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Daylighting simulation: methods, algorithms, and resources

Description: This document presents work conducted as part of Subtask C, ''Daylighting Design Tools'', Subgroup C2, ''New Daylight Algorithms'', of the IEA SHC Task 21 and the ECBCS Program Annex 29 ''Daylight in Buildings''. The search for and collection of daylighting analysis methods and algorithms led to two important observations. First, there is a wide range of needs for different types of methods to produce a complete analysis tool. These include: Geometry; Light modeling; Characterization of the natural illumination resource; Materials and components properties, representations; and Usability issues (interfaces, interoperability, representation of analysis results, etc). Second, very advantageously, there have been rapid advances in many basic methods in these areas, due to other forces. They are in part driven by: The commercial computer graphics community (commerce, entertainment); The lighting industry; Architectural rendering and visualization for projects; and Academia: Course materials, research. This has led to a very rich set of information resources that have direct applicability to the small daylighting analysis community. Furthermore, much of this information is in fact available online. Because much of the information about methods and algorithms is now online, an innovative reporting strategy was used: the core formats are electronic, and used to produce a printed form only secondarily. The electronic forms include both online WWW pages and a downloadable .PDF file with the same appearance and content. Both electronic forms include live primary and indirect links to actual information sources on the WWW. In most cases, little additional commentary is provided regarding the information links or citations that are provided. This in turn allows the report to be very concise. The links are expected speak for themselves. The report consists of only about 10+ pages, with about 100+ primary links, but with potentially thousands of indirect links. For purposes of the printed version, a list ...
Date: December 1, 1999
Creator: Carroll, William L.
Partner: UNT Libraries Government Documents Department

Structural, optical and electrical properties of WOxNy filmsdeposited by reactive dual magnetron sputtering

Description: Thin films of tungsten oxynitride were prepared by dual magnetron sputtering of tungsten using argon/oxygen/nitrogen gas mixtures with various nitrogen/oxygen ratios. The presence of even small amounts of oxygen had a great effect not only on the composition but on the structure of WOxNy films, as shown by Rutherford backscattering and x-ray diffraction, respectively. Significant incorporation of nitrogen occurred only when the nitrogen partial pressure exceeded 89 percent of the total reactive gas pressure. Sharp changes in the stoichiometry, deposition rate, room temperature resistivity, electrical activation energy and optical band gap were observed when the nitrogen/oxygen ratio was high.The deposition rate increased from 0.31 to 0.89 nm/s, the room temperature resistivity decreased from 1.65 x 108 to 1.82 x 10-2 ?cm, the electrical activation energy decreased from 0.97 to 0.067 eV, and the optical band gap decreased from 3.19 to 2.94 eV upon nitrogen incorporation into the films. WOxNy films were highly transparent as long as the nitrogen incorporation was low, and were brownish (absorbing) and partially reflecting as nitrogen incorporation became significant.
Date: June 5, 2006
Creator: Mohamed, Sodky H. & Anders, Andre
Partner: UNT Libraries Government Documents Department

A model to estimate the cost effectiveness of the indoorenvironment improvements in office work

Description: Deteriorated indoor climate is commonly related to increases in sick building syndrome symptoms, respiratory illnesses, sick leave, reduced comfort and losses in productivity. The cost of deteriorated indoor climate for the society is high. Some calculations show that the cost is higher than the heating energy costs of the same buildings. Also building-level calculations have shown that many measures taken to improve indoor air quality and climate are cost-effective when the potential monetary savings resulting from an improved indoor climate are included as benefits gained. As an initial step towards systemizing these building level calculations we have developed a conceptual model to estimate the cost-effectiveness of various measures. The model shows the links between the improvements in the indoor environment and the following potential financial benefits: reduced medical care cost, reduced sick leave, better performance of work, lower turn over of employees, and lower cost of building maintenance due to fewer complaints about indoor air quality and climate. The pathways to these potential benefits from changes in building technology and practices go via several human responses to the indoor environment such as infectious diseases, allergies and asthma, sick building syndrome symptoms, perceived air quality, and thermal environment. The model also includes the annual cost of investments, operation costs, and cost savings of improved indoor climate. The conceptual model illustrates how various factors are linked to each other. SBS symptoms are probably the most commonly assessed health responses in IEQ studies and have been linked to several characteristics of buildings and IEQ. While the available evidence indicates that SBS symptoms can affect these outcomes and suspects that such a linkage exists, at present we can not quantify the relationships sufficiently for cost-benefit modeling. New research and analyses of existing data to quantify the financial importance of SBS symptoms would enable more ...
Date: June 1, 2004
Creator: Seppanen, Olli & Fisk, William J.
Partner: UNT Libraries Government Documents Department

A method for simulatingthe performance of photosensor-basedlighting controls

Description: The unreliability of photosensor-based lighting controlscontinues to be a significant market barrier that prevents widespreadacceptance of daylight dimming controls in commercial buildings. Energysavings from the use of daylighting in commercial buildings is bestrealized through the installation of reliable photoelectric lightingcontrols that dim electric lights when sufficient daylight is availableto provide adequate background and/or task illumination. In prior work,the authors discussed the limitations of current simulation approachesand presented a robust method to simulate the performance ofphotosensor-based controls using an enhanced version of the Radiancelighting simulation package. The method is based on the concept ofmultiplying two fisheye images: one generated from the angularsensitivity of the photosensor and the other from a 180- or 360-degreefisheye image of the space as "seen" by the photosensor. This paperincludes a description of the method, its validation and possibleapplications for designing, placing, calibrating and commissioningphotosensor-based lighting controls.
Date: October 1, 2000
Creator: Ehrlich, Charles; Papamichael, Konstantinos; Lai, Judy & Revzan,Kenneth
Partner: UNT Libraries Government Documents Department