that the proposed
    rates are just and reasonable. 220 ILCS 5/9--201(c) (West 2006).
    In establishing the rates that a public utility is to charge its customers, the Commission
    considers the company's operating costs, rate base, and allowed rate of return. Citizens Utilities Co.
    v. Illinois Commerce Comm'n, 
    124 Ill. 2d 195
    , 200 (1988). Recovery of the utility's operating costs
    and the return on its rate base is known as the utility's annual revenue requirement. Generally
    speaking, a utility determines its revenue requirement by adding operating costs to invested capital
    multiplied by the rate of return. Business & Professional People for the Public Interest v. Illinois
    Commerce Comm'n, 
    146 Ill. 2d 175
    , 195 (1991) (BPI II). "The components of the revenue
    requirement have frequently been expressed in the formula 'R (revenue requirement) = C (operating
    -13-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    costs) + Ir (invested capital or rate base times rate of return on capital).' " BPI II, 
    146 Ill. 2d at
    195-
    96, quoting Citizens Utilities Co. v. Illinois Commerce Comm'n, 
    124 Ill. 2d at 200-01
    . 1
    The utility's return, or profit, is the product of the utility's allowed rate of return and its rate
    base. Both factors are determined by the Commission. Section 9--211 of the Act provides that a
    utility's rate base may include "only the value of such investment which is both prudently incurred and
    used and useful in providing service to public utility customers." 220 ILCS 5/9--211 (West 2006).
    The value of a utility's rate base investment is affected by both new investment and the decline
    in investment value due to plant depreciation. Companies purchase assets such as computers, copy
    machines, buildings, and furniture, all of which lose value each day. To give the most accurate
    portrayal of the economic reality of the business, this depreciation loss must be accounted for in the
    company's financial statements. Recording depreciation loss affects two accounts: depreciation
    expense and accumulated depreciation. Accumulated depreciation is the amount of a long-term
    asset's cost that has been allocated to depreciation expense since the date that the asset was acquired.
    The purpose of the accumulated depreciation account is to reduce an asset's carrying value to reflect
    its value loss due to wear, tear, and usage.
    Accumulated depreciation reports the amount of an asset's depreciation from the time it was
    acquired until the date of the balance sheet. The cost of an asset minus its accumulated depreciation
    is the asset's book value. The accumulated depreciation account balance does not close at the end
    of each year; therefore, it will increase each year. However, its balance cannot become greater than
    the cost of the assets.
    1
    Revenue Requirement = (Operating Costs) + (Rate Base)(Rate of Return).
    -14-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    Accounting is a double entry system of recording debits and credits so that the debits and
    credits match. To record a depreciation expense (the debit), one must also record the accumulated
    depreciation (the credit). Thus, when depreciation expense is recorded, there is also a recognition,
    or recording, of accumulated depreciation. Accumulated depreciation reduces the rate base for that
    portion of plant investment and net salvage already recouped through rates. R. Hahne, Accounting
    for Public Utilities, (MB) Rel. No. 23, at 4-15 (October 2006). If depreciation expense is known and
    measurable, accumulated depreciation is also known and measurable.
    The Illinois Administrative Code (Administrative Code) provides that a utility's revenue
    requirement may be calculated by beginning with costs incurred during a 12-month period known as
    a "test year," which may be either an historical or a future period. 83 Ill. Adm. Code §287.20,
    adopted at 
    27 Ill. Reg. 12380
    , 12382, eff. August 1, 2003. If an historical test year is chosen, the
    utility uses any consecutive 12-month period, beginning no more than 24 months before the utility's
    filing new tariffs, for which actual data are available at the time of filing. 83 Ill. Adm. Code §287.20,
    adopted at 
    27 Ill. Reg. 12380
    , 12382, eff. August 1, 2003. The supreme court has explained that the
    purpose of the test year rules is "to prevent a utility from overstating its revenue requirement by
    mismatching low revenue data from one year with high expense data from a different year." BPI II,
    
    146 Ill. 2d at 238
    .
    The historical data may be subject to "pro forma adjustments," which are estimated or
    calculated adjustments that reflect certain known and measurable changes in post-test-year data as
    specified in the rules. 83 Ill. Adm. Code §§287.20, 287.40, adopted at 
    27 Ill. Reg. 12380
    , 12382-84,
    eff. August 1, 2003. The pro forma adjustments must reflect changes affecting the ratepayers in plant
    investment, operating revenues, expenses, and cost of capital where such changes occurred during
    -15-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    the selected historical test year or are reasonably certain to occur within 12 months after the filing
    date of the tariffs and where the amounts of the changes are determinable. 83 Ill. Adm. Code
    §287.40, adopted at 
    27 Ill. Reg. 12380
    , 12384, eff. August 1, 2003.
    THE RATE CASE
    On October 17, 2007, ComEd filed tariffs that incorporated a general increase in rates for
    delivering electricity and revised other terms and conditions of service. See 220 ILCS 5/9--201 (West
    2006). ComEd proposed no change in the price of the electricity itself. ComEd asserted that a $360
    million increase in its delivery rates was necessary because the existing rates were based on costs that
    were years out of date.
    ComEd used the 2006 calendar year as an historical test year and included certain pro forma
    adjustments. ComEd proposed to increase its 2006 rate base investment amount by $1,498,317,000
    based on new plant that had been or would be implemented over a 21-month period from January
    2007 through September 2008.
    On November 28, 2007, the Commission suspended ComEd's proposed tariffs and initiated
    the underlying rate case. The Commission assigned two Administrative Law Judges (ALJs) to take
    evidence and issue a proposed order. To protect their interests, IIEC, GC Petitioners, and BOMA
    intervened. Testimony and documentary exhibits were submitted, and evidentiary hearings were held
    from April 28, 2008, to May 5, 2008.
    ComEd asserted that its reasonable and prudent delivery costs included the costs of its
    investment in new infrastructure placed into service since the last rate case. ComEd sought a pro
    forma adjustment to the rate base to include certain new plant that had entered or would enter service
    after the 2006 test year but before the end of the third quarter of 2008. ComEd argued that the costs
    -16-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    it sought to recover were prudently incurred and reasonable in amount and that the plant it included
    in the rate base was used and useful and necessary to provide delivery services.
    ComEd and the Staff submitted a joint recommendation to the Commission. First, based on
    the evidence, the Commission's rules, and relevant decisions in earlier rate cases, ComEd and the
    Staff recommended excluding from ComEd's rate base accumulated depreciation and certain taxes.
    ComEd and the Staff opined that the Commission should not reduce the rate base further by
    subtracting extra depreciation and deferred taxes, as the intervenors might propose. Second, ComEd
    and the Staff recommended that ComEd be allowed to include in the rate base new utility facilities
    placed in service through only the second quarter of 2008 if the Commission approved the joint
    recommendation as a whole. ComEd's "conditional withdrawal" of its request to include plant
    additions from the third quarter of 2008 reduced its requested rate base by about $175 million.
    On September 10, 2008, the Commission issued its order authorizing ComEd to file new
    tariffs to implement a $273,573,000 rate increase. The new rates were designed to recover an annual
    revenue requirement of $1,961,065,000, based in part on the Commission's determination that the
    value of ComEd's rate base investment was $6,694,039,000. The Commission concluded that the
    value of ComEd's test-year rate base investment should be increased by the amount of its planned
    post-test-year plant additions, without recognizing identified post-test-year decreases in existing
    investment value. Consistent with the recommendation of ComEd and the Staff, the Commission also
    excluded from the rate base the value of the distribution facilities placed in service in the third quarter
    of 2008. We address the remaining portions of the Commission's order in our analysis below.
    ANALYSIS
    -17-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    We give substantial deference to the decisions of the Commission, in light of its expertise and
    experience in this area. ComEd, 398 Ill. App. 3d at 514. Accordingly, on appeal, the Commission's
    findings of fact are considered prima facie true; its orders are considered prima facie reasonable; and
    the appellant bears the burden of proof on all issues raised. ComEd, 398 Ill. App. 3d at 514.
