What is normally used to compare alternatives that accomplish the same purpose but have unequal lives?

The annual cost method is particularly useful for comparing alternatives that serve the same function but differ in their useful life spans. This method converts the total costs of each alternative into equivalent annual costs, allowing for a straightforward comparison.

When evaluating alternatives, simply looking at total costs may not suffice, especially if one option lasts significantly longer or shorter than another. The annual cost method addresses this disparity by spreading the total cost of an alternative over its entire lifespan, factoring in capital recovery, operating costs, maintenance expenses, and any other relevant costs.

By converting all costs into an annual figure, stakeholders can assess which alternative provides the best value for money on an annual basis, making it easier to make informed decisions and select the most cost-effective option. This method effectively normalizes the different lifespans and allows for a direct comparison of costs on an annual basis.