14Purpose. The purpose of the study is to quantify the environmental performance of Smart City Solutions at urban 15 system level and thus evaluate their contribution to develop environmentally sustainable urban systems. Further, the 16 study illustrates how this quantification is conducted. 17

The building sector is responsible for extensive resource consumption and waste generation, resulting in high pressure on the environment. A way to potentially mitigate this is by including environmental considerations during building design through the concept known as eco-design. Despite the multiple available approaches of eco-design, the latter is not easily achieved in the building sector. The objective of this paper is to identify and discuss what barriers are currently hindering the implementation of eco-design in the building sector and by which measures building designers can include environmental considerations in their design process. Through a systematic literature review, several barriers to implementation were identified, the main ones being lack of suitable legislation, lack of knowledge amongst building designers, and lack of suitable tools for designers to use. Furthermore, two specific tools were identified that allow the inclusion of environmental consideration in building design, along with nine design strategies providing qualitative guidance on how to potentially minimize energy and material consumption, as well as waste generation. This paper contributes a holistic overview of the major barriers to and existing tools and method for the eco-design of buildings, and provides guidance for both future research and practice.