Does this technology make sense?
reinvent
| Posted in Energy, Heating & Insulation on
It would seem that half the heat it generates would go outside. Your opinion.
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Reinvent
I'm afraid given what I read that I would agree with you Now maybe they have some magic way to radiate all that heat in and maybe superman will fly by my house and give me a free ride..
Well, the greater the "Delta T" (difference in temperature (between the glass and the outside)), the greater the heat loss, so raising the temperature of the glass would increase heat loss, IMO. Seems like the same rationale (which I always questioned) for HVAC guys to design places with hot hair registers under windows to wash them with warm air to prevent drafts. Prevents drafts, but at what cost?
I always thought it would make more sense to put the return registers under windows and at doors to funnel the cold air washing down the windows back to the furnace to be reheated. (If you look in old books, they do show that arrangement, IIRC. Don't know when exactly HVAC guys deternmined it was better to reverse things.)
I thought this was going to be about the old technology of "green glass"--that may make some sense--it was glass that absorbed heat (from the sun, in summer) and gave it back to the room later. Heat absorbing glass was single pane and just stored the heat. That would make sense. Don't know if it would work if the heat absorbing glass were used as the inner layer of a double pane system. Seems like it would help during seasons where sun is hot in daytime, but at night it gets cool. But in summer would only delay the heating. I supose then you could have outside shutters.
It's possible.
Most heat loss through a double-pane IG unit is radiant, which is why lowE (low emissivity) glass units are 10-15° warmer on the inside than conventional IG units and have 50% greater R-value.
The Power*e units are tempered lowE IG. They apparently use the metalic lowE coating (surface #3) as the electrical resistance heater. The lowE coating would transfer little heat outward by radiation, but warm the inner glass pane which would become a radiant heat source for the interior space.
Given that they're tempered IG units and have to be site-framed, they sound pricey (and need to be individually wired as well).
I'm a bit skeptical, but there may be something to this.
Solar & Super-Insulated Healthy Homes
Edited 2/10/2008 11:47 pm ET by Riversong
The window industry has not been able to solve this problem by using double paned and triple paned glass units, sealed insulated units, films and low-e glass. Recognizing this problem, electric baseboard, forced air, and hot water radiant systems are used - but none of these effectively stops the building heat loss, drafts and discomfort caused by this window energy loss. As a result, these systems must be oversized to try to overcome this heat loss through the windows. And this oversizing increases the capital and operating costs of these heating systems.
That paragraph alone make me shake my head. It insinuates that this product will stop heat loss. Marketing hype pure and simple.
I don't like snake oil sales technique, and that is what this is.
It insinuates (sic) that this product will stop heat loss. Marketing hype pure and simple.
It doesn't simply imply that it would stop window heat loss, it states it and it relies on third party testing to prove it.
There are only two modes of heat loss through a tight window (which excludes convection or infiltration): conduction and radiation.
Conductive heat loss can occur only from a warmer material to a colder material. If the inside glass surface is heated above room temperature, then there can be no conductive heat loss - in fact all the conductive transfer would go the other way, into the room.
Radiant heat loss requires a radiant (high E) surface that is warmer than its surroundings. As I indicated in my last post, in a well-insulated window frame with thermal a break between the glass panes, most heat loss is due to radiation from the warmer inside pane to the colder outside pane, which then conducts that heat to the outside air. The space between the panes is either evacuated of air or filled with a low-conductance gas such as argon or krypton to minimize conductivity between the panes.
If there is a low-E coating on the outer surface of the inner pane (surface #3), then there is negligible radiant heat loss to the outer pane. This is why lowE windows perform so much better than clear insulated glass.
Now combine the low emissivity coating with a warm inner pane and the window heat loss will be drastically reduced, though not eliminated. This is the technology behind these powered IG units.
It makes sense.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
according to the text, it seems that the heat loss from OTHER sources inside the house are going to be zero ( well ... a practical zero )
the measurement that is missing is the TOTAL heat loss of the structure
ie: if we have a cube say 12' x 24' x 40' ( a small house )... with conventional LOw-e windows and super insulation
and we have the same cube , with the same size windows, and the same super insulation
which one is using more energy to maintain the internal comfort level ( wait.. we don't want comfort level....wait... maybe we do )
ok 2 things ...
which one is using less energy to maintain a thermometer in the interior of the house at say 70 deg
2d ... since we are radiating bodies.. which one will maintain US at our comfort level ?
if both cubes are experienceing the SAME total heat loss.... then i know that the Power-e window system will keep the occupant at a better comfort level..... because the occupants will not be radiating to the glass.... they may be radiating to 70deg walls & such ... but they will not be radiating to any 40 deg or 50deg glass
( or even 30 deg glass on a cold day )
perhaps this is what makes the power-E glass system work
i sure would like to know what both systems are actually losing to the OUTSIDE thoughMike Smith Rhode Island : Design / Build / Repair / Restore
Good point.Er... Points.Personally, I don't think any "energy" is saved. I would even suspect more energy is being used.But having spent my share of time sitting beside cold windows, I can see the point about comfort level.
Yeah, it may be cold, but at least it's a wet cold !
from dirtyturk:
The six sins of 'greenwashing'
Tuesday, February 12, 2008
Misleading the public about environmental practices or benefits.