    Though we are not bound by the Commission on questions of law, we " 'will give substantial
    weight and deference to an interpretation of an ambiguous statute by the agency charged with the
    administration and enforcement of the statute,' which in this case is the Commission." ComEd, 398
    Ill. App. 3d at 514, quoting Illinois Consolidated Telephone Co. v. Illinois Commerce Comm'n, 
    95 Ill. 2d 142
    , 152 (1983). Our review is limited to the following matters: (1) whether the Commission
    acted within its authority; (2) whether it made adequate findings to support its decision; (3) whether
    the decision was supported by substantial evidence; and (4) whether state or federal constitutional
    rights were infringed. ComEd, 398 Ill. App. 3d at 514.
    In making adequate findings, the Commission is not required to provide findings on each
    evidentiary claim; its findings are sufficient if they are specific enough to enable the court to make an
    informed and intelligent review of its order. 220 ILCS 5/10--201(e)(iii) (West 2006); City of Chicago
    v. Illinois Commerce Comm'n, 
    281 Ill. App. 3d 617
    , 623-24 (1996) (City of Chicago II). In other
    words, it must state the facts essential to its ruling so that the court can properly review the basis for
    the decision.    Business & Professional People for the Public Interest v. Illinois Commerce
    Commission, 
    279 Ill. App. 3d 824
    , 833 (1996).
    Moreover, "substantial evidence" means more than a mere scintilla; however, it does not have
    to rise to the level of a preponderance of the evidence. ComEd, 398 Ill. App. 3d at 514. It is
    evidence that a " 'reasoning mind would accept as sufficient to support a particular conclusion.' "
    -18-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    ComEd, 398 Ill. App. 3d at 514, quoting Citizens Utility Board v. Illinois Commerce Comm'n, 
    291 Ill. App. 3d 300
    , 304 (1997). "Our supreme court has held that deference to the Commission is
    'especially appropriate in the area of fixing rates.' " ComEd, 398 Ill. App. 3d at 514, quoting
    Iowa-Illinois Gas & Electric Co. v. Illinois Commerce Comm'n, 
    19 Ill. 2d 436
    , 442 (1960). On
    review, this court can neither reevaluate the credibility or weight of the evidence nor substitute its
    judgment for that of the Commission. ComEd, 398 Ill. App. 3d at 514.
    A. ComEd's Labor Costs:
    ComEd Appeal Nos. 2--08--0959 & 2--08--1037
    ComEd argues that the Commission erred by denying full recovery of salary and wages of
    certain employees. ComEd also argues that its third-quarter 2008 capital additions may be excluded
    from its rate base only under the conditions of ComEd's voluntary agreement with the Commission's
    Staff. We address the latter argument in the context of IIEC's appeal of that issue.
    In calculating its proposed revenue requirement, ComEd included compensation paid to
    salaried personnel who supported the delivery services provided to customers. Some of those
    personnel spent time on a proposed merger between ComEd's eventual parent company, Exelon
    Corporation (Exelon), and Public Service Enterprise Group Corporation (PSEG).                 ComEd
    recognized that this work does not relate to providing electric utility service and should not be
    charged to customers. Accordingly, ComEd subtracted $5,281,000 of expenses, called "incremental
    merger costs," from its revenue requirement. However, ComEd maintained that no adjustment
    should be made to reflect the salaries and benefits of other employees who performed merger-related
    activities, because those employees performed the work as unpaid overtime. ComEd sought recovery
    of 100% of the labor costs of those employees.
    -19-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    GC Petitioners objected to ComEd recovering any labor costs attributable to the employees
    who worked on both the merger and utility business. David Effron, an expert called by GC
    Petitioners, proposed to reduce ComEd's revenue requirement by an additional $2,546,000, which
    represented "non-incremental merger costs," or the entire labor cost of the employees who had
    performed their normal utility functions while also performing work related to the merger.
    Effron opined that time spent on merger activities in the test year was not necessary for utility
    service and that the cost of that time should not be recovered from ratepayers. He disagreed with
    ComEd's position that the entire salary and benefits of employees who spent time on merger-related
    activities should be included in the operating expenses. Effron opined, "[t]o the extent that the time
    of those employees was devoted to merger-related activities, it was not incurred in the provision of
    utility service in the test year, and it should not be included in the company's revenue requirement.
    It is not clear how the company knows that the time of those employees will be spent performing
    utility-related duties prospectively, but even assuming that this is correct, it is also possible that it
    would reduce the time of other employees performing such duties." Effron concluded that, if the
    employees had performed the merger work for free as ComEd alleges, no cost should be assigned to
    that work.
    ComEd declined its opportunity to cross-examine Effron. However, Kathryn Houtsma and
    Stacie Frank testified in rebuttal for ComEd. They explained that, when the salaried employees at
    issue were required to assist with the merger in 2006, they accounted for their time spent on merger
    activities by charging hours to a separate project code block. However, extra time that those
    employees spent on utility-related activities was not accounted for elsewhere in the salary and benefits
    -20-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    costs recorded on ComEd's books. Thus, eliminating any of the wages and benefits of those
    employees would understate ComEd's cost of service.
    The Commission found that the employees at issue had performed delivery-service work as
    well as merger-related work. However, the Commission expressed skepticism as to "whether these
    same employees would have performed unpaid overtime on delivery service test year activities if not
    for the merger." The Commission further stated, "it is not clear that the expenses claimed by
    [ComEd] are representative because of the merger work."
    The Commission excluded from the operating costs one-quarter of labor costs associated with
    the employees who performed both utility-services and merger-related work. Specifically, the
    Commission disallowed $637,000 as merger-related costs, which was one-quarter of the $2,546,000
    in labor costs that Effron had identified as unrecoverable. Thus, the Commission rejected GC
    Petitioners' proposal to disallow labor costs associated with those employees entirely, but the
    Commission did not allow ComEd to recover the costs in full, either. The Commission did not
    explain in detail how it chose the 25% deduction.
    On appeal, ComEd argues that the Commission's decision to exclude from the operating costs
    one-quarter of the costs attributed to the employees who performed utility-services as well as merger-
    related work is arbitrary and not supported by substantial evidence. The Commission responds that
    ComEd failed to prove that the employees at issue will not continue to handle both recoverable and
    unrecoverable work matters in the future. GC Petitioners do not renew their argument that the labor
    costs of the employees should be excluded entirely.
    The parties correctly agree that merger-related expenses are unrecoverable. Thus, the
    Commission's decision to exclude one-quarter of the challenged labor costs presents two issues: (1)
    -21-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    whether any of the labor costs are attributable to the merger and, (2) if so, how much should be
    excluded from the operating expenses component of the revenue requirement.
    In this case, the Commission's factual findings are adequate because they are specific enough
    to enable this court to make an informed and intelligent review of its order. See 220 ILCS 5/10--
    201(e)(iii) (West 2006); City of Chicago II, 281 Ill. App. 3d at 623-24. Moreover, the Commission
    heard substantial evidence to support excluding from the revenue requirement some of the challenged
    labor costs. Making a credibility determination, the Commission rejected ComEd's assertion that the
    employees performed no merger-related work during regular work hours, and the Commission
    expresses continued skepticism of ComEd's position on appeal. We agree with the Commission that
    "[a]lthough the Commission partially rejected GC Petitioners' proposed 100% disallowance of the
    labor costs for employees who allegedly spent unpaid overtime working on the merger, this does not
    mean that the Commission is obliged to accept a ComEd position which strains credulity; that the
    work performed by these salaried ComEd employees on merger issues for ComEd and its related
    affiliates was somehow a matter unrelated to their employment." Indeed, Houtsma and Frank
    testified for ComEd that the employees were required to perform the merger-related work as part of
    their employment. This court may neither reevaluate the credibility or weight of the evidence nor
    substitute its judgment for that of the Commission. ComEd, 398 Ill. App. 3d at 514. Substantial
    evidence supports the Commission's conclusion that at least some merger-related work was
    compensated and that ComEd might compensate additional work unrelated to delivery service in the
    future.
