School project help: Window tint in reducing the temperature of car.

[hhm28]

Homework Statement

Here's the question for my coursework. "Everyone knows the feeling of getting into a car that has been under the hot sun.Nobody likes it. Design an experiment and investigate the factor(s) that contribute to this condition."

Here's my question,
1)Do window tint really helps in reducing the heat entering the car since UV, visible light and IR were blocked?

2)Do the darker tint reduce more heat? (From what I have done in my experiment, darker tint didn't seem to better in heat reduction, they are approximately the same as lighter tint, or even worse.) Is that true?

2. The attempt at a solution
I have carried out an experiment by building 5 model miniature cars of equal size using cardboard and 4 of them were put on window tint of different VTL (Visible Light transmittance), while the last one was put on a plastic cover of approximately the same thickness to represent the non tinted glass. After that, 5 of them were put under the sun and the temperature inside the car is observed. (ps: no glasses were used, I simply glued the window tints/plastic covers.)

And the result I got was the non tinted (plastic cover) did has a little bit higher temperature than the rest. The non tinted car has around 55°c while the rest were slightly lower (52-53 °C).

 

[voko]

In a real world situation, a layer of tint is added to the window glass. But in your experiment, if I understand it correctly, 4 models had only the tint layer, while the other had some plastic, which stood for glass. Do you think this models the real world situation accurately?

 

[hhm28]

Is glass that important in this experiment? I don't have enough resources to run this experiment if glass is needed, I just wanted to prove that darker tint will give a better heat reduction. Anything suggestion to make the difference more significant or should I just move on and change my topic?

 

[voko]

I am not saying that you should have used glass. What I do say, is that real cars have either glass or glass + tint, while you had either plastic or tint. Do you see the discrepancy?

 

[hhm28]

Do you mean that since I represent glass with plastics, so I have to add a plastic to the tint layer to model the real life situation?

 

[voko]

I do think that plastic + tint vs plastic models adding tint, while plastic vs tint models replacing glass with tint.