Hidden trade-off: A paper product that comes from a well-managed forest but has to be transported a long way.
No proof: A claim that a product was not tested on animals, yet no evidence is provided.
View Image AdvertisementView Image
View Image
View Image
View Image
View Image
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Vagueness: Terms like chemical-free or nontoxic that aren't substantiated.
Irrelevance: A claim that is not important or that all others in the product category can make.
Lesser of two evils: Organic tobacco. Enough said.
Fibbing: Citing bogus certifications.
SOURCE: TerraChoice Environmental Marketing
Mike Smith Rhode Island : Design / Build / Repair / Restore
You apparently didn't read the text:
http://www.rgiglass.com/
Kansas State University Tests
In August 2007, these benefits were confirmed by independent tests conducted by Kansas State University. Among their findings, they concluded that the thermal radiating barrier created by the Power*e™ windows:
is essentially 100% efficient
uses less energy than many other heating systems - and that these savings increase as it becomes colder outside
stops all building heat loss through the heated Power*e™ glass
directs most of the radiant heat from the Power*e™ glass to the interior regardless of outside temperatures
will make building interiors more thermally comfortable than other conventional heating systems.
http://www.rgiglass.com/technology/
(2) It requires about 11% less total energy using the Power*e™ glass to maintain the inside room space at 70ºF when the surrounding outside temperature was 10ºF. These energy savings increase to approximately 15% when the outside temperature is 0ºF.
(3) The insulating and heating effects of the Power*e™ thermal barrier combine to make Power*e™ glass and windows essentially 100% efficient.
(4) The Power*e™ thermal radiating barrier has an infinite R-value that stops 100% of conventional building heat loss through the heated windows
c'mon..... that site is paraphrasing the test results
they don't POST the test results..
i stick with what i wrote.. i want to see the total energy use of the two structures with the only difference being the windowsMike Smith Rhode Island : Design / Build / Repair / Restore
robert...
you're familiar with the google business model...
or Certainteed....
anyways.. if major companies , that are quality oriented , find that theyre are competing technologies that they should be invested in.... they simply buy the company
if Power-E were anything at all near to being what they claimed
then Andersen, Pella or Marvin would be all over them like white on rice...
i take the claims with a large portion of salt
Mike Smith Rhode Island : Design / Build / Repair / Restore
if Power-E were anything at all near to being what they claimed
then Andersen, Pella or Marvin would be all over them like white on rice...
Power-E is an insulated glass manufacturer, not a window manufacturer.
Andersen, Pella and Marvin are window manufacturers, not glass manufacturers, and they haven't bought out AFG or Cardinal.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
And I will repeat what I posted: you apparently didn't read the text because it answered your question and the claims you purport to them were NOT made.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Did you notice it said "stops 100% of CONVENTIONAL building heat loss"All that means is the window is generating more heat than the build and thus the building heat loss will go else where.
But how earth could the window that is generating its own heat source not loose some of that heat to the outside. It dosen't have a Star Trek force field.
Complete the quotation: "stops 100% of conventional building heat loss through the heated windows"
But how earth could the window that is generating its own heat source not loose some of that heat to the outside.
I already explained that. Perhaps you don't understand low emissivity? Some of its heat - yes - but likely a negligible amount.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Edited 2/12/2008 7:19 pm ET by Riversong
I just got this response over at heatinghelp.com"I am skeptical of the claims that these windows are efficient or even an appropriate use of electrical resistance heat. Electrical resistance heating manufacturers love to throw out the fact that their products are 100% efficient, which they are. What they dont tell you is that the energy input can be much more expensive than other fuels, and the overall energy use from coal(etc) to electrical outlet is much less efficient than burning other fuels.Radiant heated windows have to increase the heat loss. You simply cannot stop heat from flowing through a window. The infinite R-value statement is extremely misleading because the windows have become a heat source to the room rather than a heat loss from the room. The issue they skirt is that they also become a heat source to the great outdoors. There is no way to stop the heat from going both ways. If there was, we would just use that glass for the windows and keep the radiant floors. Sure, if I put electric mats under my siding, my walls will have an infinite R-value, but somehow that doesn't sound efficient, even though the electric mats are "100% efficient".As you pointed out, it's all marketing-speak that seeks to obscure the truth in order to sell a product for which I can conceive of no appropriate use."What say you to that?
Your respondent is absolutely right about the misleading "efficiency" of electric heat, but I didn't think that even needed to be explained.
However, s/he fails to comprehend the heat loss mechanics of IG windows and low-E surfaces.
I've been over this already and won't repeat myself.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
ya know.... you're a difficult guy to discuss reality with...
i mean.. yur obviously intelligent.. but u do have a big chip on your shoulder
why don't you get over yourself and understand that there are a lot of people here with a lot of experience
i mean , you ain't the first guy who was ever interested in energy conservation
so, chill....
now... what makes you think that Power -E is not just the latest radiant bubble pack insulation ?
and don't lecture me about my reading comprehension skills
and gimme a break about insults and derogatory comments
yur pretty supercilious and high handed.. in case u haven't looked in the mirror yetMike Smith Rhode Island : Design / Build / Repair / Restore
now... what makes you think that Power -E is not just the latest radiant bubble pack insulation ?
