great !!! i love the simplisity and practical of this. but if you want ultra cheap heat also at night you must build the FUELLESS AIR HEATER that is proven to work.
I saw this project in a book about cheap solar energy projects. The key is the gap between the window and the plastic and making sure the bottom has a gap. Hot air rises; so the cool air is sucked in from the bottom and hot air is pushed out the top. Wonder if it would be more efficient if the sheet is dropped to the base of the window vs. just above floor level.
Well the problem w/ white plastic is that it would reflect the sun back out the window so you're right, there would be no gain. But with the window open the light is absorbed in the room and turned into heat eventually. I guess the true experiment would be to, on identically sunny days, shut the door and keep track of the temp, once with the plastic down and once with it up. I think the advantage of a solar furnace on the wall (as opposed to covering the window) is increase wall space.
hmmmmmm. the science doesn't make sense to me since the energy coming into the window doesn't change because of the plastic. The plastic doesn't make more sun/energy come into the room. hmmmmmmmm.
@thatdontmakenosense...my layman's understanding is that the BLACK surface creates more heat than the lighter surfaces that are in the room (same idea that a black seat sitting in the sun will be much hotter than a white seat sitting in the sun. To your point...if the surfaces of the room were black then hanging the black plastic would not generate any additional heat in the room.
@boat6868 ok, I'm not trying to be a contrarian here, and my understanding of physics is completely "lay," but the light that comes into the room (no plastic) is absorbed in the blue paint (say, only 40%), but the remaining energy doesn't go away, it bounces onto the dark brown desk (and it absorbs 80%of the reflected light), and etc. until all of it is converted into heat. The ONLY light that isn't eventually converted to heat energy is the light that bounces back out the window into space.
@thatdontmakenosense you raise a good question, I don't know if the light energy keeps bouncing around until it is absorbed or not...I am nowhere close to understanding this stuff, I am just a guy admiring some of the innovative homemade solar stuff that people are doing in order to see if any of it would be practical for me.
Dark colors are dark because they absorb light, rather than reflecting it. This absorbed light energy is converted to heat. Havent you ever noticed how much warmer dark clothing is with the summer sun shining on you? Or compare walking barefoot some sunny day on both concrete (light surface) and black top (dark surface) and this will be made painfully clear to you.
great !!! i love the simplisity and practical of this. but if you want ultra cheap heat also at night you must build the FUELLESS AIR HEATER that is proven to work.
antorise1 10 months ago
I saw this project in a book about cheap solar energy projects. The key is the gap between the window and the plastic and making sure the bottom has a gap. Hot air rises; so the cool air is sucked in from the bottom and hot air is pushed out the top. Wonder if it would be more efficient if the sheet is dropped to the base of the window vs. just above floor level.
quote4257 1 year ago
thanks for posting this video..the simplicity and inexpensiveness makes it a no brainer for anyone concerned about utility usage.
centervilletn 1 year ago
Well the problem w/ white plastic is that it would reflect the sun back out the window so you're right, there would be no gain. But with the window open the light is absorbed in the room and turned into heat eventually. I guess the true experiment would be to, on identically sunny days, shut the door and keep track of the temp, once with the plastic down and once with it up. I think the advantage of a solar furnace on the wall (as opposed to covering the window) is increase wall space.
thatdontmakenosense 2 years ago
Excellent! Simple, inexpensive, effective.
Nubeck 2 years ago
hmmmmmm. the science doesn't make sense to me since the energy coming into the window doesn't change because of the plastic. The plastic doesn't make more sun/energy come into the room. hmmmmmmmm.
thatdontmakenosense 2 years ago
@thatdontmakenosense...my layman's understanding is that the BLACK surface creates more heat than the lighter surfaces that are in the room (same idea that a black seat sitting in the sun will be much hotter than a white seat sitting in the sun. To your point...if the surfaces of the room were black then hanging the black plastic would not generate any additional heat in the room.
boat6868 2 years ago
@boat6868 ok, I'm not trying to be a contrarian here, and my understanding of physics is completely "lay," but the light that comes into the room (no plastic) is absorbed in the blue paint (say, only 40%), but the remaining energy doesn't go away, it bounces onto the dark brown desk (and it absorbs 80%of the reflected light), and etc. until all of it is converted into heat. The ONLY light that isn't eventually converted to heat energy is the light that bounces back out the window into space.
thatdontmakenosense 2 years ago
@thatdontmakenosense you raise a good question, I don't know if the light energy keeps bouncing around until it is absorbed or not...I am nowhere close to understanding this stuff, I am just a guy admiring some of the innovative homemade solar stuff that people are doing in order to see if any of it would be practical for me.
boat6868 2 years ago
@thatdontmakenosense
Dark colors are dark because they absorb light, rather than reflecting it. This absorbed light energy is converted to heat. Havent you ever noticed how much warmer dark clothing is with the summer sun shining on you? Or compare walking barefoot some sunny day on both concrete (light surface) and black top (dark surface) and this will be made painfully clear to you.
TheRoosterscrow 2 years ago
Great project...don't worry about the cost of the fan...they use very little electricity.
boat6868 2 years ago
Good idea - to use what you have and keep it simple. I like it.
KasinH 2 years ago
Comment removed
payday8470 2 years ago