    The Commission did not explain in its order why it chose to disallow one-quarter of the
    challenged labor costs, rather than some other amount. The Commission argues that, once it
    -22-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    identifies a recoverable cost item, such as the labor costs related to the utility-services work
    performed by the employees, the Commission is not authorized to treat the expense as zero. See
    Central Illinois Public Service Co. v. Illinois Commerce Comm'n, 
    5 Ill. 2d 195
    , 208 (1955) ("when
    a proponent of a rate change has presented sufficient evidence of his present costs and other material
    factors, the Commission cannot refuse to pass upon the reasonableness of the proposed change
    merely because unavoidable uncertainties of economic forecasting make it difficult to project those
    current figures into the future").
    In arguing that we must affirm its calculation, the Commission cites Du Page Utility Co. v.
    Illinois Commerce Comm'n, 
    47 Ill. 2d 550
     (1971), for the proposition that, in the absence of evidence
    indicating an appropriate cost recovery from 100% recovery to 100% denial, the Commission is
    authorized to choose an appropriate amount. In Du Page Utility Co., the Commission disallowed as
    an operating expense one-half of the compensation of three company officers because the claimed
    compensation was excessive and out of proportion to the services performed. Du Page Utility Co.,
    
    47 Ill. 2d at 560
    . The utility challenged the deduction as arbitrary, but the supreme court called the
    argument facetious. The officers admitted that they had no previous experience in managing a utility,
    they had worked only part time, and they had maintained only minimal contact with the day-to-day
    operations. Du Page Utility Co., 
    47 Ill. 2d at 560
    . None of the officers could produce records of
    time spent at the utility business, none maintained an office there, and each was active as president
    of one of three different construction firms. Du Page Utility Co., 
    47 Ill. 2d at 560
    . Thus, the
    supreme court determined that "the Commission was correct in its finding that the larger salaries were
    not justified." Du Page Utility Co., 
    47 Ill. 2d at 560
    .
    -23-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    However, the supreme court rejected the intervenors' attempt to go further and disallow the
    officers' salaries entirely. Du Page Utility Co., 
    47 Ill. 2d at 561
    . The court concluded that such a
    result would be arbitrary and against the manifest weight of the evidence in light of the officers'
    uncontradicted testimony that they performed part-time services that added value to the company.
    Du Page Utility Co., 
    47 Ill. 2d at 561
    . Showing the Commission deference, the court affirmed the
    decision to disallow one-half of the compensation of the officers.
    Here, the Commission takes the position that it has wide latitude to use its "business
    judgment" to reach "pragmatic solutions" by filling gaps in the record. To the extent that the
    Commission's decisions are not arbitrary or capricious and are rooted in credibility determinations,
    we agree. In Du Page Utility Co., the supreme court affirmed the Commission's 50% deduction of
    certain labor costs even though the Commission did not set forth detailed reasons for why it chose
    that percentage. This case compels a similar result. While we might have found the unrecoverable
    merger-related labor costs to constitute a different percentage of the costs at issue, our deferential
    standard of review compels us to affirm the Commission's decision to deduct 25% of the challenged
    costs.
    B. Accumulated Depreciation of Existing Plant During Post-Test-Year Period:
    IIEC Appeal No. 1--08--3313
    As noted, the Administrative Code permitted ComEd to calculate its revenue requirement by
    beginning with costs incurred during a 12-month period known as a "test year," which may be either
    an historical or future period. See 83 Ill. Adm. Code §287.20, adopted at 
    27 Ill. Reg. 12380
    , 12382,
    eff. August 1, 2003. Using data from January 1, 2006, to December 31, 2006, as an historical test
    year, ComEd calculated its 2006 rate base, which is the plant investment used in setting rates, as
    -24-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    $5,572,917,000. ComEd used its gross plant investment, accumulated depreciation, and accumulated
    deferred income tax amounts to make the calculation.
    The Administrative Code allowed ComEd to make pro forma adjustments to its rate base,
    including additional plant investment that had occurred or is "reasonably certain to occur subsequent
    to the historical test year within 12 months after the filing date of the tariffs and where the amounts
    of the charges are determinable." 83 Ill. Adm. Code. §287.40, adopted at 
    27 Ill. Reg. 12380
    , 12384,
    eff. August 1, 2003. ComEd filed its tariffs on October 17, 2007, and thus was authorized to include
    pro forma adjustments from the end of the 2006 test year through the first three quarters of 2008.
    See 83 Ill. Adm. Code §287.40, adopted at 
    27 Ill. Reg. 12380
    , 12384, eff. August 1, 2003.
    ComEd's proposed pro forma adjustments increased the rate base by $1,498,317,000. The
    post-test-year adjustment represented mainly plant additions that ComEd planned to make from
    January 2007 through September 2008, which was the 21-month period following the test year.
    However, ComEd's increase in accumulated depreciation from January 2007 through September 2008
    related only to the new, pro forma plant additions. ComEd failed to account for the way the existing
    embedded plant would accrue additional accumulated depreciation during the post-test-year period.
    Factoring in this increase in accumulated depreciation would reduce the net value of ComEd's existing
    plant, which would create a corresponding reduction in the rate base.
    IIEC proposed an adjustment to recognize the increase in accumulated depreciation of the
    existing plant during the 21-month period of ComEd's planned plant additions. Michael Gorman, an
    IIEC expert, testified that ComEd's rate base must be adjusted to account for all known and
    measurable post-test-year changes to the test-year net plant investment. Gorman calculated that
    -25-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    ComEd's failure to make the matching adjustment would overstate the utility's rate base by
    $654,505,000, which would result in $93,560,000 in excessive rates per year.
    Effron, GC Petitioners' expert, opined that the growth in accumulated depreciation during the
    post-test-year period is a change that is known and measurable with absolute certainty. Therefore,
    he opined, it is "clearly inconsistent" for the rate base to reflect plant in service through the end of
    the post-test-year period but reflect a balance of accumulated depreciation only through the end of
    the test year.
    ComEd and the Staff reached a stipulation on the issue and submitted a recommendation to
    the Commission. According to the stipulation, ComEd would voluntarily elect not to seek recovery
    of the cost of plant additions made in the third quarter of 2008. ComEd and the Staff proposed an
    18-month post-test-year period of capital additions instead of the 21 months that ComEd had
    originally requested, and, in exchange, the Staff would recommend that, among other things, the
    Commission not subtract from the rate base the existing plant's accumulated depreciation during the
    post-test-year period. By its terms, the stipulation was effective only if the Commission approved
    all of its provisions.
    The ALJs who presided over the evidentiary phase of the case issued a proposed order to the
    Commission that would allow ComEd to include in its rate base the cost of post-test-year plant
    additions, but only "to the extent they exceed accumulated depreciation." In its September 10, 2008,
    order, the Commission allowed ComEd to include in its rate base the post-test-year plant additions
    but reversed the ALJs' recognition of the change in accumulated depreciation of the existing plant as
    an offset to the value of the post-test-year plant additions.
    -26-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    Consistent with the ComEd/Staff stipulation, the Commission's order included in the rate base
    "pro forma capital additions through June 2008 with no reflection of the increase in the accumulated
    reserve for depreciation on embedded [existing] plant." Thus, the Commission allowed ComEd to
    avoid the offset for accumulated depreciation of existing plant during the post-test-year period in
    exchange for forfeiting recovery of the cost of the third quarter 2008 plant additions.