I expressed my skepticism of the product from the start. But I also made a strong case that their claims make sense, and I backed that case with thermal engineering principles.
Radiant bubble-foil is very effective in the proper application (such as to create a lowE air space around radiant tubing or as an attic radiant barrier), and completely ineffective in the improper application (such as for sub-slab insulation). Those conclusions are also based on sound thermal engineering principles.
No one else has attempted to demonstrate that Power-E can't work as claimed, though there's been a lot of opinions and unsubstantiated allegations.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Edited 2/12/2008 9:44 pm ET by Riversong
Edited 2/12/2008 9:45 pm ET by Riversong
bs.... what's the 2d law of thermodynamics ?
edit: or the first, for that matter ?
if there is zero heat loss, then the temperature in the structure will continue to rise
the occupants become roasted turkeys
<<<
No one else has attempted to demonstrate that Power-E can't work as claimed, though there's been a lot of opinions and unsubstantiated allegations.
>>>>...
100 % efficiency
zero heat loss from other sources ( classic straw man )
and
you're still skirting my two structure comparison
where's your basic skepticism ? if it sounds too good to be true .......?
do you really think everyone else here just fell off the turnip truck ?
c'mon bro... me & my partner built the first solar heated home in RI.... that was '75
i've been paying attention for a long time
this power-e sounds a lot like the gud ole double envelope houses...
so pardon my skepticism
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 2/12/2008 10:35 pm ET by MikeSmith
I generally abide by a simple principle when faced with a new technology if I can't noodle it out immediately on my own.1. Are they trying to BS me?If yes, their "real" case must be weak enough that they cannot rely on it to sell their product. Time to start waving the hands and blowing some smoke.. there is a study to pay for!If no, then I will spend the time and maybe even try it out.In this case, the marketing speak is misleading at best. A fellow I know and respect highly is making observations with this stuff that is sounding great, but this marketing stuff is making me a lot more skeptical than I was.Even Low-E glass is not particularly "green", and it's certainly not an "infinite" R-value, which has got to take the cake for the most disgustingly misleading energy claim I've ever read. Coupling low-E glass to an electric element does not magically make it more efficient.Perhaps the company has a marketing arm with a typical sociopath running it. If so, they should can him immediately, and hire someone with some integrity. All that said, it may be more effective than you might think given the very good points riversong mentioned early on and is right not to keep repeating himself about. Ultimately though, any way you slice it, the window would have to be more energy efficient with no heating element than it is with it. You might play some games with emissivity to reduce transfer over a construction without such coatings, but transfer is still driven by delta-T, and turning off the element would minimize any delta-T present....I think ;) It's entirely possible I"m missing something too. But the marketing does make me doubt it.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
I'm glad I posted this on Heatinghelp.com Check out the responses:http://forums.invision.net/Thread.cfm?CFApp=2&Thread_ID=54682&mc=12
reading mark etherington's three posts in you link
it sounds like :
the product will admirably increase the comfort level
it will facilitate lot's of glass and RFH combinations
it will not neccessarily yield a lower heat loss of the system to the exterior
and will not result in less energy use or less cost to run the system
reading the other comments, there seems to be a consensus that the add we read was poorly written and misleading
also it seems that the company mark was associated with is a different company than the one that started this threadMike Smith Rhode Island : Design / Build / Repair / Restore
Mark Eatherton worked with the OP's linked company, but he referenced IQ Glass as another, similar company.If you go to IQ Glass' site, it makes reinvent's glass manufacturers look like Consumer Reports: "Technological Miracle" is how they put it. They claim thermal panes eliminate the "assimilation" of dust on the window. Their claim of 30% increased efficiency is featured in a photo essay on a covered Ukraine swimming pool design that is only shown under construction, leaving one to wonder "30% of what"?Basically, they've figured out how to put a radiator in a window. I don't see how conventional heating could be eliminated as claimed unless occupants were content to remain fairly close to the window and forego privacy. What i'm curious about is that the first site says only the largest square area of a window acts as a radiator; e.g. a 3'x4' window is figured at .75 of effective heating area, the same as a 3'x3'. Any idea why that is?
nope... i rerad the calculations he was discussing... but most of it
........MEGO
i'm still looking for bottom linesMike Smith Rhode Island : Design / Build / Repair / Restore
As far as I can understand it,you will always lose heat through glass your just substituting the heat source. Right?
They haven't stopped the heat loss.They have simply changed where the heat that gets lost... comes from.Instead of some of the heat from your registers getting lost, some of the heat that they generate in the window, gets lost.It's the old green pea and three dixie cups, shuffle.
Yeah, it may be cold, but at least it's a wet cold !
sounds interesting but it seems like the units could only be used in fixed glass situations, not in operating sashes.
this may work well in a commercial glass office building but in a residence, it probably won't be practical.
carpenter in transition
has an infinite R- value
BEEP BEEP BEEP My BS alarm just sounded full bore!!
Yup, same here; BS alarm going off loud! I never heard of infiniute R-value, nor have I heard of 100 % efficiency. If you don't want your window radiating heat to the outside, close the drapes! Sounds real suspicious to me. Like zero point energy--just tap in, ulimited supply--run your foo fighters or what have you. Go back in time. Ron Popeil's window matic. Wait, there's more....
