Would love to see the effects of actual sunlight on a hot summer day. Maybe as a follow up in a few months, you could leave them both outside in direct sunlight and see what happens?
And paint the unpainted house... No one lives in an unpainted house and even that thin layer of paint will affect things drastically. Paint it a light brown like many houses are, or even have a black painted one for ultimate comparison (tho almost no one lives in a pure black house either; hence recommendin a neutral middle colour like brown). No doubt the studies done that convinced folks to switch to white paint were done as a comparison to a dark grey or black; to represent the difference it makes on streets, not homes. And that is a huge difference, havin walked from dark asphalt to light asphalt before when i lived in Cali. The light asphalt of our driveway was always noticeably cooler than the dark asphalt of the road
I watched a documentary in India where they painted just the roofs of houses and it made a MASSIVE difference. About 6ºC difference before and after. If you dont live in a hot country it's hard to understand how big that difference is, but its the difference between livable 40ºC and totally unlivable 46ºC At temps over 35ºC every extra 5º feels like a doubling of the temperature.
I think you should test this with real sunlight using common roof materials including slate, metal, concrete, and asphalt. I wonder if this translates well scaled up, because the ratio of surface area to volume changes. The goal is not to replace air conditioning, but to decrease use of it, saving electricity, and making cities cooler.
A wooden bird house isn't a good substitute for a common residential abode. A dark shingled roof is going to generate a lot more heat than a piece of wood
@@JustinL614 Right! He could have just placed the thermocouple underneath a small sheet of wood, one side painted, one side bare, and shown about the same result.
@@JustinL614 He's disputing that the white paint makes a substantial difference in temperature. That's going to change based on the colour and materials being used. I'm suggesting we'd see a bigger difference in temperature if the roof was covered in a dark coloured shingle.
Colour does affect the temperature to a great extent. We have a pretty hot summer here in India. So I cover our over-the roof water tank ( black in color) with white thermocol sheets during summer to shield it from the scorching sun. And it does help to keep the water cooler by 5 - 6 degC.
@@gabor6259 Yeah.. because in my place day temperature stays around 35 degC in the summer. so the water temperature should never go above 35, but it actually rises to as high as 42 degC because of radiant heating from the direct sunlight. White thermocol cuts this off and thus the water temperature stays within the limit of conductive and convective heating from the hot air. Of course, thermocol also gives some protection from the hot air as well.
I have worked in attics for about 20 years now and can definitely say the color of the roof greatly effects temperature. There was one attic I remember that i put a temperature probe in because it was so hot 97f degrees outside and in the attic it was 187f. The roof for that one was solid black shingles. The same day i had a house with light grey shingles and it was 118f. Why dont you paint the other house with black roof and see what the temperature difference is then. Wood color is naturally light.
@@peterwolf4230 I know color is important just not "more than" the other factors. I just said that because he didn't mention them. Good examples in your comment.
Very debatable which is more important than the others - I suspect it is highly dependent on what the baseline is. From a baseline standard construction house, insulation is probably the most important improvement then this second. Things like orientation can't easily be changed, neither is it cost effective to change the entire material of a roof for example.
I’m really hoping that’s a typo. There’s no way a person could survive that, it’s 30 degrees away from boiling… Edit: my mistake, I misread I thought you went INTO the attic!
This was a great test idea, however disappointed in the testing standards and assumptions. Some scrap shingles on the unpainted house would have yielded more significant results. Your control was not reasonable to expect. You usually do excellent science, and from the comments it would seem this was a little lackluster.
Yeah, agreed, a few points I'd like to tack on to this criticism, you painted the white house with both primer and white paint, effectively blocking the pores of the wood, which is naturally a fairly porous material, I'd assume the one on the right had ventilation in the form of non-clogged pores. The flashlight was pointed at an angle at the painted house and then directly over the wooden house, the testing standards weren't the greatest here and I'd love to see what other commenters are suggesting, two houses, made of similar materials to real houses, then both painted, one with the blackest black, one with the whitest white, a proper thermometer, in each.
@@Killerjerick I would also do a regular run of the mill white paint as control. That way you can see if these fancy new white paints are worth the premium by comparing the projected energy savings.
One of my Heat Transfer professors in college was Ephraim Sparrow. He basically created modern radiant heat transfer theory. He told us this (very relevant) story one day: He was working for a defense contractor in the 50s or 60s and they were charged with building metal boxes that would hold sensitive electronic equipment about 10m off the ground. They were used in the desert somewhere, so really high heat during the days. If I had to guess I’d say the boxes held sensors for the nuclear tests done in Nevada and New Mexico. His boss came to him and said, “make the boxes mirror finished because it will reflect all of the solar radiation.” He replied, “paint them white. If a black body is the best at emitting radiation then the exact opposite will be the second best emitter and it will absorb the least amount. I.e. a white body.” His boss thought he was wrong and fired him. (I’m sure there was more to it than that, but literally that’s all he said on why he was fired). About 10 years after the project ended Ephraim saw his ex boss again and his ex boss apologized and admitted that he had been wrong. Quite a brilliant man :/ That white body being the second best emitter was intuitive to him.
Keep in mind the accuracy of these (uncalibrated!!) thermocouples is rather high, especially with these simple handheld terminals where you have no control over the reference temperature inside. An accuracy error of 1-2 deg C (1.8 - 3.6 deg F) is very normal, even though the precision (which is often mislabeled as accuracy on the box) is quite good.
As long as they read the same when together at a range of temperatures, their absolute accuracy isn't all that important when comparing different temperatures apart. I have no idea if he's tested them that way.
@@JustinL614 that's a comparison between two different measurements of two uncalibrated (as far as we know) sensors. The difference is very close so you have no idea of it's real or part of the error
@@WouterVerbruggen I don’t know because he didn’t specify, but if we’re just going to speculate on the unsaid, based on what I’ve seen of his methodology and attention to detail, I would put my money on those things being calibrated. It’s not exactly an expert-level consideration…
It would be interesting to see the same test done with the wooden house's roof having part of a black asphalt shingle on it. I wonder how large (if any) the difference in temp gain from light would be at that point
@VeroMithril he said the paint reflects visible and UV best so why would he put infrared light that's not what it's advertised at being that good at reflecting
@@jabelar2008 "In a real house, there is conduction, but it is conduction of the heat absorbed into the rooftop from the light that conducts." There wouldn't be much point in insulating the walls if that was the only conductive heating. It is significant but a house can still get unbearably hot on a hot and cloudy day. I completely agree with the rest of your comment though.
@@jabelar2008 Also, hot air rises, so it doesn't make sense to say hot air from the light bulbs was causing most of the heating. It was likely the infrared.
Imagine the temperature control on your house being dependent on how clean the exterior is. “Heat wave’s coming. I’d better get out there and pressure-wash!”
My house is mostly white with some dark Grey and black accents. It is all hardie board and on a bright day the dark painted wall can get hot enough that I can't comfortably leave my hand on it while the white parts are cool to the touch. From personal experience I can say that white paint versus black paint in direct sunlight makes a huge difference.
And then you consider that at scale of not just a house but whole sets of buildings and streets, and some of it is not wood, but dark concrete and asphalt (common thermal masses) storing heat throughout the day and releasing it at night vs cooler structures that don't store that heat so they can't release it after sundown.
I see some comments already about the lack of darker material on the roof of the unfinished house, which would be mistake number one. Standard shingles are darker than that particular wood, even in their variation of colors. The second part that wasn't brought up, is that the added coating of the paint to the white house would potentially also increase the insulation factor of the white house. It's an added coating helping to hold heat or cold inside the house, while the unfinished wood house lacked that exterior coating. I would be curious to see this experiment repeated with the white painted house versus a medium or darker gray painted matching house. That'd be more accurate for a difference in temperature with matching insulating values. Or better yet, three houses, including the unfinished one in the test.
This isn't a good test, it's a very small house. That matters, because you have a surface area to volume issue. You can definitely feel the difference between a dark and light property in a hot country, it's why white is such a common colour in Mediterranean and Islamic design.
Obviously white paint isn't going to cool your house below the minimum outdoor air temperature. It's absurd to compare it to air conditioning. Of course this will keep your house much cooler than normal paint, but it has a theoretical limit imposed by the second law of thermodynamics. Refrigeration is not constrained by this same limit since it consumes energy.
