Success factors. Must have, Should have, Could have, Must-have. The value of these features is-Costs and benefits are in-Features are wanted or higher than their costs balance desirable, but not essential-The building does not function-Features are important, but-Features do not impact the without these qualities not vital buildings usability if left out-The building is illegal, unsafe-Features are painful to leave-Features can be realized if or unpractical without it out, but the building can stillthere is extra room in budget-The project cannot deliver thefunctiondesired value without it -Features may require a trade-off with other qualities-Features may require extra design effort to realizeMust, should or could?Theoretically, stakeholder needs can be assessed by looking at the added value of meeting them and the associated costs. Both are difficult to quantify, but they can be used to make a distinction between must-haves (more value than costs), should-haves (value and costs are in balance) and could-haves (more costs than value).