I never heard of infiniute R-value, nor have I heard of 100 % efficiency
All electric resistance heat is 100% efficient at the end-use.
Infinite R-value means zero conductive heat loss.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Do you have stock in this company ?
Yeah, it may be cold, but at least it's a wet cold !
Along with the cited concerns by yourself, Riversong, et. al. I have to throw in mine.
Power: 50w, DC, 4Amps. {for AC circuiting: Watts=Volts x Amperes x power factor}. Inverters are serious power eaters. Circuit to each "window"?
Coefficient of Expansion of glass. The other one is at, say, 10degrees. This little miracle is at, a stated, 115degrees. I await your wise observations. Indeed these units will be fixed and sealed so as to provide an infinite R-value, their statement, but methinks there is some merit in being concerned about the installation.
And the product. There were a number of if, ands and buts in their presentation.
I'm off to find the Kansas State Univ. findings.
edit: I have returned, having toured the University and been found wanting. I want to know (I KNOW, JUST KIDDING!) why I read: "Carcass Disposal: A Comprehensive Review -- Composting / Rendering"; "Cooling Systems for Dairy Cows"; and my favorite, "Swine Day 1999 -- Report of Progress 84".
This is obviously serious business, and no I did not list the Authors to whom I apologize.
There were no reports, testing synopsis, research papers or any similar publications that I could find which validated our miracle window. They could be there...I did not find them and I had 15,595 chances. I took the first 300.
ciao, ted
Edited 2/12/2008 8:49 pm ET by dirtyturk
About yer carcass thingie....the official name of my alma mater is Kansas State Universoty of Agriculture and Science...ask CAG why they call it it Silo Tech.....end thread hijack.
"Infinite R-value means zero conductive heat loss. "Measured HOW?The basic test for R-value use an ASTM standard here a hot plate is placed on one side and a cold one on the othr and the heat flux from hot to cold is meaured.Clearly it is not a meaningfull test where the material under test is heated by external energy source..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Considering his expertise in windows and glass I would be very interested in Oberons opinion on this
Northern Europeans have been using this technology for a number of years - it originated in Sweden if my memory is correct.
The outer lite is tempered for surviveability since non-tempered annealed glass would likely break from the stresses involved with heating the inner lite.
My number one question would be cost - both installation and operating cost. It is an electric resistance space heater...so installing this system in every window in the home would be like having separate electric space heaters in every room in the house. Sounds costly to operate.
It would certainly be comfortable to use. Room discomfort in winter is often in direct proportion to the temperature of the windows. Warmer window surface directly translates to lower thermostat setting and increased comfort.
I would also agree with several respondants that "infinite R value" is a meaningless statement. This is not an insulating system, it is a heating system that happens to double as a window. What's the R value of fire?
Still, it is a really fascinating idea and it would be really interesting to run some performance tests on one of them.....kinda wondering what one costs....
I would also agree with several respondants that "infinite R value" is a meaningless statement. This is not an insulating system, it is a heating system that happens to double as a window.
Not meaningless at all. If you understand R-value as the inverse of conductance or U-value, then any part of the building envelope that experiences no conductive heat loss has - by definition - infinite R-value.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
I'll go with Mike here:
At the end of the day, does the total energy consumption go up, down, or stay the same?
I'm willing to think about the "comfort" level from heated windows allowing the interior average temperature to be reduced but it will take some kind of proof.
I'm willing to think about the "comfort" level from heated windows allowing the interior average temperature to be reduced but it will take some kind of proof.
If you'd read the website, you would have noticed that a third-party test showed:
"It requires about 11% less total energy using the Power*e™ glass to maintain the inside room space at 70ºF when the surrounding outside temperature was 10ºF. These energy savings increase to approximately 15% when the outside temperature is 0ºF."
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Rob,
I read it. I'm having a good deal of trouble believing it.
There is no question in my mind that more than 50% of the heat generated in the window will go to the interior of the house.
There is no question in my mind that less than 100% of the heat generated in the window will go to the interior of the house.
There is also no question in my mind that if the same amount of heat is generated inside the house and has to transition through similar quality double pane low-e construction, that the total heat loss will be less.
Marc
There is also no question in my mind that if the same amount of heat is generated inside the house and has to transition through similar quality double pane low-e construction, that the total heat loss will be less.
The you might need to stretch your mind a bit. Did you read my explanations earlier in this thread? I don't feel like repeating myself.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Guess we're going to disagree then.
Be well
What I wonder (in addition to the other questions already posted) is if replacing what would normally be the coldest surface in the room with a heat source would enable one to lower the thermostat while maintaining a comfortable room.
Late to the discussion and still pondering the issue. Question :
Is there a coating material that has zero emissivity? I follow what has been said so far but would like clarification on that point.
If there is one and it is currently being used would not the windows already being manufactured have infinite r-value?
