I. Introduction
In a vehicle routing problem (VRP), a set of routes for a fleet of vehicles need to be constructed so that some specific objective(s) is optimized while the demands of customers are met within some specified operational, legal and other constraints [1]. Numerous variants of real-life VRPs have been modelled in order to optimise some objective pertaining to economic or social domains. To accommodate needs arising due to changes in the socio-economic business context, researchers are increasingly focusing on the consideration of multiple objectives instead of a single objective [2]. In this context, researchers have recently started to focus on the modelling (and minimization) of C02 emissions, a strand of research now commonly referred to as the sustainable or green VRP [3].