Anyone have any tips regarding thermal insulation to help keep the car cool despite the poor air conditioning? It seems to me that a lot of heat comes though the windows but I'm reluctant to darken the windows; I like to see the world.

Once the cabin gets somewhat cool, all I have to do is open one door for just a couple of seconds and the cabin is warm again.

Door panels insulation? Rear hatch? Spare tire area? Removing the door panels should not be difficult. Heat rises (coldness goes down). So insulating the headliner shouldn't help much. Better to insulate the floor. However it would seem pretty hard to remove the seats, tear up the existing floor insulation, and replace it with better insulating material. I did put heavy carpet custom floor mats in front and back – custom designed for the Fit. Using a windshield reflector slightly decrease the time it takes the car to cool off but ti doesn't seem to help make the temperature any lower.. What about a rear cargo area shelf? Does that help any?

I have stuffed some carpet underlayment material in the spare tire well, around the spare tire, but it doesn't seem to help much. I also have some closed cell foam cut to fit over the bare metal that is visible under the 2 cardboard flaps that are used to connect the floor of the hatch to the the rear seatbacks, when the rear seatbacks are flipped down. And I have a 2 cm layer of closed cell foam covering the floor of the luggage compartment.

 

Would be much more efficient to just tint your windows, that's the largest source of heat coming into the car

 

They do make tint with very little light blocking to them, some even 0% tint. I'm glad I put tint on mine, it's the legal limit and not hard to see through at night. I can tell it's working when I turn from going into the sun through the windshield to the tinted windows.

I've got a home brew cargo cover but not sure if it makes any difference.

Maybe try a dash cover. Insulating where the HVAC is going through might be beneficial. I know when parked my insulated/reflective sun shade helps keep the dash cool, helping the AC function more efficiently.

 

I have a custom fit sun shade with it in place when I get in the car on a hot sunny day, the large black expanse of dash is "quite hot" instead of painfully hot. I experimented with cotton terry cloth towels covering this area and it did not keep the dash as cool as the sun shade. Also my experiments show that what the sun shade does does not enable the cabin to get any cooler, it just enables it to reach its minimum temperature sooner. I don't recall the exact difference but in 90 deg weather the cabin reached minimum after something on the order of 15 minutes of driving, instead of 20 minutes. I think the tinted windows would help the most but I really don't want to tint. I seem to recall reading somewhere that the existing already slightly tinted windows are supposed to keep out about 90 percent of ultraviolet; I don't know about infra red. But the existing tint is already more than I like.

 

The Fit AC sucks and with all the glass it has it struggles to keep up. Tinting my windows helped the most.

 

This is the sun shade I have and it works really well. It's very thick so with the multiple layers it's probably insulating a fair bit. I recently moved and lost my garage space so the Fit is parked on the street facing south. It cools down fairly quickly.

https://www.autoanything.com/driving...A5833A0A0.aspx

 

I'm running limo tint all the way around. It helps a ton with the heat. I also run a front window sun shade on the windshield when parked in the sun for long periods of time.

 

Get clear ceramic tint

 

My AC is cold even on lowest setting, and it's been 117 here two days ago. Never felt FIT AC was inadequate.
Of course my car is white, I have ceramic tint all around and a light grey dash mat.

 

you literally have the most important element. Ceramic tint. I have been against tint for a long time until I tried ceramic tint my self. never used my AC ever since

 

I am not familiar with ceramic tint. Is it a treatment applied to glass surface or a film attached inside the glass?

 

it’s a film. But instead of dying the material, it’s actual ceramic particles suspended into the material. It never fades, and has much more interesting properties when it comes to heat and UV rejection. To me it also looks cleaner than dyed films. The other type is metallize or sputtered films, but due to metallic particles being used they can interfere with cellular signals.

But as with anything there are better and worse ceramic films so choose a reputable film like Llumar or 3m

 

I do think that tinting some of the windows would have the most effect upon keeping the car cool. However one of the reasons I bought a Fit was because of the outdoorsy impression you get when you are inside. You have better visibility than most cars. The more you can see, the more things coming toward you on a collision course at 120 km/hr, you can work to avoid. That means more window area, and up to a point, more light passing through the windows. With so many cars on the road that are about the same color as the asphalt paving material, limiting the amount of light coming through the windows generally makes them harder to see.

Now, after the little research I've done so far on tinting windows, the first thing I found out is that the usual nomenclature is backwards. From what I have seen, a 20% tint makes the outside look darker when you are sitting inside, than a 35% tint. It is saying that a window with so-called 20% tint, lets in 20% of the light. I would call that 20% pass-through, not 20% tint. They have got it backwards.

