%0 Journal Article %J Energy and Buildings %D 2001 %T A Method for Simulating the Performance of Photosensor-Based Lighting Controls %A Charles K. Ehrlich %A Konstantinos M. Papamichael %A Judy Lai %A Kenneth L. Revzan %X

The unreliability of photosensor-based lighting controls continues to be a significant market barrier that prevents widespread acceptance of daylight dimming controls in commercial buildings. Energy savings from the use of daylighting in commercial buildings is best realized through the installation of reliable photoelectric lighting controls that dim electric lights when sufficient daylight is available to provide adequate background and/or task illumination. In prior work, the authors discussed the limitations of current simulation approaches and presented a robust method to simulate the performance of photosensor-based controls using an enhanced version of the radiance lighting simulation package. The method is based on the concept of multiplying two fisheye images: one generated from the angular sensitivity of the photosensor and the other from a 180 or 360 deg. fisheye image of the space as seen by the photosensor. This paper includes a description of the method, its validation and possible applications for designing, placing, calibrating and commissioning photosensor-based lighting controls.

%B Energy and Buildings %V 34 %P 883-889 %G eng %L LBNL-49018 %1

Windows and Daylighting Group

%2 LBNL-49018 %0 Conference Paper %B 2001 Building Simulation 7th International Building Performance Simulation Association Conference %D 2001 %T Simulating the Operation of Photosensor-Based Lighting Controls %A Charles K. Ehrlich %A Konstantinos M. Papamichael %A Judy Lai %A Kenneth L. Revzan %X

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.

%B 2001 Building Simulation 7th International Building Performance Simulation Association Conference %C Rio de Janeiro, Brazil %8 08/2001 %G eng %L LBNL-47544 %1

Windows and Daylighting Group

%2 LBNL-47544 %0 Journal Article %J Journal of the Illuminating Engineering Society %D 1997 %T Simulating the Visual Performance of Electrochromic Glazing for Solar Control %A Charles K. Ehrlich %X

A new technology called electrochromic glazing promises to provide the building industry with a means to dynamically control the visual appearance and solar gain of windows. Electrochromic glazing is a technology which allows an otherwise ordinary looking piece of laminated glass to change tint with the application of a small electrical charge. Prototype electrochromic devices have been produced in sizes up to one square foot, however, manufacturers are several years away from producing glazing samples large enough to fill the aperture of a typical perimeter office. Tooling up for the production of large samples is prohibitively expensive unless some assurance of the marketability of these new electrochromic products can be demonstrated.

Electrochromic glazings defy traditional performance rating mechanisms because of the temporal dimension of their thermal and visual characteristics. Every electrochromic glazing assembly has an infinite number of states at which the thermal and visual appearance could be characterized. Furthermore, the rate at which the assembly changes between states is vital for a complete understanding.

%B Journal of the Illuminating Engineering Society %V 27 %G eng %L LBNL-40016 %1

Windows and Daylighting Group

%2 LBNL-40016 %0 Report %D 1996 %T Design and Evaluation of Daylighting Applications of Holographic Glazings %A Konstantinos M. Papamichael %A Charles K. Ehrlich %A Gregory J. Ward %X

When combined with appropriate electric lighting dimming controls, the use of daylight for ambient and task illumination can significantly reduce energy requirements in commercial buildings. While skylights can effectively illuminate any part of one-story buildings, conventional side windows can illuminate only a 15 ft - 20 ft (4.6 m - 6.1 m) depth of the building perimeter. Even so, the overall efficacy of daylight is limited, because side windows produce uneven distributions of daylight. Achieving adequate illumination at distances further away from the window results in excessive illumination near the window, which increases cooling loads from the associated solar heat gain. As a result, the use of larger apertures and/or higher transmittance glazings, to introduce daylight deeper than 15 ft - 20 ft (4.6 m - 6.1 m), may prove ineffective with respect to saving energy, because cooling load penalties may exceed the electric lighting savings.

The need for more uniform distribution of daylight admitted through side windows has stimulated significant research and development efforts in new fenestration designs and glazing technologies. Many of these approaches, including holographic glazings, rely on the common strategy of redirecting sunlight and reflecting it off the ceiling towards the back of the room. Prior studies on the daylight and energy performance of holographic glazings have been disappointing, however inconclusive because of poor hologram quality, low diffraction efficiency and inadequate hologram design and building application considerations [Papamichael et al 1994].

%G eng %L LBNL-44167 %1

Windows and Daylighting Group

%2 LBNL-44167