Fast and Robust External Solar Shading Calculations using the Pixel Counting Algorithm with Transparency

Project Details
  • Title: Pixelcounter
  • Date: August 8, 2017
  • Link: Pixelcounter

External solar shading calculations play an important role in energy models for buildings. Current simulation software implements polygon clipping algorithms for these calculations. However, polygon clipping suffers from several limitations, such as high computational costs and, for complex geometry, robustness issues.

These weaknesses are a major bottleneck for the simulation of large scale urban building energy modelling (UBEM). This paper introduces a graphics hardware accelerated shading algorithm that uses pixel counting and supports transparency. The algorithm has been integrated in EnergyPlus and proves to be on average 2 times faster than EnergyPlus's shading algorithm, while maintaining an accuracy of 0.01.


We investigate the intersections of architectural design, sustainability, building performance simulation and computational design. We stand for excellence in teaching and research in the area of building technology, daylight and energy modeling, passive climate control strategies and performance driven design workflows in both urban and architectural scales.


Led by: Prof. Dr. Timur Dogan
Website: Cornell AAP Profile
Email: tkdogan[at]cornell.edu


Cornell University, AAP
240B Sibley Hall
Ithaca, NY 14853,USA