Imagine if light would not only provide optimum visibility for tasks but convey meanings as well. Standards with recommended lux levels for various visual tasks have led to a quantitative understanding of lighting. However, lighting can also be used to contribute to emotion in rooms and to structure architecture. Would it be adequate to regard lighting as language sent by architects or interior designers and being received by inhabitants and citizens? Adding a semiotic perspective can help to recognize how light and shadow contributes to the meaning of the built environment.