@@peterwolf4230 It can only be cooler than the air outside if the air outside was recently cooler than it is now. If the lowest air temperature at night is 80 degrees, this paint isn't going to be enough. Obviously highly reflective paint is helpful in the summer. I'm not refuting that. It would clearly reduce the amount of air conditioning you would need. But it could never accomplish as much air conditioning is capable of.
@Number1 - it doesn't have to accomplish as much as air conditioning, because most air conditioning is actually not required. We use it as a comfort thing. If your comfortable temperature range is say up to 25C, suddenly the air con can be turned off much more often. I've spent a lot of time in places like Thailand where you have warmer than that at night and just a fan. The other point is that it's not a one or the other: air con doesn't need using every day, or every hour. So you can use something like this to reduce your costs,even if you still have air con sometimes. This is basically the same thing as getting a white car in a hot country. If you get a dark car there you are an idiot.
I remember seeing that article at some point, and if I remember right it had alot more going on than just being really white. I don't remember the exact mechanism but I'm pretty sure I remember that it would actually cool whatever surface slightly below ambient
I worked in garden building for last two years and tried everything to keep it cool. Painting it white made by far the largest difference. The part of the roof unpainted was 85C but 33C where it was white. Inside it would regularly reach 45C but stayed at about 33C after painting. I also added a spray bar to keep roof cool that allows you to get it below the ambient temp but paint was the largest effect.
I love in AZ and I've done testing with white elastomeric before suggesting it for my customers I painted the roof over my shop and left the house bare I can go on the roof in the summer 110 and up and the white roof will be about 95 f where as the uncoated will be 140 or higher it does make a difference before coating I had to turn on fans and cooler first thing after coating I didn't have to till around 2 in the afternoon now these are flat roofs where adding more insulation etc isn't a possibility all testing was done on uninsulated roof section
Out in the Midwest, where temperatures can drop well below freezing for extended periods in winter, there is some merit to having the opposite of this effect; ie maximum solar heat gain reduces energy consumption of the furnace. If only there was a paint that changed its reflectivity as ambient temperature changed. Then you could have the best of both worlds: ie minimum solar heat gain in summer, and maximum in winter.
You basically have to change the color yourself. You can have strategic things painted in a dark color for the winter, but also have a light cover for them during summer (simpler than re-painting each season or swapping differently colored parts).
Yes it is indeed working. Here in Thailand with hot temperature we use cool roof paints especiallily with metal sheet roofs buildings and the advantage is sensibly visible
Black is better at giving it off but also at absorbing it too. Ideally you would want a house that is white during the day and black at night. But given the impracticality of painting your entire house twice a day, choosing white to reduce absorption is better than choosing black for an increase in radiation.
@@davidroddini1512 You don't have to change the color in the middle of the day. White paint is already black and white. It's white when reflecting visible radiation from the sun, and black when reemiting it as infrared light.
white paint on asphalt would be really bad bc you'd be blinded when driving, like with snow, the easier, cheaper and more eco-friendly way is to just plant more trees, in the city where I live we have trees that naturally shed during winter, so we have basically a tunnel of trees that cover more than half of the ground (it drops the ambient temp around 10°c) and in winter their leaves fall so we get "free heating" for those cold months
Painting just about anything white (for the purposes of reflecting light/heat) is a bad idea for the very reason you stated. The only exception I can think of is a white car, and only because the paint is incredibly durable and washable.
It would also wear off pretty quickly in the areas of the tire tracks. And possibly make the road more slippery. But it's California, so common sense doesn't really apply.
Another interesting tech on the same lines that I've seen, is panels that have a high IR emissivity, but only in a particular band of IR called the IR window which are particular wavelengths of light the atmosphere can't re-absorb, sending the thermal energy right back out into space. When fed with a loop of a refrigerant like water from inside a building, it can create a significant temperature gradient that saves huge amounts of electricity, and cools 3x better then electricity generated by the same area of solar panels fed into a standard refrigeration system. The channel Undecided did a vid about it here th-cam.com/video/pq8xDXkbXZs/w-d-xo.html
this is ridiculous how unscientific this test was. probes in different places, holding the light in your shaky hands between the houses. putting them both in sunlight and using an infrared gun to measure temps is a much more realistic test, but I'm sure you know this.
You're saying the variables in the experiment were not well controlled, and I agree. If I was actually considering painting my house white, I would want a more controlled experiment. In fact, I would want many more experiments, such as how long the paint retained its whiteness, and so forth. That being said, the question is this...for the purposes of this video (to inform and entertain), were the variables controlled enough? Clearly, the answer is yes. You'd have to look far and wide on TH-cam to find experiments where all the controllable variables are fully controlled. While this video certainly is far from definitive, there is something to learn from it.
Just the roof itself of a home would have a far greater surface area exposed to the sunlight, plus I've never seen a hobby wood colored roof, most roofs are fairly dark. So i don't think this test was very well thought out.
Smaller things have a higher ratio of surface area and internal volume than a large object. This is also one reason infants have a hard time regulating their internal temp cause the surface area of their skin is higher for the smaller internal body volume.
This is actually an interesting way to demonstrate the difference between convection vs radiation as a heat source. As you mentioned the 100w bulbs were probably just heating the air so the heat transfer was through convection, meaning the reflectivity of the paint was basically irrelevant, while the 100k lumen flashlight radiated heat. The forms if heat transfer come up in cooking a lot too. For instance, when you put something in the oven, a glass dish will always bake faster than an opaque one, all else being equal, because the radiant heat from the heating element in the oven and the oven walls can reach the food directly in a glass dish. Kind of a sidebar comment here but its a concept many struggle with this is both an interesting demo of the concept as well as a crafty little proof of concept. Well done!
Painting streets white is INCREDIBLY stupid. The light is getting reflected ONTO people and houses etc. Its like when snow skiers get sunburns on their faces from the light reflecting off of the snow. And the glare!!! Good grief! One of the worst times to be on the road is when the sun is reflecting off at an angle straight inside the car. This would make it ten times worse.
Would love to see the same experiment with multiple houses painted with different colors. The unpainted house gives us some data, but with multiple houses, we can see if paint vs no paint is a factor. Regardless of the color. Love what you're doing!
While living in South Florida I noticed I could feel heat radiating down through my ceiling. The attic during summer was unbearable. My house had light grey shingles. I decided to paint the shingles with a highly reflective and hurricane rated white elastomer paint. It made a huge difference. The attic stayed near room temperature, and my power bills dropped by nearly half.
@@vroor32, I sold that house, and a few years later a hurricane came through. The buyers and I stayed it touch. Their roof survived. Many houses around them did not. I believe it was because I used the hurricane rated coating.
@@BottomTick oh wow 😳 was it a DIY job or did you hire it out? Also how much paint was used and did you apply primer first? I'm thinking of doing this May 2024
@@vroor32 DIY job. I don't recall the brand, but I did use a primer and three coats of elastomeric coating. I believe it was 15 gallons of elastomer. I would also suggest rolling up hill from the bottom towards the top, to squeeze it under the shingle lips.
I think the reason the painted house was hotter in the first portion was because the paint prevented some heat escaping through the small gaps the wooden house had, so the unpainted house had some heat escaping in the air that could flow between the parts of the house and through the wood itself But with a hotter heat source, the paints prevention of heating outperformed the heat escaping from the unpainted house, resulting in it becoming cooler compared to the unpainted house
What would happen if you painted a two way mirror white 2.0 on the side you can see through and the side that’s reflective would be more reflective? What about a normal mirror too? Painting the back of a mirror that doesn’t have that solid finish on it…?
Painting your roads white just seems like a brilliant way to blind drivers, and possibly jack with things like tesla's autopilot (which might think "THAT'S NOT A ROAD!") Not only that, but the effect they seek will only last so long as the paint is kept clean, otherwise it will pick up dirt, grit, rubber, etc, and lose efficiency like mad. Yet another brilliant solution, California. Couldn't expect much more from a bunch of people who decided to build a city in the middle of a desert. shrug.emoji
I mean, unless people are painting their roofs white as well, then those news claims about not needing A/C were always going to be untrue. Love the demonstration! If you really want effective, eco-friendly passive cooling, plant some shade trees.
