Climate Based Daylight Modelling (CBDM)

KJ Tait Engineers work with leading Architects and construction companies, as part of the UK Governments Education & Skills Funding Agency (ESFA) Priority School Building Programme (PSBP).

All new ESFA funded school developments are required to meet the ESFA specification for the provision of adequate daylight to teaching spaces and other occupied rooms.

Climate Based Daylight Modelling CBDM is a highly complex and accurate method of daylight analysis which analyses the available daylight through a school day.   This is a crucial tool to influence the internal space planning and external façade design of school buildings to ensure adequate daylight is available within a classroom during the school day throughout the year.  CBDM uses two criteria to assess this.

The first criterion sets a Useful Daylight Index (UDI).  This is detailed as the annual occurrence of illuminance across the work plane that is considered “useful”.

The second criterion calculates the Spatial Daylight Autonomy (sDA). This is the amount of time a space can expect to reach a target illuminance level on the working plane.

As recommended in the EFA guidance for schools, the calculation will be carried out over the course of an entire year including weekends and the holiday period between the hours of 8:30am and 4.00pm.

Internal and external obstructions immediately associated with the rooms will be included within the simulation.