@techreport {1972, title = {WINDOW 6.2/THERM 6.2 Research Version User Manual}, year = {2008}, month = {01/2008}, pages = {1-126}, institution = {Lawrence Berkeley National Laboratory}, address = {Berkeley}, abstract = {

WINDOW 6 and THERM 6 Research Versions are software programs developed at Lawrence Berkeley National Laboratory (LBNL) for use by manufacturers, engineers, educators, students, architects, and others to determine the thermal and solar optical properties of glazing and window systems.

WINDOW 6 and THERM 6 are significant updates to LBNL{\textquoteright}s WINDOW 5 and THERM 5 computer program because of the added capability to model complex glazing systems, such as windows with shading systems, in particular venetian blinds. Besides a specific model for venetian blinds and diffusing layers, WINDOW 6 also includes the generic ability to model any complex layer if the Transmittance and Reflectance are known as a function of incoming and outgoing angles.

The algorithms used in these versions of the programs to determine the properties of windows with shading layers are relatively new and should be considered as informative but not definitive.

As such, for windows with shading layers, the results are intended for research purposes only. Pending further validation efforts, results for windows with sh ading layers should not be used for NFRC certified calculations of design decisions in real buildings.

All calculations for products without shading layers are identical to those from WINDOW 5.2.

WINDOW 6 Research Version includes all of the WINDOW 5 capabilities with the addition of shading algorithms from ISO15099 which are incorporated into the program, as well as an extension of those algorithms with the matrix calculation method.

THERM 6 Research Version includes all of the THERM 5 capabilities with the addition of being able to import and model WINDOW 6 glazing systems with shading devices. Those THERM 6 files with shading devices can them be imported into the WINDOW 6 Frame Library and whole windows with shading devices can then be modeled in WINDOW 6.

}, author = {Robin Mitchell and Christian Kohler and Joseph H. Klems and Michael D. Rubin and Dariush K. Arasteh and Charlie Huizenga and Tiefeng Yu and Dragan C. Curcija} } @conference {11848, title = {Evaluating Fenestration Products for Zero-Energy Buildings: Issues for Discussion}, booktitle = {SimBuild 2006: Building Sustainability and Performance Through Simulation}, year = {2006}, month = {08/2006}, address = {Cambridge, MA}, abstract = {

Computer modeling to determine fenestration product energy properties (U-factor, SHGC, VT) has emerged as the most cost-effective and accurate means to quantify them. Fenestration product simulation tools have been effective in increasing the use of low-e coatings and gas fills in insulating glass and in the widespread use of insulating frame designs and materials. However, for more efficient fenestration products (low heat loss products, dynamic products, products with non-specular optical characteristics, light redirecting products) to achieve widespread use, fenestration modeling software needs to be improved.

This paper addresses the following questions:

1) Are the current properties (U, SHGC, VT) calculated sufficient to compare and distinguish between windows suitable for Zero Energy Buildings and conventional window products? If not, what data on the thermal and optical performance, on comfort, and on peak demand of windows is needed.

2) Are the algorithms in the tools sufficient to model the thermal and optical processes? Are specific heat transfer and optical effects not accounted for? Is the existing level of accuracy enough to distinguish between products designed for Zero Energy Buildings? Is the current input data adequate?

}, author = {Dariush K. Arasteh and Dragan C. Curcija and Yu Joe Huang and Charlie Huizenga and Christian Kohler} } @techreport {1768, title = {RESFEN5: Program Description}, year = {2005}, month = {05/2005}, institution = {Lawrence Berkeley National Laboratory}, abstract = {

A computer tool such as RESFEN can help consumers and builders pick the most energy-efficient and cost-effective window for a given application, whether it is a new home, an addition, or a window replacement. It calculates heating and cooling energy use and associated costs as well as peak heating and cooling demand for specific window products. Users define a specific scenario by specifying house type (single-story or two-story), geographic location, orientation, electricity and gas cost, and building configuration details (such as wall, floor, and HVAC system type). Users also specify size, shading, and thermal properties of the window they wish to investigate. The thermal properties that RESFEN requires are: U-factor, Solar Heat Gain Coefficient, and air leakage rate. RESFEN calculates the energy and cost implications of the window compared to an insulated wall. The relative energy and cost impacts of two different windows can be compared.