Reflecting all the sunlight in a neighborhood will probably make the neighborhood hotter outside. There is this one job sight I go to where it's semi enclosed on three sides and in front of a tall white wall. It gets like 20 degrees hotter than ambient in that spot. So yes, white paint will lower energy consumption, but I wouldn't be surprised if it made things more unpleasant outside. If you had a lot of buildings close together you could create a really bad heat trap. Additionally trying to drive on a glaring white road wouldn't be too good on the eyes either.
Most homes in the U.S. for the last 20 years are very well sealed. Its such that if you loose power for an extended period of time, you need to open a window or door to allow fresh air to circulate in. If you painted a house with this, the ambient temperature of the outside air wont have much of an influence on the inside temperature. I would imagine that in hot areas, the paint would pay for itself in lower electricity bills in just a few years.
Interesting! Parts of my patio gets direct sunshine hitting it 12 hours a day during the summer. I put a small pop-up tent on it to try and help cool the area and I am on my second replacement tarp after 4 years. When I replace the tarp again, I will try this paint and see how f there is a difference. I will use my remote Nest sensor to detect the temps between the two.
This experiment is comically flawed, thermal mass plays a great role, a small heat difference will not effect a small house temperature but it will change the peak temperature of a real house.
While this may be a good way to cool down dense urban areas. I think it's important that we account for the effects this could have on people's eyes. This could essentially cause snowblindness on a sunny day.
Love the video! I'd love to see this again with the unpainted wood house actually painted a darker color. The light wood is actually lighter than a lot of rooftops. Many houses have dark green, gray, or black roofs. I'd love to see another comparison where the one house is painted a dark color.
There's no question that more reflective surfaces don't absorb as much sunlight. But the claims being made about this "air conditioning" paint are different - they are claiming that their special paint reflects visible light very well but does not reflect infrared as much. They are then claiming that it can still radiate away heat from the house (as infrared) but not absorb as much heat-producing light from the sun. I've seen some pretty reputable sources echo this claim, but I have my doubts. For one thing, while the sun does emit most of its heat as visible light, it still emits more IR than a roof would. It may come down to exactly which wavelengths are passed vs absorbed by the atmosphere.
Interesting, but definitely a flawed test. Flashlight was clearly aimed mostly at the white house in the video, and you also can't take into account for the space/volume or surface area of the exterior of a real home. All of these effects would be multiplied, especially with windows sealed. Perhaps a larger scale test, placed outdoors during the summer time later in the year. Ultimately, I think you would reach the same conclusion that the white paint makes a difference, but I think you would see a much more significant change.
The thing with white paint on houses is that in the summer sun, it can be literally blinding. This is why we often see pastels on houses in tropical environments.
They make a ceramic powder that you can add to paint that will make it protect from heat. I watched bob villa do a demo of it where they painted a piece off of a shipping container but they only painted a portion in the middle, then they took a torch to one end and half the other and it didn’t burn him. The combination of these two would be amazing.
Maybe paint both of them so one isnt more porous than the other and also have them out on a sunny day instead of using a close heat source, wouldnt inverse square law play a part somewhat too ?
My father started a coating company in 1979 we coated huge industrial buildings roofs white. Timed the HVAC units on off time was reduced in peak summer heat in NY. "Inland coatings" rubberized liquid stops leaks and reduce heat . Best product we ever used. PS most roofs are black dark brown. Also Sun emits infrared. Flashlight also?
Great video! I'm curious to know how well would a solar oven that uses this ultra white paint perform against a "regular" solar oven made with reflective sides. My bet is that a solar oven made with ultra white walls wouldn't perform very well, but it would be nice to know how much worse would it be.
You have to use paint that reflects IR light, not UV/visible. It's not just about how "white" your paint is. I've used a white roof coating (OAF Dakcoat Reflex AQ WIT), and it makes for an incredible difference in temperature under the roof.
Just because we think of infra-red as heat, doesn't make it so. Infra red is just a wavelength, nothing more, and actually incident sunlight doesn't have much.
@@peterwolf4230 Yes. Light is not heat. Heat is produced by the absorption of light. IR is easily absorbed than other wavelengths so people think of it is heat.
@@peterwolf4230 Sunlight at the top of Earth's atmosphere is composed (by total energy) of about 50% infrared light, 40% visible light, and 10% ultraviolet light. The atmosphere in particular filters out over 70% of solar ultraviolet, especially at the shorter wavelengths.... So, I think you're wrong...
I have observed that plastic fibres in lawn chair weave that were white lasted longer than other colors. I had rescued an old lawn chair from the curb, it looked like it was made in the 70's. The brown and tan colored fibres were disintegrated and the darker faibres even crumbled in my hand, but the fibres in the weave that were white reimained strong enough that I was able to sit in the chair a couple of times. There wasn't enough of those fibres to hold me up for more than a couple uses, but they were intact it was an obvious difference. It had to be weathering from the sun. When I re-wove the chair I chose white. We'll see how many decades from 2017 it lasts this time! I would say from this showns the big advantage to painting your house or anything white is for longevity of the material. A white house should then need new siding less often than it's colorful neighbors.
The cooling coatings that scientific article was about doesn't just reflect, it is also a very good IR emitter. It can actually reduce the temperature below the 'in the shade' ambient temperature.
Light paint radiates less heat so it will also cool slower. This means that you need to run a high intensity test for a few hours to get a real reading.
My house's attic used to get 145F during the summer midday sun. Applying white Roofguard 700 brought my attic down to 5 degrees above outside ambient temperature. Heat no longer penetrates the insulation in the evening saving about $60 per month on the mean. The sealer covers the asphalt shingles protecting them from damage and excess heat. It's the way to go.
I have seen this microballoon additive for house paint that is supposed to increase the insulation significantly. Wouldn't you like to do a series on various schemes to save heating/cooling energy?
My comment about this would be that painting a single house would not have that big of an effect because all the other houses' materials would get warm and warm the air but of you apply this to a whole neighborhood the effect can certainly net a few degrees, even outside. Another thing that can be done and that we do here is to grow vines on the house. In summer, the leaves catch the sunlight and transform it into every to grow. In winter, the leaves die off so the sun can reach our buildings bricks and warm them up. Helps save energy in all seasons.
The brighter whites do indeed help. I purposely had a white steel roof installed after removing slate, and measured a 20 degrees Fahrenheit reduction in the attic. Now I can keep the 2nd floor apartment comfortably cooler with a smaller ac unit. The down-side is if you live where it snows, then you lose the ability to have snow & ice melt on a sunny but freezing cold day. The best of both worlds could be accomplished on buildings and roads if the surfaces could be switched back and forth from white to black when desired/needed. Someone needs to design roofing that has reversible panels or something similar to gain the effect. Then, make it affordable as well.
As someone who grew up in the highlands, I easily get exhausted in the lowlands because of the hot air. You just can't escape it. You had to go into a contained mall with aircon.
I think the incandescent bulbs aren't a good substitute for sunlight, as they have a huge emission in the IR spectrum, which the paint should be "trying" to absorb/emit
The cooling effect is only really present in studies where they place a sheet of polyethylene over the paint, this prevents convection from the warm air/ breeze. Since the IR passes through the plastic, it can get cooler than without the plastic. Just thought I'd mention that.
The white paint for houses shown at the start is based on barium sulphate, and is not the same as the White 2.0. The point of the barium sulphate paint is not that it is just highly reflective (white 2.0 is more reflective), but that it is also highly _emissive_ in the IR part of the spectrum - this is what allows the barium sulphate paint to cool _below_ ambient temperature, since it is emitting more energy than it absorbs. That's why it's touted as being similar to air conditioning, since you actually get radiative cooling from the paint rather than just a high proportion of energy reflected off it.
I would be very interested in an experiment checking the effectiveness of radiant barriers as they are installed in houses. They are typically a reflective coating on the underside of the roof deck. They are supposed to reflect heat away, but it seems that the dark roof is going to absorb the sunlight and the heat is going to be conducted into the attic, and the radiant barrier would have little or no effect. But people that install them swear that they are extremely effective in keeping the house cooler.
