Nanotechnology involves engineering materials and devices at the molecular scale, typically 1 to 100 nanometers in size. Architects are exploring how to incorporate nanotechnology into building design to create stronger, lighter, and more durable materials that are also self-cleaning, anti-microbial, and energy efficient. Some envisioned applications include nano-reinforced concrete, self-healing coatings, photovoltaic skin, and smart windows that change tint and insulation properties.