1.1 本指南涵盖了处理建筑投资项目经济分析输入值不确定性的技术。它还推荐了评估项目经济结果低于预期或预期的风险的技术。 2. 1.2 这些技术包括盈亏平衡分析、敏感性分析、风险调整贴现、均值-方差标准和变异系数、决策分析、模拟和随机优势。 1.3 这些技术可以与衡量经济表现（如寿命）的经济方法结合使用- 周期成本分析、净效益、效益成本比、内部收益率和回收。 1.4 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 建筑物等长寿命项目的投资具有项目寿命、运营和维护成本、收入以及影响项目经济性的其他因素的不确定性。 由于这些可变因素的未来值通常未知，因此很难进行可靠的经济评估。 5.2 项目投资分析的传统方法是将项目评估的经济方法应用于项目输入变量的最佳猜测估计，就像它们是某些估计一样，然后以单值确定性术语表示结果。当评估项目时，不考虑分析输入的不确定性，决策者可能没有足够的信息来衡量和评估投资结果与预期不同的项目的风险。 5.3 风险分析是一套理论和实践，旨在帮助决策者评估其风险敞口和风险态度，从而选择最适合他们的投资。 注1: 决策者是指负责投资决策的个人或群体。例如，决策者可能是首席执行官或董事会。 5.4 不确定性和风险定义如下。不确定性（或确定性）是指对经济分析的可变输入的知识状态。 如果决策者不确定输入值，则存在不确定性。如果决策者确信，那么就有了确定性。风险是指风险暴露或风险态度。 5.4.1 风险敞口是指投资于经济结果低于预期（目标）或预期的项目的概率。 5.4.2 风险态度，也称为风险偏好，是指决策者愿意冒险或对结果不确定的投资进行赌博。具有不同风险态度的决策者的含义是，已知风险敞口的给定投资可能在经济上为不特别厌恶风险的投资者所接受，但为另一个非常厌恶风险的投资者所完全无法接受。 注2: 为完整起见，本指南涵盖了风险厌恶和风险承担态度。然而，大多数投资者很可能厌恶风险。本文描述的原则既适用于投资者具有不同程度风险厌恶的典型情况，也适用于一些投资者承担风险而其他投资者规避风险的非典型情况。 5.5 在处理不确定性、风险或两者的每种情况下，没有任何一种技术可以被称为最佳技术。什么是最好的取决于以下方面:数据的可用性、资源的可用性（时间、金钱、专业知识）、计算辅助工具（例如，计算机服务）、用户理解、衡量风险暴露和风险态度的能力、决策的风险态度- 制造商、项目的风险敞口水平以及相对于机构投资组合的投资规模。

1.1 This guide covers techniques for treating uncertainty in input values to an economic analysis of a building investment project. It also recommends techniques for evaluating the risk that a project will have a less favorable economic outcome than what is desired or expected. 2 1.2 The techniques include breakeven analysis, sensitivity analysis, risk-adjusted discounting, the mean-variance criterion and coefficient of variation, decision analysis, simulation, and stochastic dominance. 1.3 The techniques can be used with economic methods that measure economic performance, such as life-cycle cost analysis, net benefits, the benefit-to-cost ratio, internal rate of return, and payback. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Investments in long-lived projects such as buildings are characterized by uncertainties regarding project life, operation and maintenance costs, revenues, and other factors that affect project economics. Since future values of these variable factors are generally not known, it is difficult to make reliable economic evaluations. 5.2 The traditional approach to project investment analysis has been to apply economic methods of project evaluation to best-guess estimates of project input variables as if they were certain estimates and then to present results in single-value, deterministic terms. When projects are evaluated without regard to uncertainty of inputs to the analysis, decision-makers may have insufficient information to measure and evaluate the risk of investing in a project having a different outcome from what is expected. 5.3 Risk analysis is the body of theory and practice that has evolved to help decision-makers assess their risk exposures and risk attitudes so that the investment that is the best bet for them can be selected. Note 1: The decision-maker is the individual or group of individuals responsible for the investment decision. For example, the decision-maker may be the chief executive officer or the board of directors. 5.4 Uncertainty and risk are defined as follows. Uncertainty (or certainty) refers to a state of knowledge about the variable inputs to an economic analysis. If the decision-maker is unsure of input values, there is uncertainty. If the decision-maker is sure, there is certainty. Risk refers either to risk exposure or risk attitude. 5.4.1 Risk exposure is the probability of investing in a project that will have a less favorable economic outcome than what is desired (the target) or is expected. 5.4.2 Risk attitude, also called risk preference, is the willingness of a decision-maker to take a chance or gamble on an investment of uncertain outcome. The implications of decision-makers having different risk attitudes is that a given investment of known risk exposure might be economically acceptable to an investor who is not particularly risk averse, but totally unacceptable to another investor who is very risk averse. Note 2: For completeness, this guide covers both risk averse and risk taking attitudes. Most investors, however, are likely to be risk averse. The principles described herein apply both to the typical case where investors have different degrees of risk aversion and to the atypical case where some investors are risk taking while others are risk averse. 5.5 No single technique can be labeled the best technique in every situation for treating uncertainty, risk, or both. What is best depends on the following: availability of data, availability of resources (time, money, expertise), computational aids (for example, computer services), user understanding, ability to measure risk exposure and risk attitude, risk attitude of decision-makers, level of risk exposure of the project, and size of the investment relative to the institution’s portfolio.