Radiant barriers do work because high reflecting materials are also low emitting. The roof gets hot, the roof decking gets hot, but the heat isn’t radiated into the attack space. And in winter, the heat from the ceilings (or rather the insulation atop the ceilings) is reflected back. Of course, it’s better to reflect the heat away before it ever gets to the roof decking. Keeping everything lower temperature prolongs life of the building materials.
I put hempcrete around my kitchen window to cover exposed brick where a greenhouse used to be an it stays 55°f no matter the temperature, below 0 to 100 and even the edges touching the stucko that aborbs cold an heat were at the same temperature. Best insulator homes hands down. I added silicone powder and magnesium oxide to weatherproof it we get a lot of rain. Normal hempcrete gets weak from heavy drenching but never molds and is a strong repellent for insects because of the high lime content.
The problem with using ultra-white paint to cool the streets/houses is that the light doesn't disappear. The problem is shifted to somewhere else. E.g if there are 3 houses, left and right ones are painted white, and middle house is painted darker color, then that middle house receives additional the energy from both of the houses. White roads would also send their energy to buildings next to the road + into the eyes of drivers as "glare". I wonder, if you could paint a bowl using this super white color and use it as a magnifying glass...to focus light and burn something. I know it wont "focus" into a single point because the light scatters, but it should still focus the light onto smaller area.
Interesting, what would be a great experiment would be to get 2 ice chests, (blue Igloo is pretty standard), leave one stock, wrap one in refelix(sp) wrap (shiny) and one with this paint and stick them outside with a frozen water bottle and watch the temp change. Also where did you source the paint?
the unpainted house could also be more transparent to heat and it's also less thermal mass. Meaning it's able to eject more heat quicker than a painted house. Think say aluminum foil vs a baking sheet when pulling out of the oven. The foil cools near instantly whereas the tray stays hot for a while.
You probably should have started this discussion with a quick refresher of how heat is transmitted: Conduction, convection, and radiation. If you're going to use models of houses, they probably ought to combat heat transmission in the ways houses do: insulation, sealing air gaps, and the effect you went for: reflectivity. They're all covered to some extent, but pointing out that there are three modes of heat transmission at the start prevents viewers from conflating them later. I live in a southern state, so (with the exception of the Feb 2021 freak cold wave) we usually care more about blocking heat than retaining it. As a result, I've done all the insulating I can, so the focus now is on maximizing reflectivity. I have the whitest shingles my roofer could supply, and that helped a lot immediately (since they were installed in the summer). Inside the attic there is also radiant barrier to reflect back most of the head that penetrates. The exterior walls are all being painted white this year as well. Any light that is absorbed turns into heat, so my goal is to drive that back. I even pressure wash the walk and steps in front of my house (which faces west, incidentally, so it really gets blasted all afternoon) in the spring. That gets them as white as possible before the summer sun hits them. The sun definitely puts out a lot more radiant heat than a few lightbulbs or even your mega flashlight.
Pretty sure you need to test them outside to see the effect. As well as reflecting visible light, these cooling paints reflect infrared light back into the atmosphere, where it escapes since it cannot absorb it, leading to a net loss in energy from the house's perspective and cooling it down. By doing the experiment inside the infrared light cant escape.
Part of the idea with the cooling paint is radiative cooling. It's supposed to emit light (I think in the 8-13 nm range) which isn't absorbed by the atmosphere, so that it can dump that heat directly into space. It notably doesn't work if the sky is too cloudy, or if there are obstructions. Testing the paint inside means it can't radiate heat into space as all the radiative heat exchange is with the walls of the room. An indoor test could only ascertain its reflective insulation properties, but insulation can only delay the rate at which it heats up. Unless you have a very fancy room, this isn't the kind of thing you test indoors. Plus I don't think I've heard anyone say this stuff is "better than air conditioning". It might reduce the need for air conditioning, and as part of an overall design approach it *might* replace air conditioning for cooling (but NOT for dehumidifying), but that's a bit of a different claim.
Most of the heat island statements aren’t comparing white to wood. They’re comparing white to black asphalt roads or dark asphalt shingles or flat black roofs commonly covered with EPDM. EDIT: Clarifying that typical asphalt shingles are not necessarily black, but usually are a dark color that would absorb more light than an unfinished light wood.
I can personally attest to this being untrue on an enclosed trailer. In the summer sun, internal temperatures could get over a 115°f, I painted the roof with white elastomeric silicone, and the temps stay below 95°, always. I used a remote temperature probe and ran the test for a few weeks, it averaged around 20° cooler in the same temp and sun conditions. On top of that, The inside of the roof would quite literally burn your skin if you touched it. With the white paint, it stays cool to the touch.
I've noticed that for some reason green doesn't seem to heat up as much as other colours and I also noticed plants are green and manage to sit in sun all day without ever getting too hot. I wonder if there's any truth to it or it's just my mind playing tricks on me and I just feel cooler in green🤔
It's mostly mind tricks. Plants stay cool by evaporation, so green plants and green paint won't be the same temp, all else being equal. The plants cool themselves and the air around them, which keeps us cooler too.
Would love to see the effects of actual sunlight on a hot summer day. Maybe as a follow up in a few months, you could leave them both outside in direct sunlight and see what happens?
This or the same experiment as in the video with infrared heaters
And paint the unpainted house... No one lives in an unpainted house and even that thin layer of paint will affect things drastically. Paint it a light brown like many houses are, or even have a black painted one for ultimate comparison (tho almost no one lives in a pure black house either; hence recommendin a neutral middle colour like brown).
No doubt the studies done that convinced folks to switch to white paint were done as a comparison to a dark grey or black; to represent the difference it makes on streets, not homes. And that is a huge difference, havin walked from dark asphalt to light asphalt before when i lived in Cali. The light asphalt of our driveway was always noticeably cooler than the dark asphalt of the road
Also a third house, using normal paint
ASAP science did it already with a whole house
I watched a documentary in India where they painted just the roofs of houses and it made a MASSIVE difference. About 6ºC difference before and after.
If you dont live in a hot country it's hard to understand how big that difference is, but its the difference between livable 40ºC and totally unlivable 46ºC
At temps over 35ºC every extra 5º feels like a doubling of the temperature.
I think you should test this with real sunlight using common roof materials including slate, metal, concrete, and asphalt. I wonder if this translates well scaled up, because the ratio of surface area to volume changes. The goal is not to replace air conditioning, but to decrease use of it, saving electricity, and making cities cooler.
I also want to know the difference between white concrete and clay tiles...
I agree. Scaled up might be different but I'm not a scientist so idk
@@phs125 see this th-cam.com/video/_r6FdS-O3_8/w-d-xo.html
Have you noticed that the floor on what the houses were standing was totaly black?
I think I’m contrast, what about for the winter to use less heat? You would want to find a way to “switch” to a fully black house.
A wooden bird house isn't a good substitute for a common residential abode. A dark shingled roof is going to generate a lot more heat than a piece of wood
I suppose you're right. Maybe there is some way we can make the dark shingled roof, not dark?
This experiment doesn't need to consider that because it's just to measure the effect of white paint vs not white paint. The houses are for laughs.
@@JustinL614 Right! He could have just placed the thermocouple underneath a small sheet of wood, one side painted, one side bare, and shown about the same result.
@@JustinL614 He's disputing that the white paint makes a substantial difference in temperature. That's going to change based on the colour and materials being used.
I'm suggesting we'd see a bigger difference in temperature if the roof was covered in a dark coloured shingle.
@@Trag1cMag1c True. To be fair we'd have to have two identical real houses but that's alot to ask for.
Colour does affect the temperature to a great extent. We have a pretty hot summer here in India. So I cover our over-the roof water tank ( black in color) with white thermocol sheets during summer to shield it from the scorching sun. And it does help to keep the water cooler by 5 - 6 degC.
Are you sure it's the color and not the thickness of the sheet?
Bhai me bhi india se hu. Desi chookra
@@gabor6259 Yeah.. because in my place day temperature stays around 35 degC in the summer. so the water temperature should never go above 35, but it actually rises to as high as 42 degC because of radiant heating from the direct sunlight. White thermocol cuts this off and thus the water temperature stays within the limit of conductive and convective heating from the hot air. Of course, thermocol also gives some protection from the hot air as well.
*color
@@taffyadam6031 India isn't part of the only country to spell colour without a "u".
