Simulation software that can be used to model window system performance.



Calculates detailed and total fenestration product U-values and Solar Heat Gain Coefficient consistent with ASHRAE SPC142, ISO15099, and the National Fenestration Rating Council (NFRC)


Calculates 2-D heat transfer through window frames and edges


Calculates the optical properties of all coated and uncoated glazings, laminates, and applied films

International Glazing Database (IGDB)

Optical data for glazing products used by WINDOW 5.2 and Optics 5.1, including NFRC-approved products

Complex Glazing Database (CGDB)

A database of shading materials and systems, such as roller shades and venetian blinds, that can be used by WINDOW 6 to calculate thermal and optical characteristics of window products with these shading systems


Calculates the daylighting performance of windows, skylights, and electric lighting systems in any arbitrary space


Models hourly building energy use by combining the best features of DOE-2 and BLAST for greater accuracy


A PC program for calculating the heating and cooling energy use, and visual and thermal comfort, of commercial building façades

Background publications: [COMFEN 3.0] [Updates]


A PC program for calculating the heating and cooling energy use of windows in residential buildings


A multi-parameter optimization program designed for minimization of an objective function, such as annual energy use, that is calculated by an external simulation program such as EnergyPlus or DOE-2

Building Controls Virtual Testbed

The Building Controls Virtual Test Bed (BCVTB) is a software environment that allows expert users to couple different simulation programs for co-simulation, and to couple simulation programs with actual hardware

Modelica Buildings Library

The Modelica Buildings library is a free open-source library with dynamic simulation models for building energy and control systems