    On November 7, 2008, two of the five Commissioners filed a dissenting opinion against the
    majority's refusal to account for the contemporaneous change in post-test-year accumulated
    depreciation. The dissent stated that deducting accumulated depreciation in the calculation of a rate
    base should prevent the utility from earning a further return on investment that has already been
    recovered through depreciation expense.         The dissent concluded that "the failure to record
    accumulated depreciation on existing embedded plant in the post-test-year period, in which additional
    plant is being factored into rate base, provides a windfall for the utility and provides an opportunity
    for the utility to over-earn between rate cases. This action clearly encourages other utilities to extend
    the duration of the test period as far as possible."
    IIEC agrees with the Commission's dissenting opinion. IIEC makes three related arguments
    in support of the conclusion that the Commission erroneously increased ComEd's rate base by failing
    to recognize the offset of post-test-year accumulated depreciation in the existing plant. First, IIEC
    argues that the Commission exceeded its authority because the rate base increase violates section 9--
    211 of the Act. Second, IIEC argues that the Commission violated sections 287.20 and 287.40 of
    title 83 of the Administrative Code, as well as established test-year principles, by mismatching 2008
    gross plant investment and 2006 test-year accumulated depreciation. Third, IIEC argues that the
    Commission's decision was distorted by its misapprehension that past decisions affected its duty and
    -27-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    authority to decide this case based only on the record before it. GC Petitioners concur in IIEC's
    position.
    1. Section 9--211 of the Act
    The Act requires the Commission to establish "just and reasonable" rates. 220 ILCS 5/9--101
    (West 2006). Section 9--211 of the Act provides that a utility's rate base may include "only the value
    of such investment which is both prudently incurred and used and useful in providing service to public
    utility customers." (Emphasis added.) 220 ILCS 5/9--211 (West 2006). To determine just and
    reasonable rates, a utility's rate base, operating costs, and revenues are matched over the test year.
    BPI II, 
    146 Ill. 2d at 237-38
    . Here, the dispute on the accumulated depreciation issue is not whether
    the planned plant additions will be used and useful, but how to measure the value of all the plant in
    service.
    Accumulated depreciation reduces plant investment at original cost by the decline in
    investment value recorded in the reserve for accumulated depreciation, and it is the basis for
    determining the capital cost component (rate of return x rate base) of the utility's revenue
    requirement. Heinz, ComEd's expert, testified that customers pay only for net plant, not for gross
    plant, which is the cost of the plant at the time of installation. Heinz admitted that ComEd had
    accounted for depreciation expense and that the accumulated depreciation reduces rate base.
    We agree with IIEC and GC Petitioners that the Commission departed from standard utility
    cost accounting when it used gross plant to measure ComEd's rate base in the new plant additions.
    In every context other than the post-test-year plant addition proposal, ComEd and the Staff calculated
    ComEd's rate base investment by offsetting gross plant investment with the accumulated depreciation
    on all plant in service. ComEd and the Staff accounted for accumulated depreciation for the existing
    -28-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    plant during the 2006 test year and for the plant additions during the post-test-year period, but they
    did not account for accumulated depreciation of the existing plant during the post-test-year period.
    We conclude that the Commission miscalculated the value of the plant investment by
    recognizing increases in rate base investment value due to post-test-year additions without
    recognizing contemporaneous offsetting decreases in the value of that investment attributable to
    ongoing depreciation. Section 9--211 essentially requires the Commission to ensure that a utility's
    approved rate base does not exceed the investment value that the utility actually uses to provide
    service. The measure of the amount of investment so dedicated must account for both increases and
    decreases over a consistent period. Under section 9--211, contemporaneous increases and decreases
    to rate base are not severable items that can be given disparate treatments. The utility's plant in
    service and net plant are opposing sides of a coin. The Commission approved a rate base that
    exceeds the investment value ComEd actually dedicates to utility services. The approval of excess
    rate base violates section 9--211 by overstating ComEd's revenue requirement. See 220 ILCS 5/9--
    211 (West 2006).
    2. The Administrative Code and Test-Year Principles
    IIEC argues that the Commission violated sections 287.20 and 287.40 of title 83 of the
    Administrative Code, as well as corresponding test-year principles, by mismatching 2008 gross plant
    investment and 2006 test year accumulated depreciation.
    The Commission's rules give a utility the discretion to request pro forma adjustments to
    historical data in the post-test-year period, but those adjustments must account for "all known and
    measurable changes." 83 Ill. Adm. Code §§287.20, 287.40, adopted at 
    27 Ill. Reg. 12380
    , 12382-84,
    eff. August 1, 2003. Specifically, the Administrative Code requires that the pro forma adjustments
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    1--08--3030, 1--08--3054, 1--08--3313 cons.
    to an historical test year "shall reflect changes affecting the ratepayers in plant investment, operating
    revenues, expenses, and cost of capital where such changes occurred during the selected historical
    test year or are reasonably certain to occur subsequent to the historical test year within 12 months
    after the filing date of the tariffs and where the amounts of the changes are determinable." (Emphasis
    added.) 83 Ill. Adm. Code §287.40, adopted at 
    27 Ill. Reg. 12380
    , 12384, eff. August 1, 2003. The
    increase in the accumulated depreciation on the existing plant during the post-test-year period, in
    which the additional plant is being factored into the rate base, is a change that affects ratepayers and
    therefore must be factored into the rate base. See 83 Ill. Adm. Code §287.40, adopted at 
    27 Ill. Reg. 12380
    , 12384, eff. August 1, 2003.
    Our conclusion is supported by BPI II. In that case, the utility argued that depreciation is not
    subject to test-year principles because, if those principles applied, utilities would be forced to choose
    between filing yearly rate cases or forgoing recovery of the costs of construction incurred during that
    year. BPI II, 
    146 Ill. 2d at 238-39
    . The supreme court disagreed, concluding that depreciation is
    subject to test-year principles for the following reasons:
    "The rationale for capitalizing construction costs does not mean that depreciation is
    not an expense. The plants have limited useful lives, and each year that a plant is in service
    a portion of its useful life is expended. Depreciation recognizes the cost of that portion of the
    asset which is expended in a given year, regardless of the time period in which the
    construction costs were actually paid. Thus, even though there is no cash outlay in the
    current year, depreciation is treated as an operating expense for financial reporting purposes,
    and more importantly for purposes of determining [the utility's] revenue requirement. For this
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    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    reason, we hold that depreciation is an expense subject to test-year principles." BPI II, 
    146 Ill. 2d at 239
    .
    Accumulated depreciation is simply the amount of a long-term asset's cost that has been
    allocated to depreciation expense since the asset was acquired. As depreciation of the asset's cost
    is treated as a recoverable operating expense, accumulated depreciation must also be recognized as
    a reduction to the rate base for that portion of plant investment and net salvage recouped from the
    rates. Consistent with the matching requirement, accumulated depreciation is subject to test-year
    principles because depreciation expense is subject to test-year principles. See BPI II, 
    146 Ill. 2d at 239
    . We agree with IIEC and GC Petitioners that ignoring the decline in value of the embedded plant
    during the post-test-year period artificially boosted the value of ComEd's rate base in violation of test-
    year principles.
    ComEd's reading of the test-year principles to exclude accumulated depreciation for the pro
    forma period creates an incentive for the utility to always seek upward pro forma adjustments,
    regardless of any decline in actual net plant, so the utility can recover an amount that ignores
    accompanying depreciation accumulating over the same period. This interpretation results in a
    consistently and unavoidably inflated rate base and an inescapably inaccurate picture of the utility's
    finances. ComEd's interpretation is plainly inconsistent with the Commission's treatment of plant
    investment where the utility adopts a future test year under section 287.20(b).                 ComEd's
    interpretation also is plainly inconsistent with basic matching principles. We hold that, under these
    circumstances, the Commission abused its discretion.
    3. Precedential Effect of the Commission's Prior Decisions
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    1--08--3030, 1--08--3054, 1--08--3313 cons.
    IIEC argues that the Commission's decision on the accumulated depreciation issue was
    distorted by its misapprehension that past decisions affected its duty and authority to decide this case
    exclusively on the record presented. GC Petitioners concur in IIEC's position. The Commission's
    decision, in part, relied upon three of its prior decisions: (1) docket No. 05-0597 (appealed in No.
