Cities have a critical role to play in securing a net-zero future. Despite accounting for less than 2% of the Earth's surface, they consume 78% of the world’s energy and produce more than 60% of overall greenhouse gas emissions. With projections indicating that the world’s urban population will rise to 68% by 2050, a 13% increase from 2018, cities must urgently seek out innovative solutions to balance the needs of growing citizen populations, in a manner which is sustainable and consistent with a zero-carbon trajectory. This paper will explore how digital twin technology has been leveraged to pursue Limerick’s net-zero vision; their ultimate aim being to go beyond this and become Ireland’s first "Positive Energy City"by 2050, meaning that it will generate more energy than it consumes.