I have worked in attics for about 20 years now and can definitely say the color of the roof greatly effects temperature. There was one attic I remember that i put a temperature probe in because it was so hot 97f degrees outside and in the attic it was 187f. The roof for that one was solid black shingles. The same day i had a house with light grey shingles and it was 118f. Why dont you paint the other house with black roof and see what the temperature difference is then. Wood color is naturally light.
There are plenty of other factors that cause that more than shingle color.
@Justin - of course, roof materials, insulation, angle, design etc.
But colour is important.
@@peterwolf4230 I know color is important just not "more than" the other factors. I just said that because he didn't mention them. Good examples in your comment.
Very debatable which is more important than the others - I suspect it is highly dependent on what the baseline is. From a baseline standard construction house, insulation is probably the most important improvement then this second. Things like orientation can't easily be changed, neither is it cost effective to change the entire material of a roof for example.
I’m really hoping that’s a typo. There’s no way a person could survive that, it’s 30 degrees away from boiling…
Edit: my mistake, I misread I thought you went INTO the attic!
This was a great test idea, however disappointed in the testing standards and assumptions. Some scrap shingles on the unpainted house would have yielded more significant results. Your control was not reasonable to expect. You usually do excellent science, and from the comments it would seem this was a little lackluster.
Yeah, agreed, a few points I'd like to tack on to this criticism, you painted the white house with both primer and white paint, effectively blocking the pores of the wood, which is naturally a fairly porous material, I'd assume the one on the right had ventilation in the form of non-clogged pores. The flashlight was pointed at an angle at the painted house and then directly over the wooden house, the testing standards weren't the greatest here and I'd love to see what other commenters are suggesting, two houses, made of similar materials to real houses, then both painted, one with the blackest black, one with the whitest white, a proper thermometer, in each.
except he thinks hexagons dont tesselate
In TH-cam language: Your video was shit
@@Killerjerick I would also do a regular run of the mill white paint as control. That way you can see if these fancy new white paints are worth the premium by comparing the projected energy savings.
@@FrotLopOfficial Video definitely wasn't shit, just not up the the standards we normally hold him to
One of my Heat Transfer professors in college was Ephraim Sparrow. He basically created modern radiant heat transfer theory. He told us this (very relevant) story one day:
He was working for a defense contractor in the 50s or 60s and they were charged with building metal boxes that would hold sensitive electronic equipment about 10m off the ground. They were used in the desert somewhere, so really high heat during the days. If I had to guess I’d say the boxes held sensors for the nuclear tests done in Nevada and New Mexico. His boss came to him and said, “make the boxes mirror finished because it will reflect all of the solar radiation.” He replied, “paint them white. If a black body is the best at emitting radiation then the exact opposite will be the second best emitter and it will absorb the least amount. I.e. a white body.” His boss thought he was wrong and fired him. (I’m sure there was more to it than that, but literally that’s all he said on why he was fired). About 10 years after the project ended Ephraim saw his ex boss again and his ex boss apologized and admitted that he had been wrong.
Quite a brilliant man :/ That white body being the second best emitter was intuitive to him.
Keep in mind the accuracy of these (uncalibrated!!) thermocouples is rather high, especially with these simple handheld terminals where you have no control over the reference temperature inside. An accuracy error of 1-2 deg C (1.8 - 3.6 deg F) is very normal, even though the precision (which is often mislabeled as accuracy on the box) is quite good.
60.1 vs 60.8 before he started. He explained that one was higher than the other and that was the reason for the difference.
As long as they read the same when together at a range of temperatures, their absolute accuracy isn't all that important when comparing different temperatures apart. I have no idea if he's tested them that way.
@@Bob5mith yep, but indeed we dont know if they do
@@JustinL614 that's a comparison between two different measurements of two uncalibrated (as far as we know) sensors. The difference is very close so you have no idea of it's real or part of the error
@@WouterVerbruggen I don’t know because he didn’t specify, but if we’re just going to speculate on the unsaid, based on what I’ve seen of his methodology and attention to detail, I would put my money on those things being calibrated. It’s not exactly an expert-level consideration…
It would be interesting to see the same test done with the wooden house's roof having part of a black asphalt shingle on it. I wonder how large (if any) the difference in temp gain from light would be at that point
@VeroMithril he said the paint reflects visible and UV best so why would he put infrared light that's not what it's advertised at being that good at reflecting
@@tacct1kk715 Exactly. Incandescent lights put out mostly infrared light, so this is likely why the second test had better results.
@@jabelar2008 "In a real house, there is conduction, but it is conduction of the heat absorbed into the rooftop from the light that conducts."
There wouldn't be much point in insulating the walls if that was the only conductive heating. It is significant but a house can still get unbearably hot on a hot and cloudy day. I completely agree with the rest of your comment though.
An infrared lamp provides something opposite to the sun, not closer.
@@jabelar2008 Also, hot air rises, so it doesn't make sense to say hot air from the light bulbs was causing most of the heating. It was likely the infrared.
Imagine the temperature control on your house being dependent on how clean the exterior is.
“Heat wave’s coming. I’d better get out there and pressure-wash!”
Or, imagine a color-changing roof that darkens in cold weather and lightens in hot weather so it helps regulate interior temperature without HVAC.
My house is mostly white with some dark Grey and black accents. It is all hardie board and on a bright day the dark painted wall can get hot enough that I can't comfortably leave my hand on it while the white parts are cool to the touch. From personal experience I can say that white paint versus black paint in direct sunlight makes a huge difference.
And then you consider that at scale of not just a house but whole sets of buildings and streets, and some of it is not wood, but dark concrete and asphalt (common thermal masses) storing heat throughout the day and releasing it at night vs cooler structures that don't store that heat so they can't release it after sundown.
I see some comments already about the lack of darker material on the roof of the unfinished house, which would be mistake number one. Standard shingles are darker than that particular wood, even in their variation of colors. The second part that wasn't brought up, is that the added coating of the paint to the white house would potentially also increase the insulation factor of the white house. It's an added coating helping to hold heat or cold inside the house, while the unfinished wood house lacked that exterior coating.
I would be curious to see this experiment repeated with the white painted house versus a medium or darker gray painted matching house. That'd be more accurate for a difference in temperature with matching insulating values. Or better yet, three houses, including the unfinished one in the test.
This isn't a good test, it's a very small house. That matters, because you have a surface area to volume issue. You can definitely feel the difference between a dark and light property in a hot country, it's why white is such a common colour in Mediterranean and Islamic design.
*Mediterranean and Middle Eastern design.
@Lord Talos, yeah that's fair.
Obviously white paint isn't going to cool your house below the minimum outdoor air temperature. It's absurd to compare it to air conditioning.
Of course this will keep your house much cooler than normal paint, but it has a theoretical limit imposed by the second law of thermodynamics. Refrigeration is not constrained by this same limit since it consumes energy.
One advantage could be that it longer keeps the cooler temperature from the night
It's not a question of "cooling down", but "not getting hot". A house can absolutely be cooler than outside air temperature, without air con.
@@peterwolf4230 It can only be cooler than the air outside if the air outside was recently cooler than it is now. If the lowest air temperature at night is 80 degrees, this paint isn't going to be enough.
Obviously highly reflective paint is helpful in the summer. I'm not refuting that. It would clearly reduce the amount of air conditioning you would need. But it could never accomplish as much air conditioning is capable of.
@Number1 - it doesn't have to accomplish as much as air conditioning, because most air conditioning is actually not required. We use it as a comfort thing. If your comfortable temperature range is say up to 25C, suddenly the air con can be turned off much more often. I've spent a lot of time in places like Thailand where you have warmer than that at night and just a fan.
The other point is that it's not a one or the other: air con doesn't need using every day, or every hour. So you can use something like this to reduce your costs,even if you still have air con sometimes.
This is basically the same thing as getting a white car in a hot country. If you get a dark car there you are an idiot.
I remember seeing that article at some point, and if I remember right it had alot more going on than just being really white. I don't remember the exact mechanism but I'm pretty sure I remember that it would actually cool whatever surface slightly below ambient
Just park a white car and a black car in the sun for the same time and feel the difference when you get in. Colour makes a huge difference.