    2--06--1284); (2) docket No. 01--0423; and (3) docket Nos. 07--0241 and 07--0242 (appealed in No.
    1--08--2055). The Commission referred to those decisions as "settled precedent" that barred
    departure from the one-sided post-test-year adjustments. The Commission feared that reaching a
    contrary result would invite a charge of acting arbitrarily and capriciously.
    Illinois courts have consistently held that "decisions of the Commission are not res judicata."
    See, e.g., A. Finkl & Sons Co. v. Illinois Commerce Comm'n, 
    250 Ill. App. 3d 317
    , 323 (1993). The
    concept of public regulation requires that the Commission have power to deal freely with each
    situation that comes before it, regardless of how it may have dealt with a similar or even the same
    situation in a previous proceeding. Mississippi River Fuel Corp. v. Illinois Commerce Comm'n, 
    1 Ill. 2d 509
    , 513 (1953). A record containing new evidence or argument that implicates past decisions
    compels reconsideration on the new record and may require a different result. See 220 ILCS 5/10--
    103 (West 2006) ("any finding, decision or order made by the Commission shall be based exclusively
    on the record for decision in the case"). Thus, we agree with IIEC that the decisions the Commission
    cited as precedent did not compel the Commission to disregard the increase in accumulated
    depreciation of the embedded plant during the post-test-year period.
    4. Remand
    In its appellate brief, ComEd anticipates the argument of IIEC and GC Petitioners that the
    Commission erred in failing to recognize the increase in the accumulated depreciation. ComEd
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    1--08--3030, 1--08--3054, 1--08--3313 cons.
    argues that, if we reverse any part of the Commission's approval of the stipulation, we must remand
    the cause to afford ComEd the opportunity to include in its rate base its third-quarter 2008 plant
    additions. ComEd contends that the exclusion of the additions can be sustained only under the
    conditions of ComEd's voluntary agreement with the staff not to include them. ComEd argues that,
    if the stipulation is voided, it would be "manifestly unfair" to exclude from the rate base plant
    additions that ComEd would be entitled to include. ComEd implies that we should remand the cause
    with directions for the Commission to add to the rate base the third-quarter 2008 plant additions
    because, according to ComEd, the same type of evidence that the Commission accepted as supporting
    ComEd's plant additions through the second quarter of 2008 also supports including ComEd's third-
    quarter additions.
    GC Petitioners respond that ComEd's voluntary forfeiture of the recovery of the third-quarter
    additions was a waiver of an earlier claim for greater recovery that was "strategically abandoned."
    Thus, GC Petitioners argue that we should remand the case with directions for the Commission to
    deduct from the rate base the accumulated depreciation that the Commission erroneously omitted,
    without allowing ComEd to petition for recovery of the third-quarter additions. While we agree that
    the Commission abused its discretion in failing to account for the accumulated depreciation of the
    existing plant during the post-test-year period, we conclude that unilaterally altering the ComEd/Staff
    stipulation would be manifestly unfair to ComEd.
    However, we also reject ComEd's proposal that we direct the Commission to include the
    third-quarter additions to the rate base. The Commission did not enter findings of fact regarding the
    third-quarter 2008 additions, and the Commission is the fact-finding body. BPI II, 
    146 Ill. 2d at
    196
    -33-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    ("In the ratemaking scheme, the Commission and not the court is the fact-finding body"). Apart from
    examining whether the Commission acted outside the scope of its authority or infringed upon a
    constitutional right, a court is limited to reviewing whether the Commission set out adequate findings
    of fact supporting its decision and whether the findings are against the manifest weight of the
    evidence. BPI II, 
    146 Ill. 2d at 196
    . Considering that the Commission has not had the opportunity
    to make findings of fact regarding the third-quarter 2008 plant additions, we decline to direct the
    Commission to take any action on remand other than allowing ComEd to petition for their inclusion
    in the rate base.
    C. Rider SMP: System Modernization Project:
    GC Petitioners (AG/CUB) Appeal Nos. 1--08--3008 & 1--08--3030
    GC Petitioners argue that the Commission erred in increasing ComEd's rate base. First, GC
    Petitioners echo IIEC's argument that the Commission violated its rules by failing to account for
    accumulated depreciation, resulting in unjust and unreasonable rates and an overvalued rate base, in
    violation of the Act. Second, GC Petitioners argue that a provision known as Rider SMP is contrary
    to settled ratemaking principles and is not justified by the evidence. We addressed the accumulated
    depreciation issue in the context of IIEC's appeal.
    ComEd proposed Rider SMP, a "system modernization project" charge to customers, to
    immediately recoup the costs of modernizing its delivery system toward a "smart grid." According
    to ComEd, the rider was new and innovative and created a mechanism for funding discretionary
    projects that are not necessary for the distribution service. One of the building blocks of the
    technology is advanced metering infrastructure (AMI), which consists of a communication system,
    advanced meters, and computer software and hardware to process the information collected from the
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    1--08--3030, 1--08--3054, 1--08--3313 cons.
    new meters. The first step toward an AMI system is a pilot program called "Phase 0," which involves
    installing 200,000 advanced meters. AMI would allow ComEd to achieve cost savings and improved
    efficiency by phasing out 675 full-time meter reader and supervisor positions, eliminating meter
    reading equipment, improving bill collections, reducing billing errors, and disconnecting nonpaying
    customers more efficiently. ComEd argued that Rider SMP would give customers the benefits of the
    technology earlier than might otherwise occur, because ComEd could not afford the project without
    the rider. As proposed, ComEd would provide the Commission with an annual list of projects for
    Rider SMP treatment. The Commission would have an opportunity to approve or deny recovery for
    each project, but the Commission could not alter the list.
    The Commission approved Rider SMP for the limited purpose of implementing Phase 0,
    commending ComEd for its initiative in pursuing a smart grid but criticizing ComEd for taking a
    project-by-project approach without a clear goal. The Commission noted that "[t]he estimates of cost
    in the record have varied greatly and the estimates of benefits have been sporadic at best." The
    Commission further found that "[t]he lack of a consistent, thorough analytic approach to estimating
    [smart grid] benefits simply highlights another shortcoming: ComEd is asking for special recovery
    for these projects that--whatever their level, all parties agree--could have long-term economic
    benefits, but as proposed, ratepayers do not share the economic benefits." The Commission ruled
    that, after the completion of Phase 0, ComEd may file Rider SMP again to seek recovery for
    additional smart grid investments.
    GC Petitioners argue that we must reverse the approval of Rider SMP because (1) Rider SMP
    violates the rule against single-issue ratemaking; (2) Rider SMP violates the rule against retroactive
    ratemaking; (3) Rider SMP violates test-year principles; and (4) ComEd did not prove that Rider
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    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    SMP is necessary. We conclude that the Commission committed reversible error because Rider SMP
    is not supported by substantial evidence. Rider SMP is a classic example of improper single-issue
    ratemaking because AMI is the type of cost that should be addressed through normal ratemaking
    procedures. Because we conclude that Rider SMP amounts to improper single-issue ratemaking, we
    need not consider GC Petitioners' alternative arguments for invalidating it.
    The rule against single-issue ratemaking makes it improper to consider in isolation changes
    in particular portions of a utility's revenue requirement. BPI II, 
    146 Ill. 2d at 244
    . The rule ensures
    that the utility's revenue requirement is based on the utility's aggregate costs and the demand on the
    utility, rather than on certain specific costs related to a component of its operation. BPI II, 
    146 Ill. 2d at 244
    .    Often a change in one item of the revenue-requirement formula is offset by a
    corresponding change in another component of the formula. For instance, certain expenses for one
    aspect of a utility's business may be offset by savings in another area, thus removing the need for
    greater revenue. BPI II, 
    146 Ill. 2d at 244
    ; Finkl, 250 Ill. App. 3d at 325. If rates are increased based
    solely on one factor, the ratemaking structure becomes distorted because there is no consideration
    of the changes to the other elements of the revenue formula, such as the operational savings from the
    improvements. BPI II, 
    146 Ill. 2d at 244
    .
