Wow! Smarty-pants! What an excellent explanation. 😀

A double door !!! ( a soft insulating mat like waterproof cladding on the outside of the garage door !!! ) I am a retired sound engineer.

Hi! First time watcher, just glanced at your video history and subbed immediately ^_^ I'm an HVAC engineer. Your basic design, here, is pretty good, but you got a little bit of the physics slightly wonky. You seem like you'd probably be interested, so I thought I'd comment. I'm gonna overexplain a few things that I strongly suspect you (Wesley) already know because you're not the only person who will probably read this: First of all, when you think about insulation, heating, and cooling for a space, if you just think about temperatures, you're not getting the whole picture. Instead, you also wanna be thinking about the *rate* at which heat *moves* from one location to another. "Heat" is a type of energy that gives a substance a "temperature," but they're not the same thing. It can be tough to hold "heat" and "temperature" as different concepts in your head, so here's an example: tinfoil in the oven. Why doesn't tinfoil burn you when you pull it straight out of a hot oven? We know intuitively that, just like everything else in the oven, the tinfoil has to be the same temperature as the inside of the oven to begin with. That's the point of ovens! So, when your delicate, fleshy finger first makes contact with the foil, that foil's *temperature* is as hot as every other metal part inside the oven. The reason your fingers don't burn is that it takes very little *heat* to raise the *temperature* of a thin sheet of aluminum up to oven temperatures - so little heat that, when it all rushes into your finger as the aluminum's temperature equalizes with your body, you barely perceive it as "warm." Despite the layperson-aimed advertising, A/C units don't come in sizes based on "floor area" or "degrees." They come in heat-moving-rate sizes. When you think about this problem with the roll-up door, you don't wanna be thinking "the inside surface of this door gets too hot (temperature) on a hot day, so we should lower that temperature." You want to be thinking "heat moves too quickly through this door on a hot day, so we need to slow down that heat." When the shop heats up in the summer, it's because the walls are letting in heat faster than the A/C can push heat back outside. There are three main types of heat transfer worth talking about here: conductive, convective, and radiant: Conductive heat transfer is when heat is *conducted* through a physical material, or through contact between physical materials. Convective heat transfer is when a liquid or gas moves heat by physically rearranging the hot and cold parts of itself ("flowing") to move heat from one location to another. (You may be familiar with "convection" ovens that distribute heat more evenly by actively circulating the hot air inside.) Radiant heat transfer is kinda like magic; it's where heat energy is kinda "beamed" from one object to another as electromagnetic radiation without really impacting anything in between. It's tempting to think of "radiation" as being "that thing from nukes that'll kill you," but radiation includes all sorts of other phenomena as well: visible light, infrared light, UV light, FM and AM radio waves, WiFi waves, Bluetooth waves, microwaves, and so forth. I think most people would find it uncontroversial - perhaps even intuitively obvious - that heat goes from Hot Things to Cold Things, and not the other way around. It's also relatively intuitive that heat moves faster from a Hot Thing to a Cold Thing when the temperature difference between those two things is bigger. This is true whether we're talking about moving heat through conduction, convection, or radiation. The situation is simplest with conduction; twice as big a temperature difference between the Hot Side and the Cold Side means twice the rate of heat transfer between them. It's allllmost as simple with convection, though there can be some things about the way the liquid or gas moves that can make it not exactly proportional. Radiation is more complicated, but it still follows the basic "heat goes from hot thing to cold thing - bigger temperature difference equals faster heat transfer" rule. (For folks who aren't math-averse, the heat transfer rate is proportional to the difference between the fourth powers of the two temperatures, with both temperatures measured in degrees Kelvin or Rankine, not Fahrenheit or Celsius.) So! With all of that said: If we think about the barrier you've made (leaving out paint and adhesives for simplicity) we've got: outdoors > rollup door > a thin pocket of air > reflective foil surface > foam insulation > wood panel > indoors From an engineering perspective, we'd want to think about what the temperatures will be in between each of these steps, and what types of heat transfer will occur within each of these steps: The first temperature we care about is probably one of the most complicated ones - the temperature at the boundary between "outdoors" and "rollup door." On a hot day, the air might be 108°F, but anybody who's ever bought a windshield sunshade can tell you that the surface of the rollup door will probably be hotter than that if it's in direct sunlight. Most people have some intuitive understanding that, if the door was painted black, it would get hotter than if it was painted white. This is because white paint bounces back more of the sun's radiation in the visible light spectrum, and black paint absorbs more of it. As said in the video, making the door's surface reflective would bounce away even more of the incoming radiation, probably bringing the surface temperature closer to the 108°F "background" temperature of the air around it. Then, as the heat moves through the thin metal material of the rollup door, there would be a small temperature drop to the inside surface of the door. Most metals are so good at conducting heat that the temperature difference between the outside surface and the inside surface probably wouldn't be very big, but there would still be a difference - because, as we know, heat only goes from a (relatively) Hot Thing to a (relatively) Cold Thing. Then we get to the area where your (Wesley's) physics got a little wonky: the part where the heat traverses the thin pocket of air between the inside surface of the door and the reflective foil surface. In this air pocket, the primary form of heat transfer would be *convective* heat transfer. Specifically, the air next to the inside surface of the door would get warmer from that contact and begin to rise, rising until it hits the top of that air pocket, then turning to fall along the reflective foil surface, transferring heat into the foil surface as it goes until it hits the bottom of the air pocket and turns back up to rise, again. Air is a decent thermal insulator, all things considered; thin, sealed, circulating air pockets like this are why double- and triple-paned windows are better insulators than single-pane ones. Regarding your (Wesley's) radiation concept, there would be *some* small amount of heat radiation from the interior surface of the door to the reflective surface opposite, but not a lot. Moreover, the radiative heat transfer between the inside surface of the door and the foil would still go from the Hot Thing to the Cold Thing, overall. The reflectiveness of the foil is basically reducing the smallest piece of the overall heat-transfer-rate pie, there. Then there's the foam insulation and the wood panel. Wood is a better insulator than metal, but it's not great compared to purpose-built insulation foam. Insulation foam is also better than a sealed, thin pocket of circulating air. If you wind up wanting to juice up your design, here, you could do it by laying in another layer of foam of the same thickness. It'd literally be twice as insulating. Meanwhile, if we think about the test rig you built, it goes: outdoors > reflective surface > foam insulation > wood panel > indoors This puts the reflective surface facing the sun. There's a HUGE temperature difference between that sheet of foil and the literal surface of the sun, so making that surface reflective represents a reduction of a bigger piece of the overall heat-transfer-rate pie, compared to the location in the air pocket against the door. This makes the experiment not very representative of the final design. If you wanted a more representative test, you could seal up the outside surface of each of those test boxes with a sheet of metal comparable to that of the roll-up door. All that said, I think this is a great design that's probably going to serve you well, and I love the experimental approach you took for this design. I'm glad I found your channel!

