Waldram was wrong!

Purpose – This paper follows the author's previous paper published in Structural Survey (Vol. 25 No. 2, pp. 98‐116), in which certain accepted methodologies, used in rights to light calculations were challenged. Now, following publication of the doctoral thesis entitled “The validity of daylight calculations in rights to light cases”, the aim is to examine two aspects of the calculation process – the Waldram diagram and the level of daylight that should be considered sufficient for ordinary purposes. Design/methodology/approach – First, the mathematics of the Waldram diagram for rights to light cases are compared with the proposed alternative, which recognises a non‐uniform CIE sky as opposed to the artificial concept of the uniform sky proposed by Waldram. Second, the amount of light sufficient for ordinary use is measured in a controlled environment and compared with previous methodologies. Findings – The proposed diagram more closely replicates the results of real measurements taken in a room, and the amount of daylight that should be considered as being the minimum necessary for ordinary use is likely to be around 2.5 times that currently accepted. Practical implications – These results demonstrate that advice previously given by experts in court on the sufficiency of daylight to a building is flawed. Originality/value – While many are questioning the validity of daylight calculations in rights to light cases, this paper establishes the proof that a new approach is required.