Sunlight Exposure (ASE). sDA is a metric describing annual sufficiency of ambient daylight levels in interior environments. See Daylight autonomy and LEED documentation sections for more details. Evaluation method Field measurements In existing buildings, field measurements can be undertaken to evaluate daylighting performance. Illuminance measurements on a grid is a basic level to derive an average illuminance of a space. The spacing of the measurement points vary with project purposes. The height of these points depends on where the primary task is performed. In most office spaces, desk level (0.762m above the floor) will be measured. Based on measurements, average illuminance, maximum-to-minimum uniformity ratio, and average-to-minimum uniformity ratio will be calculated and compared to the recommended lighting level. A diagnostic survey specific to lighting can be conducted to analyse the satisfaction of building occupants. Computational simulations Computational simulations can predict daylighting condition of a space much faster and more detailed than hand calculations or scale model testing. The simulations allow for the effects of climate with hourly weather data from typical meteorological year. Computer models are available which can predict variations in internally reflected light. Radiosity and ray-tracing are methods can deal with complex geometry, allow complex sky distributions and potentially produce photorealistic images. Radiosity methods assume all surfaces are perfectly diffusing to reduce computational times. Ray-tracing techniques have accuracy and image rendering capacity. Daylighting metrics and analyses Daylight autonomy is the percentage of time that daylight levels are above a specified target illuminance within a physical space or building. The calculation is based on annual data and the predetermined lighting levels. The goal of the calculation is to determine how long an individual can work in a space without requiring electrical lighting, while also providing optimal visual and physical comfort. Daylight autonomy is beneficial when determining how daylight enters and illuminates a space. The drawback, however, is that there is no upper limit on luminance levels. Therefore, a space with a high internal heat gain deemed uncomfortable by occupants, would still perform well in the analysis. Achieving daylight autonomy requires an integrated design approach that guides the building form, siting, climate considerations, building components, lighting controls, and lighting design criteria. Continuous Continuous daylight autonomy, is similar to daylight autonomy but partial credit is attributed to time steps when the daylight illuminance lies below the minimum illuminance level. For example, if the target illuminance is 400 lux and the calculated