If so that part of the marketing claim is supercilious. Question :
Is the rate of radiant heat transfer affected by the Delta "T"? Question:
Assuming infinite r-value of the glass area itself would not the conductive heat transfer thought the perimeter of the glass surface where the seals are rise because of a higher Delta "T" across those areas? Comfort levels within the space enclosed by this glass system would undoubtedly be nicer (and therefore potentially allow for an actual reduction in energy use). No "cold" convective currents being set up by air washing the cold glass , no radiant heat loss from "warm body" mass through the glass.
They can't get your Goat if you don't tell them where it is hidden.
" Question :
Is there a coating material that has zero emissivity?I follow what has been said so far but would like clarification on that point.
If there is one and it is currently being used would not the windows already being manufactured have infinite r-value?
If so that part of the marketing claim is supercilious."I doubt that there is any that is absolutely zero, but probably some that are small enough for this discussion.A mirrored coating (as in vacuum bottle) would be close. But don't forget, that in any material selection there are trade off's. In this case we are talking about a window, thus it needs to be somewhat transparent to visable radiation, but not to infra red radiation. So the mirror coating is out.But the basic premise is all wrong. emmisivity has nothing to do with R value.R-value is a measure of resistance to heat transfer by CONDUCTENCE. The test proceedure, per ASTM standards, is a heated plate is put in direct contact with the material under test and on the otherside is a cooler plate. Then the amount of heat transfered between then is meausred.This is purely by conductive transfer. And in general materials that are are good radiant barriers (low emissivity, high reflectivity) are are very good heat conduction. One exampel would be a thin sheet of highly polished silver. The R-value will be almost zero, and the reflectivity almost 1.00.But we are talking about a glass window unit. So the material is under test is a layer of glass, a gas space, a high reflective/low emissive layer, and a glass layer.The test plate transfer heat to the first glass by conduction. (For this I am assuming that the radiant barrier is on the inside fo the first glass. I know that it varies and also sometime is is a separate layer, but a) I really don't remember all of the differences, and b) for this purpose I don't thing that it is signficant.)So the plat heats the outside of the first plate, then via the conduction through the glass the inside of the glass is heated, then conduction through the radiant coating to the gas side of the radiant barrier.Then the hot radiant material transfers heat to the other inside of the other glass via ***. The the heat is transfered via the conduction through the 2nd glass to the receiving test plate.*** Between the glass/radiant material and the glass on the other side of the gas heat is transfered by;a) Conduction - the gas is heated heats the gas next to it, etc and it heats the 2nd glass.b) convection - the gas is heated by the first side and expands and circulate up and heats the glass on the other side where it cools and falls and repeats.The type of gas and the spacing of the glass plates are adjusted for different tradeoffs of the two types of heat transfer, cost, window size (thickness), etc.A vacuum eliminates both of those methods of heat tranfer as in a vacuum bottle.c) radiation - the heated radiant barrier emits radiant energy to the 2nd' test plate. This is small because of the low emisivity of the material. But this is not the type of radiant energy that it is designed to "block"." Question :
Is the rate of radiant heat transfer affected by the Delta "T"?"Sorta. EVERYTHING that is above absolute zero radiates radiant energy proportional to the FOURTH POWER of the absolute tempature and everything RECEIVES radaint energy.It also depends on the emissivity of the material and the shape. http://en.wikipedia.org/wiki/Thermal_radiation" In a practical situation and room-temperature setting, objects lose considerable energy due to thermal radiation. However, the energy lost by emitting infrared heat is regained by absorbing the heat of surrounding objects. For example, a human being, roughly 2 square meter in area, and about 307 kelvins in temperature, continuously radiates about 1000 watts. However, if people are indoors, in a room of 296 K, they receive back about 900 watts from the wall, ceiling, and other surroundings, so the net loss is only about 100 watts. Clothes (having poorer thermal conductivity than human skin, therefore reducing the speed of heat loss from the human body to surrounding environment) reduce this loss still further."And you might want to read the whole article.And http://en.wikipedia.org/wiki/Heat_transferAnd somemore technical resources.http://www.tpub.com/content/doe/h1012v2/css/h1012v2_48.htm
http://www.tpub.com/content/doe/h1012v2/index.htm
http://panda.unm.edu/Courses/Finley/P262/ThermalRad/ThermalRad.html.
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Thanks for your reply Bill. ""But the basic premise is all wrong. emmisivity has nothing to do with R value."" I should have reread my post . I knew and understand the difference. I didn't word my question carefully enough at all.
I was trying to question what would make this Low "E" thermo pane window any higher in R-Value than any other window of the same type. Clearly the addition of an integral heat source will not do that. So as I suggested the claim to have infinite R-value is superfluous.
They can't get your Goat if you don't tell them where it is hidden.
Question :Is there a coating material that has zero emissivity?
No - only the theoretical "black body" allows zero emissivity
The best LowE glass coating currently available on the market has an emissivity of .024.
Question :Is the rate of radiant heat transfer affected by the Delta "T"?
Sure, it has to be, but since the window is warmer than ambient air (inside and outside) heat transfer "thru" the window has become less - intuitive.
Question:Assuming infinite r-value of the glass area itself would not the conductive heat transfer thought the perimeter of the glass surface where the seals are rise because of a higher Delta "T" across those areas?
Good question (all good questions!) - seems like it would be.
Under almost any circumstance, I would think that this system would certainly affect overall room comfort level and it would allow for lower thermostat settings since cold windows are a definite cause of higher thermostat settings.