Next, I've found out that marketers of tinting film and tinting services don't say 20% of what. They just say "20%." This of course is a statement that is meaningless. Does is let 20 percent of all electromagnetic radiation in? Does it let in 20% of visible light? Does it let in 20% of infra red, ultraviolet? What?

2Rismo2, given the way the naming system works, if I had a window with 0% tint, my conclusion would be that it lets in 0% of the light – although I'm not sure if that means 0% of visible light or not. Nevertheless, whatever light we are talking about, 0% would mean that it is opaque to that light. So why do you say 0% has "very little light blocking." If you are looking at it the other way around, then 0% tint would mean no tint – it is does not block any light.

Can someone explain what is actually going on, using technical terms, instead of vague and obfuscating marketing terms?

My question becomes what kind of tinting material keeps out the most heat but at the same time lets the most light pass though. Those marketing percentage figures don't tell me that. Yes sometimes you want to reduce the amount of light coming through, for example when driving toward the sun, but I can do that with sunglasses. In fact that would be my preferred method. Also, I like to be able to see what is going on inside the car. Especially since the car has a black interior. The more light coming through the windows, the more easily I can find that gray coin that I dropped on the floor.

I have not found a sun shade or a dash cover to be helpful. High quality full coverage custom cut sun shade makes the large expense of dashboard area under the windshield just slightly cooler compared to not having the sun shade. Maybe like 105° F instead of 125°. This would mean that driving off with the windows closed, the cabin would cool down to its lowest temperature maybe 8 minutes sooner. But it only affects the time. The cabin won't get any cooler. What I do when I get in the car is open the windows in both front doors. Then I drive off. This rapidly gets the cabin down to the outdoor temperature and humidity. Having a windshield sun shade does not appreciably affect how long this takes. So I stopped bothering with the sunshade.

I tried covering the dash with some cotton terrycloth towels in light gray and light yellow.. When I got in the car I discovered that the expanse of black plastic underneath the towels was almost as hot as had the cloth not been there. It might have taken a bit longer for the dash to heat up. I didn't test that. But that is pretty irrelevant given that often the dash will still have time to reach maximum temperature before I get into the car.

 

Once again use tint. These cars stay hot without it. They make black and clear tint. If black is too much for you then have clear installed. Keeps the heat out and your windows are still clear to see out of.

Also they sell dash mats on ebay for around $50 shipped. I have a black one on my dash to keep the glare off of and heat from destroying the top of it. Also the car's paint color has everything to do with it. The darker colors stay hot while colors like white will help the car stay cool.


My car in 115 degrees with no issues. Dark tint and white paint is a must in hot climates.

 

Forgive me if I’m getting too basic, but I’ll try to explain from the start. There are three primary ways a hot object can heat up a cold object. 1. Is Convection, which is the movement of the heated air around the hot object due to differences in density. (Think of baseboard heaters). 2. Is Conduction, which is the flowing of heat or thermal energy through a conductor of heat, such as a metal bar. (Think of touching the handle of an all-metal skillet, the handle isn’t on the heating element but the heat has travelled through the metal, into the handle). 3. Is Radiation, which is the emitting of ‘heat waves’ or ‘heat particles’ from a hot object, outwards from a source of concentrated heat (Think of the heat you feel from a red hot stove element or dish shaped heater, even when you are far from it).

In our case, the majority of the heat we feel when we sit in our cars does not come from the engine, rather it comes from sun. Some heat does get from the exhaust system into the cabin, but Honda as most manufacturers has done a pretty good job of shielding the heat from the body of the car, and therefore its a very minimal source of heat. The sun is the main source of heat in the car because of two reasons, first by heating up the body of the car which can be lessened by having a lighter/white paint job. However this is a minor factor compared to the heat from the sun that is radiated THROUGH the glass, and heats up the interior of the car. Untreated glass allows the RADIATED heat energy to pass through, but then holds the heat by not allowing CONVECTION of the hot air to the outside, and by being a poor transmitted of heat thus blocking CONDUCTION. So we want to block the main source of heat, rather than focusing on the minor sources, which in our case means blocking the RADIATED heat that is getting in through the windows.

If we insulate the floor and roof of the cabin, it might seem like we will block heat, but because its not the main way heat enters the car, what we are doing is leaving the door wide open for heat to enter through the windows, but preventing the heat from escaping out. Unless we block the main source of heat, we won’t prevent the inside from getting hot. Thus tinting.