RESFEN 3.0 was a major improvement over previous versions because it performs hourly calculations using a version of the DOE 2.1E (LBL 1980, Winkelmann et al. 1993) energy analysis simulation program. RESFEN 3.1 incorporates additional improvements including input assumptions for the base case buildings taken from the National Fenestration Rating Council (NFRC) Annual Energy Subcommittee{\textquoteright}s efforts.

}, author = {Robin Mitchell and Yu Joe Huang and Dariush K. Arasteh and Charlie Huizenga and Steve Glendenning} } @techreport {1894, title = {THERM 5/WINDOW 5 NFRC Simulation Manual}, year = {2003}, abstract = {

This document, the THERM 5 / WINDOW 5 NFRC Simulation Manual, discusses how to use the THERM and WINDOW programs to model products for NFRC certified simulations and assumes that the user is already familiar with those programs. In order to learn how to use these programs, it is necessary to become familiar with the material in both the THERM Users Manual and the WINDOW Users Manual. In general, this manual references the Users Manuals rather than repeating the information.

If there is a conflict between either of the User Manual and this THERM 5 / WINDOW 5 NFRC Simulation Manual, the THERM 5 / WINDOW 5 NFRC Simulation Manual takes precedence. In addition, if this manual is in conflict with any NFRC standards, the standards take precedence. For example, if samples in this manual do not follow the current taping and testing NFRC standards, the standards not the samples in this manual, take precedence.

}, author = {Robin Mitchell and Christian Kohler and Dariush K. Arasteh and John Carmody and Charlie Huizenga and Dragan C. Curcija} } @conference {11950, title = {Improving Information Technology to Maximize Fenestration Energy Efficiency}, booktitle = {Performance of Exterior Envelopes of Whole Buildings VIII}, year = {2001}, month = {12/2001}, address = {Clearwater Beach, FL}, abstract = {

Annual heating and cooling energy loads through fenestration products in both residential and commercial buildings are a significant fraction of national energy requirements. In the residential sector, 1.34 and 0.37 quads are required for heating and cooling respectively (DOE Core Data Book, 2000). In commercial buildings, cooling energy use to compensate for fenestration product solar heat gain is estimated at 0.39 quads; heating energy use to compensate for heat loss through fenestration products is estimated at 0.19 quads. Advanced products offer the potential to reduce these energy uses by at least 50\% (Frost et. al. 1993). Potential electric lighting savings from fenestration products are estimated at 0.4 quads if daylight can be used effectively so that electric lighting in commercial building perimeter zones can be reduced.

Software has begun to make an impact on the design and deployment of efficient fenestration products by making fenestration product performance ratings widely available. These ratings, which are determined in part using software programs such as WINDOW/THERM/Optics, VISION/FRAME, and WIS, can now easily be used by architects, engineers, professional fenestration product specifiers, and consumers. Information on the properties of fenestration products has also influenced state and national codes (IECC, ASHRAE 90.1) and aided voluntary market transformation programs, such as the Efficient Windows Collaborative and the Energy Star Windows program, which promote efficient fenestration products.

}, author = {Dariush K. Arasteh and Robin Mitchell and Christian Kohler and Charlie Huizenga and Dragan C. Curcija} } @techreport {1971, title = {WINDOW 5.0 User Manual for Analyzing Window Thermal Performance}, year = {2001}, author = {Robin Mitchell and Christian Kohler and Dariush K. Arasteh and Charlie Huizenga and Dragan C. Curcija} } @techreport {1892, title = {THERM 2.1 NFRC Simulation Manual}, year = {2000}, month = {07/2000}, pages = {260}, abstract = {

This document, the THERM 2.1 NFRC Simulation Manual, discusses how to use THERM to model products for NFRC certified simulations and assumes that the user is already familiar with the THERM program. In order to learn how to use THERM, it is necessary to become familiar with the material in the THERM User{\textquoteright}s Manual.

