jm-cibse-ts-2015-04.pdf (1.38 MB)
Download file

Climate-based daylight modelling and its discontents

Download (1.38 MB)
conference contribution
posted on 11.01.2016, 13:37 authored by John MardaljevicJohn Mardaljevic
In 2013 the UK Education Funding Agency (EFA) made climate-based daylight modelling (CBDM) a mandatory requirement for the evaluation of designs submitted for the Priority Schools Building Programme (PSBP). School designs submitted to the PSBP must achieve certain ‘target’ criteria for the useful daylight illuminance metric. This is believed to be the first major upgrade to mandatory daylight requirements since the introduction of the daylight factor more than half a century ago. In the US, a climate-based daylight metric approved by the IESNA has appeared in the latest version of LEED. Perceived as long overdue in some quarters, in others the EFA decision was seen as controversial and is not without its critics. Whilst it may appear that the case for CBDM has effectively been made, and that wider adoption in standards and guide- lines is likely, it is important not to ignore or dismiss out-of-hand the critics of CBDM. Nor should it be overlooked that CBDM and the metrics derived using it are both still evolving. This paper: reviews the recent developments; the reactions to them; and, forecasts what might be expected in the near future. Attention is given to the formulation of the PSBP requirements for daylight and how the various stakeholders have responded to this major new development in building codes.



  • Architecture, Building and Civil Engineering

Published in

CIBSE Technical Symposium


MARDALJEVIC, J., 2015. Climate-based daylight modelling and its discontents. Presented at the Simple Buildings Better Buildings? Delivering performance through engineered solutions, CIBSE Technical Symposium, London, April 16-17th.




AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at:

Publication date



This paper is presented with permission from the conference organisers..




London, UK

Usage metrics