I worked in garden building for last two years and tried everything to keep it cool. Painting it white made by far the largest difference. The part of the roof unpainted was 85C but 33C where it was white. Inside it would regularly reach 45C but stayed at about 33C after painting. I also added a spray bar to keep roof cool that allows you to get it below the ambient temp but paint was the largest effect.
I love in AZ and I've done testing with white elastomeric before suggesting it for my customers I painted the roof over my shop and left the house bare I can go on the roof in the summer 110 and up and the white roof will be about 95 f where as the uncoated will be 140 or higher it does make a difference before coating I had to turn on fans and cooler first thing after coating I didn't have to till around 2 in the afternoon now these are flat roofs where adding more insulation etc isn't a possibility all testing was done on uninsulated roof section
Out in the Midwest, where temperatures can drop well below freezing for extended periods in winter, there is some merit to having the opposite of this effect; ie maximum solar heat gain reduces energy consumption of the furnace. If only there was a paint that changed its reflectivity as ambient temperature changed. Then you could have the best of both worlds: ie minimum solar heat gain in summer, and maximum in winter.
You basically have to change the color yourself. You can have strategic things painted in a dark color for the winter, but also have a light cover for them during summer (simpler than re-painting each season or swapping differently colored parts).
Yes it is indeed working. Here in Thailand with hot temperature we use cool roof paints especiallily with metal sheet roofs buildings and the advantage is sensibly visible
But black is better for giving off thermal radiation? Would have liked to see one painted a really dark black too.
Black is better at giving it off but also at absorbing it too. Ideally you would want a house that is white during the day and black at night. But given the impracticality of painting your entire house twice a day, choosing white to reduce absorption is better than choosing black for an increase in radiation.
@@davidroddini1512 Lol makes me think we'll have flipping roofs in the future.
@@davidroddini1512 maybe by using the ultra black cloths to cover the house automatically at night
@@davidroddini1512 You don't have to change the color in the middle of the day. White paint is already black and white. It's white when reflecting visible radiation from the sun, and black when reemiting it as infrared light.
We need the difference between white 2.0 and regular white paint for something like this experiment.
And also the ultra black paints he has previously used.
I'd be very much interested in that too! Is it actually worth to purchase white 2.0 as opposed to eg white acrylic based on titanium?....
white paint on asphalt would be really bad bc you'd be blinded when driving, like with snow, the easier, cheaper and more eco-friendly way is to just plant more trees, in the city where I live we have trees that naturally shed during winter, so we have basically a tunnel of trees that cover more than half of the ground (it drops the ambient temp around 10°c) and in winter their leaves fall so we get "free heating" for those cold months
Painting the road white seems like a terrible idea. How many cars pass before it's covered in dirt/oil/soot?
Painting just about anything white (for the purposes of reflecting light/heat) is a bad idea for the very reason you stated. The only exception I can think of is a white car, and only because the paint is incredibly durable and washable.
Not to mention how blinding it could be
It would also wear off pretty quickly in the areas of the tire tracks. And possibly make the road more slippery. But it's California, so common sense doesn't really apply.
Lighter colours may work i.e. lighter grey or brown like some older roads. But not white, too bright etc.
Another interesting tech on the same lines that I've seen, is panels that have a high IR emissivity, but only in a particular band of IR called the IR window which are particular wavelengths of light the atmosphere can't re-absorb, sending the thermal energy right back out into space.
When fed with a loop of a refrigerant like water from inside a building, it can create a significant temperature gradient that saves huge amounts of electricity, and cools 3x better then electricity generated by the same area of solar panels fed into a standard refrigeration system.
The channel Undecided did a vid about it here
th-cam.com/video/pq8xDXkbXZs/w-d-xo.html
Exactly. I'm glad someone on here brought this up. This is where people are getting the air conditioning claim from.
I ended up painting the hood and roof of my Cherokee white to help with summer heat and it is a noticeable difference.
this is ridiculous how unscientific this test was. probes in different places, holding the light in your shaky hands between the houses. putting them both in sunlight and using an infrared gun to measure temps is a much more realistic test, but I'm sure you know this.
Very odd video, felt like it was just slapped together for content.
Yes an incredibly weak video for this channel, I'm used to higher quality.
You're saying the variables in the experiment were not well controlled, and I agree. If I was actually considering painting my house white, I would want a more controlled experiment. In fact, I would want many more experiments, such as how long the paint retained its whiteness, and so forth. That being said, the question is this...for the purposes of this video (to inform and entertain), were the variables controlled enough? Clearly, the answer is yes. You'd have to look far and wide on TH-cam to find experiments where all the controllable variables are fully controlled. While this video certainly is far from definitive, there is something to learn from it.
@Ernie - he didn't answer anything, at all with this test. Seriously, this falls under junk science he's done it so badly.
Didn't even leave a link for Stuart Semple's White 2.0
Just the roof itself of a home would have a far greater surface area exposed to the sunlight, plus I've never seen a hobby wood colored roof, most roofs are fairly dark. So i don't think this test was very well thought out.
Smaller things have a higher ratio of surface area and internal volume than a large object. This is also one reason infants have a hard time regulating their internal temp cause the surface area of their skin is higher for the smaller internal body volume.
Roofs being darker in reality just means the effect will be larger.
0:55 is that article about "Infrared Cooling Paint"? Because if it is it is much more than just white paint and you should try that.
This is actually an interesting way to demonstrate the difference between convection vs radiation as a heat source. As you mentioned the 100w bulbs were probably just heating the air so the heat transfer was through convection, meaning the reflectivity of the paint was basically irrelevant, while the 100k lumen flashlight radiated heat. The forms if heat transfer come up in cooking a lot too. For instance, when you put something in the oven, a glass dish will always bake faster than an opaque one, all else being equal, because the radiant heat from the heating element in the oven and the oven walls can reach the food directly in a glass dish. Kind of a sidebar comment here but its a concept many struggle with this is both an interesting demo of the concept as well as a crafty little proof of concept. Well done!
Painting streets white is INCREDIBLY stupid. The light is getting reflected ONTO people and houses etc. Its like when snow skiers get sunburns on their faces from the light reflecting off of the snow. And the glare!!! Good grief! One of the worst times to be on the road is when the sun is reflecting off at an angle straight inside the car. This would make it ten times worse.
Would love to see the same experiment with multiple houses painted with different colors. The unpainted house gives us some data, but with multiple houses, we can see if paint vs no paint is a factor. Regardless of the color. Love what you're doing!
While living in South Florida I noticed I could feel heat radiating down through my ceiling. The attic during summer was unbearable. My house had light grey shingles. I decided to paint the shingles with a highly reflective and hurricane rated white elastomer paint. It made a huge difference.
The attic stayed near room temperature, and my power bills dropped by nearly half.
Really? I'm toying with painting my roof shingles too. That's good to know
@@vroor32, I sold that house, and a few years later a hurricane came through. The buyers and I stayed it touch.
Their roof survived. Many houses around them did not. I believe it was because I used the hurricane rated coating.
@@BottomTick oh wow 😳 was it a DIY job or did you hire it out? Also how much paint was used and did you apply primer first? I'm thinking of doing this May 2024
@@vroor32 DIY job. I don't recall the brand, but I did use a primer and three coats of elastomeric coating. I believe it was 15 gallons of elastomer.
I would also suggest rolling up hill from the bottom towards the top, to squeeze it under the shingle lips.
So many problems with this test.
Paint the other house with same thickness of paint. Set temp probes to same height. Put both in actual sunlight.
I think the reason the painted house was hotter in the first portion was because the paint prevented some heat escaping through the small gaps the wooden house had, so the unpainted house had some heat escaping in the air that could flow between the parts of the house and through the wood itself
But with a hotter heat source, the paints prevention of heating outperformed the heat escaping from the unpainted house, resulting in it becoming cooler compared to the unpainted house
What would happen if you painted a two way mirror white 2.0 on the side you can see through and the side that’s reflective would be more reflective? What about a normal mirror too? Painting the back of a mirror that doesn’t have that solid finish on it…?
Painting your roads white just seems like a brilliant way to blind drivers, and possibly jack with things like tesla's autopilot (which might think "THAT'S NOT A ROAD!")
Not only that, but the effect they seek will only last so long as the paint is kept clean, otherwise it will pick up dirt, grit, rubber, etc, and lose efficiency like mad.
