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Solar heat gain coefficient of complex fenestrations with a venetian blind for differing slat tilt angles

Description: Measured bidirectional transmittances and reflectances of a buff-colored venetian blind together with a layer calculation scheme developed in previous publications are utilized to produce directional-hemispherical properties for the venetian blind layer and solar heat gain coefficients for the blind in combination with clear double glazing. Results are presented for three blind slat tilt angles and for the blind mounted either interior to the double glazing or between the glass panes. Implications of the results for solar heat gain calculations are discussed in the context of sun positions for St. Louis, MO.
Date: August 1996
Creator: Klems, J. H. & Warner, J. L.
Partner: UNT Libraries Government Documents Department

Fenestration System Performance Research, Testing, and Evaluation

Description: The US DOE was and is instrumental to NFRC's beginning and its continued success. The 2005 to 2009 funding enables NFRC to continue expanding and create new, improved ratings procedures. Research funded by the US DOE enables increased fenestration energy rating accuracy. International harmonization efforts supported by the US DOE allow the US to be the global leader in fenestration energy ratings. Many other governments are working with the NFRC to share its experience and knowledge toward development of their own national fenestration rating process similar to the NFRC's. The broad and diverse membership composition of NFRC allows anyone with a fenestration interest to come forward with an idea or improvement to the entire fenestration community for consideration. The NFRC looks forward to the next several years of growth while remaining the nation's resource for fair, accurate, and credible fenestration product energy ratings. NFRC continues to improve its rating system by considering new research, methodologies, and expanding to include new fenestration products. Currently, NFRC is working towards attachment energy ratings. Attachments are blinds, shades, awnings, and overhangs. Attachments may enable a building to achieve significant energy savings. An NFRC rating will enable fair competition, a basis for code references, and a new ENERGY STAR product category. NFRC also is developing rating methods to consider non specular glazing such as fritted glass. Commercial applications frequently use fritted glazing, but no rating method exists. NFRC is testing new software that may enable this new rating and contribute further to energy conservation. Around the world, many nations are seeking new energy conservation methods and NFRC is poised to harmonize its rating system assisting these nations to better manage and conserve energy in buildings by using NFRC rated and labeled fenestration products. As this report has shown, much more work needs to be done ...
Date: November 30, 2009
Creator: Benney, Jim
Partner: UNT Libraries Government Documents Department

Energy performance analysis of prototype electrochromic windows

Description: This paper presents the results of a study investigating the energy performance of three newly developed prototype electrochromic devices. The DOE-2.1 E energy simulation program was used to analyze the annual cooling, lighting, and total electric energy use and peak demand as a function of window type and size. The authors simulated a prototypical commercial office building module located in the cooling-dominated locations of Phoenix, AZ and Miami, FL. Heating energy use was also studied in the heating-dominated location of Madison, WI. Daylight illuminance was used to control electrochromic state-switching. Two types of window systems were analyzed; i.e., the outer pane electrochromic glazing was combined with either a conventional low-E or a spectrally selective inner pane. The properties of the electrochromic glazings are based on measured data of new prototypes developed as part of a cooperative DOE-industry program. The results show the largest difference in annual electric energy performance between the different window types occurs in Phoenix and is about 6.5 kWh/m{sup 2} floor area (0.60 kWh/ft{sup 2}) which can represent a cost of about $.52/m{sup 2} ($.05/ft{sup 2}) using electricity costing $.08/kWh. In heating-dominated locations, the electrochromic should be maintained in its bleached state during the heating season to take advantage of beneficial solar heat gain which would reduce the amount of required heating. This also means that the electrochromic window with the largest solar heat gain coefficient is best.
Date: December 1, 1996
Creator: Sullivan, R.; Rubin, M. & Selkowitz, S.
Partner: UNT Libraries Government Documents Department

Office worker response to an automated venetian blind and electric lighting system: A pilot study

Description: A prototype integrated, dynamic building envelope and lighting system designed to optimize daylight admission and solar heat gain rejection on a real-time basis in a commercial office building is evaluated. Office worker response to the system and occupant-based modifications to the control system are investigated to determine if the design and operation of the prototype system can be improved. Key findings from the study are: (1) the prototype integrated envelope and lighting system is ready for field testing, (2) most office workers (N=14) were satisfied with the system, and (3) there were few complaints. Additional studies are needed to explain how illuminance distribution, lighting quality, and room design can affect workplans illuminance preferences.
Date: March 1998
Creator: Vine, E.; Lee, E.; Clear, R.; DiBartolomeo, D. & Selkowitz, S.
Partner: UNT Libraries Government Documents Department

