WINDOW — The Complete Guide: Free U-Value, SHGC and Visible Transmittance of Glazing Systems
WINDOW is software from Lawrence Berkeley National Laboratory (LBNL) for computing the thermal and optical properties of glazing systems. You define the layer build-up — glass panes, coatings, gas gaps and frame — and get the U-value, solar heat gain coefficient (SHGC) and visible transmittance. The results serve as input data for whole-building energy simulation.
WINDOW
Lawrence Berkeley National Laboratory
Thermal and optical properties of glazing systems — U-value, SHGC and visible transmittance.
Get it from the vendorWhat you get
- International glass database — spectral data for commercial glass products from many manufacturers.
- Glazing systems — double and triple glazing, low-emissivity coatings and argon or krypton fill.
- Frames — combining frame sections calculated in THERM into a whole window.
- Shading — blinds and shades, in the appropriate versions.
- Export — window data for use in EnergyPlus.
What to know
WINDOW runs on Windows only, and free registration may be required to download. Calculations follow the American NFRC standards and their environmental conditions; European and other national standards define different calculation conditions, so U-values may differ slightly. You can define your own environmental conditions.
Related tools
For heat transfer in frame sections and thermal bridges — THERM. For building energy simulation — EnergyPlus through OpenStudio. For daylight calculations — Radiance.
THERM
Lawrence Berkeley National Laboratory
2D heat transfer analysis of envelope sections — thermal bridges, U-value and condensation checks.
Get it from the vendorEnergyPlus
US Department of Energy
Annual building energy simulation — envelope, HVAC, thermal comfort and daylight. The US DOE engine.
Get it from the vendorOpenStudio
National Renewable Energy Laboratory
Graphical workflow on top of EnergyPlus — geometry, systems and scenario comparison.
Get it from the vendor
Radiance
Lawrence Berkeley National Laboratory
Physically accurate daylight and lighting simulation — the basis for green building light calculations.
Get it from the vendorThe bottom line
WINDOW is a professional, free tool for anyone who designs, checks or specifies windows — energy consultants, window manufacturers and architects.