Software Tools
Software
WINDOW
Berkeley Lab WINDOW is a publicly available computer program for calculating total window thermal performance indices (i.e. U-values, solar heat gain coefficients, shading coefficients, and visible transmittances). Berkeley Lab WINDOW provides a versatile heat transfer analysis method consistent with the updated rating procedure developed by the National Fenestration Rating Council (NFRC) that is consistent with the ISO 15099 standard. The program can be used to design and develop new products, to assist educators in teaching heat transfer through windows, and to help public officials in developing building energy codes.
For more information or user support, email [email protected] or visit the WINDOW Forum.
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THERM
THERM is a state-of-the-art 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'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.
THERM can be used with the Berkeley Lab WINDOW program. THERM's results can be used with WINDOW's center-of-glass optical and thermal models to determine total window product U-factors and Solar Heat Gain Coefficients. These values can be used, in turn, with the RESFEN program, which calculates total annual energy requirements in typical residences throughout the United States.
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COMFEN
COMFEN is a tool designed to support the systematic evaluation of alternative fenestration systems for project-specific commercial building applications. COMFEN provides a simplified user interface that focuses attention on key variables in fenestration design. Under the hood is Energy Plus, a sophisticated analysis engine that dynamically simulates the effects of these key fenestration variables on energy consumption, peak energy demand, and thermal and visual comfort. The results from the Energy Plus simulations are presented in graphical and tabular format within the simplified user interface for comparative fenestration design cases to help users move toward optimal fenestration design choices for their project.
For more information contact [email protected].
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RESFEN
Today's energy-efficient windows can dramatically lower the heating and cooling costs associated with windows while increasing occupant comfort and minimizing window surface condensation problems. However, consumers are often confused about how to pick the most efficient window for a residence. Product information typically offers window properties: U-factors or R-values, Solar Heat Gain Coefficients or Shading Coefficients, and air leakage rates. However, the relative importance of these properties depends on site- and building-specific conditions. Furthermore, these properties are based on static evaluation conditions that are very different from the real situation a window will be used in.
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.
For more information contact [email protected].
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Optics
The Optics computer program is designed for work with optical data for glass and glazing layers. Integration with the International Glazing Database (IGDB) makes it easy to build stacks of multiple glass layers and calculate the resulting optical properties. The program works transmittance and reflectance as a function of wavelength. This allows for calculation of integrated values, such as visible transmittance, according to a range of standards.
For more information contact [email protected].
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Complex Glazing Database (CGDB)
The CGDB is a new optical properties database for optically scattering (complex) systems, such as shading devices and materials (e.g., venetian blinds, roller shades, drapes, cellular shades, shade fabrics, etc.), light redirecting materials (e.g., prismatic films, etc.) and scattering glazing (e.g., diffuse glass, glazing frits, decorative glass, etc.). This database is similar in nature to its more well-known counterpart for specular glazing, the IGDB.
Currently there are not approved procedure to measure large number of different categories of shading materials and/or devices. These procedure and measuring criteria are currently being developed at LBNL. After the publication of measurement procedure, an inter-laboratory comparison (ILC) will be conducted as soon as there are several laboratories that will participate in the ILC. The ILC is expected to be completed, and a full report published, within a year of its commencement. Upon completion of a successful ILC, with at least 1 commercial laboratory showing competence, commercial measurement of scattering systems will be approved.
In the meantime, all measurements for CGDB will be done by LBNL. If you have a product that you would like to be measured and/or included in the CGDB, please contact us via email at [email protected].
The LBNL WINDOW and THERM simulation programs (versions 6 and higher) have the capability to model "complex glazing systems" which include woven shades, venetian blinds, fritted glass, and other systems that can be characterized by BSDF (Bi-Directional Scattering Distribution Function) files.
To support the modeling of these complex systems, it is necessary to characterize the optical and thermal properties of the materials and the systems being modeled.
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AERCalc
AERCalc is used to calculate the annual energy performance of window attachments working with the Attachments Energy Ratings Council. The program allows a user to import windows with attachments from a WINDOW database, specify the air leakage values for specific products such as window panels, calculate the annual energy performance for heating and cooling based on EnergyPlus hourly simulations, and export the results.
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Radiance
Radiance is a suite of programs for the analysis and visualization of lighting in design. It employs advanced Monte Carlo ray-tracing with optimizations for complex building geometries and fenestration systems.
Radiance is used in windows software tools for the calculation of optical properties of optically complex window products, including light-redirecting glazing and films, shading products, etc. Special module called genBSDF is used for this purpose.
Radiance is also used for rendering rooms in COMFEN and Berkeley Lab WINDOW software tools, based on the choice of window and/or shading products. It is also used for creating room luminance maps used in determining glare and daylight availability.
Further information about Radiance, including the download link can be found at www.radiance-online.org.
ADELINE
ADELINE is an integrated lighting design computer tool developed by an international research team within the framework of the International Energy Agency (IEA) Solar Heating and Cooling Programme Task 12.
ADELINE provides architects and engineers with accurate information about behavior and the performance of indoor lighting systems. Both natural and electrical lighting problems can be solved, in simple rooms or the most complex spaces.
Obtain ADELINE from: www.iea-adeline.de
EnergyPlus
EnergyPlus™ is a whole building energy simulation program that engineers, architects, and researchers use to model both energy consumption—for heating, cooling, ventilation, lighting and plug and process loads—and water use in buildings.
Obtain EnergyPlus from: energyplus.net
GenOpt
GenOpt® is an optimization program for the minimization of a cost function that is evaluated by an external simulation program, such as EnergyPlus, TRNSYS, Dymola, IDA-ICE or DOE-2. It has been developed for optimization problems where the cost function is computationally expensive and its derivatives are not available or may not even exist. GenOpt can be coupled to any simulation program that reads its input from text files and writes its output to text files. The independent variables can be continuous variables (possibly with lower and upper bounds), discrete variables, or both. Constraints on dependent variables can be implemented using penalty or barrier functions.
Obtain GenOpt from: gundog.lbl.gov/GO/
Retrofit Energy Savings Estimation Model (RESEM)
A PC-based tool designed to allow Department of Energy (DOE) Institutional Conservation Program (ICP) staff and participants to reliably determine the energy savings directly caused by ICP-supported retrofit measures implemented in a building.
Superlite
A PC-based software tool developed to aid architects and designers in daylighting analysis.