Paper Conference

Proceedings of BSO Conference 2016: Third Conference of IBPSA-England

     

Automatic Calculation Of A New China Glare Index

Yi Chun Huang, Tsung-Hsien Wang

Abstract: Lighting simulation is widely accepted and used to evaluate lighting performance including glare metrics. Digital technologies such as Computer Aided Design (CAD) and Building Information Modeling (BIM) can ideally reduce time consuming manual efforts in glare evaluation workflows and are commonly used to achieve automatic workflows. However, varying BIM standards and information interoperability present challenges when new metrics are introduced and existing tools can no longer achieve automatic workflows. Using a case study of the new China daylighting glare metric, we discuss the gaps in current software tools and present a new prototypical software to automate the calculation of the China Daylight Glare Index (DGIChinₐ). Besides practical usage in industry, the new software facilitates technical investigations and clarifications for DGIChinₐ, and discussions for future developments too large (MOHURD, 2012). The prevalent Daylight Glare Index (DGI) originally proposed by Hopkinson (1972) is modified and included in the China national standard “GB50033-2013 Standard for Daylighting Design of Buildings”. This modification results in difficulty in using current software tools to evaluate the new metric. China Daylight Glare Index (DGIChinₐ) Specifically, DGIChinₐ makes two modifications. First, the definition of a glare source includes the entire window brightness rather than sections of windows that have brightness above a certain multitude of adaptation levels. As DGIChinₐ is meant to evaluate the objective effect of windows, DGIChinₐ disregards the conventional definition of glare sources as determined by adaptation levels. The formulation of DGIChinₐ is thus identical to the common Hopkinson DGI except for the definition of 𝐿𝑠 in glare constant equation (2) below: in BIM necessary for practical industry usage. 𝐷𝐺𝐼𝐶'(𝑛𝑎 = 10𝑙𝑜𝑔 𝐺𝑛 (1)
Pages: 395 - 402
Paper:
bso2016_1010