Modern data centres face significant challenges in sustainability and cost optimisation. Hyperscale facilities, large colocation centres, and emerging AI applications demand robust power solutions to ensure continuous power supply and cost efficiency throughout the site's lifecycle while maintaining controlled Capex and Opex. Achieving this requires a holistic approach to system optimisation, starting from the initial design phase and incorporating thoughtful architectural choices. This fireside chat will provide a comprehensive overview of various design concepts and their impact on data centre systems' total cost of ownership (TCO), highlighting strategies for enhancing sustainability and cost-effectiveness.