Mirrors Could Replace Air Conditioning

A mirror that sends heat into the frigid expanse of space has been designed by scientists to replace air-conditioning units that keep buildings cool on Earth.Researchers believe the mirror could slash the amount of energy used to control air temperatures in business premises and shopping centres by doing away with power-hungry cooling systems.Around 15 per cent of the energy used by buildings in the U.S. goes on air conditioning, but the researchers' calculations suggest that in some cases, the mirror could completely offset the need for extra cooling.In a rooftop comparison of the device in Stanford, California, scientists found that while a surface painted black reached 60°C more than ambient temperature in sunlight, and bare aluminium reached 40°C more, the mirror was up to 5°C cooler than the surrounding air temperature."If you cover significant parts of the roof with this mirror, you can see how much power it can save. You can significantly offset the electricity used for air conditioning," said Shanhui Fan, an expert in photonics at Stanford University who led the development of the mirror. "In some situations the computations say you can completely offset the air conditioning."Buildings warm up in a number of different ways. Hot water boilers and cooking facilities release heat into their immediate surroundings. In hot countries, warm air comes in through doors and windows. Then there is visible light and infra-red radiation from the sun, which also heat up buildings.A thermal radiatorThe Stanford mirror was designed in such a way that it reflects 97 per cent of the visible light that falls on it. But more importantly, it works as a thermal radiator. When the mirror is warmed up, it releases heat at a specific wavelength of infrared light that passes easily through the atmosphere and out into space.To make anything cool requires what engineers call a heat sink: somewhere to dump unwanted heat. The heat sink has to be cooler than the object that needs cooling or it will not do its job. For example, a bucket of ice will cool a bottle of wine because it becomes a sink for heat in the liquid. Use a bucket of hot coals and the result will the very different. The Stanford mirror relies on the ultimate heat sink: the universe itself.The mirror is built from several layers of wafer-thin materials. The first layer is reflective silver. On top of this are alternating layers of silicon dioxide and hafnium oxide. These layers improve the reflectivity, but also turn the mirror into a thermal radiator. When silicon dioxide heats up, it radiates the heat as infrared light at a wavelength of around 10 micrometres. Since there is very little in the atmosphere that absorbs at that wavelength, the heat passes straight out to space.The total thickness of the mirror is around two micrometres, or two thousandths of a millimetre."The cold darkness of the universe can be used as a renewable thermodynamic resource, even during the hottest hours of the day," the scientists write in Nature. In tests, the mirror had a cooling power of 40 watts per square metre at ambient temperature.Writing in the journal, Mr. Fan puts the installed cost of mirrors at between $20 and $70 per square metre and calculates an annual electricity saving of 100MWh per year on a three storey building.Mr. Fan said that the mirror could cool buildings - or other objects - simply by putting it in direct contact with them. Coating the roof of a building with the mirror would prevent heating from sunlight but do little to remove heat from its interior. More likely, the mirror would be used to cool water or some other fluid that would then be pumped around the building. He ruled out the idea of using the mirrors to slow down global warming. "Roof space accounts for only a small portion of the Earth's surface, so at this point we don't think this would be a geoengineering solution. Rather, our contribution on the green house gas emission issue is simply to reduce electricity consumption," he said. "I'm really excited by the potential it has and the applications for cooling," said Marin Soljai, a physicist at MIT. "You could use this on buildings so you have to spend much less on air conditioning or maybe you wouldn't need it at all. You could put it on top of shopping malls. With a large enough surface you could get substantial cooling."- Guardian Newspapers Limited, 2014

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What Are the Effects on Hearing of in Ear Headphones?
The main effect on hearing is the volume of the sound. Both the intensity and duration matter. However, it seems like hearing loss from personal music players is not as prevalent as from other causes like gunfire or occupational noise exposure (see also here).The specific problem with in-ear headphones is people tend to listen to them louder than other types of headphones, here is an example study that shows this result. So, in summary, there is not anything wrong with in-ear headphones if you listen at a low volume, but be wary that peoples' tendency is to listen louder with in-ear headphones, and you already mentioned liking loud music. The volume is going to be your problem.Be very wary with your hearing though: once you have lost hearing, there is no way to get it back at this time. Hearing aids only temporarily compensate for the loss. You might be okay now but regret a lifetime of noise exposure by the time you are an older adult.References:Clark, W. W. (1991). Noise exposure from leisure activities: a review. The Journal of the Acoustical Society of America, 90(1), 175-181. Hodgetts, W. E. , Rieger, J. M. , & Szarko, R. A. (2007). The effects of listening environment and earphone style on preferred listening levels of normal hearing adults using an MP3 player. Ear and hearing, 28(3), 290-297.Mostafapour, S. P., Lahargoue, K., & Gates, G. A. (1998). Noiseinduced hearing loss in young adults: The role of personal listening devices and other sources of leisure noise. The Laryngoscope, 108(12), 1832-18391. Best Cheap On Ear Headphones?Sorry, but quality DOES have a price and it is NOT that low! If REAL quality is an issue, please go for REPUTABLE brands only such as B&W, Sennheiser (most affordable), Shure, Grado, Denon, AKG, Audio-Technica (NOT to be mixed with Technic which is utter rubbish as well!), Etymotic or Beyerdynamic. Things like V-Moda, Klipsch, Sony, Panasonic, JVC and Philips are ONLY "okay-ish" indeed. Please do NOT fall a victim to FASHION ACCESSORIES by buying Boombox, Ministry of Sound, Sol/Republic/Revolution, Noontec Zoro's, Benetton, a-jays, iFrogz, Marley, Fanny Wang, Razer, Karl Kani, WESC, Turtle, JH, Dr.Dre/Beats/Solo, Ludacris/Soul, Koss, Skullcandy, Lady GaGa, Skullcrushers, Monsters nor Bose, because they are ALL seriously overhyped and overpriced "fashion blingbling gimmicks" with a very poor durability and sound quality, NOTHING else (and those who try to claim they are good do NOT know ANYTHING about QUALITY anyway!), BE THEM FAKE OR NOT! Also, please do NOT go for the overly thumping bass that only distorts everything else, focus on GOOD sound quality and durability IN GENERAL.2. What is the best pair of over-the-ear headphones?Panasonic Retro Headphones - (RP-HTX7-G1) *This model number is for the green ones which I have, There is also Red and White..and if you search online, Pink can be found* I bought these at Target on sale for $39.99 They are by far the best headphones that I've ever had. (And the cutest!) They are also very soft, and cushy so they do not hurt your ears. Regular price (At Target) Is $57.99, but they can be found online cheaper.3. What are the best over the ear headphones for sound quality and noise insulation?Well, according to hi-if afficionado Steve Gutenberg these headphones are THE best in the world:Abyss AB-1266 headphones run $5,495, but they are worth itNow, you can try on your Sony's, Sennheisers, AKG, Beyer etc but if you want some excellent headphones those are for mere paupers. Sell that new car back to the dealership and buy a runaround and make yourself truly happy... life is simple than you think!Qualifier:i do not sell audio equipment for a living, nor work in any aspect of audio. I use audio equipment at home. I do not own a pair of the above headphones because I know I will listen too much and too loud on them and so would finish off my hearing. Steve Guttenberg has been in audio a very long time and has been a professional reviewer for many many years. He has listened to probably many hundreds of headphones over the years (along with much other home audio equipment). I enjoy his YouTube channel as the shorts are just enough to watch each episode. I am not affiliated to Steve Guttenberg in any way.What are the best over the ear headphones for sound quality and noise insulation?
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