Developing a dynamic envelope/lighting control system with field measurements

Description: The feasibility of an intelligent venetian blind/lighting control system was tested in a 1:3 scale model outdoors under variable sun and sky conditions. The control algorithm, block direct sun and meet the design workplane illuminance level, was implemented using commercially available and custom designed blind and lighting systems hardware. While blocking direct sunlight, the blinds were properly controlled to maintain the design workplane illuminance within a tolerance of -10%, +25% when there was sufficient daylight. When daylight levels alone were inadequate, the electric lighting control system maintained the design workplane illuminance. The electric lighting could be turned off if a user-specified time period at minimum power was exceeded. Lighting energy savings of 51-71% (southwest) and 37-75% (south) was attained for the period from 8:00 to 17:00 on clear sunny days, compared to a fixed, partially closed blind with the same lighting system. Practical details for implementation and commissioning are discussed. The impact of control variations, such as profile angle, time step interval, and control area, on energy demand is investigated.
Date: May 1, 1996
Creator: DiBartolomeo, D.L.; Lee, E.S.; Rubinstein, F.M. & Selkowitz, S.E.
Partner: UNT Libraries Government Documents Department

Visual quality assessment of electrochromic and conventional glazings

Description: Variable transmission, ``switchable`` electrochromic glazings are compared to conventional static glazings using computer simulations to assess the daylighting quality of a commercial office environment where paper and computer tasks are performed. RADIANCE simulations were made for a west-facing commercial office space under clear and overcast sky conditions. This visualization tool was used to model different glazing types, to compute luminance and illuminance levels, and to generate a parametric set of photorealistic images of typical interior views at various times of the day and year. Privacy and visual display terminal (VDT) visibility is explored. Electrochromic glazings result in a more consistent glare-free daylit environment compared to their static counterparts. However, if the glazing is controlled to minimize glare or to maintain low interior daylight levels for critical visual tasks (e.g, VDT), occupants may object to the diminished quality of the outdoor view due to its low transmission (Tv = 0.08) during those hours. RADIANCE proved to be a very powerful tool to better understand some of the design tradeoffs of this emerging glazing technology. The ability to draw specific conclusions about the relative value of different technologies or control strategies is limited by the lack of agreed upon criteria or standards for lighting quality and visibility.
Date: September 1, 1996
Creator: Moeck, M.; Lee, E.S.; Rubin, M.D.; Sullivan, R. & Selkowitz, S.E.
Partner: UNT Libraries Government Documents Department

Energy efficient louver and blind. Final technical progress report, third quarter 1996

Description: In the month of July, we completed the energy testing at Lawrence Berkeley Labs. The final testing was done with blinds in 15 degree position. This is a comfortable blind angle that allows for view of the outside while allowing for natural light to enter the room. It was found that the energy savings are much higher at this angle. At zero degree blind angle the savings were 150W/sq. meter, in the 15 degree the heat gain is cut by 225W/sq. meter. During the same period the heat gain in control chamber was 500W. (See graph plotting {open_quotes}Sample Heat Flows{close_quotes} From July 21 to 29 on next 3 pages). The heat gain reduction achieved in tests if used in commercial blinds, would result in an energy pay back period or one year and nine months.
Date: October 14, 1996
Creator: Khajavi, S.
Partner: UNT Libraries Government Documents Department

A new method for predicting the solar heat gain of complex fenestration systems

Description: A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bidirectional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorbances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient. The method has been applied to one of the most optically complex systems in common use, a venetian blind in combination with multiple glazings. A comparison between the scanner-based calculation method and direct system calorimetric measurements made on the LBL MoWiTT facility showed good agreement, and is a significant validation of the method accuracy and feasibility.
Date: March 1, 1995
Creator: Klems, J.H.; Warner, J.L. & Kelley, G.O.
Partner: UNT Libraries Government Documents Department

