ASTM E1121-2007e1 Standard Practice for Measuring Payback for Investments in Buildings and Building Systems《建筑物和建筑物系统的投资回报率测算的标准实施规程》.pdf
《ASTM E1121-2007e1 Standard Practice for Measuring Payback for Investments in Buildings and Building Systems《建筑物和建筑物系统的投资回报率测算的标准实施规程》.pdf》由会员分享,可在线阅读,更多相关《ASTM E1121-2007e1 Standard Practice for Measuring Payback for Investments in Buildings and Building Systems《建筑物和建筑物系统的投资回报率测算的标准实施规程》.pdf(9页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: E 1121 071Standard Practice forMeasuring Payback for Investments in Buildings andBuilding Systems1This standard is issued under the fixed designation E 1121; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTESection 2.2 was editorially corrected in January 2009.1. Scope1.1 This practice provides a recommended procedure forcalculati
3、ng and applying the payback method in evaluatingbuilding designs and building systems.2. Referenced Documents2.1 ASTM Standards:2E 631 Terminology of Building ConstructionsE 833 Terminology of Building EconomicsE 917 Practice for Measuring Life-Cycle Costs of Buildingsand Building SystemsE 964 Pract
4、ice for Measuring Benefit-to-Cost and Savings-to-Investment Ratios for Buildings and Building SystemsE 1057 Practice for Measuring Internal Rate of Return andAdjusted Internal Rate of Return for Investments in Build-ings and Building SystemsE 1074 Practice for Measuring Net Benefits and Net Sav-ings
5、 for Investments in Buildings and Building SystemsE 1185 Guide for Selecting Economic Methods for Evalu-ating Investments in Buildings and Building Systems2.2 Adjuncts:Discount Factor Tables Adjunct to Practices E 917, E 964,E 1057, E 1074, and E 112133. Terminology3.1 DefinitionsFor definitions of
6、terms used in thispractice, refer to Terminologies E 631 and E 833.4. Summary of Practice4.1 This practice is organized as follows:4.1.1 Section 2, Referenced DocumentsLists ASTM stan-dards and adjuncts referenced in this practice.4.1.2 Section 3, DefinitionsAddresses definitions of termsused in thi
7、s practice.4.1.3 Section 4, Summary of PracticeOutlines the con-tents of the practice.4.1.4 Section 5, Significance and UseExplains the signifi-cance and use of this practice.4.1.5 Section 6, ProceduresDescribes step-by-step theprocedures for making economic evaluations of buildings.4.1.6 Section 7,
8、 Objectives, Alternatives, and ConstraintsIdentifies and gives examples of objectives, alternatives, andconstraints for a payback evaluation.4.1.7 Section 8, Data and AssumptionsIdentifies dataneeded and assumptions that may be required in a paybackevaluation.4.1.8 Section 9, Compute Payback PeriodP
9、resents alter-native approaches for finding the payback period.4.1.9 Section 10, ApplicationsExplains the circumstancesfor which the payback method is appropriate.4.1.10 Section 11, LimitationsDiscusses the limitations ofthe payback method.5. Significance and Use5.1 The payback method is part of a f
10、amily of economicevaluation methods that provide measures of economic perfor-mance of an investment. Included in this family of evaluationmethods are life-cycle costing, benefit-to-cost and savings-to-investment ratios, net benefits, and internal rates of return.5.2 The payback method accounts for a
11、ll monetary valuesassociated with an investment up to the time at which cumu-lative net benefits, discounted to present value, just pay offinitial investment costs.5.3 Use the method to find if a project recovers its invest-ment cost and other accrued costs within its service life orwithin a specifi
12、ed maximum acceptable payback period(MAPP) less than its service life. It is important to note that thedecision to use the payback method should be made with care.(See Section 11 on Limitations.)1This practice is under the jurisdiction of ASTM Committee E06 on Perfor-mance of Buildings and is the di
13、rect responsibility of Subcommittee E06.81 onBuilding Economics.Current edition approved April 1, 2007. Published April 2007. Originallyapproved in 1986. Last previous edition approved in 2002 as E 1121 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer
14、Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from ASTM International Headquarters. Order No. ADJE091703.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
15、 PA 19428-2959, United States.6. Procedures6.1 The recommended steps for making an economic evalu-ation of buildings or building components are summarized asfollows:6.1.1 Identify objectives, alternatives, and constraints,6.1.2 Select an economic evaluation method,6.1.3 Compile data and establish as
16、sumptions,6.1.4 Convert cash flows to a common time basis, and6.1.5 Compute the economic measure and compare alterna-tives.6.2 Only the step in 6.1.5, as applied to measuring payback,is examined in detail in this practice. For elaboration on thesteps in 6.1.1-6.1.4, consult Practices E 964 and E 917
17、, andGuide E 1185.7. Objectives, Alternatives, and Constraints7.1 Specify the kind of building decision to be made. Makeexplicit the objectives of the decision maker. And identify thealternative approaches for reaching the objectives and anyconstraints to reaching the objectives.7.2 An example of a
18、building investment problem thatmight be evaluated with the payback method is the installationof storm windows. The objective is to see if the costs of thestorm windows are recovered within the MAPP. The alterna-tives are (1) to do nothing to the existing windows or (2)toinstall storm windows. One c
19、onstraint might be limited avail-able funds for purchasing the storm windows. If the paybackperiod computed from expected energy savings and windowinvestment costs is equal to or less than the specified MAPP,the investment is considered acceptable using this method.7.3 Whereas the payback method is
20、appropriate for solvingthe problem cited in 7.2, for certain kinds of economicproblems, such as determining the economically efficient levelof insulation, Practices E 917 and E 1074 are the appropriatemethods.8. Data and Assumptions8.1 Data needed to make payback calculations can becollected from pu
21、blished and unpublished sources, estimated,or assumed.8.2 Both engineering data (for example, heating loads,equipment service life, and equipment efficiencies) and eco-nomic data (for example, tax rates, depreciation rates andperiods, system costs, energy costs, discount rate, project life,price esc
22、alation rates, and financing costs) will be needed.8.3 The economic measure of a projects worth variesconsiderably depending on the data and assumptions. Usesensitivity analysis to test the outcome for a range of the lesscertain values in order to identify the critical parameters.9. Compute Payback
23、Period9.1 The payback method finds the length of time (usuallyspecified in years) between the date of the initial projectinvestment and the date when the present value of cumulativefuture earnings or savings, net of cumulative future costs, justequals the initial investment. This is called the payba
24、ck period.When a zero discount rate is used, this result is referred to asthe “simple” payback (SPB). The payback period can bedetermined mathematically, from present-value tables, orgraphically.9.2 Mathematical Solution:9.2.1 To determine the payback period, find the minimumsolution value of PB in
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