An appraisal is an unbiased professional opinion of a home's value. Appraisals are almost always used in purchase and sale transactions and commonly used in refinance transactions. In a purchase and sale transaction, an appraisal is used to determine whether the home's contract price is appropriate given the home's condition, location, and features. In a refinance, it assures the lender that it isn't handing the borrower more money than the home is worth.
In New Zealand, the terms "valuation" and "valuer" usually relates to one who undertakes that professional role in terms of the Valuer Act 1948 requirements or the unregulated or voluntarily self-regulated (if members of PINZ) plant and machinery, marine or art valuers. Whereas, the term "appraisal" is usually related to an estimate by a real estate sales person or licensed agent under the Real Estate Agents Act 2008. The Real Estate Institute of New Zealand includes many valuer members, but the governing legislation for sales and agency (disposal of interests of land on behalf of others) does not extend to include provision for that role by valuers regardless of membership of NZIV, RICS or PINZ.
In the United States, appraisals are for a certain type of value (e.g., foreclosure value, fair market value, distressed sale value, investment value). The most commonly used definition of value is Market Value. While Uniform Standards of Professional Appraisal Practice (USPAP) does not define Market Value, it provides general guidance for how Market Value should be defined:
Automated valuation models (AVMs) are growing in acceptance. These rely on statistical models such as multiple regression analysis, machine learning algorithms or geographic information systems (GIS). While AVMs can be quite accurate, particularly when used in a very homogeneous area, there is also evidence that AVMs are not accurate in other instances such as when they are used in rural areas, or when the appraised property does not conform well to the neighborhood.
Unlike appraisers, assessors have no federal requirement for certification. In states that mandate certification for assessors, the requirements are usually similar to those for appraisers. For example, the International Association of Assessing Officers (IAAO) offers the Certified Assessment Evaluator (CAE). This designation covers topics that include property valuation for tax purposes, property tax administration, and property tax policy. Applicants are required to have a bachelor's degree prior to obtaining the designation.
These appraisers also perform valuations on commercial property ranging from single to multiple tenant office buildings, shopping centers, retail, industrial, malls, hospitals, health care facilities, warehouses, and hotels to multi-family apartment buildings, co-ops, senior housing, condominium developments, and even vacant land, agricultural, and golf courses. Regardless of the property type or local zoning, they'll determine the highest and best use of the project and assess the value using the actual or projected cash flow from the property's rent roll and financial statements, using both cap rates for capitalizing year one net operating income (NOI) and discounted cash flow (DCF) of multiple future income streams. If you're a commercial lender, investor, builder, contractor, architect, or agent, you'll want to use these appraisers to conduct a feasibility analysis of any income producing real estate project you may be considering. They can also help consult on construction costs and projected absorption rates. They generally produce a commercial narrative appraisal when engaged for any commercial assignment.