A new sustainability framework for urban underground space

In the past two decades, great efforts have been made to develop sustainability solutions for the built environment. One way to measure the efficacy of such solutions is by using sustainability indicators. Greater use of underground space is one of the proposed solutions. However, a detailed review of the current construction sector sustainability indicator systems, such as the Building Research Establishment Environmental Assessment Method and Civil Engineering Environmental Quality Assessment and Awards Scheme, shows that there is a need for a bespoke sustainability indicator framework system tailored to urban underground space. The aim of this paper is to extend previous discussions about the role of underground space in urban areas, with the intention of addressing this shortfall. A new framework is proposed, called Uspear, developed on the basis of the Sustainable Project Appraisal Routine framework revised and restructured specifically for application on urban underground space projects. By the use of an innovative weighting system adopted through extensive stakeholder engagement, the new framework represents a comprehensive indicator framework for addressing sustainability in underground urban space projects.