Tutorial: Rationale, Concepts, and Techniques for Lighting Vertical Surfaces

The luminance of walls or facades is an important factor for accentuating architectural elements. Light supports spatial orientation by making boundaries visible. In interior spaces, vertical illuminance also contributes to visual perception, for example when wallwashers highlight merchandise in shops or illuminate paintings in museums. After studying this article, the reader will be able to: 1. Explain why vertical illumination enhances visual tasks, contributes to impressions of brightness, and accentuates interior and exterior architecture; 2. Distinguish the techniques of wallwashing, grazing light, and wallslot lighting; 3. List technical and economic criteria for specifying luminaires; 4. Arrange luminaires appropriately to avoid problems such as poor uniformity; 5. Discuss illuminance levels for different applications; and 6. Follow a design process for the practical planning of vertical surface illumination.