[Christ]

Originally Posted by aerohead

How I see it,is that the ultraviolet radiation,which is streaming in from the sun,is converted to infrared as it is intercepted by the metal roof.For the albedo of the roof,heat will build until it reaches some equilibrium temp.Inside the car,you'd be exposed to infrared radiation eminating from the sheetmetal above,and since the roof and headliner has a composite heat transfer coefficient ( the inverse of it's R-value) the air inside the car would also build do to conduction across the temp differential(delta-T)from the roof to cabin air temp,until some equilibrium is reached ( about 140-degrees F around here in the summer).The headliner(mine has some polypropylene foam in it) acts as a buffer,providing some shielding from the infrared,and also slowing heat transfer,to give the AC a little break.So I'll think of the headliner in terms of heat gain or heat loss for either the heater or AC to deal with.

I'm sure the headliner does have a buffering effect, but equalization will still happen, insulation or not. Just because a house is completely insulated and sealed does not mean it will never reach outside temperature.

Heat from the sun is entering the car primarily through the transmission of light energy passing through the window into heat. The metal actually should act like a giant heat sink, helping to relieve the car of that heat which passes through the window.

Regardless of any of this, paint color does not (has not, and never will) affect interior temperature of a vehicle.

It will affect your perception though, as we all well know that you get hotter wearing a black shirt in the summer.