A concern about carbon fiber roof (green House)

[gmund1948]

Maybe ?

A Black carbon fiber roof may likely be a bit of a confinement issue for me and I have not checked how carbon fiber, especially Black will disapate heat
being that my composite hard tops on other cars were blistering hot and
were worse inside than metal, Now I am sure that in Germany it wont be bad
but in Phoenix, It wasnt super hot in Spain

What do you think ?

I didnt search on this so I hope is not a repost

[Big Windy]

there are good cf roof arguments going on in regards to how it is going to look over time. as far as heat dissipation goes, the cf should be better at distributing the heat over the surface. only problem is that i am not sure if it has as much insulation below it as the normal roof does. if you live in phoenix it is going to be hot as hell anyway, and it is not going to make a difference. no matter where you live, the difference between cf and regular as far as temp goes is going to be negligible (you aren't going to notice). you can always use the auto fan function to help circulate air.

[swamp2]

The US is BMW largest market. They test in Death Valley, CA. They have environmental test chambers that are even more severe than Death Valley. With the proper selection of resin and clearcoat the CF roof can be more durable than a painted metal roof. I am not the least bit concerned about the longevity of the roof. Ask some M6 guys as well!

[GregW / Oregon]

Originally Posted by swamp2

The US is BMW largest market. They test in Death Valley, CA. They have environmental test chambers that are even more severe than Death Valley. With the proper selection of resin and clearcoat the CF roof can be more durable than a painted metal roof. I am not the least bit concerned about the longevity of the roof. Ask some M6 guys as well!

I thought the question was relative to heat being absorbed by the CF and transmitted into the cabin. Black anything will absorb more heat energy than lighter colors, of course. CF is a better insulator than metal, and I would guess the amount of infrared absorption is about the same.

[Garrett]

Originally Posted by GregW / Oregon

I thought the question was relative to heat being absorbed by the CF and transmitted into the cabin. Black anything will absorb more heat energy than lighter colors, of course. CF is a better insulator than metal, and I would guess the amount of infrared absorption is about the same.

Why would heat absortion matter though? Let alone how much is transmitted into the cabin. Carbon Fiber doesn't magnify heat, so if it absorbed twice as much as a normal black roof, it not like your car is going to be 2x hotter. 95degree outside and 180 inside...lol

It's an absolute moot point the very second you turn your AC on, the 2 degree more your car might heat up due to some ill concieved thoery, is rendered pointless.

I'm just curious as to how this would be a concern to anyone ans what thought process leads up to such an inquiry from an owners viewpoint.







-Garrett

[Robert]

Originally Posted by Garrett

Why would heat absortion matter though? Let alone how much is transmitted into the cabin. Carbon Fiber doesn't magnify heat, so if it absorbed twice as much as a normal black roof, it not like your car is going to be 2x hotter. 95degree outside and 180 inside...lol

It's an absolute moot point the very second you turn your AC on, the 2 degree more your car might heat up due to some ill concieved thoery, is rendered pointless.

I'm just curious as to how this would be a concern to anyone ans what thought process leads up to such an inquiry from an owners viewpoint.
-Garrett

Black absorbs light, which is energy, therefore a black roof will heat up much faster than a light colored roof which reflects more energy. Once the roof is hot it will dissipate energy into the cabin and since black absorbs more energy more energy is dissipated. (I think this has something to do with moving from higher to lower potential energy state.) Like you said the HVAC on the vehicle should be more than sufficient to handle the extra heat but some drivers like to keep A/C off. So if heat is a problem then consider painted CF roof or get the moonroof.

[Epacy]

Originally Posted by bobbo

Black absorbs light, which is energy, therefore a black roof will heat up much faster than a light colored roof which reflects more energy. Once the roof is hot it will dissipate energy into the cabin and since black absorbs more energy more energy is dissipated. (I think this has something to do with moving from higher to lower potential energy state.) Like you said the HVAC on the vehicle should be more than sufficient to handle the extra heat but some drivers like to keep A/C off. So if heat is a problem then consider painted CF roof or get the moonroof.

So, how is any of this any different than owning a black car?

[Keto]

Originally Posted by Epacy

So, how is any of this any different than owning a black car?

Shh... no rational thoughts allowed. At least the plastic will likely conduct less heat than a black steel roof.

[nechronics]

dare I say most useless thread yet

[GregW / Oregon]

Originally Posted by Epacy

So, how is any of this any different than owning a black car?

Probably isn't. As I noted, if anything, CF plastic is a better insulator than steel sheet; but, it is so thin that doen't make much difference.

[GregW / Oregon]

Originally Posted by nechronics

dare I say most useless thread yet

Shows the desperation on this forum--nothing new to talk about since the last reviews.

[dcaero]

Originally Posted by Garrett

Why would heat absortion matter though? Let alone how much is transmitted into the cabin. Carbon Fiber doesn't magnify heat, so if it absorbed twice as much as a normal black roof, it not like your car is going to be 2x hotter. 95degree outside and 180 inside...lol

It's an absolute moot point the very second you turn your AC on, the 2 degree more your car might heat up due to some ill concieved thoery, is rendered pointless.

