A building under construction and set to open in New York City in 2002 may earn the distinction of being the world’s greenest high-rise apartment complex. The 26-floor, 250-unit building is intended to be 30 percent more energy efficient than state codes require. It will take advantage of natural light, use motion-controlled and dimmable lighting, and feature energy-efficient appliances. Solar panels will be used to generate electricity for common areas and hallways. Water from bathtubs and washing machines will be recycled for use in toilets and maintenance work. The high-tech, eco-friendly features are expected to push up building costs by about 15 percent.