Buildings currently account for a large proportion of the world's energy consumption and produce large amounts of carbon emissions. Meanwhile, multiple scientific gaps remain in academia on the use of ocean energy technologies to realise coastal zero-energy buildings. Based on these circumstances, this paper proposes a hybrid system comprising a sea-sourced cooling system, floating solar photovoltaic panels, and tidal stream generators to support a coastal zero-energy building located in Hong Kong. In this study, multiple cases were created in the dynamic energy simulation software TRNSYS to fully investigate the impact of different mix ratios of renewable energy systems and number of batteries on a zero-energy building. The techno-economic and environmental performance was demonstrated by analysing the energy matching performance of the system, a 20-year return on investment, and annual operational equivalent CO2 emissions. The results of the study indicated that in the absence of batteries, most cases are technically and economically feasible. In all cases, significant reductions in annual equivalent CO2 emissions were achieved. With the addition of batteries to enhance the energy matching capability, the technical performances of all cases were enhanced. Furthermore, the presence of batteries would compromise the economic and environmental performance of the system because of the high costs and energy losses. However, even with a battery count of 10, the performance of most cases improved compared with the reference case, demonstrating the feasibility of the proposed system.