7 Matching Results

Search Results

Advanced search parameters have been applied.

Visual Comfort Analysis of Innovative Interior and Exterior Shading Systems for Commercial Buildings using High Resolution Luminance Images

Description: The objective of this study was to explore how calibrated high dynamic range (HDR) images (luminance maps) acquired in real world daylit environments can be used to characterize, evaluate, and compare visual comfort conditions of innovative facade shading and light-redirecting systems. Detailed (1536 x 1536 pixel) luminance maps were time-lapse acquired from two view positions in an unoccupied full scale testbed facility. These maps were analyzed using existing visual comfort metrics to quantify how innovative interior and exterior shading systems compare to conventional systems under real sun and sky conditions over a solstice-to-solstice test interval. The results provide a case study in the challenges and potential of methods of visualizing, evaluating and summarizing daily and seasonal variation of visual comfort conditions computed from large sets of image data.
Date: January 11, 2011
Creator: Konis, Kyle; Lee, Eleanor & Clear, Robert
Partner: UNT Libraries Government Documents Department


Description: The concept of cost benefit analysis leads directly to the use of visual performance (i.e., the speed or accuracy with which a visual task is performed) rather than derived metrics such as ESI or VL as the basic visibility related performance parameter. The 1977 IES Design Committee's recommended specification procedure does not have visual performance in its formulation and hence will not lead to cost~effective general lighting designs. We discuss the direct calculation of average relative visual performance (RVP) and then present a reasonably accurate approximation which has significant advantages in speed and flexibility. Finally, we attempt to assess the conditions under which this procedure will provide useful information.
Date: August 1, 1980
Creator: Clear, Robert & Berman, Sam
Partner: UNT Libraries Government Documents Department

Measured Off-Grid LED Lighting System Performance

Description: This report is a product of our ongoing effort to support the development of high-quality yet affordable products for off-grid lighting in the developing world that have good potential to succeed in the market. The effort includes work to develop low-cost testing procedures, to identify useful performance metrics, and to facilitate the development of industry standards and product rating protocols. We conducted laboratory testing of nine distinct product lines. In some cases we also tested multiple generations of a single product line and/or operating modes for a product. The resultsare summarized in Table 1. We found that power consumption and light output varied by nearly a factor of 12, with efficacy varying by a factor of more than six. Of particular note, overall luminous efficacy varied from 8.2 to 53.1 lumens per watt. Color quality indices variedmaterially, especially for correlated color temperature. Maximum illuminance, beamcandlepower, and luminance varied by 8x, 32x, and 61x respectively, suggesting considerable differences among products in terms of service levels and visual comfort. Glare varied by1.4x, and was above acceptable thresholds in most cases. Optical losses play a role in overall performance, varying by a factor of 3.2 and ranging as high as 24percent. These findings collectively indicate considerable potential for improved product design.
Date: December 18, 2008
Creator: Granderson, Jessica; Galvin, James; Bolotov, Dmitriy; Clear, Robert; Jacobson, Arne & Mills, Evan
Partner: UNT Libraries Government Documents Department

Advanced Benchmarking for Complex Building Types: Laboratories as an Exemplar

Description: Complex buildings such as laboratories, data centers and cleanrooms present particular challenges for energy benchmarking because it is difficult to normalize special requirements such as health and safety in laboratories and reliability (i.e., system redundancy to maintain uptime) in data centers which significantly impact energy use. For example, air change requirements vary widely based on the type of work being performed in each laboratory space. We present methods and tools for energy benchmarking in laboratories, as an exemplar of a complex building type. First, we address whole building energy metrics and normalization parameters. We present empirical methods based on simple data filtering as well as multivariate regression analysis on the Labs21 database. The regression analysis showed lab type, lab-area ratio and occupancy hours to be significant variables. Yet the dataset did not allow analysis of factors such as plug loads and air change rates, both of which are critical to lab energy use. The simulation-based method uses an EnergyPlus model to generate a benchmark energy intensity normalized for a wider range of parameters. We suggest that both these methods have complementary strengths and limitations. Second, we present"action-oriented" benchmarking, which extends whole-building benchmarking by utilizing system-level features and metrics such as airflow W/cfm to quickly identify a list of potential efficiency actions which can then be used as the basis for a more detailed audit. While action-oriented benchmarking is not an"audit in a box" and is not intended to provide the same degree of accuracy afforded by an energy audit, we demonstrate how it can be used to focus and prioritize audit activity and track performance at the system level. We conclude with key principles that are more broadly applicable to other complex building types.
Date: August 1, 2010
Creator: Mathew, Paul A.; Clear, Robert; Kircher, Kevin; Webster, Tom; Lee, Kwang Ho & Hoyt, Tyler
Partner: UNT Libraries Government Documents Department

Subject Responses to Electrochromic Windows

Description: Forty-three subjects worked in a private office with switchable electrochromic windows, manually-operated Venetian blinds, and dimmable fluorescent lights. The electrochromic window had a visible transmittance range of approximately 3-60%. Analysis of subject responses and physical data collected during the work sessions showed that the electrochromic windows reduced the incidence of glare compared to working under a fixed transmittance (60%) condition. Subjects used the Venetian blinds less often and preferred the variable transmittance condition, but used slightly more electric lighting with it than they did when window transmittance was fixed.
Date: March 3, 2006
Creator: Clear, Robert; Inkarojrit, Vorapat & Lee, Eleanor
Partner: UNT Libraries Government Documents Department

A Design Guide for Early-Market Electrochromic Windows

Description: Switchable variable-tint electrochromic (EC) windows preserve view out while modulating transmitted light, glare, and solar heat gains. Consumers will require objective information on the risks and benefits of this emerging technology as it enters the market in 2006. This guide provides such information and data derived from a wide variety of simulations, laboratory tests, and a 2.5-year field test of prototype large-area EC windows evaluated under outdoor sun and sky conditions. This design guide is provided to architects, engineers, building owners, and others interested in electrochromic windows. The design guide provides basic information about what is an electrochromic window, what it looks like, how fast does it switch, and what current product offerings are. The guide also provides information on performance benefits if more mature product offerings were available.
Date: May 1, 2006
Creator: Lee, Eleanor S.; Selkowitz, Stephen E.; Clear, Robert D.; DiBartolomeo, Dennis L.; Klems, Joseph H.; Fernandes, Luis L. et al.
Partner: UNT Libraries Government Documents Department