So yeah there’s some tint jargon to get passed. Here’s the main thing. There’s the tint level, and there’s the visible light transmission (or VLT) amount. They are the opposite of each other. For example, a super dark limo tint might be 95% dark AKA 5% VLT, meaning it’s tinted 95% or lets through 5% of light. So it can get confusing if the two numbers become used interchangeable, but just try to figure out if the number is the Tint % value, or the VLT % value.

E.G.
10% Tint = 90% VLT = very clear.
70% Tint = 30% VLT = much darker.

Now take note that this is often in terms of VISIBLE light transmission. Of course we only see the visible parts of light that our eyes can detect, but the sun is a full spectrum source of light. So part of the light from the sun can’t be detected by our eyes, but its still there.

Infrared is light with longer wavelengths than red, and we can feel as heat because it warms our skin when it hits us. It is a ‘colour’ of light that is ‘more red’ than red, and is heading toward the direction of things like microwaves and radio waves. We cannot see it but typically heat that is radiated by objects like embers of a fire are infrared light.

Ultraviolet or UV light is shorter wavelengths than purple/violet, but we cannot see it although it does have an effect on us. It a ‘colour’ of light that is ‘more blue’ or ‘more purple’ than violet, and is heading towards the direction of x-rays and gamma rays. These are high energy waves that cause skin damage and are responsible for colour pigments becoming bleached in the sun as they break down.

In the same way that lets say a beer bottle can be tinted green or tinted brown, or sunglasses can have a yellow tint or a blue tint, things can be tinted to allow SOME colours of light through, and block others. With cheap window tints, they typically just block SOME of the VISIBLE LIGHT so that everything appears darker for either aesthetics or for making the windows like permanent sunglasses.
Well engineered window tints can be made to block the ‘INVISIBLE COLOURS’ of infrared and UV, while letting through ‘VISIBLE COLOURS’. Because you want to maintain the ‘NON SUNGLASSES DARKENING’ look of normal clear windows, you want a LOW TINT% or a HIGH VLT% tinted window. However as people on this thread have said, you want one with very good INFRARED BLOCKING. A good film with very good ULTRAVIOLET BLOCKING will have the added benefit of slowing down degradation of the plastics in your cabin, and (arguably) may prevent long term skin diseases like cancer.

Most well made tint films have very good Infrared blocking and UV blocking built into them. You cannot tell simply by looking at them, since the Infrared and UV blocking isn’t visible to your eyes. However we can ‘FEEL’ Infrared, so if you have a heat lamp and put a good tint in front of it, you will FEEL it blocking the heat. Manufacturers are able to create films with different VLT% so that they look anything from clear to almost black, but all having more or less the same Infrared and UV blocking ability.

If you are concerned about being hot inside the cabin, but you want to maintain the best visibility you can in your car, you want to get a quality window tint with VERY GOOD HEAT or INFRARED BLOCKING, and these films will almost always have good UV blocking since there’s no reason not to when you’re making the film material. However to maintain visibility you want a film with a LOW TINT % otherwise known as a HIGH VISIBLE LIGHT TRANSMISSION %.

Typically a 30% tint or 70% VLT is noticeable, but not considered to be dark. Anything that is LESS TINTED or MORE VLT than that will look clear.

Hope this helps friend .

Edit: Lastly, not every manufacturer publishes their IR and UV blocking %, but you can sometimes look up online to see what others have measured. Branded like 3M and Llumar are notably very good at blocking IR and UV when you purchase their middle to top tier lines of tint films.

 

I don't think you have told me anything I don't already know. The problem remains that if the manufacturer does not tell you whether their percentage number is the percent of light blocked, or the percent of light let through, and doesn't tell you what part of the spectrum they are referring to with their percentage number (and light transmission from outside the car to in may differ from light transmission from inside to out) I still only have useless marketing jargon to go by, and do not have sufficient factual information to make a choice regarding what kind of tinting film to use. Yes, I have already understood that tinting the glass is going to be substantially more helpful than adding thermal insulation. Yes, I want to let in visible light and keep out infrared light. The original glass already keeps out a large portion of the ultraviolet light, so we don't have to concern ourselves with how much ultraviolet light the tinting film keeps out. But as you said, not every manufacturer publishing their IR blocking figures – and as I mentioned they typically do not makes it clear whether their figure is for how much IR gets through or for how much IR is being blocked. As far as I can tell no brands provide this information in an unambiguous manner.. So there is no way form me to choose what kind of film to buy other than by doing the measurements myself. I might have to spend quite a lot of time learning how to do that, and I don't know how much the equipment needed to do that, would cost.