In general, this manual references the THERM User{\textquoteright}s Manual rather than repeating the information.

If there is a conflict between the THERM User{\textquoteright}s Manual and the THERM 2.1 NFRC Simulation Manual, the THERM 2.1 NFRC Simulation Manual takes precedence.

}, author = {Robin Mitchell and Christian Kohler and Dariush K. Arasteh and Elizabeth U. Finlayson and Charlie Huizenga and Dragan C. Curcija and John Carmody} } @conference {1890, title = {THERM 2.0: A Building Component Model for Steady-State Two-Dimensional Heat Transfer}, booktitle = {Building Simulation 99, International Building Performance Simulation Association (IBPSA)}, year = {1999}, month = {09/1999}, address = {Kyoto, Japan}, abstract = {

THERM 2.0 is a state-of-the-art software program, available without cost, that uses the finite-element method to model steady-state, two-dimensional heat-transfer problems. It includes a powerful simulation engine combined with a simple, interactive interface and graphic results. Although it was developed primarily to model thermal properties of windows, it is appropriate for other building components such as walls, doors, roofs, and foundations, and is useful for modeling thermal bridges in many other contexts, such as the design of equipment.

}, author = {Charlie Huizenga and Dariush K. Arasteh and Elizabeth U. Finlayson and Robin Mitchell and Brent T. Griffith and Dragan C. Curcija} } @conference {1847, title = {State-of-the-Art Software for Window Energy-Efficiency Rating and Labeling}, booktitle = {ACEEE 1998 Summer Study on Energy Efficiency in Buildings}, year = {1998}, month = {08/1998}, address = {Pacific Grove, CA}, abstract = {

Measuring the thermal performance of windows in typical residential buildings is an expensive proposition. Not only is laboratory testing expensive, but each window manufacturer typically offers hundreds of individual products, each of which has different thermal performance properties. With over a thousand window manufacturers nationally, a testing-based rating system would be prohibitively expensive to the industry and to consumers.

Beginning in the early 1990s, simulation software began to be used as part of a national program for rating window U-values. The rating program has since been expanded to include Solar Hear Gain Coefficients and is now being extended to annual energy performance.

This paper describes four software packages available to the public from Lawrence Berkeley National Laboratory (LBNL). These software packages are used to evaluate window thermal performance: RESFEN (for evaluating annual energy costs), WINDOW (for calculating a products thermal performance properties), THERM (a preprocessor for WINDOW that determines two-dimensional heat-transfer effects), and Optics (a preprocessor for WINDOWs glass database).

Software not only offers a less expensive means than testing to evaluate window performance, it can also be used during the design process to help manufacturers produce windows that will meet target specifications. In addition, software can show small improvements in window performance that might not be detected in actual testing because of large uncertainties in test procedures.

}, author = {Dariush K. Arasteh and Elizabeth U. Finlayson and Yu Joe Huang and Charlie Huizenga and Robin Mitchell and Michael D. Rubin} } @article {1880, title = {Teaching Students about Two-Dimensional Heat Transfer Effects in Buildings, Building Components, Equipment, and Appliances Using THERM 2.0}, journal = {ASHRAE Transactions}, volume = {105, Part 1}, year = {1998}, month = {01/1999}, address = {Chicago, IL}, abstract = {

THERM 2.0 is a state-of-the-art software program, available for free, that uses the finite-element method to model steady-state, two-dimensional heat-transfer effects. It is being used internationally in graduate and undergraduate laboratories and classes as an interactive educational tool to help students gain a better understanding of heat transfer. THERM offers students a powerful simulation engine combined with a simple, interactive interface and graphic results. Although it was developed to model thermal properties of building components such as windows, walls, doors, roofs, and foundations, it is useful for modeling thermal bridges in many other contexts, such as the design of equipment. These capabilities make THERM a useful teaching tool in classes on: heating, ventilation, and air-conditioning (HVAC); energy conservation; building design; and other subjects where heat-transfer theory and applications are important. THERMs state-of-the-art interface and graphic presentation allow students to see heat-transfer paths and to learn how changes in materials affect heat transfer. THERM is an excellent tool for helping students understand the practical application of heat-transfer theory.