@@brodyjohnstancliff4822 Wow Brodyjohn! That was a paper you wrote there. It was very interesting. Can I ask a silly ? though? If he painted the outside door, let's say chrome, would that be even better than the insulation? Or did I totally screw up what you were saying? I also wanted to say that you definitely have a way with words. Do you write often?

@@tracybowling1156 Well, without running the actual numbers, and without knowing the direction (north/nouth/east/west) the door faces, it's tough for me to say for sure whether just a shiny paint job would be better than just the insulation on the inside, but "both" would definitely be better than just one of the other. (The direction matters because it changes the amount of direct sunlight the door would get on a hot day.) Also, thanks very much for the complement! Explaining engineering stuff to people who aren't engineers is a big part of my day job, so I get a lot of practice. ^_^

did you see his subscribe tattoo around his waist?

The stare down just before that moment... intimidating the part into stillness.

And you could make wine with the grapes😊

Even an old school roll-up bamboo screen that shades the outside of the door to reduce the heat gain on the outside would make a big difference.

I am confused, did I miss the tattoo?

I gather that I was distracted and missed a moment of clever editing, so I guess I just have to watch the whole video again. Oh well 😉

23:55

This is a good suggestion and something people don't realize about window blinds. Yes they are blocking the sunlight but they are still letting heat in, because the the sunlight is still heating the blinds which are on the inside. It's much better to shade the window on the outside.

I was embarrassed I didn't catch my wording till editing. 🤷‍♂️

I was wondering if that was intentional, but he's too much of a Dad to just not acknowledge a good pun on camera.

@@nefariousyawn It's true

neat idea :)

Thanks!

Thanks! One video I watched recommended foil-covered panels that fit in the spaces in the garage door, with the foil toward the door, but big enough that they curve out away from the door to create the necessary air gap.

I have an issue in my bedroom with my wall facing full sun most of the day. Can I do this in my bedroom wall? I don’t mind putting it on top of the wall do you think that might help? The room gets incredibly hot and I have to use a window unit in addition to my central air because of course this is the room I sleep in and I can’t change it for another it’s the largest one

@@sharonnewmanehrlich7203 you mean a window unit in the wall? I should of clarified, I put it in an unused door. If you want to put an a/c in that room, I'd recommend a mini-split. That would keep the room as cold as you wanted. Otherwise if you want to cool the room, the only solution is shade, heat reflection paint outside or more insulation...

I was thinking the same thing. That charisma that speaks volumes. And his humour is spot on with mine lol

A couple of the links in the video description are videos by AtticFoil. They do a great job of explaining the effectiveness of a radiant barrier and the need for an air gap.

My degree is in theatre, with a big background in tech. I've built many a flat! 🤓

Was just going to say, this construction reminded me of what I was told were called Hollywood flats. #techiesrule

@@sgsax yup, those are Hollywood (aka Studio) flats alright! I was laughing my arse off at that fact when @Wesley Treat read the stickers from the Luan maker about which side was the front as that is super important when making a flat. Seeing his degree comment above (I have a tech theatre degree too!) explains why he found it just as funny. :)

If you have a window that has sealed gas inside it, it can pop the seals and void your warranty if there is one. I used tint on my window and it mentioned it could but as it was western window in florida with no shade from about 12 til sunset it had long ago leaked out.

The door is white. An exterior barrier isn't practical at this time. 👍

You only really need an air gap if there's radiant barrier involved, but I get what you're saying. The heat is brutal!

Thanks!

Thank you! The door is already white, though.

Thanks! That satin was perfect to prevent glare from the lights, too!

I very much wanted to order a FLIR camera to show the difference, but I couldn't justify the cost for another toy to play with. 🤓

@@WesleyTreat : Get an Armor 9! It's a nice inexpensive water-and-dust-proof FLIR camera that happens to also make phone calls. :)