Evaluating exchange constants

One of the main challenges in using a penalty function is determining the value of the exchange constant, for example what the correct balance is between the two conflicting objectives for the design.

Often this comes down to experience, otherwise it involves significant amounts of research.

For transport vehicles, the exchange constant can be estimated by the fuel cost saving per mass reduction of the vehicle, evaluated over the life of the vehicle. Some of these values are listed below. For other applications, exchange constants can depend on other properties such as performance, style, and perceived worth of a product to a consumer.