Europe is currently experiencing the consequences of climate change and environmental degradation. Making a less energy-demanding society is the goal of the next decade to reduce the impact of the energy sector on the environment. However, the strategy for a sustainable society must include the building sector besides the energy sector. The building sector accounts for almost half of the final energy consumption in the European Union, with heating and cooling representing a significant portion of this demand. Natural-based solutions are needed to extend the concept of high-performance buildings to existing ones. This study explores the possibility of using the environment and natural resources to reduce the energy demand of a business centre office building in Seville, which features a highly glazed thermal envelope in a warm climate and was built before the transposed EPBD’s first version in Spain. The proposed solution is a dual system that integrates electricity generation and cooling production based on renewable energy and environmental heat sinks. During the day, a conventional photovoltaic solar system reduces dependence on traditional electrical supply. At night, the surface of solar modules is converted into a heat dissipator for cold water production. An energy assessment of the building was conducted using the EnergyPlus simulation tool and a validated model for the water natural cooling technique. Current weather conditions, including the impact of ongoing climate change, were taken into account by considering a typical meteorological year for the period 2007–2021. A cost-effective methodology was used to size the PV system and the passive cooling system. The dual system/technique allows for cold water production for air conditioning, consuming 41% less electricity than the conventional system and utilizing only 53% of collected water during dry years to generate cold air. The hybrid solution covers 70% of the cooling demand for fresh air and achieves a 20% reduction in electricity demand for the designed PV system. The efficiency of the hybrid cooling system is demonstrated by a seasonal COP of 4.5, while the conventional heat pump presents a seasonal COP of 2.7.