Uniformity as a quality attribute
For the impact of vertical lighting, uniformity both in the horizontal and vertical axis is the decisive quality criterion. This influences the visual impression more strongly than the absolute mean illuminance. Practically-oriented wallwashers such as ERCO double focus lens wallwashers feature special asymmetric light distribution that also achieve good uniformity on high walls and simultaneously enable relatively short distances to the wall. With this characteristic they achieve significantly higher illuminance levels at eye level compared to standard wallwashers.