    Single-issue ratemaking is prohibited because it considers changes in isolation, thereby
    ignoring potentially offsetting considerations and risking understatement or overstatement of the
    overall revenue requirement. Citizens Utility Board v. Illinois Commerce Comm'n, 
    166 Ill. 2d 111
    ,
    137 (1995). However, a rider, or automatic adjustment, can change a rate without requiring a utility
    to delay recovery until it files a general rate case. Citizens Utility Board, 166 Ill. 2d at 133. In its
    most recent pronouncement on the issue, the supreme court described riders as follows:
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    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    "[A] rider mechanism merely facilitates direct recovery of a particular cost, without direct
    impact on the utility's rate of return. The prohibition against single-issue ratemaking requires
    that, in a general base rate proceeding, the Commission must examine all elements of the
    revenue requirement formula to determine the interaction and overall impact any change will
    have on the utility's revenue requirement, including its return on investment. The rule does
    not circumscribe the Commission's ability to approve direct recovery of unique costs through
    a rider when circumstances warrant such treatment." Citizens Utility Board, 166 Ill. 2d at
    138.
    Because a rider is a method of single-issue ratemaking, by nature, it is not allowed absent a
    showing of exceptional circumstances. Finkl, 250 Ill. App. 3d at 326. The risk of single-issue
    ratemaking requires that all riders be closely scrutinized to prevent understatement or overstatement
    of the overall revenue requirement. City of Chicago II, 281 Ill. App. 3d at 627. However, the
    Commission has the power to authorize a rider in a proper case and such authorization will not be
    reversed absent an abuse of discretion. City of Chicago v. Illinois Commerce Comm'n, 
    13 Ill. 2d 607
    ,
    614 (1958) (City of Chicago I).
    1. City of Chicago I
    In City of Chicago I, the supreme court highlighted the Commission's discretion in selecting
    the means by which rates are set and costs are recovered and determining the appropriateness of the
    rider mechanism in certain circumstances. In that case, the intervenors contested an order approving
    the utility's tariff revision providing for a rider to reflect changes in its wholesale cost of natural gas.
    In approving the rider, the supreme court noted that the Act, taken as a whole, contemplates that the
    Commission's power is not limited to determining a mere charge or a particular rate; rather, the
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    1--08--3030, 1--08--3054, 1--08--3313 cons.
    Commission has the power to change, under certain conditions, any part of a rate schedule, rule, or
    regulation that in any manner affects the rates charged. City of Chicago I, 
    13 Ill. 2d at 611
    . The
    intervenors challenged the rider on the basis that the gas pipeline company, which purchased or
    produced the gas, was a subsidiary of the distributing company, and thus the distributing company
    had indirect control over the gas prices it paid. City of Chicago I, 
    13 Ill. 2d at 614
    . The supreme
    court rejected the argument, noting that wholesale gas prices were regulated by federal law that
    granted the Federal Power Commission authority to fix rates. City of Chicago I, 
    13 Ill. 2d at 614
    .
    2. Finkl
    In Finkl, the Commission approved a rider so the utility could recover costs associated with
    certain demand-side management programs. Finkl, 250 Ill. App. 3d at 319. The Commission
    concluded that the rider was the most appropriate method of recovery of the costs because " 'the
    actual expenses are difficult to predict in advance, especially given the fact that neither the
    Commission nor [the utility] has extensive experience in the implementation of [demand-side] analysis
    and programs, and may fluctuate from year to year and from month to month.' " Finkl, 250 Ill. App.
    3d at 322. The Appellate Court, First District, reversed, concluding that the rider violated the
    prohibition against single-issue ratemaking because the Commission had authorized the utility to
    charge customers for the demand-side management program costs without considering whether other
    factors offset the need for additional charges. Finkl, 250 Ill. App. 3d at 326. The order was an abuse
    of discretion because it isolated one operating expense for full recovery without considering whether
    changes in other expenses or increased sales and income obviated the need for increased charges to
    consumers. Failing to account for such an offset might have resulted in impermissibly charging
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    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    ratepayers more to cover the utility's expenses and pay a return to its investors. Finkl, 250 Ill. App.
    3d at 326.
    The costs covered by the rider in Finkl involved payroll for specifically identified planning and
    similar positions; personnel training, education, and travel; contractors' and consultants' costs;
    out-of-pocket promotion and computer costs; and conducting workshops. Finkl, 250 Ill. App. 3d
    at 327. The First District concluded that "[s]uch costs reveal no greater potential for unexpected,
    volatile or fluctuating expenses which [the utility] cannot control, than costs incurred in estimating
    base ratemaking." Finkl, 250 Ill. App. 3d at 327.
    3. CILCO
    In Central Illinois Light Co. v. Illinois Commerce Comm'n, 
    255 Ill. App. 3d 876
     (1993)
    (CILCO), the First District found that the Commission had not abused its discretion in allowing a
    rider mechanism for the utility to recover certain coal tar remediation costs. CILCO, 255 Ill. App.
    3d at 885. The court noted that the costs were expected to vary widely from year to year, depending
    on the type of remediation activities: from a few thousand dollars for investigation costs to millions
    of dollars for cleanup costs. The court viewed the costs as the type of unexpected, volatile, and
    fluctuating costs that are more efficiently addressed through a rider mechanism. CILCO, 255 Ill.
    App. 3d at 885.
    The CILCO court interpreted Finkl as holding simply that the Commission had abused its
    discretion in allowing a rider recovery mechanism for the demand-side management costs at issue.
    The CILCO court did not read Finkl broadly "as holding that the Commission does not have the
    authority to allow recovery of costs through riders." CILCO, 255 Ill. App. 3d at 885.
    4. City of Chicago II
    -39-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    In City of Chicago II, the city charged the utility a franchise fee for customers living within
    the municipality, and the utility recovered the expense through the general rates it charged all its
    customers. Finding the recovery unfair, the Commission ordered the utility to remove local franchise
    fees and other franchise costs from base rates for all its customers and to localize recovery of those
    costs by adding a separate line-item charge on the bills of customers who reside in the city. Under
    the order, residents of the city were to pay a pro rata share of the franchise fee that the city charged
    the utility, while residents of other municipalities were to pay their share of franchise costs imposed
    by their own municipalities. City of Chicago II, 281 Ill. App. 3d at 619.
    The First District affirmed the Commission's proposed restructuring of the rates, again noting
    that Finkl did not limit the use of a rider to only those cases where expenses are unexpected, volatile,
    or fluctuating. City of Chicago II, 281 Ill. App. 3d at 628. The court concluded that the rider was
    "a reallocation which did not have any impact whatsoever on [the utility's] overall revenue
    requirement." City of Chicago II, 281 Ill. App. 3d at 629. The court emphasized that the franchise
    fee already was included in the utility's overall rate structure and, therefore, the rider merely facilitated
    direct recovery of a particular cost, without direct impact on the utility's rate of return. City of
    Chicago II, 281 Ill. App. 3d at 629.
    5. Citizens Utility Board
    In Citizens Utility Board, the Commission approved a rider allowing electric utilities to
    recover expenses created by their liability under federal and state environmental law. The costs at
    issue were incurred to remediate environmental damage from coal tar residue found at former
    manufactured-gas-plant sites. Citizens Utility Board, 166 Ill. 2d at 116. Noting that a rider
    mechanism is effective and appropriate for cost recovery when a utility is faced with unexpected,
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    1--08--3030, 1--08--3054, 1--08--3313 cons.
    volatile, or fluctuating expenses, the supreme court concluded that using the rider mechanism, outside
    the context of a traditional rate proceeding, did not violate the prohibition against single-issue
    ratemaking. Citizens Utility Board, 166 Ill. 2d at 139. The court emphasized the Commission's
    finding that there were wide variations and difficulties in forecasting the costs of investigation and
    remediation activities. Citizens Utility Board, 166 Ill. 2d at 138. Thus, the court held that "riders can
    generally be expected to provide a more accurate and efficient means of tracking costs and matching
    such costs with recoveries than would base rate recovery methods." Citizens Utility Board, 166 Ill.
