Continuous Daylight Autonomy

Zach Rogers proposed Continuous Daylight Autonomy (cDA) in 2006 as a basic modification of Daylight Autonomy. Continuous Daylight Autonomy awards partial credit in a linear fashion to values below the user defined threshold. If 300 lux were specified as the DA threshold (DA300) and a specific point exceeded 300 lux 50% of the time on an annual basis, then the cDA300 might result in a value of approximate 55-60% or more. For example, say a certain interior grid point has 150 lux due to daylight at a given time step, DA300 would give it 0 credit for that time step whereas cDA300 would give it 150/300=0.5 credit for that time step. For the graphs above, we selected a Continuous Daylight Autonomy threshold of 300 lux (cDA300). The graphical percent values represent the percentage of the floor area that exceeds 300 lux for at least 50% of the time giving partial credit for time steps below 300 lux. 

References:
• Reinhart, C. F., Mardaljevic, J., & Rogers, Z. (2006). Dynamic Daylight Performance Metrics for Sustainable Building Design. Leukos, 3(1), 7-31.