Window tint
 

Does tinting windows really reduce the temperature inside the car?

I'm looking into ways to keep the heat out of the car and window tint is the option that shows up most often. I took a moment to think about it and here's what I got:

A reflective coating on the window would physically reduce the amount of light/heat entering the glass, but not so with normal window tint. The darker color absorbs more light/heat than normal glass, so less makes its way directly into the car. But where does that energy go? It gets radiated as heat on both sides of the glass, in particular into the car.

So what am I getting wrong?

...I can empirically answer: "Yes"

...anything that contributes to keeping solar rays from getting 'into' the car interior means there's less work for the A/C to do in cooling the air.

...an empirical example is when you drive under a cloud shadow on a hot day and the A/C suddenly "seems" to work better...it's the same A/C unit, only the solar loading (through the windows) has changed.

Are you looking to tint the windscreen ? Just wondering as it is the biggest window in the car - look at your avatar - the profile pic of your 307 and look how long the windscreen is.

The problem is that windscreen tinting can be illegal in some places for safety - police in the UK don't like it at all.

Maybe one of those beach sun reflector type things might help there though ?

Wouldn't it be better to leave the windows clear and have the rays bounce back off the light-colored interior and back out of the car, rather than having a black non-reflective coating on the windows that simply absorbs the rays and turns them into heat?

Check this thread out:

http://ecomodder.com/forum/showthrea...load-8617.html

"Tint" referred to low-e glazing in the attached story. Not exactly black stick-on plastic.

I live in Tucson AZ. (Like Oldteleman) And everything we have is tinted (except the windshield). Comming out after sitting a long time in the sun it might still be 150F instead of 160F inside the car. (In the summer I keep a couple of paper towels that I use to grab the seat belt otherwise you can get first degree burns on metal parts of the belt.
However the real help is while driving. The A/C can cool the cabin better if the windows are tinted.
So my answer is: Tinting only helps "soak" temperature a little but helps total heat load on A/C a lot.

I just ran 1750 miles from sacramento ca to dallas tx. July 13-29 and back. I have tint installed at the legal limits for ca. I ADDED GILA(brand name) window FILM BLACK (peel and cling). to all the windows (except the front). I put a 9 inch strip across the top on the front. I can tell you that when I made a short stop, like for a potty break, I would come back to a car that was still cool. THat never happened in CA.
Understand I was basicly at 95% block. BUT man what a difference it made.
The GILA product is intended for house windows so the clarity was not what auto tint would be. But it was inexpensive, and very easy to install and temporary.
I have always tinted my cars and it does make a difference. Also, there is a difference between tint and film. And in the automotive line of products, there are basic tint and then a better product that was a metalic feature (I'm blanking on the brand) THe metalic product is the best BUT it can block gps signals. So if you have factory GPS, let your installer know.
Also almost ALL the automotive products block 99% uv rays regaudless of the % of tinting. YOu can actually get a clear that is 99% uv block.
Most of the upscale cars, I know mercedes and infiniti for sure, have a reflective quality on the glass that is installed already to keep the cars cooler. Mercedes tend to have a sight blue look to them from the factory.

There are so many disadvantages to film, I'll wait for actual A-B-A testing before deciding.

Now if only they'd sell Low-E replacement windshields... I'd pay extra for that.

There are so many disadvantages to film, I'll wait for actual A-B-A testing before deciding.

Wow, what could "so many" possibly be??
I have been having my cars tinted for 20 yrs....probably 8 cars .......and never had a problem.

Backing up a steep driveway in pitch black conditions, for one. Reduced visibility at night, more negative attention from the cops, a film that's easy to scratch and hard to repair. Every aftermarket tint job I've seen has eventually developed bubbles, usually after the tint shop is gone and buried. I've removed tint from two cars because of bubbling, and it was a nightmare of solvent and razor blades. On one car, the tint came off in little shards.

And still no empirical proof that it reduces the temperature of the car. (A-B-A, or at least two otherwise identical cars sitting side-by-side; no "it feels cooler.")

No no, I have a sun reflector which I deploy when parked. I'd only tint the windows behind the driver. Here, tinting the front glass is illegal, and the front side windows can't be tinted to less than 70%.

But I brought this up because I want to understand how making the glass darker actually keeps the heat out. I want the physics of it (well, at an advanced high school level).

I believe the way that it works is because less total IR energy is entering the greenhouse of the car. Some of it is simply absorbed, but some of that is radiated out to the outside air rather than the inside, which is where all of it would have gone without the tint. And some of it is reflected from the tint; even ones that just "look dark" will reflect some IR radiation. (And visible light as well.)

