Climate Based Daylight Analysis (CBDA)

Climate Based Daylight Analysis (CBDA) has become the industry standard daylight assessment method for schools following the adoption as a mandatory requirement by the Department for Education (DfE) Generic Design Brief (GDB).

The assessments predict various radiant or luminous quantities using daylight conditions derived from standard meteorological datasets in order to predict the levels of daylight to a room.

CBDA assesses two criteria:

• Spatial Daylight Autonomy (SDA)
  • Daylight Autonomy is the amount of time a space can expect to reach a target illuminance level on the working plane. This criterion is aimed at delivering an energy efficient space.

• Useful Daylight Index (UDI)
  • UDI-a (100 to 3000 lux) assesses where daylight is acceptable and electric lighting would not be required for the majority of the day. Achieving a high UDI-a percentage signifies the space is predominantly day lit throughout.

Walker Energy Analysis uses the the latest Daysim DIVA4Rhino software to calculate CBDA assessment. We have a wealth of experience and knowledge of the latest legislation to help your building comply with the regulations.

Analysis and optimisation at an early stage can ensure the building facade is designed right from the get go and save money in the long run.