
8 N.Y.3d 591 (2007)
869 N.E.2d 634
838 N.Y.S.2d 458
In the Matter of CONSOLIDATED EDISON COMPANY OF NEW YORK, INC., Respondent,
v.
CITY OF NEW YORK et al., Appellants.
Court of Appeals of the State of New York.
Argued May 2, 2007.
Decided June 5, 2007.
*592 Michael A. Cardozo, Corporation Counsel, New York City (Paul T. Rephen, Rita D. Dumain and Robert J. Paparella of counsel), for appellants.
*593 Podell, Schwartz, Schechter & Banfield, LLP, New York City (Gary Schuller and William E. Banfield of counsel), for respondent.
James J. O'Keeffe, Albany, and Philip G. Hembdt for New York State Board of Real Property Services, amicus curiae.
*594 Donna M.C. Giliberto, Albany, and A. Kevin Crawford for the Association of Towns of the State of New York and another, amici curiae.
Judges CIPARICK, GRAFFEO, READ, SMITH, PIGOTT and JONES concur.

OPINION OF THE COURT
Chief Judge KAYE.
The issue before us in this tax certiorari proceeding is whether functional obsolescence due to excess construction costs was appropriately considered in fixing the value of certain speciality *595 property. On the particular record before us, we agree with the trial court and Appellate Division that it was.
Petitioner Consolidated Edison Company of New York, Inc. (Con Edison) brought this tax certiorari proceeding pursuant to RPTL article 7 challenging the City of New York's assessments on its Arthur Kill electric generating station for the tax years 1994/1995 through 1998/1999. The generating station is comprised of two steam generating units (installed in 1959 and 1969) and one gas turbine (installed in 1970).
At a bench trial, the parties agreed that, as an electrical generating facility, the subject property is considered a "specialty" and should therefore be appraised using the Reproduction-Cost-New-Less-Depreciation (RCNLD) method of valuation. This method seeks to determine the value of a property by estimating the cost to construct a replica using the same materials and techniques as the subject facility (reproduction cost), less depreciation. The parties differed, however, as to whether functional obsolescence due to excess construction costs could be subtracted from the reproduction cost as a component of depreciation. Functional obsolescence due to excess construction costs is the difference between the property's reproduction cost and the cost of replacing the existing property with a facility of similar productive capacity using modern materials and technology (replacement cost).
Con Edison's expert included the value of functional obsolescence due to excess construction costs, lowering the appraisal for tax assessment purposes. Although the City's expert did not include this factor in his appraisal, which was significantly higher, he conceded on cross-examination that in conducting a reproduction cost valuation, appraisers typically consider functional obsolescence due to excess construction costs. Indeed, the only reason he did not do so in this instance was counsel's instruction that under New York law it would be improper. In his view, an appraisal that allowed for functional obsolescence due to excess construction costs would still be considered a proper reproduction cost appraisal under industry standards, even if it yielded a result consistent with replacement cost.
Supreme Court adopted Con Edison's calculation and a divided Appellate Division affirmed. The City appeals as of right based on the two-Justice dissent. We now affirm.
The valuation of assessed property is, of course, essentially a question of fact, the courts' principal task being to discern the *596 most accurate estimation of value for the specific property before it. Thus, where, as here, "the determinations of value made at nisi prius have been affirmed at the Appellate Division, those valuations must be upheld unless there has been an error of law in the use of an erroneous theory of valuation or unless the record does not contain evidence to support them" (Matter of B. Altman & Co. v City of White Plains, 57 NY2d 904, 905-906 [1982]).
The City argues that the trial court and Appellate Division erred as a matter of law by accepting Con Edison's use of functional obsolescence due to excess construction costs in calculating depreciation. According to the City, no such measure should be included under the RCNLD method because, in doing so, the appraiser effectively substitutes the established reproduction cost methodwhich looks to the value of the current property on the taxable status daywith a replacement cost method focused on the value of a hypothetical future facility.
While recognizing that the RCNLD method should be utilized for valuing speciality property, we have not previously considered whether functional obsolescence due to excess construction costs can be included under that method (see e.g. Matter of Brooklyn Union Gas Co. v State Bd. of Equalization & Assessment, 65 NY2d 472, 485 [1985]; Matter of Allied Corp. v Town of Camillus, 80 NY2d 351, 356-360 [1992]). In the context of this case, however, we conclude that the City's arguments are misplaced. We cannot hold that the theory of valuation adopted by the courts below was erroneous as a matter of law.
The City's expert witness agreed that functional obsolescence due to excess construction costs is in fact a proper element of depreciation under the reproduction cost methodology, even in cases where it yields a valuation consistent with replacement cost. Moreover, Con Edison's appraisal methodology finds support in the relevant appraisal literature (see Appraisal Institute, The Appraisal of Real Estate ch 14 ["The Cost Approach"], ch 16 ["Depreciation Estimates"] [12th ed 2001]). Indeed, we have previously noted that one problem often identified with RCNLD valuation is "its tendency to ascribe too little weight to such factors as ... functional obsolescence" (Town of Camillus, 80 NY2d at 357). Thus, allowing for increased consideration of functional obsolescence may, in the appropriate case, further the purpose of valuation proceedingsto arrive at a fair and realistic appraisal of the value of the property at issue (see Matter of Saratoga Harness Racing v Williams, 91 NY2d 639, 643 [1998]).
*597 That being said, we do not adopt a rule that functional obsolescence due to excess construction costs is an appropriate consideration in every tax assessment matter where RCNLD is the applicable method. To the contrary, valuation remains largely a question of fact, and the courts have considerable discretion in reviewing the relevant evidence as to the specific property before them. Here, we find no legal error in that review.
Accordingly, the judgment appealed from and order of the Appellate Division brought up for review should be affirmed, with costs.
Judgment appealed from and order of the Appellate Division brought up for review affirmed, with costs.