Edited 2/18/2008 8:06 am ET by Oberon
How is the u value for insulated glass calculated currently?
I seem to remember an "edge of glass" vs. "center of glass" debate many years ago. Is it averaged now or weighted in some way? Also, is the sash material factored into such calculations, or is the u value we see on a window unit just for the glass only?
When a salesperson discusses the R-value of a window unit he or she is often (almost always?) talking about the center-of-glass reading for the window. Center-of-glass is the warmest point on a window system and therefore normally gives the highest R-value for that window. Is it accurate? Sure. Is it misleading? Sure.
U-factor, as posted on the NFRC site or on the window sticker is the performance of the entire window unit - glass, sash, frame. Yet, as been often mentioned, it is possible to covert the U-factor into R-value since they are inverse of one another. In that case the R-value would reflect the performance of the entire unit not just center-of-glass - but how would anyone know whether they had the center-of-glass reading or the entire window reading when presented with an R-value for that window? (There are valid reasons for not using R-value with windows...but that is for a different post)
For that matter, what is there to prevent a window salesperson from converting the center-of-glass R-value into U-value when presenting their window to a potential buyer?
So, a consumer might be presented an actual, full-unit, U-factor of .30 from company A. Now a salesman from company B tells the consumer that their window has a U-factor of .25 versus company A's .30. But what the salesperson doesn't explain (and truthfully may not even realize) that company B's U-value is derived from center-of- glass R-value simply converted to U-value...the consumer thinks that they are getting better performance if they go with company B's product, but in actual fact company B may have a lower energy performing unit.
If the window has an NFRC sticker giving the U-factor, that is the entire window unit. If a salesperson (or website) is bragging up their window's R-value numbers, you might just reach for that grain of salt.
At times people are confused that a website or salesperson has R-value and U-factor numbers (for the same window) that are not inverse of one another. In those cases, it is quite likely that the salesperson does have the whole-unit U-factor, but is using the center-of-glass R-value as a sales tool since that number will be higher and people are intuned to R-value while not many consumers understand U-factor...bigger is occasionally better.
Edited 2/18/2008 8:55 am ET by Oberon
Another question for you if you don't mind. It has been awhile since I looked into Low "E" technology but my memory is that it could either deter heat gain from solar gain or deter heat loss from radiation through the glass. The type of coating, location and application all affected this. This technology is all about controlling heat loss, what are your thoughts about heat gain? Edit: And yet another question. this one is from Heating help. How do window coverings affect this technology? Not may house are going to be situated such that not having drapes, curtains, blinds etc. will be viewed as desirable by the occupants.
Edited 2/18/2008 2:27 pm by dovetail97128
If a double-glazed window has a relatively non-conductive frame and a thermal break in the glass spacer, then most of it heat loss and gain is in the form of radiant energy from one glass pane to the other.
This is why lowE coatings are so effective at reducing the effective U/value of a window assembly.
To prevent heat loss, the best location for the lowE coating is surface #3 (counting from the outside). To prevent heat gain, the best location for the lowE coating is surface #2.
The pyrolitic (hard) coating on surface #3 offers the best Solar Heat Gain Coefficient for passive solar applications. The sputtered (soft) coat on surface #2 offers the lowest SHGC to prevent summer (or winter East & West orientation) overheating.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Edited 2/19/2008 9:05 pm ET by Riversong
Thank you for the info. The heated window does sound as if it has merit. I am just asking and learning.
They can't get your Goat if you don't tell them where it is hidden.
All LowE coatings are designed to stop certain types of infrared radiant energy from penetrating the glass/coating - but not all LowE coatings are designed to stop all forms of infrared energy from doing so.
Direct solar heat gain occurs in the near or shortwave portion of the infrared spectrum; whereas heat from your heating system, oven, light bulbs, even heat radiating from furniture, floors, walls that may have been initially warmed by direct sunlight occurs in the far or longwave portion of the infrared spectrum.
All LowE coatings are designed to stop longwave infrared. The difference occurs in the shortwave portion of the spectrum where some coatings will block direct solar gain and some won't.
If you want direct solar gain thru your glass you want to use a high solar heat gain coating. Most (but not all) pyrolytic or hard coats fall into this category.
If you want to block direct solar heat gain thru the glass then you need to use a low solar heat gain product. Most (but not all) sputter or soft coats fall into this category.
If you want direct solar heat gain thru a window system, high solar gain hard coats will typically allow about 12-14% more solar heat thru the glass than will the high solar gain soft coats. But, the soft coats will have about a 12-14% increase in U-factor over the hard coats...so there is a trade-off depending on which coating is used in the window.
Where there is no trade-off is that a window with any type of LowE coating will always outperform a window made with clear glass.
Thanks , Between all that I have read now I am getting a handle on this.
They can't get your Goat if you don't tell them where it is hidden.
Here is more to get a handle on:http://forums.invision.net/Index.cfm?CFApp=2&Message_ID=384528It would appear the guys at Heating Help are just as curious to get straight info as we are. You will note a guy named Mark Eatherton who is apparently involved with the development of these windows trying to answer some Q.
Thanks , I was there a few days back and will have to return again to catch up on it.
