01681nas a2200157 4500008004100000050001500041245006800056210006700124260003600191520112500227100002501352700003401377700001401411700002401425856007401449 2001 eng d aLBNL-4754400aSimulating the Operation of Photosensor-Based Lighting Controls0 aSimulating the Operation of PhotosensorBased Lighting Controls aRio de Janeiro, Brazilc08/20013 a

Energy savings from the use of daylighting in commercial buildings are realized through implementation of photoelectric lighting controls that dim electric lights when sufficient daylight is available to provide adequate workplane illumination. The dimming level of electric lighting is based on the signal of a photosensor. Current simulation approaches for such systems are based on the questionable assumption that the signal of the photosensor is proportional to the task illuminance. This paper presents a method that simulates the performance of photosensor controls considering the acceptance angle, angular sensitivity, placement of the photosensor within a space, and color correction filter. The method is based on the multiplication of two fisheye images: one generated from the angular sensitivity of the photosensor and the other from a 180- or 360-degree fisheye image of the space as seen by the photosensor. The paper includes a detailed description of the method and its implementation, example applications, and validation results based on comparison with measurements in an actual office space.

1 aEhrlich, Charles, K.1 aPapamichael, Konstantinos, M.1 aLai, Judy1 aRevzan, Kenneth, L. uhttps://facades.lbl.gov/publications/simulating-operation-photosensor02740nas a2200181 4500008004100000050001900041245006200060210006200122260003100184520212100215100003402336700002502370700002102395700002102416700002702437700002302464856007102487 1994 eng d aLBL-35382 Rev.00aSimulating the Energy Performance of Holographic Glazings0 aSimulating the Energy Performance of Holographic Glazings aFreiburg, Germanyc04/19943 a

The light diffraction properties of holographic diffractive structures present an opportunity to improve the daylight performance in side-lit office spaces by redirecting and reflecting sunlight off the ceiling, providing adequate daylight illumination up to 30 ft (9.14 m) from the window wall. Prior studies of prototypical holographic glazings, installed above conventional view windows, have shown increased daylight levels over a deeper perimeter area than clear glass, for selected sun positions. In this study, we report on the simulation of the energy performance of prototypical holographic glazings assuming a commercial office building in the inland Los Angeles climate.

The simulation of the energy performance involved determination of both luminous and thermal performance. Since the optical complexity of holographic glazings prevented the use of conventional algorithms for the simulation of their luminous performance, we used a newly developed method that combines experimentally determined directional workplane illuminance coefficients with computer-based analytical routines to determine a comprehensive set of daylight factors for many sun positions. These daylight factors were then used within the DOE-2.1D energy simulation program to determine hourly daylight and energy performance over the course of an entire year for four window orientations.

Since the prototypical holographic diffractive structures considered in this study were applied on single pane clear glass, we also simulated the performance of hypothetical glazings, assuming the daylight performance of the prototype holographic glazings and the thermal performance of double-pane and low-e glazings. The results of our analyses show that these prototypical holographic glazings did not save significant electric energy or reduce peak electricity demand compared to conventional energy-efficient window systems in inland Los Angeles office buildings, mainly because of their low diffraction efficiency. Finally, we address various design and implementation issues towards potential performance improvement.

1 aPapamichael, Konstantinos, M.1 aBeltran, Liliana, O.1 aFurler, Reto, A.1 aLee, Eleanor, S.1 aSelkowitz, Stephen, E.1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/simulating-energy-performance02011nas a2200133 4500008004100000050001400041245011500055210006900170260002400239520148000263100003401743700002501777856007501802 1993 eng d aLBL-3394500aSimulating the Daylight Performance of Fenestration Systems and Spaces of Arbitrary Complexity: The IDC Method0 aSimulating the Daylight Performance of Fenestration Systems and  aAdelaide, Australia3 a

A new method to simulate the daylight performance of fenestration systems and spaces is presented. This new method, named IDC (Integration of Directional Coefficients), allows the simulation of the daylight performance of fenestration systems and spaces of arbitrary complexity, under any sun, sky and ground conditions. The IDC method is based on the combination of scale model photometry and computer-based simulation. Physical scale models are used to experimentally determine a comprehensive set of directional illuminance coefficients at reference points of interest, which are then used in analytical, computer-based routines, to determine daylight factors or actual daylight illuminance values under any sun, sky and ground conditions.

The main advantage of the IDC method is its applicability to any optically complex environment. Moreover, the computer-based analytical routines are fast enough to allow for hourly simulation of the daylight performance over the course of an entire year. However, the method requires appropriate experimental facilities for the determination of the Directional Coefficients. The IDC method has been implemented and used successfully in inter-validation procedures with various daylight simulation computer programs. Currently, it is used to simulate the daylight performance of fenestration systems that incorporate optically complex components, such as Venetian blinds, optically treated light shelves and light pipes.

1 aPapamichael, Konstantinos, M.1 aBeltran, Liliana, O. uhttps://facades.lbl.gov/publications/simulating-daylight-performance-0