    2d at 138-39.
    From this line of cases, we glean a guiding principle for testing a rider's validity: the
    Commission has discretion to approve a utility's proposed rider mechanism to recover a particular
    cost if (1) the cost is imposed upon the utility by an external circumstance over which the utility has
    no control and (2) the cost does not affect the utility's revenue requirement. In other words, a rider
    is appropriate only if the utility cannot influence the cost (Citizen's Utility Board, 166 Ill. 2d at 138
    ("a rider mechanism is effective and appropriate for cost recovery when a utility is faced with
    unexpected, volatile, or fluctuating expenses")) and the expense is a pass-through item that does not
    change other expenses or increase income (Citizen's Utility Board, 166 Ill. 2d at 138 (a valid rider has
    no "direct impact on the utility's rate of return")).
    Our test reconciles the approval of diverse riders, including (1) a rider to recoup increases in
    the wholesale cost of natural gas, where the cost was set by a federal agency (City of Chicago I, 
    13 Ill. 2d at 614
    ); (2) a rider to recoup expenses for government-mandated environmental remediation
    (Citizens Utility Board, 166 Ill. 2d at 138-39; CILCO, 255 Ill. App. 3d at 885); and (3) a rider to
    recoup a franchise fee that a municipality charges the utility (City of Chicago II, 281 Ill. App. 3d at
    -41-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    628-29). In each instance, the expense was an externality imposed on the utility, and the expense was
    passed directly on to the consumer without affecting the utility's return on investment.
    Our test also explains the rejection of the rider for payroll expenses of demand-side
    management programs (Finkl, 250 Ill. App. 3d at 327). In Finkl, the rider was declared invalid
    because the proposed recovery was for expenses that were completely within the utility's control.
    Furthermore, the Commission had not considered whether changes in other expenses or increased
    sales and income obviated the need for the added charges to customers. Finkl, 250 Ill. App. 3d at
    326.
    Rider SMP does not meet the criteria to warrant single-issue ratemaking. The expenses
    related to AMI and the smart grid technologies, including Phase 0, are not unexpected, volatile, or
    fluctuating, as ComEd alone dictates the program's scope and, therefore, its costs. The capital costs
    associated with AMI and the smart grid technologies are not the result of legislative mandate, but
    rather are the result of ComEd's decision to innovate to reduce other costs. ComEd can cover the
    expenses by a fiscal and operational plan that is completely within the utility's control. The
    Commission heard no evidence that the system modernization costs might produce unacceptable
    financial outcomes if not afforded special treatment.
    In fact, ComEd proposed Rider SMP precisely because the improvements are expected to
    reduce other expenses and increase income in the long term, which affects the utility's revenue
    requirement. To allow Rider SMP would be to improperly consider in isolation changes in a
    particular portion of a utility's revenue requirement. See BPI II, 
    146 Ill. 2d at 244
    . The system
    modernization program is desirable precisely because the increased costs would be more than offset
    by a positive, corresponding change in another component of the revenue requirement formula.
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    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    Increasing the rates based solely on the costs of the program would distort the ratemaking structure.
    See BPI II, 
    146 Ill. 2d at 244
    . The evidence showed that ComEd historically has invested in capital
    distribution improvements and recouped those costs through traditional ratemaking procedures, and
    the system modernization program should be treated no differently.            We conclude that the
    Commission abused its discretion, and we reverse Rider SMP because it constitutes improper single-
    issue ratemaking that is not justified by any special circumstances. See Finkl, 250 Ill. App. 3d at 327
    (the Commission erred as a matter of law in allowing rider costs normally recovered through the usual
    ratemaking procedure).
    D. Rider 25: Nonresidential Space-heating Customers:
    BOMA Appeal No. 1--08--3054
    In 2006, the Commission allowed the termination of a provision known as Rider 25, and
    BOMA appealed to this court. ComEd, 398 Ill. App. 3d at 522. Rider 25 had established a
    preferential rate for certain nonresidential space-heating customers, including BOMA's members.
    Instituted at a time when ComEd generated electricity, Rider 25 was created to encourage the use
    of electricity during the off-peak, winter months to balance usage with the peak summer months when
    air conditioning is widely used. The goal was for ComEd's power plants to operate at peak efficiency
    throughout the year.
    When the Commission eliminated Rider 25, the rates charged to BOMA members were
    increased to match those paid by other customers. Pointing out that numerous building owners had
    equipped their buildings with electric space heaters in reliance on Rider 25, BOMA argued that
    paying the new rates would result in "rate shock" and that the alternative of replacing the current
    -43-
    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    heating systems with nonelectrical systems would be prohibitively expensive. ComEd, 398 Ill. App.
    3d at 522.
    We affirmed the Commission's decision to do away with Rider 25. ComEd, 398 Ill. App. 3d
    at 527. We emphasized the undisputed evidence that, because ComEd no longer generates electricity,
    ComEd's costs to deliver electricity are the same at all times during the year. The end-use
    characteristics of ComEd's customers do not affect its costs of providing delivery service. ComEd,
    398 Ill. App. 3d at 526.
    In this rate case, BOMA proposed that the Commission reinstate Rider 25, thereby creating
    a rate structure that differentiates between nonresidential customers depending on whether they use
    electricity for space heating. ComEd responded that doing so would give space-heating customers
    an unwarranted rate subsidy that would not reflect the cost of service.
    The Commission approved rates that differentiate residential customer classes based on their
    use of electric space heating. BOMA requested and was denied similar treatment for nonresidential
    customers. The Commission rejected BOMA's proposal to establish a separate class or distribution
    charge for nonresidential electric space-heating customers, finding that Rider 25 was not cost justified
    and should not be reinstated. The Commission concluded as follows:
    "ComEd no longer has generating capacity and Rider 25 has been eliminated. Supply
    charges are not the subject of this proceeding. There is no evidence that delivery service
    costs vary seasonally. The record shows that distribution facilities must be planned and built
    to meet customers' maximum loads, regardless of when those may occur. There is no basis
    in this record to conclude that it costs ComEd less to serve nonresidential customers who use
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    1--08--3030, 1--08--3054, 1--08--3313 cons.
    some of their electric service for space heating. Nor is there a public policy issue which
    would justify a deviation from a cost causing allocation."
    BOMA revisits Rider 25 in this appeal. BOMA argues that the Commission's order violates
    the Act by increasing the rates ComEd charges to BOMA's nonresidential electric space-heating
    members. First, BOMA argues that the change amounts to unreasonable discrimination between
    classes of service. Second, BOMA argues that the change is not justified on the basis of cost. Third,
    BOMA argues that the nonresidential space-heating customers are improperly subsidizing nonspace-
    heating customers within the same customer class. Finally, BOMA contends that the Commission
    failed to consider BOMA's substantial evidence to support these theories.
    The Commission's evidentiary conclusion is prima facie true (see 220 ILCS 5/10--201(d)
    (West 2006)), and we defer to its factual findings. To obtain a reversal of the Commission's findings
    on this issue, BOMA must prove that the opposite conclusion is clearly evident. Continental Mobile
    Telephone Co. v. Illinois Commerce Comm'n, 
    269 Ill. App. 3d 161
    , 171 (1994). For the following
    reasons, we conclude that BOMA has failed to meet this burden.
