High Performance Solar Control Windows, Final Report

This report describes investigations carried out during a 23-month period on the use of ion-beam sputtered, metal-dielectric layers for fabricating high-performance solar-control windows for office buildings and residences. As such it represents a continuation and extension of a previous LBL contract (No. 1667000) and proprietary KCI developments.

Two basic types of windows were studied. The first was optimized for rejecting incident solar energy during the cooling season while maintaining high daylight transmittance. The second was optimized for transmission of solar energy and reduction of thermal losses in the heating season by maximizing reflectivity in the long-wave infrared (i.e., transparent heat mirror). Various compromise configurations for performing both functions were also considered. The program covered original equipment (glass) and retrofit (plastic) substrate materials. Various metal-dielectric combinations, including Cu-SiO₂, Bs-SiO₂ (Bs = brass), Bs-Al₂O₃, Ag-SO₂, and Ag-Al₂O₃, were used to obtain the necessary optical characteristics. Extensive weathering tests were conducted to demonstrate that the final systems developed are capable of extended life in a practical environment.

Roll-to-roll (1 wide) coating was demonstrated for retrofit office and residential windows on various forms of polyester. Comparable window performance was achieved on polypropylene and teflon FEP substrates.

A brief economic analysis is presented which indicates that KCIs processing is completely consistent with the price structure in the solar-control film industry.