Goal modeling for sustainability: The case of time

Goal models have established themselves as a means to capture often conflicting needs of stakeholders and reason about how alternative solutions may impact those needs, allowing for trade-off assessments at the early stages of development. More recently, goal models have been extended with the notion of indicators that allow quantitative, real-life measurements to be used in addition to qualitative measurements to more precisely assess trade-offs. While goal models are most often used in the context of systems or software development, they are well suited to any type of development effort that involves a large set of diverse stakeholders. Sustainability Engineering is an emerging discipline that fits this profile, requiring everyone from individuals to large communities to be considered to maximize social benefit while minimizing negative ecological impact. This paper proposes a method to combine the high-level, qualitative assessment from goal models with the rigorous, detailed, quantitative sustainability assessment based on time cost that is applicable to varied types of development projects. The method is demonstrated through a development project from the construction industry and modeled with the Goal-oriented Requirement Language.