They can't get your Goat if you don't tell them where it is hidden.
and I will note that Mark is a stand up, sharp guy with a very good reputation in our industry. That said, I still don't like the marketing on this product ;)-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Check out the second to last post by 'Joseph E Sullivan'http://forums.invision.net/Index.cfm?CFApp=2&Message_ID=386503
thanks for the update noticeMike Smith Rhode Island : Design / Build / Repair / Restore
Thanks! The results will be darned interesting.
I have bookmarked the page for future reference.
Another use for this technology - the transparent toaster:
View Image
now that's a good oneMike Smith Rhode Island : Design / Build / Repair / Restore
I can see your point, but since R-value is used specifically to represent resistance to heat flow of an insulating material, infinite R-value, used in this context, has no real meaning other than to impress (or to confuse) the consumer.
I can see your point, but since R-value is used specifically to represent resistance to heat flow of an insulating material, infinite R-value, used in this context, has no real meaning...
Apparently you don't see my point.
R-value doesn't "represent" resistance to heat flow - it's a mathematical measurement of resistance to heat conductance (btu/sf-hour). If there is zero but/sf per hour conducting through a material or assembly, then it is mathematically precise say that it has an infinite R-value, which is the same as saying there is zero conductance.
1/K = R
1/0 = infinity
Simple math.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Edited 2/15/2008 9:22 pm ET by Riversong
Did I miss something, but in my school in about 7th grade we learned that you cannot divide by zero. Maybe you can do it using imaginary numbers? But even so, I would think that in real life that would be as useful as finding the square root of a negative number. (I know it is done, but is the answer anything meaningful (to a normal person in their normal world).)
Did I miss something, but in my school in about 7th grade we learned that you cannot divide by zero.
That might be what they taught in 7th grade, but if you stayed with math until high school, you would have learned that 1/0=infinity
Not to beat a horse that is so dead it's mulch, by your simple math, if one works backwards from your equation 1/0 = infinity, then infinity X 0 = 1. Last I knew, I admitedly learned this a long, long time ago (long before high school where I guess all the abstruse keys to the Universe were presented), 0 times anything was 0. Or in more precise mathmatical terms, n X 0 = 0.
Yes, in simple algebra division by zero results in paradoxes.
However, in 1931 Kurt Gödel proved with his incompleteness theorem that any mathematical system at least as complicated as algebra must be internally inconsistent.
So mathematicians simply "solved" this inconsistency by saying that division by zero is "not allowed".
So mathematicians simply "solved" this inconsistency by saying that division by zero is "not allowed".
Not exactly correct.
Division by zero is "undefine."
Division by zero is therefor not infinty, that is a definition
It has been over 35 years since I took my last calc.4 course at U of L and maybe somethings changed.
Can you give me a source for this new math?
Did they still have any mechanical calculators?I can remember which they where.The Monroe rotary similar to the one show here.http://en.wikipedia.org/wiki/Monroe_Calculator_CompanyOr the Friend automatic mechanical caculator.http://www.rdrop.com/~jimw/jcgm-vcfii.shtmlWe never used them, but there was a small room next the computure room with them in it. They would do a number of operation. Multiply, divide, and maybe sq root.But you could put in a zero and try divide and the carriage would just cycle back and forth until you unplugged it..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
this is the handcrank model Monro all the field offices had when i went to work
in '69
View ImageMike Smith Rhode Island : Design / Build / Repair / Restore
Can you guys break this discussion down to a level I can understand? Like, if two guys got on a train in Chicago headed east with "The dreaded new technology windows" and five illegal aliens, real ones from outer space, not just another country intercepted the train with their intergalactic battle cruiser and got on the train in Toledo with regular windows but one of the original guys got off in Pittsburgh what would the r-value of the steel skin of the roof of the train be when the battle cruiser approaches said train in New Jersey with a full scale ion laser assault?
the punchline is:
no..
you identify yourself... i'm a lighthouseMike Smith Rhode Island : Design / Build / Repair / Restore
Is that a trick question? What color is the train and how fast is it going?
You were a few years ahead of me Bill. I didn't get started for real untill after my stint in the Navey. You also went to Speed School,.. out of my league or at least my work ethic back then:)
A&S didn't have any of those old monsters around, but I used one for years in the product development lab at Celanese Coatings.
We weren't allowed to use electronic calculator when I first started back to U of L. I think it was around 72 that they let us retire our slide rules.
0 times anything was 0
You're both right. As you approach 1/0, you approach infinity, and since math geeks don't like infinity, they just say you can't go there.
If you graph 1/10, 1/9, 1/8,...1/1, 1/.5, etc. you'll see what I mean.
As you approach 1/0, you approach infinity
It is all in the approach.
There in lies the crux of the issue. You can get infinity small or infinitly large but division by zeroe is undefine.
Try it 1/ 1x 10 to the minus 1000 power will still get you an answer.
It is like that darn bunny, it just keps going and going, and going,.......
At the risk of sounding like an idiot to the masses, here's my two cents.
