Traditional engineering requires evaluating designs before implementing them. Evaluating a design predicts the properties of a reasonable implementation and the value of these properties to a stakeholder. Software engineering has some (though not enough) relevant evaluation techniques but lacks frameworks to compare, develop, and apply those techniques in a manner that respects h value varies by stakeholder. We present an adaptation of economists' value models that, given a design and a development method, predicts value to a client. We give examples supporting our approach. Even in its preliminary state, our approach helps to explain and characterize design evaluation techniques and shows sufficient promise to justify further development.