Yet another brilliant solution, California. Couldn't expect much more from a bunch of people who decided to build a city in the middle of a desert. shrug.emoji
Exactly. Seems like a silly idea to me. I'm sure it would have an effect on grip as well. Maybe they've tested these things, but I'm not so sure.
This is a good thing to experiment. Especially to answer the question for once and for all.
It gives strong indications but doesn’t answer the question “once and for all”
It's a really badly done test
@@peterwolf4230 agreed
I mean, unless people are painting their roofs white as well, then those news claims about not needing A/C were always going to be untrue. Love the demonstration!
If you really want effective, eco-friendly passive cooling, plant some shade trees.
8 degrees is okay for just a paint. Cannot be compared with AC, but definitely you feel a lot cooler than nothing
Am I the only one that thought "why doesn't he just leave the houses in the actual sun to represent more accurate results?"
Reflecting all the sunlight in a neighborhood will probably make the neighborhood hotter outside. There is this one job sight I go to where it's semi enclosed on three sides and in front of a tall white wall. It gets like 20 degrees hotter than ambient in that spot.
So yes, white paint will lower energy consumption, but I wouldn't be surprised if it made things more unpleasant outside.
If you had a lot of buildings close together you could create a really bad heat trap. Additionally trying to drive on a glaring white road wouldn't be too good on the eyes either.
Most homes in the U.S. for the last 20 years are very well sealed. Its such that if you loose power for an extended period of time, you need to open a window or door to allow fresh air to circulate in. If you painted a house with this, the ambient temperature of the outside air wont have much of an influence on the inside temperature. I would imagine that in hot areas, the paint would pay for itself in lower electricity bills in just a few years.
22° is a huge difference to 30° in Celsius for anyone who lives in hot climates. That is what most public AC units are set to.
right? 22 degrees would almost feel icy compared to 30
...Why not just do this experiment outside lol
When I was in grade school I was dreaming of a paint that would change from Black to white, depending on the temperature. Action lab Go!
This is not a good test in my opinion you just have to use sun light and span the readings in between a few days of sun and average it.
Interesting! Parts of my patio gets direct sunshine hitting it 12 hours a day during the summer. I put a small pop-up tent on it to try and help cool the area and I am on my second replacement tarp after 4 years. When I replace the tarp again, I will try this paint and see how f there is a difference. I will use my remote Nest sensor to detect the temps between the two.
This experiment is comically flawed, thermal mass plays a great role, a small heat difference will not effect a small house temperature but it will change the peak temperature of a real house.
While this may be a good way to cool down dense urban areas. I think it's important that we account for the effects this could have on people's eyes. This could essentially cause snowblindness on a sunny day.
wear sunglasses
Love the video! I'd love to see this again with the unpainted wood house actually painted a darker color. The light wood is actually lighter than a lot of rooftops. Many houses have dark green, gray, or black roofs. I'd love to see another comparison where the one house is painted a dark color.
There's no question that more reflective surfaces don't absorb as much sunlight. But the claims being made about this "air conditioning" paint are different - they are claiming that their special paint reflects visible light very well but does not reflect infrared as much. They are then claiming that it can still radiate away heat from the house (as infrared) but not absorb as much heat-producing light from the sun. I've seen some pretty reputable sources echo this claim, but I have my doubts. For one thing, while the sun does emit most of its heat as visible light, it still emits more IR than a roof would. It may come down to exactly which wavelengths are passed vs absorbed by the atmosphere.
It would be interesting to see the same test in cold temperatures to see if the white house gets colder ?
those drivers are getting their eyes melted while driving in a white street...
also for the love of everything you consider sacred, please use °C
Interesting, but definitely a flawed test. Flashlight was clearly aimed mostly at the white house in the video, and you also can't take into account for the space/volume or surface area of the exterior of a real home. All of these effects would be multiplied, especially with windows sealed. Perhaps a larger scale test, placed outdoors during the summer time later in the year. Ultimately, I think you would reach the same conclusion that the white paint makes a difference, but I think you would see a much more significant change.
Even if it's not "better than", it can heavily increase the efficiency of ac and help reduce heat absorption in places you can't air condition.
Exactly. People with ‘cool roofs’ report needing 15% to 25% less AC.
The thing with white paint on houses is that in the summer sun, it can be literally blinding. This is why we often see pastels on houses in tropical environments.
That is what the sunglasses are for.
So what if you paint your house white 2.0 in winter and vantablack 3.0 in summer?
Couldn't you have put the houses outside in actual sunlight? Really, curious
They make a ceramic powder that you can add to paint that will make it protect from heat. I watched bob villa do a demo of it where they painted a piece off of a shipping container but they only painted a portion in the middle, then they took a torch to one end and half the other and it didn’t burn him. The combination of these two would be amazing.
i dont like the idea of my streets looking like an army of birds had diarrhea
@Grace 💞 what the hell is this and what the hell is wrong with you
@@pluto8234 it's on every every every single single single comment
@@vilmfilm oh god no
Maybe paint both of them so one isnt more porous than the other and also have them out on a sunny day instead of using a close heat source, wouldnt inverse square law play a part somewhat too ?
I love your videos
Mediterranean villages have been doing this for milenia, and they keep doing it today. Something that persistent in time must work, and it does...
Tank you for the best information 😉
My father started a coating company in 1979 we coated huge industrial buildings roofs white.
Timed the HVAC units on off time was reduced in peak summer heat in NY.
"Inland coatings" rubberized liquid stops leaks and reduce heat .
Best product we ever used.
PS most roofs are black dark brown.
Also Sun emits infrared. Flashlight also?
a
b
d
D
@@zabuki1740 thats right
Great video!
I'm curious to know how well would a solar oven that uses this ultra white paint perform against a "regular" solar oven made with reflective sides.
My bet is that a solar oven made with ultra white walls wouldn't perform very well, but it would be nice to know how much worse would it be.
You have to use paint that reflects IR light, not UV/visible. It's not just about how "white" your paint is. I've used a white roof coating (OAF Dakcoat Reflex AQ WIT), and it makes for an incredible difference in temperature under the roof.
Just because we think of infra-red as heat, doesn't make it so. Infra red is just a wavelength, nothing more, and actually incident sunlight doesn't have much.
@@peterwolf4230 Yes. Light is not heat. Heat is produced by the absorption of light. IR is easily absorbed than other wavelengths so people think of it is heat.
@@peterwolf4230 Sunlight at the top of Earth's atmosphere is composed (by total energy) of about 50% infrared light, 40% visible light, and 10% ultraviolet light. The atmosphere in particular filters out over 70% of solar ultraviolet, especially at the shorter wavelengths.... So, I think you're wrong...
You need to use real sunlight as it has way more infrared light. You also need to use a paint that is white to the infrared.
Black conducts heat better. Maybe they should run some of the water lines under the roads so everyone can have free hot water.
I have observed that plastic fibres in lawn chair weave that were white lasted longer than other colors. I had rescued an old lawn chair from the curb, it looked like it was made in the 70's. The brown and tan colored fibres were disintegrated and the darker faibres even crumbled in my hand, but the fibres in the weave that were white reimained strong enough that I was able to sit in the chair a couple of times. There wasn't enough of those fibres to hold me up for more than a couple uses, but they were intact it was an obvious difference. It had to be weathering from the sun.
When I re-wove the chair I chose white. We'll see how many decades from 2017 it lasts this time!
I would say from this showns the big advantage to painting your house or anything white is for longevity of the material. A white house should then need new siding less often than it's colorful neighbors.
The cooling coatings that scientific article was about doesn't just reflect, it is also a very good IR emitter. It can actually reduce the temperature below the 'in the shade' ambient temperature.
This is kinda like my first science fair project in Grade 1. Seeing how different colours affect temperature. Weird throwback for me... lol
Light paint radiates less heat so it will also cool slower. This means that you need to run a high intensity test for a few hours to get a real reading.
My house's attic used to get 145F during the summer midday sun. Applying white Roofguard 700 brought my attic down to 5 degrees above outside ambient temperature. Heat no longer penetrates the insulation in the evening saving about $60 per month on the mean. The sealer covers the asphalt shingles protecting them from damage and excess heat. It's the way to go.
