Increasing temperatures have worldwide become a high health risk. High humidity aggravates the risk and reduces the comfort perception. Conventional air conditioners produce annually the equivalent of 2150 million carbon dioxide tons per year. Dehumidification is responsible for a large portion of it. Membrane-based dehumidification is energy-efficient since water vapor removal is carried out at isothermal conditions without toxic materials. This work demonstrates a membrane dehumidification system based on industry-ready prototypes containing polymeric hollow fibers coated with a green polyphenol coating, showcasing/exhibiting a remarkable water vapor transport rate with selectivity. Long-term testing proved over a year of operation with only a minimal decline in vapor transport. And the proposed system has 4–5 times higher coefficient of performance (COP) than conventional dehumidifiers, and it is a highly competitive energy-saving device with a low contribution to emissions and a smaller footprint.