Windows and Daylighting Group

U2 - LBL-23581 ER - TY - CONF T1 - Determining Daylight Illuminance in Rooms Having Complex Fenestration Systems T2 - International Daylighting Conference Proceedings Y1 - 1986/11// A1 - Jong-Jin Kim A1 - Konstantinos M. Papamichael A1 - Stephen E. Selkowitz A1 - Mark Spitzglas A1 - Michael F. Modest AB - Traditional computational models predict daylight illuminance in a space by dividing window surfaces into discrete areas and then calculating the apparent luminance of each window element by multiplying the luminance of the natural light source in a given viewing direction by the window transmittance in that direction. This approach works well for conventional glazing materials but is incapable of modeling commonly used, but complex, window systems such, as those with specular reflective venetian blinds. We describe a new approach that combines measured luminance distributions for complex window systems with a flux transfer calculation within the space. This method resembles the calculation of illuminance from electric light fixtures where the candlepower distribution of the fixtures is measured and used as an input to the calculation. Based on the variable luminance characteristics of the window system, the SUPERLITE program calculates illuminance at the workplane over the entire space. The measurement techniques and mathematical implementation in the SUPERLITE program are described. This approach allows a wide range of complex window and shading systems to be evaluated without continuous changes in the computational program. A special apparatus for measuring the bidirectional transmittance of window systems has been built in conjunction with this approach. Sample results from the program are compared to measurements made in scale models in a sky simulator. JF - International Daylighting Conference Proceedings CY - Long Beach, CA U1 -Windows and Daylighting Group

U2 - LBL-20542 ER - TY - CONF T1 - Development of Regression Equations for a Daylighting Coefficient-of-Utilization Model T2 - International Daylighting Conference Proceedings Y1 - 1986/11// A1 - Jong-Jin Kim A1 - Konstantinos M. Papamichael A1 - Stephen E. Selkowitz AB - When hourly energy simulation models are used to predict the performance of multi-zone buildings, they may be required to perform more than 2,000 daylight analyses in a single simulation. The traditional approach is to use a very fast computational model, which of necessity must be a very simple model. Coefficient of utilization models have been widely used as simple design tools but have been severely limited in their applicability to complex and realistic fenestration systems and building designs. This paper present a new coefficient of utilization (CU) model for daylighting that combines the ease of use of CU models with the ability to predict illuminance under a wide range of conditions. The model consists of seven regression equations normalized to exterior vertical surface illuminance. These equations describe daylight illuminance as a function of position in a room and are sensitive to all of the significant design variables. The equations are derived from parametric analysis using a mainframe daylighting computer model (SUPERLITE). We describe how these equations were developed and their physical and theoretical background. Comparisons between direct calculation and CU results for sample rooms are demonstrated. JF - International Daylighting Conference Proceedings CY - Long Beach, CA U1 -Windows and Daylighting Group

U2 - LBL-20539 ER - TY - JOUR T1 - Scale Model Measurements for a Daylighting Photometric Data Base JF - Journal of the Illuminating Engineering Society Y1 - 1985/ SP - 44 EP - 61 A1 - Mark Spitzglas A1 - Mojtaba Navvab A1 - Jong-Jin Kim A1 - Stephen E. Selkowitz AB - We present initial results of a study to produce a high-precision photometric reference data base using scale model photometry and computational daylighting prediction tools. For this study the SUPERLITE computer code was used. We illustrate the importance and difficulty of fine-tuning the scale model experimental set-up and measurement procedures to produce highly precise results. We discuss the advantage of separating the direct component of illumination from the internal reflected component as an aid to understanding discrepancies between measurements and calculations. We use results of the study to suggest the circumstances in which calculation procedures should be used to generate the references, and those in which the precise scale model photometry is the recommended technique. Further research directions in the field are described. VL - 15 IS - 1 U1 -Windows and Daylighting Group

U2 - LBL-17286 DO - 10.1080/00994480.1985.10748633 ER - TY - CONF T1 - The DOE-2 and Superlite Daylighting Programs T2 - Passive 82 Y1 - 1982/ A1 - Stephen E. Selkowitz A1 - Jong-Jin Kim A1 - Mojtaba Navvab A1 - Frederick C. Winkelmann AB - We describe the capabilities and limitations of two daylighting computer programs, the algorithms used in each, results of validation studies, and sample results using each of these programs. We also describe features now under development for both programs which should further extend their usefulness as design tools. JF - Passive 82 CY - Knoxville, TN U1 -Windows and Daylighting Group

U2 - LBL-14569 ER -