Cooling Cars with Sunshades

Complexity level:	4
Project cost ($):	90
Time required:	1 day to prepare, 1 day for the science project experiment
Material availability:	Easily found
Safety concerns:	Ensure that cars are driven by persons with valid driving licenses.

Hypothesis

The reflective bubble sunshade will be the most effective cooling.

Overview

Sunshade

The interior of a car that is parked outdoors on a hot sunny day can reach temperatures of up to 90 °C. This drastic increase temperature is caused by a combination of hot temperatures outside the car and lack of proper ventilation for the hot air to escape out of the car. Utraviolet radiation from the sun also enters through the windscreen and heats up the air in the car. The front windscreen also sometimes acts like a magnifying glass, intensifying the sun rays, and make the car interior hotter on sunny days.

These extreme conditions will not only cause a lot of discomfort to the driver and his passengers, they can also damage the interior of the car. The two methods that are normally used to reduce the build up of temperature in the car are tinting the car windows or using sunshades. Tinting the window involves permanently installing a film on the window of the car. In some countries, this is not permitted by law.

Sunshades on the other hand, are removable. They are very effective in blocking the sun’s rays from entering through the car’s windshield. Sunshades are able to prevent and block about 99% of the sun’s ultraviolet rays from entering inside the car.

Scientific Terms

Ultraviolet radiation, insulators

Materials

The materials required for this science fair project:
- 3 cars – of thesame make and model, interior and color
- 1 reflective bubble sunshade
- 1 reflective foam sunshade
- 1 infrared thermometer

Procedure

1. For this science project, the independent variable is the type of sunshade used – no sunshade, a reflective bubble sunshade and a reflective foam sunshade. The dependent variable is the temperature on the dashboard. This is determined by using an infrared thermometer. The constants (control variables) are the color of the car, the outside temperature, the make and model of the car.

2. The 3 cars are first inspected to ensure that the car’s model, interior color, body paint color, seat cushion and steering wheels are all identical.

3. The 3 cars are then parked directly under the sun. They should not be parked under a shade or in a place where the shadow of a tree or building may be cast over the cars. The temperatures on the cars’ dashboards are checked using the infrared thermometer every 2 hours between 8:00 am and 6:00 pm to ensure they are identical.

4. On the second day of the experiment, the first doesn’t get a sunshade. The second car will be fitted with a reflective bubble shade while the third car will be fitted with a reflective foam shade. The sunshades should be cover the entire front windscreens of the cars.

5. The three cars are parked under the sun once gain as described in procedure 2. The temperatures on the dashboards are checked once more every 2 hours between 8:00 am and 6:00 pm. The temperatures are recorded in the table below.

Results

It was observed that the car which had been installed with the reflective bubble sunshade had the lowest cabin temperature.

Location measured	Sunshade type	Temperature measured (°C)
8:00AM	10:00AM	12:00 Noon	2:00PM	4:00PM	6:00PM
Dashboard	No sunshade	25.7	52.7	76.3	79.4	73.2	56.3
Reflective foam	24.3	48.5	67.6	75.3	64.3	51.3
Reflective bubble	24.7	43.9	62.3	68.4	60.8	46.5

The graph below represents the results of our experiment:

Automobile sunshades effectiveness science project

Conclusion

The hypothesis that cars with reflective bubble sunshades have the lowest interior temperature is proven to be true.

The use of sunshades inside a car on bright sunny days hels to reduce temperatures by about 8 to 10 °C. They certainly make quite a difference! Besides helping to keep the cabin at comfortable temperatures, they also help to protect our car’s interior from discoloration and cracking.

Also consider

What would happen if the experiment were to be repeated by using cars with tinted glass?

The experiment can also be repeated by using cars with different colors and sunshades.

References

Is your car an oven? - http://www.roadandtravel.com/autonewsandviews/2005/sunshades.htm

Cool your wheels - http://editorial.autos.msn.com/article.aspx?cp-documentid=434615

What should I consider when buying car shades? - http://www.wisegeek.com/what-should-i-consider-when-buying-car-shades.htm

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