Glass Explore is a webapp that calculates the thermal, solar and optical properties of double-glazing architectural glass. The properties are calculated depending on your choice of glass, manufacturers’ coatings and gas cavity.
I wrote it for a couple of reasons:
- Unless you know exactly what glass and coating you are looking for, LBNL WINDOW can be a little clunky
- Manufacturers’ tools (I like Saint Gobain Calumen tool) only include their products, unless you have special privileges
- I wanted to know how it worked! How DO you calculate the U-value of a double glazing unit?
The app is at glass-explore.floatingintheclouds.com and www.glassexplore.com
Changelog (May 2026)
- EN410/ EN673 calculation engine added, previously only NFRC
- Flip coated glass to back (so can have back or front).
- Fuzzy search of IGDB
- Gas mixtures
- Latest IGDB (v111.0)
- Share buildup with you nerd-glass friends
- (Moved hosting from Heroku to Railway. Cheaper, bur main reason for update. Everything broke.)
Open source libraries
Glass Explore uses the following key libraries:
- pyWinCalc: LBNL python-wrapper around C++ WinCalc engine, which sits under bonnet (hood!) of LBNL WINDOW software.
- Dash: Python framework for building webapps.
Verifications
Glass Explore has not been vigorously verified! Its a toy – use LBNL WINDOW and glass manufacturers’ verified tools and data.
That aside:
North American NFRC
Outputs should match LBNL WINDOW, essentially the same code calculating properties.
European EN410 and EN673
[May 2026]
It is difficult to use pyWinCalc to get robust EN 410 and EN 673 numbers (not through lack of trying). LBNL WINDOW does include CEN and EN 673 settings, but not clear how this is implemented using WinCalc engine.
Anyway, Glass Explore uses pyWinCalc for EN410 optical properties, but the U-value (EN 673) and solar factor (EN 410) are my own implementations using methods described in these standards.