Our FIRST residential radiant window project (ME)

[Deleted User]

Yes to the sensor on the pane and the outside sensor. On multiple glazings, we will install more than one sensor, and if need be go series parallel, or have some spares to fall back on just in case.

This IS some really cool technology.

We're working on a set of contacts for operable windows. In this case, they pulled the internal window stops and replaced only the glass. We have 4 more to do on this house. It just depends....

And yes, it is much easier to hide the wires in new construction than it is in retrofit considerations, but with Wire Mold, we can give a pretty decent finished product. The power to the windows is 48 volts DC, hence Class 2.

ME

[Deleted User]

High up on Lookout Mountain...

When I first walked into this guys house, I could feel the "cold 70" pulling on the heat in my body. "Haven't been comfortable in this room since we moved in 6 years ago. We crank the T stat up to 80 degrees to get reasonably comfy, and I can't afford to do that..."

My first thought, RADIANT WINDOWS...

The manufacturer gave the homeowner a GREAT deal, just for the opportunity to classify it as their first residential retrofit. I met with the homeowner and his wife last Friday, and they are THRILLED with the new system. "If I hadn't just spent big bucks replacing all the other windows in this house, I'd seriously consider doing the whole darned house"

Based on what I saw in his yet to be completed basement, I can understand why. His double pane windows had a surface temperature of 55 degrees F. Now THAT will suck the heat right off your skin... As opposed to the newly installed windows, running at 88 degrees F.

By the way, it was around 16 dergees F outside at the time these pictures were taken. What really blows me away is the fact that the outside panes of the heated units are only a couple of degrees F warmer than the UNHEATED glass.

One of them thar things that just defies explanation. Now the INCREASE in overall COMFORT is something that is truly priceless...

From his wife, "I can not believe the difference in comfort. Use to be the kids would fight over who got to sit furthest AWAY from the windows. Now, they fight over who gets to sit NEXT to the windows..."

We're changing the face of comfort and the way we address human comfort needs...

Questions?

ME

Steve Ebels_3

Radiant Windows???

Something new from Bill Gates??

Enlighten me as to what exactly you're referring to oh Guru of all things related to BTU's!

Kevin_in_Denver_2

Let us know how his utility bill changes

If it doesn't go up much, maybe you really have something.

Weezbo

Even window pane had to be improved for this century..

it is the true magic of mr. Sunshine*~/:)

Mike Dunn

radiant windows

IQGlass.com

[Deleted User]

Bill Gates not involved....

YET.

This is an established company who approached IQG and found out that they are VERY proud of their product ($125.00/sq. ft.), and also found that their product has "issues".

This company is RGIglass.com

They are a division of Busick Insulated Glass, a locally owned and operated company.

One of Busick's employees, along with two electricians came up with a better mouse trap, got it UL CSA certified, and applied for a patent (patent pending) on the process.

They approached me because they are not in the "comfort" business, and really have no idea as to the proper application of these devices. We are working together to get some trial installations completed to show increases in comfort (SIGNIFICANT), associated operating costs, and determine best route manner and method of installation and control.

We had our company Christmas party last Friday, and debuted the product to our cadre of architects, engineers, suppliers, contractors and customers, and it was WELL received. People wanting to place orders for units NOW...

As I've explained to the maufacturer, there is STILL a lot of foot work to be done, and you have to crawl before you can walk, and you have to walk before you can run. We're at the crawling stage.

But the preliminary results ae VERY interesting...

Thanks for asking.

ME

[Deleted User]

Kevin...

In your apartment complexes, if we retrofitted the glass to these systems, your RESIDENTS Would be paying for their OWN energy consumption. Then, the natural forces of ($) conservation would kick in :-)

You'd only have to provide DHW at that point...

ME

Unknown

BTU rating?

Mark,

How do these windows regulate ? Room thermostat? Outdoor sensor?

wheels

[Deleted User]

ODR with internal room thermostat...

The unit has a temperature limiting device to limit the surface temperature to 115 degrees F. At that point, and an outdoor temperture of 10 above zero and a room temp of around 68 degrees, KSU calculated a net output of 136 btu/sq ft/hour.

The ODR is a tekmar 256, with a starting temperature of 80 degrees F and an ending temperature of 115 degrees F at design condition. All the above is over ridden by a room sensing thermostat, tekmar 507. So, if there is a lot of solar gain , or internnal gains, the windows are shut down. Response time to sensible emmitance is less than 10 minutes.

THanks for asking!

ME

Dave Yates (GrandPAH)_8

C'mon Wheels!

It's a double-hung zone valve(G). Chust needs a man-well achustment.

Mark - way too cool, er I mean hot, stuff! Nice catch.

Humnnnn, so now who installs windows and who installs heat?!? The lines are blurring.

