Building designers are increasingly relying on complex fenestration systems to reduce energy consumed for lighting and HVAC in low energy buildings. Radiance, a lighting simulation program, has been used to conduct daylighting simulations for complex fenestration systems. Depending on the configurations, the simulation can take hours or even days using a personal computer. This paper describes how to accelerate the matrix multiplication portion of a Radiance three-phase daylight simulation by conducting parallel computing on heterogeneous hardware of a personal computer. The algorithm was optimized and the computational part was implemented in parallel using OpenCL. The speed of new approach was evaluated using various daylighting simulation cases on a multicore central processing unit and a graphics processing unit. Based on the measurements and analysis of the time usage for the Radiance daylighting simulation, further speedups can be achieved by using fast I/O devices and storing the data in a binary format.

%B Journal of Building Performance Simulation %2 LBNL-6461E %R 10.1080/19401493.2013.795193 %0 Report %D 2012 %T Validation of the Window Model of the Modelica Buildings Library %A Thierry Stephane Nouidui %A Michael Wetter %A Wangda Zuo %XThis paper describes the validation of the window model of the free open-source Modelica Buildings library. This paper starts by describing the physical modeling assumptions of the window model. The window model can be used to calculate the thermal and angular properties of glazing systems. It can also be used for steady-state simulation of heat transfer mechanism in glazing systems. We present simulation results obtained by comparing the window model with WINDOW 6 the well established simulation tool for steady-state heat transfer in glazing systems. We also present results obtained by comparing the window model with measurements carried out in a test cell at the Lawrence Berkeley National Laboratory.

%8 07/2012 %2 LBNL-5735E %0 Conference Paper %B 12th International Conference of the International Building Performance Simulation Association (Building Simulation 2011) %D 2011 %T Acceleration of Radiance for Lighting Simulation by using Parallel Computing with OpenCL %A Wangda Zuo %A Andrew McNeil %A Michael Wetter %A Eleanor S. Lee %XThis study attempted to accelerate annual daylighting simulations for fenestration systems in Radiance ray-tracing program. The algorithm was optimized to reduce both the redundant data input/output operations and floating-point operations. To further accelerate the simulation speed, calculation for matrices multiplications was implemented in parallel on a graphics processing unit using OpenCL, a cross-platform parallel programming language. Numerical experiments show that combination of above measures can speed up the annual daylighting simulations 101.7 times or 28.6 times when sky vector has 146 or 2306 elements, respectively.

%B 12th International Conference of the International Building Performance Simulation Association (Building Simulation 2011) %C Sydney, Australia %P p. 110-117 %8 11/2011 %G eng %1Windows and Daylighting Group

%2 LBNL-5049E