Report Number




Radiant Barriers; Buildings


The Florida Solar Energy Center (FSEC) has monitored several automobiles over the last two months in order to investigate how hot interior temperatures in parked cars might be reduced through the use of improved technology, car shades. We observed interior temperatures in un-shaded stationary automobiles in Cape Canaveral, Florida to commonly reach 150 °F and dashboard temperatures to rise to nearly 200 °F. We found the addition of a conventional cardboard car shade behind the automobile windshield on sunny days to reduce the interior air temperatures by an average of 15 °F. Dashboard temperatures were reduced by 40 °F.

We found radiant barrier system (RBS) car shades to offer further improvements over conventional cardboard shades. RBS car shades are similar to conventional ones, but have a low emissivity foil backing laminated to the interior facing surface of the shade. When using an RBS car shade, automobile interior air temperatures are reduced an average of 3 - 5 °F over conventional shades; the steering wheel and dashboard temperatures are reduced by a further 6 - 11 °F.

The advantages of the RBS car shade are relatively unaffected by venting by car windows. Such venting results in less difference in air temperature between a standard and RBS car shade (1.4 °F). However, the reductions in the dashboard temperatures and steering wheel temperatures are relatively unchanged by venting; an RBS car shade still results in an 8 °F reduction in the car dash temperature. We tested a number of different car shade configurations. Contrary to popular belief, we found that a two sided foil faced car shade actually performs no better than an RBS car shade with foil only on the interior face.

There is considerable need for further experimentation in this area to perform a comprehensive analysis of static automobile thermal performance. FSEC intends to actively pursue further sources of funding for this research.

Date Published



Reference Publication: Parker, D., "Analysis of Radiant Barrier Car Shade Performance: Preliminary Experiments and Proof of Concept", August 1988.

Local Subjects

Buildings - Radiant Barriers


FSEC Energy Research Center® Collection



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