}, author = {Charlie Huizenga and Dariush K. Arasteh and Elizabeth U. Finlayson and Robin Mitchell and Brent T. Griffith} } @techreport {1891, title = {THERM 2.0: a PC Program for Analyzing Two-Dimensional Heat Transfer through Building products}, year = {1998}, abstract = {

THERM is a state-of-the-art, Microsoft Windows?-based computer program developed at Lawrence Berkeley National Laboratory (LBNL) for use by building component manufacturers, engineers, educators, students, architects, and others interested in heat transfer. Using THERM, you can model two-dimensional heat-transfer effects in building components such as windows, walls, foundations, roofs, and doors; appliances; and other products where thermal bridges are of concern. THERM{\textquoteright}s heat-transfer analysis allows you to evaluate a product?s energy efficiency and local temperature patterns, which may relate directly to problems with condensation, moisture damage, and structural integrity.

This version of THERM includes several new technical and user interface features; the most significant is a radiation view-factor algorithm. This feature increases the accuracy of calculations in situations where you are analyzing non-planar surfaces that have different temperatures and exchange energy through radiation heat transfer. This heat-transfer mechanism is important in greenhouse windows, hollow cavities, and some aluminum frames.

}, author = {Elizabeth U. Finlayson and Robin Mitchell and Dariush K. Arasteh and Charlie Huizenga and Dragan C. Curcija} } @article {11906, title = {Guidelines for Modeling Projecting Fenestration Products}, journal = {ASHRAE Transactions}, volume = {104, Part 1}, year = {1997}, month = {01/1998}, address = {San Francisco, CA}, abstract = {

Heat transfer patterns in projecting fenestration products (greenhouse windows, skylights, etc.) are different than those with typical planar window products. The projecting surfaces often radiate to each other, thereby invalidating the commonly used assumption that fenestration product interior surfaces radiate to a uniform room air temperature. The convective portion of the surface heat transfer coefficient is also significantly different from the one used with planar geometries, and is even more dependent on geometry and location. Projecting fenestration product profiles must therefore be modeled in their entirety. This paper presents the results of complete cross section, variable film-coefficient, 2-D heat transfer modeling of two greenhouse windows using the next generation of window specific heat transfer modeling tools. The use of variable film-coefficient models is shown to increase the accuracy with which simulation tools can compute U-factors. Simulated U-factors are also determined using conventional constant film coefficient algorithms. The results from both sets of simulations are compared with measured values.

}, author = {Dariush K. Arasteh and Elizabeth U. Finlayson and Dragan C. Curcija and Jeff Baker and Charlie Huizenga} } @conference {11532, title = {Advances in Thermal and Optical Simulations of Fenestration Systems: The Development of WINDOW 5}, booktitle = {Thermal Performance of the Exterior Envelopes of Buildings VI Conference }, year = {1995}, month = {12/1995}, address = {Clearwater Beach, FL}, abstract = {

WINDOW is a personal-computer-based computer program used by manufacturers, researchers, and consumers to evaluate the thermal performance properties (U-factors, solar heat gain and shading coefficients, and visible transmittances) of complete windows and other fenestration systems. While WINDOW is used by thousands of users in the United States and internationally and is at the foundation of the National Fenestration Rating Council{\textquoteright}s U-factor and solar heat gain property procedures, improvements to the program are still necessary for it to meet user needs. Version 5, intended for release in late 1995, is being developed to meet these needs for increased accuracy, a flexible and state-of-the-art user interface, and the capabilities to handle more product types.