Bob Gagnon plumbing and heating

Will it cut down

On the passive solar gain through the window? A buddy of mine works for a company that makes a plastic film that is supposed to allow passive gain through the window, but insulate against heat loss, from the house to the outside. He's trying to get me a piece. It is good to see so many companies working on this from so many different angles. Good job Mark, you are on the cutting edge. Bob Gagnon

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Unknown

sooooo

on the 256 you use just one sensor on one window and assume all the others are the same???

this is really cool technology.

do you replace the sash, just the glass or the entire window?

Better suited for new construction?

[Deleted User]

Minimal reduction in solar gains...

Bob, this is the same low E glazing that is typically used on residential construction. It doesn't reduce the amount of solar gain by anymore than conventional low e windows.

There is a local company called Ravenbrick that has a material similar to what you describe. We've been trying to contact them to no avail...

Sounds like there may be some compatability of our products.

ME

scott w.

windows that blow cold air

Really cool, I can now replace the windows and throw away the boiler?

If you can just get those windows to blow cold air in the summer, can do away with the unico also!

ALH_4

Very Interesting

I think it's a very intriguing idea to heat using what would normally be heat loss portals. I dont understand how they get the heat to all go inward and so little outward, but there are a lot of things I dont understand. I cannot imagine these windows do not increase the heat loss. I'm not sure a low temperature on the outside of the glass necessarily means low heat transfer to the outdoors. How do you accurately measure the temperature of the glass panes?

I guess typically the window guy would install the windows and the electrician would install the wiring. Where does this leave the heating guy? ;-)

I'm not sure what to think of these windows.

Dave Yates (GrandPAH)_8

same thoughts here

ME,

Thinking along the same lines here. If we put a warm layer up against one of the greatest heat loss areas, won't that increase the heat loss by a fairly wide margin? What prevents the direct transfer of BTUs through the glazing? What diff will there be in heat loss from an untreated room vs. one that is treated? I can see the comfort issues are going to improve & maybe that's more than enough to justify a greater heat loss.

Unknown

I'm here too. I could see maintaining a surface temp of something like 70-80 degrees to match the MRT you want and "negate" the window load, which would be TOTALLY FANTASTIC as supplemental heat or comfort improvement as a retrofit..... but cranking up any further than that (to meet the rest of the room load) would seem to be the absolutely least efficient possible way to heat the room.

I wouldn't put a pane of glass under my joist radiant system over a cold basement and consider that "efficient". Nor an R-whatever you could get out of a glass assembly.

Maybe I'm missing something?

Gordy

Heatloss

I have the same thoughts on the heatloss too. But I guess there is a heatloss there anyway, may as well heat the cold spot for comfort sake.

I would think keeping the glass close to the room temp. to keep the losses low, and keeping the cold glass surface from sucking the heat off of you would be best, if you already have a heating system.

If the glass is going to be the heat source for the building, then that is a different animal you need that output. I believe Mark has talked before this is an ideal solution for foam domes (SIP) construction!

I'm interested in the retro fit end of this whole deal. How many new houses in your areas with el cheapo windows.

The window treatments concern me, kinda the bear rug on the radiant floor scenerio. Not all women like the pella blinds between the panes which is the best remedy for the windows function.

One other concern is KILOWATTS to run these babies gotta share some usage info. Mark, this is key when your payin 11 cents a kilo in my area.

Gordy

jp_2

approx 10 watt/per sq ft

thats a rough est from marks upper post. 136 btu/sqft max.

a 10 x 10 window then use 1 Kwh, that adds up quick.

quick fix for improper designs

Plumdog_2

wattage

I looked back at the site and read more about this stuff. Sounds like they get the glass, install the e-magic layer, then have the glass framed with whatever material is going to match (could be vinyl, wood, or whatever). I would like to know the wattage used for say 21 sq. ft. at design temp (10 deg). They are working on movable contacts for operators and sliders. I want it.

[Deleted User]

Andrew, Dave Rob and Gordy...

I will attempt to answer all of your questions the best I can.

The glass was recently tested at the National Gas Machineary Lab's at Kansas State University by none other than Dr. Kirby Chapman.

His test rig consisted of a box, 4' cube, built out of 1/2" OSB plywood. This box had a heated window inside one wall of the box. There was also a small electric heater inside of the box. This whole assembly was placed inside of a large cooler that was maintained at 10 degrees above zero fahrenheit. There were sensors on all four surfaces of the glass at numerous cross sectional areas, and numerous sensors within the "conditioned" space. These sensors included radiometers that can measure the amount of radiant energy striking a given surface, as well as conventional thermistors, and electric meters connected to the glass as well as the back up electrical heater..

The glass was operated at its maximum allowable surface temperature until a point of thermal stability was acheived. At that point, it was determined that 85% of the energy being put into the glass was making it into the box. All in the form of radiant energy. It was also determined that the energy loss from the inside of the box to the outside through the glass was completely negated.

It was also determined that the net contribution of energy to the glass (excluding window increased R value, and a higher human comfort factor at a lower ambient temperature) was 136 btu/sq foot per hour.

