Searching for information within websites involves electric energy consumption thus determining the carbon footprint of web navigation. This paper proposes a new eco-sustainable approach to website design and evaluation, which aims at minimizing the duration of information search, reducing the carbon footprint of web navigation, and optimizing the eco-usability of websites. The complex relationship between objective search time, estimated search time, home page complexity, and subjective usability found by Rigutti, Fantoni and Gerbino (2015) is discussed and elaborated to develop: (1) an empirically-grounded guideline for website eco-usability; (2) a normative measure of eco-usability based on the time needed to reach search goals; (3) a new procedure for the evaluation of website eco-usability built upon such a normative measure. Our proposal is intended as a first step towards future investigations of the complexity of websites, capable of integrating user and environmental needs, and promoting a more sustainable web.