I have seen this microballoon additive for house paint that is supposed to increase the insulation significantly. Wouldn't you like to do a series on various schemes to save heating/cooling energy?
My comment about this would be that painting a single house would not have that big of an effect because all the other houses' materials would get warm and warm the air but of you apply this to a whole neighborhood the effect can certainly net a few degrees, even outside.
Another thing that can be done and that we do here is to grow vines on the house. In summer, the leaves catch the sunlight and transform it into every to grow. In winter, the leaves die off so the sun can reach our buildings bricks and warm them up. Helps save energy in all seasons.
The brighter whites do indeed help. I purposely had a white steel roof installed after removing slate, and measured a 20 degrees Fahrenheit reduction in the attic. Now I can keep the 2nd floor apartment comfortably cooler with a smaller ac unit. The down-side is if you live where it snows, then you lose the ability to have snow & ice melt on a sunny but freezing cold day. The best of both worlds could be accomplished on buildings and roads if the surfaces could be switched back and forth from white to black when desired/needed. Someone needs to design roofing that has reversible panels or something similar to gain the effect. Then, make it affordable as well.
As someone who grew up in the highlands, I easily get exhausted in the lowlands because of the hot air. You just can't escape it. You had to go into a contained mall with aircon.
Shouldn't solar panels also reflect some radiant heat with the advantage that they produce electricity?
I think the incandescent bulbs aren't a good substitute for sunlight, as they have a huge emission in the IR spectrum, which the paint should be "trying" to absorb/emit
So does the sun.. it's the IR spectrum that would be causing most heating on a surface
The full cooling effect is noted when the construction is a layer that reflects some heat built upon a layer that allows some heat to escape.
The cooling effect is only really present in studies where they place a sheet of polyethylene over the paint, this prevents convection from the warm air/ breeze. Since the IR passes through the plastic, it can get cooler than without the plastic. Just thought I'd mention that.
The white paint for houses shown at the start is based on barium sulphate, and is not the same as the White 2.0. The point of the barium sulphate paint is not that it is just highly reflective (white 2.0 is more reflective), but that it is also highly _emissive_ in the IR part of the spectrum - this is what allows the barium sulphate paint to cool _below_ ambient temperature, since it is emitting more energy than it absorbs. That's why it's touted as being similar to air conditioning, since you actually get radiative cooling from the paint rather than just a high proportion of energy reflected off it.
I would be very interested in an experiment checking the effectiveness of radiant barriers as they are installed in houses. They are typically a reflective coating on the underside of the roof deck. They are supposed to reflect heat away, but it seems that the dark roof is going to absorb the sunlight and the heat is going to be conducted into the attic, and the radiant barrier would have little or no effect. But people that install them swear that they are extremely effective in keeping the house cooler.
Radiant barriers do work because high reflecting materials are also low emitting. The roof gets hot, the roof decking gets hot, but the heat isn’t radiated into the attack space. And in winter, the heat from the ceilings (or rather the insulation atop the ceilings) is reflected back.
Of course, it’s better to reflect the heat away before it ever gets to the roof decking. Keeping everything lower temperature prolongs life of the building materials.
@theactionlab what about painting your house with thermoshield or supertherm AND white 2.0?
I would love it if you did this experiment.
I put hempcrete around my kitchen window to cover exposed brick where a greenhouse used to be an it stays 55°f no matter the temperature, below 0 to 100 and even the edges touching the stucko that aborbs cold an heat were at the same temperature. Best insulator homes hands down. I added silicone powder and magnesium oxide to weatherproof it we get a lot of rain. Normal hempcrete gets weak from heavy drenching but never molds and is a strong repellent for insects because of the high lime content.
The problem with using ultra-white paint to cool the streets/houses is that the light doesn't disappear. The problem is shifted to somewhere else. E.g if there are 3 houses, left and right ones are painted white, and middle house is painted darker color, then that middle house receives additional the energy from both of the houses. White roads would also send their energy to buildings next to the road + into the eyes of drivers as "glare". I wonder, if you could paint a bowl using this super white color and use it as a magnifying glass...to focus light and burn something. I know it wont "focus" into a single point because the light scatters, but it should still focus the light onto smaller area.
Interesting, what would be a great experiment would be to get 2 ice chests, (blue Igloo is pretty standard), leave one stock, wrap one in refelix(sp) wrap (shiny) and one with this paint and stick them outside with a frozen water bottle and watch the temp change. Also where did you source the paint?
the unpainted house could also be more transparent to heat and it's also less thermal mass. Meaning it's able to eject more heat quicker than a painted house. Think say aluminum foil vs a baking sheet when pulling out of the oven. The foil cools near instantly whereas the tray stays hot for a while.
I would love to see this with the white one and vanta black outside in actual sunlight!
The cut at 4:22 Houses didn't move away from each other being pushed by the light right? That looked weird
You probably should have started this discussion with a quick refresher of how heat is transmitted: Conduction, convection, and radiation. If you're going to use models of houses, they probably ought to combat heat transmission in the ways houses do: insulation, sealing air gaps, and the effect you went for: reflectivity. They're all covered to some extent, but pointing out that there are three modes of heat transmission at the start prevents viewers from conflating them later.
I live in a southern state, so (with the exception of the Feb 2021 freak cold wave) we usually care more about blocking heat than retaining it. As a result, I've done all the insulating I can, so the focus now is on maximizing reflectivity. I have the whitest shingles my roofer could supply, and that helped a lot immediately (since they were installed in the summer). Inside the attic there is also radiant barrier to reflect back most of the head that penetrates. The exterior walls are all being painted white this year as well. Any light that is absorbed turns into heat, so my goal is to drive that back. I even pressure wash the walk and steps in front of my house (which faces west, incidentally, so it really gets blasted all afternoon) in the spring. That gets them as white as possible before the summer sun hits them. The sun definitely puts out a lot more radiant heat than a few lightbulbs or even your mega flashlight.
Don't the road become blindingly bright after being painted white on a sunny day?
Pretty sure you need to test them outside to see the effect. As well as reflecting visible light, these cooling paints reflect infrared light back into the atmosphere, where it escapes since it cannot absorb it, leading to a net loss in energy from the house's perspective and cooling it down. By doing the experiment inside the infrared light cant escape.
What would happen, if you would mix up the whitest white, and the blackest black? Would it turn into the grayest gray?
Part of the idea with the cooling paint is radiative cooling. It's supposed to emit light (I think in the 8-13 nm range) which isn't absorbed by the atmosphere, so that it can dump that heat directly into space. It notably doesn't work if the sky is too cloudy, or if there are obstructions. Testing the paint inside means it can't radiate heat into space as all the radiative heat exchange is with the walls of the room. An indoor test could only ascertain its reflective insulation properties, but insulation can only delay the rate at which it heats up. Unless you have a very fancy room, this isn't the kind of thing you test indoors.
Plus I don't think I've heard anyone say this stuff is "better than air conditioning". It might reduce the need for air conditioning, and as part of an overall design approach it *might* replace air conditioning for cooling (but NOT for dehumidifying), but that's a bit of a different claim.
Most of the heat island statements aren’t comparing white to wood. They’re comparing white to black asphalt roads or dark asphalt shingles or flat black roofs commonly covered with EPDM.
EDIT: Clarifying that typical asphalt shingles are not necessarily black, but usually are a dark color that would absorb more light than an unfinished light wood.
I can personally attest to this being untrue on an enclosed trailer. In the summer sun, internal temperatures could get over a 115°f, I painted the roof with white elastomeric silicone, and the temps stay below 95°, always. I used a remote temperature probe and ran the test for a few weeks, it averaged around 20° cooler in the same temp and sun conditions. On top of that, The inside of the roof would quite literally burn your skin if you touched it. With the white paint, it stays cool to the touch.
i painted my roof with lime and it helped alot, the ceiling temperature became lower than the walls, while before it was the other way around
I've noticed that for some reason green doesn't seem to heat up as much as other colours and I also noticed plants are green and manage to sit in sun all day without ever getting too hot.
I wonder if there's any truth to it or it's just my mind playing tricks on me and I just feel cooler in green🤔
It's mostly mind tricks. Plants stay cool by evaporation, so green plants and green paint won't be the same temp, all else being equal. The plants cool themselves and the air around them, which keeps us cooler too.