If the electric grid keeps the inner pane at 70 degrees and the room is 70 degrees the heat transfer through the window from interior sources would be 0. If heat flows from a warmer substace to a colder one if there is 0 delta T there is 0 transfer
Hence the argument about infinite r-value. I don't know whether or not it's accurate to say 0 heat transfer equals infinite r but after the detailed information and supporting sources River supplied regarding a question I posted I'm not inclined to doubt him. The real question I believe is how much energy it costs to accomplish that and how much of that extra energy is lost through the outer pane.
BTW, the train is mauve and traveling infinitly fast.
Oh, mauve? Then the R-value is the cube root of the speed of the train times the wave length of mauve light divided by Avogadro's number.
I always forget, does mauve propagate more red shift or blue shift?-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
That's the beauty of it--it's neutral!
How fast would the train be going if it was coated in this:http://crave.cnet.com/8301-1_105-9855485-1.html?tag=bl
Pretty cool! That material would be excellent for those portable holes used by cartoon characters!
Train would still go the speed of light, but you wouldn't see it.
A train mauving at the speed of light divided by guacamole cannot stand.
Well said. I couldn't agree more!
I think we've all been hijacked by the conductor of the train though and the OP may not be happy. (Nothing worse than an unhappy opey. Yippee o kai aye!)
Okay, time for more coffeeeeee!
You can argue semantics about the R-value claim. But, ultimately, it's an obviously misleading claim intended to convey a sense of extreme energy efficiency, preying on the uneducated, whether or not you want to argue the physics or math of it is really irrelevant.Anyone who would understand the truth of the matter would not be interested in the claim, so it would be ridiculous to make it for them. That only leaves people who don't understand what it means as the target audience..-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
I did understand your point, and I am very familiar with the formula for R-value: (hr x degrees F x sqft) / Btu and the formula for U-value: Btu / (hr x degrees F x sqft)...but in my earlier comment I was specifically looking at the claim of infinite R-value - as presented in the web site for the average consumer - and not for an engineer.
In that context the consumer understands R-value to "represent" how much insulation they are putting into their walls. In that context to use infinite R-value sounds really cool but it simply means that the window is warmer than ambient room air and therefore there is no heat loss thru the window...again, I think that to use "infinite R-value" is misleading and has no meaning - for the potential consumer.
To restate, what is the R-value of fire?
Can you show me an ASTM standard showing how to test a product for R or U value when that product has an active heat source..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I found this to be a very interesting thread. Listening to the discussion there are valid points to both arguments.
If the goal of a product is to conserve energy, but consumes it in the process the answer to everyones question(engineering debates aside) is will your electric bill go up enough to offset the fuel you would save on your heating system.
In our area electric rates recently just about doubled. So disregarding the initial cost of this technology, if my gas bill for a set amount of degree days was $1000.00 and the electric utility cost was $250.00 for a total of $1250.00 would installing these windows save $250.00 on gas but raise my electric bill to $400.00 for a net annual increase of $150.00? I don't know the answer but it seems this is hard proof of a products value.
When a manufacturer makes claims that involve percentages, validated tests in a lab, etc. it all sounds great but in the real world where utility rates vary widely it would be interesting to see real world data on total consumption.
You may now critique or bash me at will.FIRE!!!!!!!!
How dare you make sense.
Sorry. It's a curse. BTW have I thanked everyone enough for the answer to my post about insulating with XPS? Thank you, and you and you and that guy over there, and you and you and you etc. My wife will appreciate not having to listen to me agonize for 6 months over what I should do only to find out that winter is here again and I can't do anything outs... hey wait a minute. I might be onto something :)
I agree, I also find this thread to be really interesting.
As I mentioned in my initial posting, this technology has been available and has been in use in northern Europe for a number of years.
I have read about it in the past and the folks who use it in Europe swear that it works as well as advertised - there are claims that it does eliminate the need for other heating sources in some cases.
I don't know if it is true or not. I have never worked with it, nor have I ever seen actual numbers crunched. I think the idea is fascinating and I would love to bring one into my lab to play with - but it isn't on the near-term agenda (still...).
Anyway, I might feel that the website (for the company being commented on this thread) could be better - perhaps a little more ordinary consumer-oriented - and less whiz-bang-cool - but I would not bash, nor endorse, the technology or product unless I had a lot more real world performance data.
edit: I take back part of the previous paragraph. That website is no better and certtainly not worse than 99% of the marketing sites on line. Marketing folks build those sites to sell product - there is nothing wrong with whiz-bang-cool. If the folks who built the site want to use statements like "infinite R-value" then it is up to the consumer to find out what it really means (I still see it as misleading, but that is a different argument). The site is what it is and if it works for the folks who put it on line then more power to them. And actually, that site really is better than a lot of other "window" sites on line IMHO.
And I never bash folks on line - although I may disagree with other folks' opinions.
Edited 2/18/2008 8:31 am ET by Oberon
""Not meaningless at all. If you understand R-value as the inverse of conductance or U-value, then any part of the building envelope that experiences no conductive heat loss has - by definition - infinite R-value."" What is different in these windows that makes for the "no conductive heat loss"?
I can buy your statement as a blanket statement , but it seems to also state that windows have no conductive heat loss.
A Low "E" coating doesn't change conductive heat loss in my understanding. EDIT: I just read the whole thread at Heatinghelp and now I understand the answer to this one.
Edited 2/17/2008 11:50 pm by dovetail97128