IGDB

The IGDB is a collection of optical data for glazing products. Spectral transmittance and reflectance is measured in a spectrophotometer and contributed to the IGDB by the manufacturer of the glazing product subject to a careful review.

IGDB

About the International Glazing Database (IGDB)

The IGDB is a collection of optical data for glazing products. Spectral transmittance and reflectance is measured in a spectrophotometer and contributed to the IGDB by the manufacturer of the glazing product subject to a careful review.

What Are the Relationships Between LBNL, the NFRC and the IGDB?

LBNL maintains and publishes the IGDB. NFRC is by far the single most important user of the IGDB. The NFRC window rating system is powered by the LBNL WINDOW program, which in turn relies on the IGDB for input data. NFRC charges a fee to the data supplier for any data that is used in the rating system. This NFRC revenue is used to support LBNL for the operation of collecting the data.

The U.S. Department of Energy (DOE) provides support for the optical laboratory, participation in standards activities and related research. This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Building Technology, State and Community Programs of the U.S. Department of Energy, under Contract No. DE-AC03-76SF00098.

Is the IGDB a Part of the LBNL WINDOW and Optics Programs?

A very close relationship exists between the IGDB and LBNL computer programs like WINDOW. In fact, the IGDB is part of the download package with WINDOW. Most of the experimental input data required by the program to calculate the energy performance indices (e.g., U-factor and g-factor) of a window comes from the IGDB. The most basic purpose of WINDOW is to calculate the properties of combinations of simple glazing materials (e.g., double and triple glazing units), whose properties are drawn from the IGDB. Other programs, however, including those developed at LBNL and elsewhere can read data from the IGDB.

A common occurrence is a request for a password to open the IGDB file directly in MS Access. The solution to this problem is to create a user database with all the entries in it and then access that file directly. The password exists to give users the confidence to use the IGDB with knowledge that it has not been tampered with.

What Types of Materials Are Passed Through the Review Process?

The IGDB currently only allows inclusion of specular glazing materials without patterns. This could be monolithic glass, plastic, laminates, applied films on glass, or thin-film coated glass. Diffusing or light redirecting glazing or shading devices are not allowed at present. With the release of WINDOW 6 and the CGDB diffuse glazing will be accepted on an experimental basis. A major impediment is the lack of a reliable standard test procedure diffusing components and for complex shading systems.

One type of "attachment" product present in the IGDB is the applied film. Although technically a retrofit product like other types of shading systems, it has the distinction of also being a specular material. Thus, it can easily be incorporated into the technical part of the rating system, although the procedure defined by NFRC 304 is different than for an originally purchased window unit. There is a measurement issue relating to the interference fringes common in applied films that is different from other types of specular glazing.

Can Laminates and Applied Films Be Calculated?

It is even possible to design new glazing materials such as laminates and applied films by combining sub-components such as glass, interlayer and coating, derived from materials in the IGDB, using the Optics software or similar programs. Some equations used in this process are sensitive to edge cases where the transmittance and/or absorption is close to zeros which makes it very sensitive to noise in the measured data of some products.

Acknowledgements

The International Glazing Database could not exist without the support from the following institutes:

U.S. Department of Energy

LBNL Windows and Daylighting Group

National Fenestration Rating Council

And last but not least all data submitters (see list of members of the peer review committee) who participate in providing data for the database.

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Building Technology, State and Community Programs of the U.S. Department of Energy, under Contract No. DE-AC03-76SF00098.