WINDOW 5 includes the capabilities to define and model the thermal performance of frames/dividers and their associated edge effects. Currently, such an analysis must be performed outside of WINDOW and requires simplifications to be made to frame profiles or is based on the use of generic frame and edge correlations. WINDOW{\textquoteright}s two-dimensional thermal model is composed of four sections: a graphical input, automatic grid generation, an finite-element analysis (FEA) solution, and the display of results. In the graphical input section, users are able to directly import a computer-aided design (CAD) drawing or a scanned image of a window profile, replicate its exact geometry, and assign material types and boundary conditions. The automatic grid generation is transparent to the user, with the exception of the requirement that complex shapes (i.e., an aluminum extrusion) be broken down into simpler polyshapes. Inclusion of an automatic grid generation makes detailed "true geometry" frame-and-edge heat-transfer analysis accessible to users without extensive knowledge of numerical methods of heat-transfer analysis. After the cross section is meshed it is sent to the FEA engine for solution and the results are returned. A postprocessor allows for the visual display of temperature and heat flux plots. Note that while this two-dimensional heat-transfer tool is being developed specifically for fenestration products, it also can be used to analyze other building envelope components.

WINDOW 5 also will include a built-in version of a national laboratory{\textquoteright}s program that allows the user to estimate the orientation-dependent annual energy impacts of a given window in a typical residence in various U.S. climates. This program is based on regressions to a database of DOE2.1 runs. Future versions will include a similar feature for commercial buildings.

Other technical additions include an improved angular/ spectral model for coated and uncoated glazings, the ability to analyze the optical properties of nonhomogeneous layers, and the ability to model the effects of laminated glazing layers. A door module permits the user to compute the total U-factors of exterior doors based on component U-factors calculated using the two-dimensional FEA module.

}, author = {Elizabeth U. Finlayson and Dariush K. Arasteh and Michael D. Rubin and John Sadlier and Robert Sullivan and Charlie Huizenga and Dragan C. Curcija and Mark Beall} } @techreport {1970, title = {WINDOW 4.1: Program Description}, year = {1994}, abstract = {

WINDOW 4.1 is a publicly available IBM PC compatible computer program developed by the Windows and Daylighting Group at Lawrence Berkeley Laboratory for calculating total window thermal performance indices (i.e. U-values, solar heat gain coefficients, shading coefficients, and visible transmittances). WINDOW 4.1 provides a versatile heat transfer analysis method consistent with the rating procedure developed by the National Fenestration Rating Council (NFRC). The program can be used to design and develop new products, to rate and compare performance characteristics of all types of window products, to assist educators in teaching heat transfer through windows, and to help public officials in developing building energy codes.

WINDOW 4.1 is an update to WINDOW 4.0. The WINDOW 4 series is a major revision to previous versions of WINDOW. We strongly urge all users to read this manual before using the program. Users who need professional assistance with the WINDOW 4.1 program or other window performance simulation issues are encouraged to contact one or more of the NFRC-accredited Simulation Laboratories.

}, author = {Dariush K. Arasteh and Elizabeth U. Finlayson and Charlie Huizenga} } @techreport {1968, title = {Window 4.0: Documentation of Calculation Procedures}, year = {1993}, abstract = {

WINDOW 4.0 is a publicly available IBM PC compatible computer program developed by the Building Technologies Group at the Lawrence Berkeley Laboratory for calculating the thermal and optical properties necessary for heat transfer analyses of fenestration products. This report explains the calculation methods used in WINDOW 4.0 and is meant as a tool for those interested in understanding the procedures contained in WINDOW 4.0. All the calculations are discussed in the International System of units (SI).

}, author = {Elizabeth U. Finlayson and Dariush K. Arasteh and Charlie Huizenga and Michael D. Rubin and M. Susan Reilly} }