Approved Method: IES Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE)

The metrics described in this document are intended to be applicable to common workplace environments. They are based on an analysis of open offices, classrooms, meeting rooms, multi-purpose rooms, and service areas in libraries and lobbies, and so are most applicable to areas with similar visual tasks. These metrics are neither counter to, nor do they supersede, IES task lighting criteria for these space types. These metrics do not directly address energy consumption, as electric lighting management is highly variable. The area of analysis for these metrics is ideally a coherent “space”, defined by opaque walls and access to daylight through at least one wall or ceiling surface. It is also possible to apply these metrics to the “regularly occupied” floor area of a building, or some part of a building, such as one floor plate. It is important to specify the “area of analysis” to which the percentages apply. These metrics were derived from a study of daylit spaces in the continental United States, and thus are most applicable to similar latitudes and cultures.