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Improved Solar Control Car Glazing in the Rearward Field of View-An Approach to Update Regulations
ISSN: 0148-7191, e-ISSN: 2688-3627
Published October 01, 1987 by SAE International in United States
Annotation ability available
People often modify their vehicles with dark tints on the side windows behind the B-pillar and in the backlite even though this can be against the law. Passenger comfort is the motivating factor for these actions.
Although luminous transmittance of automotive glazing is regulated in many countries, the rearward field of view is not as clearly defined as the 180° forward field of view. The minimum legally allowed limit for the reflectance of a rearview mirror is 35% according to FMVSS 111. A combination of a backlite of 40% luminous transmittance together with a rearview mirror of 70% reflectance is not permitted, although in terms of visibility it renders the same result as a backlite of 70% transmittance together with a rearview mirror of 40% reflectance.
Normally tinted glazing is offered by manufacturers as solar control glazing. The effectiveness of tinted glazing especially green glazing and coated green glazing is discussed. A proposal to increase the thermal comfort in the car is made by recommending darker tints than normally used or the application of printed ceramic dots, on the glazing.
An investigation was carried out by means of a driving simulator to determine how drivers react when looking through windshields with various degrees of luminous transmittance in the range of 90% to 40%. A windshield with scattered light produced by surface damages was also investigated.
Results obtained with the driving simulator show that a small amount of scattered light impairs the driver's vision much more than windows with a normal depth of tint. Dark windows can be tolerated in locations in the car where the images normally observed are of high contrast levels.
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CitationWeigt, P. and Albrecht, H., "Improved Solar Control Car Glazing in the Rearward Field of View-An Approach to Update Regulations," SAE Technical Paper 872000, 1987, https://doi.org/10.4271/872000.
- National Highway Traffic Safety Administration (NHTSA), “Federal Auto Safety Laws and Motor Vehicle Window Tinting”, August, 1985 Interpretation Report to FMVSS 205
- Regulation VESC-20, Vehicle Equipment Safety Commission Performance Requirements for Motor Vehicle Sun Screening Devices, Approved July 1980
- ECE Regulation No. 43 “Uniform provisions concerning the approval of safety glazing and glazing materials.
- ECE Regulation No. 46 “Uniform provisions concerning the approval of rearview mirrors, and of motor vehicles with regard to the installation of rearview mirrors”.
- EEC Directive No. 71/127 EWG; Directive by the Council dated 01 March, 1971 to harmonize the legal provisions for member nations concerning rearview mirrors for automobiles. (71/127 EWG, revised due to the membership statute of 1972, the decision made by the Council on 01 January, 1973, the statute relative to the accession of Greece of 1979 and due to 79/795/EWG and the accession of Spain and Portugal of 1985).
- EEC-Directive No. 77/649 EWG; Directives by the Council dated 27 September, 1977 for harmonization of the legal provisions of member nations concerning the driver's field of view in the automobile. (77/649/EWG, changed by 81/643/EWG.
- EEC Directive No. 81/643 EWG; has been incorporated in 77/649 EWG.
- DIN 6169; Teil 2 (Part 2) - Farbwiedergabe, Farbwiedergabe-Eigenschaften von Lichtquellen in der Beleuchtungstechnik (Color Rendering, Color Rendering Properties of Light Sources in the Field of Lighting)
- Flat Glass for Building, Commission of the European Committees, Industrial Processes, Building and Civil Engineering, Report EUR 8069 EN pp 195-213
- Proposed Standard Solar-Radiation Curves for Engineering Use, Moon Parry, Massachusetts Institute of Technology
- Draft International Standard ISO/DIS 7730 “Moderate Thermal Environment - Determination of the PMV and PPD indices and specification of the conditions for thermal comfort”
- Rompe, K., Engel, G., “The effects of windshields with varying degrees of transmittance on the driver's vision during night-time driving” TUEV-Bericht Nummer: 100/05/11
- Rorape, K., Engel, G., “The Influence of Scattered Light in Windshields on Driver's Vision during Night Driving”, SAE Paper 840385