Recommended Practice for Measuring Simple and Discounted Payback for Investments in Buildings and Building Systems

摘要

This report describes how to calculate simple and discounted payback measures of economic performance of buildings and building systems. Formulas for calculating payback, applications for evaluating and selecting projects, and limitations in the use of payback analysis are discussed. The simple payback method measures the time between the date of initial project investment and the date when cumulative future earnings or savings on that investment, net of cumulative future costs, just pay off the investment. The discounted payback method measures the time between the date of initial project investment and the date when the present value of future earnings or savings, net of the present value of future costs, just equals the initial investment. This recommended practice will assist the private and public building communities in making cost-effective decisions in the design, operation, maintenance, and retrofit of buildings.