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Vehicle Cooling Systems

Improvements to efficiently, safely, and inexpensively cool vehicles during prolonged sun exposure

National Renewable Energy Laboratory

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Vehicles can heat up quickly when parked in sunny locations.
Vehicles can heat up quickly when parked in sunny locations.

Technology Marketing Summary

Vehicles left in sunny areas can quickly heat up to temperatures as high as 50-70 degrees C (122-158 degrees F) or even up to 121 degrees C (250 degrees F) in certain geographical areas. The windows and windshields of vehicles cause this greenhouse effect. Excess heat damages instrument panels (dash boards) and electronic equipment, causes passenger thermal discomfort, and increases fuel consumption and emissions with heavy air conditioning loads. Scientists at NREL have designed efficient, safe, and inexpensive new ways to improve vehicle cooling capabilities.


1. Passive Instrument Panel Cooling System: This invention uses passive heat pipes to transfer heat from instrument panels to exterior portions of the vehicle in order to significantly reduce the temperature of the instrument panel. Minimizing the incremental temperature of the instrument panel reduces the amount of volatile organic compounds released, decreases passenger discomfort, relaxes thermal requirements on instrument panel materials, and reduces damage done to equipment. Additionally, air conditioning systems must use an average of 500 W of energy to overcome the heat released by instrument panels, which have low thermal conductivity. Using NREL’s passive instrument panel cooling system reduces fuel consumption and emissions while remaining inexpensive and efficient.

2. Vehicle Cabin Cooling System: Air conditioning is the largest supplementary consumption of fuel in vehicles. This trend has been exacerbated recently due to passenger demands to cool the interiors within 120 seconds of entering sun-heated vehicles. Vehicles overheat due to solar radiation heating the windows which then radiate heat into the trapped air in the cabin space. The Vehicle Cabin Cooling System uses natural convection currents to capture the heated boundary layer of air on the inside surface of windows and exhaust this warm air outside the vehicle. Using only an intermittent fan, the system uses very little energy and greatly increases the fuel economy and reduces the emissions of the vehicle. Additionally, this cooling system does not allow dust to enter, nor does it compromise the security of the vehicle.

  • Cost-effective and efficient solutions
  • Increases fuel economy by decreasing air conditioning loads
  • Lowers tailpipe emissions
  • Increases passenger thermal comfort
Applications and Industries
  • Automotive
  • Transportation
  • Construction Equipment
  • Marine
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Patent 6,964,294
Passive cooling system for a vehicle
A passive cooling system for a vehicle (114) transfers heat from an overheated internal component, for example, an instrument panel (100), to an external portion (116) of the vehicle (114), for example, a side body panel (126). The passive cooling system includes one or more heat pipes (112) having an evaporator section (118) embedded in the overheated internal component and a condenser section (120) at the external portion (116) of the vehicle (114). The evaporator (118) and condenser (120) sections are in fluid communication. The passive cooling system may also include a thermally conductive film (140) for thermally connecting the evaporator sections (118) of the heat pipes (112) to each other and to the instrument panel (100).
National Renewable Energy Laboratory 11/15/2005
Technology Status
Development StageAvailabilityPublishedLast Updated

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To: Eric Payne<>