The main “energy saving indicator,” from among nine green building indicators, evaluates the electrical power consumption of air conditioners and lighting. This study developed a small indoor personal office system with a 500W proton exchange membrane fuel cell (PEM fuel cell) as the power source, composed of LED indoor lighting, air fan, LED table lamp, notebook computer, printer, and acoustic equipment. Under continuous operations of 24h, this office system will generate 12kwh of electricity, which reduces 7.656kg of carbon dioxide output. If continuously operated for 1 year, it will generate 4,320kwh electricity, which reduces 2,756.16kg of carbon dioxide output. In addition, the side product water can be recycled as landscape water.