Window Properties: measurements, simulations and ratings

Determining the thermal and optical performance of window systems is essential to researchers striving to develop improved products and to window manufacturers who need to demonstrate the energy performance of their products to architects, engineers, builders, and the general public. LBNL is involved in basic research in this field, in developing software and test procedures to analyze and quantify window heat transfer and optics, and in developing standards and rating procedures.

Infrared Laboratory experiments provide surface temperature maps of window products. A companion Traversing System measures air velocity and air temperatures near the surface of test specimens.

The MoWiTT facility provides accurate measurements of the heat flow through complete window systems subjected to real weather conditions. MoWiTT results have been used to validate the performance of emerging technologies and research prototypes as well as to validate thermal performance models.

WINDOW is a PC program which determines window product heat transfer as a function of glazing characteristics, gas-fills, and frame properties.

The International Glazing Database (IGDB) provides glazing layer (peer-reviewed) optical data for over 1000 commercially available products; this data is used with the WINDOW and Optics software.

THERM is a PC program for analyzing 2-D heat transfer effects through window frames and other building products. It can be used as a stand alone program or as a companion to WINDOW.

Comfort research takes the existing knowledge base on human thermal comfort in buildings and applies it to fenestration products.

LBNL provides Technical Support to the NFRC in order to ensure that the results of fenestration research are utilized in US window rating and labeling efforts.

Hardware and procedures for use in the field to verify components used in advanced windows have been developed at LBNL.

For general information or questions on software use, contact WINDOWHelp@lbl.gov;