As to quantifiable effects, I do not have any numbers. There is a significant amount of anecdotal evidence, but we all know how reliable that can be.

Still, I intend to have it done (professionally) on my car at some point.

-soD

CLev,

Wow, your comments certainly don't reflect "emperical Proof". How about we take a picture of "EVERY AFTERMARKET TINT JOB" we see today and lets see if everyone has bubbles.
In 20 years I have never see a bubble in one car I have owned with tint. Not one. I always use a shop that is obviuosly in business and don't pay the cheapest price but I don't get the most expensive either. And in CA where you live, there are legal limits on tint. So if you cant see uot the back window.....it's above the limit.
I currently have 209k miles on my Q45 with 'AFTERMARKET TINT'. not one bubble, not one scratch. BTW 90% of all cars with decernable tint had it installed AFTER it left the factory.

I believe you guys have also missed one big thing that should help you keep your car cooler.

Insulating the roof. I know that once temps get higher than 90 degrees here I can feel the heat coming through my headliner. And of course, behind the headliner is nothing more than the bare roof.

So I am planning on insulating my roof with sound supressing filler, the same used in speaker boxes (Looks like cotton) to see if it absorbs some of the radiating heat and therefore help me cool the vehicle.

That's because there isn't any--on either side of the argument. I don't care if people tint their windows, but I don't think it should be part of the EM Efficiency Mods list until somebody does empirical testing. Otherwise, it's in the same camp as "freer-flowing" exhaust, HHO contraptions and K&N filters.

You forgot polishing aluminum parts for a 10% hp gain! My fiero has no tint on the side windows because they are down most of the time...no A/C!

I doubt anyone can prove it in a real-world scenario where other variables lead to more variation than the gain you may hope to see.

Tinting affects the AC, ventilation, or the opening of windows, which in turn affects FE - so it's very indirect.
The effect is also temperature-dependant and seasonal - factors which will only add more, and more important variables.

Proving this on a car will require a far more controlled environment than the wide open road.


It's a bit like MetroMPG's experiment with airtabs: they definitely smoothed out the airflow on the back of his car - which should have a positive effect - but under his test conditions he couldn't prove they effectively reduced his FE.
Would NASA list them as a spin-off of their research if they didn't work ... for their intended purpose ?

My background - professional window tinter for 7 years. I own my own business.

Does tint reduce heat inside the car? Yes.

But there's more to tint than just black plastic.

There's traditional dyed film, which is just black plastic. There's also "deep dyed" or pigmented polyester films. These films are a step above dyed because of their durability, but they still have poor heat rejection typically. Here is MADICO Charcool 35% (total solar energy rejection 40%):

http://www.hurricanetint.com/madico/accord_ch35_55.jpg

Next comes "high performance films" which is typically a dyed or pigmented film with aluminum sputtered or vapor deposited onto the film. This provides increased heat rejection through reflecting the heat. Of course the disadvantage can be reduced radio reception (if your antenna is embedded in the glass) and reduced reception of RF devices (GPS, keyless entry, tire pressure monitor systems, etc). Very high metal content gives that "chrome" look and gives even better heat rejection. Here's Global HP Fusion 50% (total solar energy rejection 43%):

http://www.hurricanetint.com/civicdo...hpfusion50.jpg



The next revolution in tinting was ceramic films. Instead of a metal being deposited on the film they used a ceramic component. These are typically non-conductive and therefore do not interfere with RF signals. These films typically provide EXCELLENT heat rejection. Here's a 67 GTO with Geoshield 50% and 40% ceramic (total solar energy rejection 47% and 53%):

http://www.hurricanetint.com/geoshie...d50_40_390.jpg

Finally there's a few newer films out there with different technologies. LLumar ATX (Axcess) and CTX come to mind. ATX used "cermet" which is a non-conductive metal wrapped in a ceramic. 3M Crystalline uses an infra-red absorbing dye in the scratch resistant coating to provide good heat rejection (with some obviously drawbacks).

So there's plenty of films out there with excellent heat rejection that aren't dark and don't have "disadvantages" of backing into stuff (hey, learn to drive).

Think about it, a ceramic 50% has a higher total solar energy rejection (47%) than a dyed limo tint (typically about 40% to 45%). So you don't need to go dark to get good heat rejection!!!



Now, having said all that. Will tint give you better MPG?