Cooling your home naturally

Description: This fact sheet describes some alternatives to air conditioning which are common sense suggestions and low-cost retrofit options to cool a house. It first describes how to reflect heat away from roofs, walls, and windows. Blocking heat by using insulation or shading are described. The publication then discusses removing built-up heat, reducing heat-generating sources, and saving energy by selecting energy efficient retrofit appliances. A resource list is provided for further information.
Date: October 1, 1994
Partner: UNT Libraries Government Documents Department

Summer-heat-gain control in passive-solar-heated buildings: fixed horizontal overhangs

Description: An aspect of passive cooling relates to cooling load reduction by the use of solar controls. When there is a substantial winter heating requirement, and when the winter heating needs are met in part by a passive solar heating system, then the potential aggravation of summer cooling loads by the heating system is an important design issue. A traditional solution is the use of a fixed, horizontal shading overhang. An approach to quantitative design rules for the sizing of a shading overhang to minimize total annual space conditioning energy needs is outlined.
Date: January 1, 1981
Creator: Jones, R.W.
Partner: UNT Libraries Government Documents Department

Sun-shades as a passive cooling element

Description: A discussion of the importance of proper sun-shade design is presented by showing results of thermal performance evaluation of a building with and without sun-shades. The analysis was carried out by using a simulation model developed by Shaviv and Shaviv. The criteria for evaluating sunshades is based on the total energy consumption of the building for cooling, heating, and artificial lighting. We find that the best solution for shading is external sun-shades and we present a method developed by Shaviv for their design. Several designs of external sun-shades are presented.
Date: January 1, 1980
Creator: Shaviv, E
Partner: UNT Libraries Government Documents Department

Testing of Air-Flow Windows for Evaluation and Application

Description: A description is given of how the performance of air-flow windows was assessed in comparison to a conventional window of good current design. Tests were performed in the University Building Environment and Energy Laboratory which allowed tests quite representative of actual application conditions in a variety of vertical orientations. The actual application condition requirement necessitated some approximations to the energy measurements which are not found in guarded hot box or calorimeter kinds of approaches to performance evaluations. The testing technique and required approximations are described. A possible type of solar-residential application is also described briefly.
Date: December 1980
Creator: Boehm, R. F. & Brandle, K.
Partner: UNT Libraries Government Documents Department

Cool Pool development. Quarterly technical report No. 3, July 1-September 30, 1980

Description: The Cool Pool is a shaded evaporating pool that is connected to thermal mass storage in a thermosyphon configuration. The system requires no moveable insulation. The pool is placed outside a building, and the thermal mass, vertical tubes full of water, are inside the living space. The pool must be elevated so that its water level is as high or higher than the water level in the tubes for thermosyphoning to work properly. The pool is shaded to prevent heating by direct solar radiation. A schematic of the Cool Pool is shown and how it works is described. Tests performed at Living Systems at Winters, California and analytical results are discussed.
Date: September 1, 1980
Creator: Batts, D.
Partner: UNT Libraries Government Documents Department

Options for passive energy conservation in site design

Description: At a time of concern for energy supplies and costs it is essential to examine the energy-conserving potential of once again using natural energy systems and patterns that exist on any site on which a building is to be or has been placed. This state-of-the-art study examines existing research and applications of land planning and design for energy-conservation purposes. It is organized around the basic principles of natural heating and cooling factors and the impact of site elements on human comfort, regional adaptation of these principles, steps in the site planning and design process, and energy-conservation options available in each of the steps. This is supplemented by an appendix and a bibliography of additional references. The principles of site planning and design for energy conservation deal with the impact of the sun and wind on natural elements and, conversely, ways in which landforms, water, and vegetation affect the impact of the sun and wind on limited sections of the earth. For instance, the sun is able to naturally warm certain slopes more than others, certain surface materials naturally accentuate the warmth of the sun, while certain naturally occurring elements, such as vegetation, block and control the sun. The wind moving over the earth's surface has certain natural directions, patterns, and characteristics. By recognizing these and by introducing or removing impediments it is possible to modify these patterns to provide natural ventilation and to conserve energy. Four commonly accepted regional divisions were utilized to illustrate the differing applications of these principles in the temperate, hot-humid, hot-arid, and cool regions of the continental U.S. The typical site planning or design process was superimposed over each region to illustrate the various energy conservation options possible, depending upon the precise decision made in each step in each region. 300 references.
Date: June 1, 1978
Partner: UNT Libraries Government Documents Department