I'm just curious as to how this would be a concern to anyone ans what thought process leads up to such an inquiry from an owners viewpoint.

-Garrett

I grew up in phx and now live in tucson. Not that I think the CF roof will make a difference. but FYI the inside of cars here sitting out in a parking lot (while say your inside shopping) can get to 130 degrees Fahrenheit. And 2 secs after you turn on the AC makes no difference, you can very well drive from one store to another and never cool off. just some friendly info as I saw your from Michigan.

[m_bazeepaymon]

Originally Posted by GregW / Oregon

Shows the desperation on this forum--nothing new to talk about since the last reviews.

nothing tops the desperation of having that thread talking about the type of material the Trim is made of lol

[JEllis]

Isnt the roof actually CF enforced fiberglass. I was under the impression that the roof is actually mostly fiberglass.....

Jason

[GregW / Oregon]

Originally Posted by dcaero

I grew up in phx and now live in tucson. Not that I think the CF roof will make a difference. but FYI the inside of cars here sitting out in a parking lot (while say your inside shopping) can get to 130 degrees Fahrenheit. And 2 secs after you turn on the AC makes no difference, you can very well drive from one store to another and never cool off. just some friendly info as I saw your from Michigan.

My E46 M3 has a remote function that opens all windows and the suroof from the remote so you can vent it before getting in. Does the E90 have that?

[swamp2]

Originally Posted by JEllis

Isnt the roof actually CF enforced fiberglass. I was under the impression that the roof is actually mostly fiberglass.....

Jason

Pretty sure I read somewhere the number of layers and the orientation of the CF fabric used to make the roof. Can't find the reference quickly right now. Makes sense to me. The part need strength and stiffness and fiberglass is nowhere close to CF. If the design was not as stressed and someone wanted to design more of a poser part you could certainly use multiple layers of fiberglass and a thin outer layer of CF just for looks.

[Big Windy]

cf has secret german engineering that has built a/c pores that are connected to iDrive to aid in heat dissipation.

[oneshare325]

green House.....

[Garrett]

Originally Posted by bobbo

Black absorbs light, which is energy, therefore a black roof will heat up much faster than a light colored roof which reflects more energy. Once the roof is hot it will dissipate energy into the cabin and since black absorbs more energy more energy is dissipated. (I think this has something to do with moving from higher to lower potential energy state.) Like you said the HVAC on the vehicle should be more than sufficient to handle the extra heat but some drivers like to keep A/C off. So if heat is a problem then consider painted CF roof or get the moonroof.

That has nothing to do with CARBON FIBER, it has to do with a BLACK roof. All my cars have always been black....

His concern was over a CF roof, not a black one. Meaning, I don't understand his heat-saok question directly related to the carbon fiber..? Basically, a moot point!

I go shopping too, doesnt matter where you live, when it's 90 ~ 105 and your car heat up inside it takes common sense to leave your windows cracked about an inch and when approuching the car hit your remote to releive the car of it added temp. I have Remote start intigrated into my cars (not sure if that possible with the e90) so the car has been running for a few minutes... Ahhh cool leather on a hot day!

Start the car and THEN put your belongings away. You can't even touch my roof when it hot, black roofs could easily cook an egg. I highly doubt a CF roof will be as hot as a black roof. But worring about having that extra heat SOAK INTO THE CAR is anal, considering that the car with a white roof is going to get heat soak too. The difference between a CF roof and a black one won't matter to the inside temp.





-Garrett

[poiney]

It's difficult to get good data, insulation of the roof will probably matter regarding CF. Anyway, regarding the impact on color with a standard roof:

Study I read measured cars on a hot day ~ 90F?, the experimenter measured/estimated ~ 5 degree (F) increase in the cabin of black surface car over white or silver, all things being equal, in steady state. The surface temperature difference was ~ 50C higher IIRC, illustrating the efficacy of the insulation.

I would expect that if one lives in very hot region, that one would benefit from a white top as compared to black top, maybe not huge, but noticable.

[Garrett]

Originally Posted by poiney

It's difficult to get good data, insulation of the roof will probably matter regarding CF. Anyway, regarding the impact on color with a standard roof:

Study I read measured cars on a hot day ~ 90F?, the experimenter measured/estimated ~ 5 degree (F) increase in the cabin of black surface car over white or silver, all things being equal, in steady state. The surface temperature difference was ~ 50C higher IIRC, illustrating the efficacy of the insulation.

I would expect that if one lives in very hot region, that one would benefit from a white top as compared to black top, maybe not huge, but noticable.

Yes, but only noticible when entering the vehicle. After you open the car up that 5 degree(F) difference is lost pretty quickly.

If you leave a Black car sit in the open for 5 hours with the windowed shut, and then leave an identicle White car parked right next to it but with the windows down and the test the ambient interior temperatures of both cars 30 seconds after the doors are opened, I bet it won't be 5 degree's difference.

But, that isn't the question at hand, it was strickly related to a CF roof.

30 seconds with A/C on and in both instances it's a moot point...!

[phoenixbmwlife]

Oh I wish there was something new and exciting in this forum to read about.