Most likely not. The only time it would really help is on the rare days that it will allow you to be comfortable enough to turn off the AC and keep the windows up. As we all know, if the AC is on (no matter what setting) it's still turning on that compressor. So it's really an all or nothing kind of thing.


But, tint will provide instant comfort (less of a hot feeling from the sun while driving), reduce fighting with the little lady over the AC controls (she's hot in the sun, you're not in the shade, tint helps balance that), and provide 99% UV rejection (less skin cancer risk).

Oops, sorry, in my lengthy discussion I kind of skipped this one.

1.) The tint and window now absorbs more of the heat. This in turn is dissipated through driving because the wind cools the glass.

2.) Tint reflects heat. This comes down to the type of tint as I mentioned. Metal and ceramic components are used to reflect the heat.

Kind of like how a black tshirt gets hotter in the sun than a white tshirt.

So it's a combination of the two. The total solar energy rejection of the film is a good way to compare films based on which reject more heat.

Some films focus on the infrared spectrum too.

I recently added almost clear tint to all my house windows, it stops a lot of UV and heat from getting in the house, it has reduced inside temps by at least 10 degrees.
As a test I put some on my front windshield and side windows, only the top 6-12 inches as it was scraps. It definitely helps lower temps, If I could I would do all the windows.
Here is a link to the product I used.
Energy Film - Energy Efficient - Insulating Window Film

Interesting product, no adhesive? Is it the super thick rubbery static cling stuff with horrible clarity? The thicker a film is the lower the optical clarity.

TSER of 48% is pretty good, if it's true.

Take the "infra-red" rejection with a grain of salt as there is no standard test of IR rejection.

Considering the price, I'd rather it have an adhesive. The films I install have a lifetime warranty against bubbling or falling off, I can't say that much for static cling.

darkdan, I think there was an adhesive version as well, I chose the static one for the house in case I needed to remove it.
Yes this is a little thick buy clears up to be not so distortable.

I use to be a lab technician at an optical. i ground plastic and glass lenses to fit people's vision perscription. part of this process is making sure the glass or plastic lenses had at least 94% uva and uvb blocking capability. we had a nifty little machine which shine a special uv light and you would hold the glass or plastic eye glasses lens in the light. there was a sensor behind the light, and the lens, which measured how much of the uv was blocked or absorbed by the lens.

most of the time it had to block at least 94%, as i said. if it did not meet this criteria, we had special liquids which we could immerse the lens in, under about 180 degrees of heat for a period of time to increase it's uv blocking capability.

standard cheap cr-39 plastic lenses which most people have in their eye glasses do not naturally block the uv rays. they have to be immersed in that chemical i mentioned for about 10 minutes to build up enough of the chemical to block the uv rays to an acceptable level.

polycarbonate lenses which are used in all safety eye glass lenses as well as childrens glasses naturally block uva and ubv rays to near 100% according to the machine i had.
a 1/8 sheet of polycarbonate from lowes also blocked the various uv rays to near 100%.

glass lenses used in eyeglasses naturally block uva and uvb rays to near 100% as well.

a few things i learned from this nifty machine was that uva and uvb are naturally blocked by the glass used in eyeglasses without any special coating or films. being the curious as a cat type, i "borrowed" the machine one weekend and took it home to test my car glass and my house's windows.

what i found was that the car's rear and side windows blocked more then 94% of the various uv rays. the windshield blocked nearly 100% of them. this is not surprising since the windshield of most cars is laminated with some sort of plastic, i think polycarbonate?!?!. some one correct me if i am wrong on that.

adding just a few percent of tint to a car's side window resulted in near 100% uv blocking. adding limo black like i currently have on my car did not increase the uv blocking by much since you cannot block more then 100% when 100% is all of the uv rays. but limo black seems to greatly decrease the time it takes my hot ass interiour to cool off during the day when i get in the car and its scalding hot inside.

so to re-cap,

car glass blocks most of the uv rays right off the showroom floor with no tint at all.

windshield do it even better even with no tint.

adding dark tint somehow helps keep the car drastically cooler

its good to "borrow" things.

and yes i got fired from that job... you figure out why.

I had a Regal with mildly tinted windows, tinted by a tint shop. At about 7 to 8 years old, the tint started to get air bubbles in it. When I finally got tired of the air bubbles, I took it to a tint shop and paid $50.00 and they put it under a heat lamp for a few hours and then scraped it off with what looked like a plastic scraper. {I've scraped off tint before and it was too much like work. :eek:}

That said, my daughters Altima windshield was tinted with a nearly clear tint made for rejecting heat that she swears works well. The rest of the windows were tinted at the same time, but they only used the clear stuff on the windshield. It's on my to-do list to have the clear stuff put on all of my car windows, right after I get cruise control.