    1. Sufficiency of the Evidence
    We first address BOMA's last issue: whether the Commission's rejection of Rider 25 is
    supported by substantial evidence. The Commission placed nonresidential space-heating and
    nonspace-heating customers in the same rate class based on the factual finding that there is no
    evidence that it costs ComEd less to deliver electricity to nonresidential space-heating customers than
    to nonresidential nonspace-heating customers.
    Paul Crumrine, ComEd's then-director of regulatory strategies and services, testified regarding
    the history and purpose of Rider 25, why it is no longer necessary, and how reinstating it would
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    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    create an unfair subsidy for BOMA's members. Crumrine stated that Rider 25 is a relic from the pre-
    restructuring era when electricity came from generators owned by ComEd, when electricity supply
    costs at those plants were significantly lower in the winter, and when both supply and delivery costs
    were recovered under a single, "bundled" charge. Supply and delivery rates are now priced and
    regulated separately, or "unbundled," and any seasonal differences in energy costs should be reflected
    only in supply charges, not in the delivery rates set by the Commission in this case. He also opined
    that space-heating customers' higher winter use does not affect their delivery costs. Distribution
    facilities must be planned and built to meet customers' maximum use, regardless of the season in
    which it occurs or whether that energy is being used for space heat or for some other purpose. As
    a result, the costs of distribution service are not lower for nonresidential space-heating customers.
    Crumrine concluded that, whatever sense Rider 25 might have made before deregulation, when
    ComEd owned generation facilities and the costs of power production varied seasonally, Rider 25
    is no longer justified by cost. Reinstating Rider 25 would, therefore, create an unjustified subsidy of
    nonresidential space-heating customers. The Commission was free to base its factual finding on
    Crumrine's testimony, the Commission's finding deserves deference, and we conclude that the decision
    is supported by substantial evidence.
    2. Discrimination Claim
    Section 9--241 of the Act provides that no public utility shall, as to rates or other charges,
    services, facilities, or any other respect, make or grant any preference or advantage to any
    corporation or person or subject any corporation or person to any prejudice or disadvantage; and no
    public utility shall establish or maintain any unreasonable difference as to rates or other charges,
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    1--08--3030, 1--08--3054, 1--08--3313 cons.
    services, facilities, or any other respect, either as between localities or as between classes of service.
    220 ILCS 5/9--241 (West 2006).
    BOMA argues that, by not differentiating the nonresidential customer classes based on space-
    heating use, the Commission approves discriminatory treatment between rates and classes of
    customers, in violation of section 9--241 of the Act. In support of this position, BOMA points to
    evidence that, as to residential customers, it costs less to deliver electricity to space-heating customers
    than to nonspace-heating customers. The difference in the delivery cost results in different rates for
    the two classes of residential customers: the space-heating customers pay less than the nonspace-
    heating customers. BOMA argues that Rider 25 is necessary to carry over the same rate differential
    to nonresidential customers so that the space-heating customers pay less than the nonspace-heating
    customers.
    The Commission responds that BOMA did not demonstrate that residential and nonresidential
    space-heating customers share characteristics that affect the cost of delivery. Simply because certain
    residential and nonresidential customers may use some of their electricity for space heat does not
    establish that the other uses by the two groups are sufficiently alike that the rate differential should
    apply to both. The Commission emphasizes evidence that the facilities charge for a residential space-
    heating customer is less than for a residential nonspace-heating customer, which creates two different
    revenue requirements for ComEd. The difference in the revenue requirements for the two classes of
    residential customers is rooted in the number of customers and their usage. The Commission stated
    in its order that the record is devoid of evidence that it costs ComEd less to supply electricity to
    nonresidential space-heating customers than to nonresidential nonspace-heating customers, and we
    defer to that factual finding.
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    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    3. Cost Justification
    BOMA argues that the rate increases for nonresidential space-heating customers are not
    justified on the basis of cost. BOMA again cites the reduced cost to supply electricity to residential
    space-heating customers as a reason for charging less to nonresidential space-heating customers,
    including BOMA's members. BOMA states that it "submitted uncontroverted evidence that parallels
    are apparent for the nonresidential customers, and nonresidential customers that heat with electric
    spaceheat pay more for electricity on a per unit basis than customers that heat with some other fuel
    source." However, BOMA's citation to the record for this proposition is not to evidence at all; it is
    to the argument portion of a pleading, presented to the Commission, that a cost differential for the
    two classes of nonresidential customers may be inferred from the data available for the two classes
    of residential customers.
    BOMA has never presented empirical data that the cost of delivering electricity to a
    nonresidential customer varies based on the customer's use of some of that electricity for space heat.
    Apparently, such data is available to show the cost differential for residential customers, and BOMA
    does not assert that data for nonresidential customers cannot also be collected. Rather than focusing
    on measurable delivery costs, BOMA relies on evidence that its nonresidential space-heating members
    have incurred a steep increase in energy costs since the elimination of Rider 25. However, it is
    undisputed that Rider 25 established a subsidy for BOMA's members such that the rates charged were
    not based on the costs of delivery. Thus, the evidence of the rate increase is consistent with the
    elimination of Rider 25, in that rates were brought in line with actual delivery costs. The rate increase
    is not proof that the former treatment of nonresidential space-heating customers was based on the
    costs of delivery and the current treatment is not.
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    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    The Commission asserts that the new rates are based on costs, and the Commission stated in
    its order that delivery costs no longer vary seasonally. The record shows that delivery facilities must
    be planned and built to meet customers' maximum loads whenever they occur, and there is no basis
    to conclude that it costs ComEd less to deliver electricity to nonresidential customers if they use some
    of the electricity for space heat. ComEd witnesses Alongi and Jones testified that there was
    "absolutely no cost based justification" to set nonresidential distribution facilities charges as BOMA
    had proposed. Thus, when the rates are the same for all nonresidential customers--regardless of
    whether they use space heat--the rates are based on costs.
    4. Subsidization Claim
    BOMA also argues that the elimination of Rider 25 has resulted in nonresidential space-
    heating customers improperly subsidizing other nonresidential customers who do not use space heat.
    The Commission determined that it costs the same to deliver electricity to all nonresidential customers
    and, therefore, the nonresidential customers all pay the same rate. The Commission heard substantial
    evidence from which to draw this conclusion. The space-heating customers pay more for electricity
    simply because they use more electricity than nonspace-heating customers. Therefore, there is no
    improper subsidy. The Commission could rely on ComEd's testimony that, since ComEd no longer
    generates electricity, there is no longer a reason to charge nonresidential space-heating customers less
    than nonresidential nonspace-heating customers, and to do so would actually amount to an improper
    subsidy in itself. Also, the Commission could rely on ComEd's testimony that it did not analyze
    BOMA's proposed discount because it was based on an outdated cost of service study.
    CONCLUSION
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    Nos. 2--08--0959, 2--08--1037, 2--08--1137, 1--08--3008,
    1--08--3030, 1--08--3054, 1--08--3313 cons.
    We hold that (1) the Commission heard substantial evidence to support excluding from the
    operating costs 25% of the challenged labor costs for ComEd employees who worked on both utility-
    delivery services and merger work; (2) the Commission abused its discretion in excluding from the
    rate base the increase in accumulated depreciation of existing plant during the post-test-year period;
    (3) the Commission abused its discretion in approving Rider SMP, because the rider amounts to
    improper single-issue ratemaking; and (4) the Commission did not abuse its discretion in rejecting
    Rider 25, because the rider was not cost justified and would have improperly subsidized
    nonresidential customers who use space heat. We remand the cause for the Commission to revisit
    the accumulated depreciation issue, including allowing ComEd to request recovery of the aggregate
    cost of the third-quarter 2008 plant additions. We express no opinion as to whether the Commission
    should include in the rate base those costs, but we note that ComEd has the burden of proof on
    remand.
    For the preceding reasons, the decision of the Commission is affirmed in part and reversed
    in part, and the cause is remanded for further proceedings consistent with this opinion.
    Affirmed in part and reversed in part; cause remanded.
    HUTCHINSON and HUDSON, JJ., concur.
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