It seems to me that if we could come up with a reasonable method to insulate a vehicles interior and then use a heat rejecting window film on all of the windows {if it would actually work}, increased FE would be easier to accomplish. The concept works at home. :o

I've got a UV meter. Tempered automotive glass stops about 65% of UV light. More importantly, is what part of the spectrum (I'm guessing UVB and not the more dangerous UVA).

Windshields are laminated with PVB and from what I've heard of people with other types of UV meters (mine requires it to be slide over the glass, some just need to be on one side) windshields stop about 85% to 90% of UV light. This is one of the big reasons why dashes don't crack as much anymore.

gasstingy, it works at home because the air conditioner gets turned off. If the tint on a car could make it so people would turn the AC off for a while, then FE would go up.

Here we go.

Clear annealed, passing 89% of UV light (so blocking 11%).

http://www.hurricanetint.com/geoshie...ples_clear.jpg

Automotive tempered glass (2005 Ford Focus, my new car), passing 40% of UV light:

http://www.hurricanetint.com/geoshie...mples_auto.jpg

Automotive tempered + Geoshield 50% ceramic tint, passing 0% of UV light:

http://www.hurricanetint.com/geoshie...les_tinted.jpg

This meter is actually for eye glasses. As you can see the scale is 1 - 3% transmission as "safe"

I've just been quoted 450 euro / 589 US $ to have 5 windows on my V50 tinted.
At that sort of pricing, I'd rather slab some foil on them myself.

Europe is about the only place that still has decent prices for tint (from a tinter's perspective). It's not just a product, but it's a service so the skill of the installer is important.

But DIY tint always looks horrible. Don't take your classy car (I've always wanted a V50) and ruin it's appearance with a DIY job.

That depends on the car. W/ older models that's usually the case, and in order to reduce the cooling people will turn up the temperature, which just mixes the cool air w/ warmer air. On newer vehicles, the cool air tends to be stored and gradually let out so the AC compressor can cycle on and off depending on the temperature the occupants want, so for newer cars it can help w/ gas mileage.

Skill certainly is important, and you pay for skilled labour, but that's a bit excessive IMO.

Even the Volvo sunshades aren't that expensive :p
(They are rather effective, and even look like window tint from a distance, but they add more weight)


Don't worry, I like its looks too, so I don't plan on ruining them ;)
If I'm not happy with the result, it'll come off faster than it has gone on :D

darkdan, I absolutely agree. I did a DIY job of installing tint on a station wagon I had years ago and found it was not my forte. It looked terrible. A professional job (IMHO) is cheaper than the frustration / aggravation of a job poorly done by me. :mad: I've always maintained that I'd rather be mad about the price than the quality.

+1 from here too.

I wasn't aware any cars cycled the compressor (except maybe the ones that you set a temperature).

Most build within the last ~5-10 years (give or take) do so AFAIK. It's really obvious at idle on w/ early 8th gen Corollas for instance. You can watch the idle speed move around as the AC compressor cycles on/off and can hear some sort of vacuum operated passageway open up when the temp gets high enough. Newer cars are probably a lot more refined in terms of engagement, but it's pretty much run of the mill now.

Darkdan,

Wow.......we've been schooled!!!!!!
thanks a bunch. Nice presentation!!!

:thumbup::thumbup::thumbup::thumbup::thumbup::thum bup::thumbup::thumbup::thumbup::thumbup::thumbup:: thumbup::thumbup::thumbup::thumbup::thumbup::thumb up::thumbup::thumbup:

Thanks! I appreciate it.

Tinted my new focus with Geoshield ceramic 50%:

http://www.hurricanetint.com/geoshie...eoshield50.jpg

Rolling on 15s son!

50% is the legal limit in MN.

My scangauge came in the mail yesterday (wow, ordered it Tuesday from ecomodder.com and it arrived Friday, can't beat that). I mounted it on the steering wheel column because I'm not creative.

my sg actually sits on the clear plasitc in front of the gauges. I use the sg MPH function because my speedo is off due to tire size. Also, after a while u realize you are looking away from your normal field if the sg is not dead in front of you.

http://i678.photobucket.com/albums/v...cangaugeII.jpg

Tinting my windows seemed to really reduce residual head inside my car.