Dr. Chapman could not explain why surface number 1 and 2 (counted from the outside headed in) were staying as cool as they were, and said he thought possibly there were micro counter currents of convection occuring within the space (5/8") between the windows that enhanced its resistance to outward heat flow.

I do not know the answer. And at this point, I don't worry about it. The overall assesment was this. Due to a combination of the increased glass R value (infinite)increased human comfort at a lower air temperature, and increase MRT within the dwelling, real time energy savings over a conventional electric base board or fan powered unit would be on the scale of approximatley 30 %.

The fact of the matter is this. At an 80 degree delta T, the R2 glass would lose 40 btu's per hour per square foot. In real time, with the glass heated to 115 degrees F, it only lost 24 btu's per square foot per hour.

The facts in and of themselves are real hard to ignore.

Think about all of the glass walls that we deal with that can't be satisfied with a radiant floor, and in some cases, radiant floors AND baseboard installed in the Long Island fashion. Why? Because of all the cold glass....

What if the glass loss weren't there? Think people would be more comfortable?

Think two stage control here. First stage maintains glass at zero energy loss (70 to 80 deg.F surface temp) for the room (relatively low back loss from the glass too because it is no where near it's maximum allowable surface temperature). The room continues to drop in temperature, and stage 2 kicks in and takes the glass from idle (70 to 80) to a positive heat production mode (115 degrees F max).

What does this do for the heating contractor? It SUBSTANTIALLY reduces the required physical plant required to maintain good comfort conditions within the conditioned space, first by negating the window loss, secondly by increasing the MRT within the conditioned space. This reduction in required plant equates to a lower installed cost for the "comfort system" as a whole, and reduces the amount of energy the home would use over all.

More importantly, I have MANY "orphan" jobs, where we have the typical glass wall, and cold internal occupants that short of cranking the thermostat to a rediculously high setting (75, 80?) there is NO WAY that comfort will be found. Until the introduction of this glass.

The glass has been installed in a larger restaurant here in Denver that was suffering from cold window syndrome. Since installation, no more complaints.

I have worked on NUMEROUS commercial buildings, where the outside skin of the building is a glass wall. It wasn't designed to have people line their desks up right at the outside window line, but given an opportunity, they WILL move thier desks right against the cold window wall.

Directly overhead is a commercial high temperature perimeter radiant panel (hydronic) system operating at 180 degrees F. The desk occupants are STILL complaining about a cold draft that comes down the window, across their desk top, dropping cold air right in their lap.

Not with the windows heated. In fact, the perimter hydronic radiant heating system can be completely turned off...

Not trying to put the hydronic heating contractor out of business. Trying to bring his installed costs down, and increase human comfort, all while providing the ultimate in energy efficiency.

Hopefully this answered everyones questions. If I missed any one, tag on.

Thanks for listening, and asking questions.

ME

Gordy

Glass Coating??

Mark, does the glass coating have anything to do with the lack of transfer outward? Look at the delta t of an oven window. When its 400* in the oven you can still touch the glass, its hot but not untouchable.

I have to say what I do like is the simplicity, and a product (the window) becoming duel purpose. You will certainly not talk anyone out of windows in a building may as well use them to heat it if you can.

When you look at some of the mechanical rooms on this site, while quite beautiful to the pros. They are almost if not intimidating to someone who is not familiar with the logistics of radiant heat mechanicals.
I tend to wonder how many people who look to buy a home that has radiant heat take a look at the mechanical room, and it looks so complex that they are afraid to buy into it. Asspecially when all they have ever had to do before is replace a F/A furnace filter.

I'm not knocking the installs I find them quite beautiful...but the average person. Thats where simplicity comes in.



Gordy

[Deleted User]

No special glass coatings on this one...

The IQ glass people make a claim to a reflective material on their glass, but this one has no special reflective coatings, YET...

The only thing really special about this glass is the method of bus bar connection (proprietary) to the glass, and the metal oxides applied to the surface of the glass, which is the same oxides used for creating a low e glass.

In fact, the low e safety glass is purchased from a major manufacturer of tempered safety glass, that being Pilkington Glass, a company that has been around since 1852.

The IQ folks also use (primarily) 120 to 240 volts (DC optional).

The RGI unit uses 48 volts DC. Directly compatible with Solar PV and Hydrogen Fuel Cell technologies

We are working on electrifying a mirror for use as augmentation when there is not enough window surface available, or for internal core situations, where no window exists.

Fogless mirrors anyone?

ME

[Deleted User]

Wattage of consumption...

In talking to one of the co inventors (master electrician) he said that the amount of watts used per square foot depends upon a number of variables. Those variables being, the A.U.S.T. (Average Unheated Surface Temperature), surrounding air temperatures, and reflective MRT that the glass is actually seeing.

He said that in their lab, where they took the door off of a freezer and replaced it with the RGI Glass, even at design condition (0 degrees OSA temp, 70 degrees ISA temp, maintaining a surface temp of 115 degrees F) the unit pulses at about a 50% duty cycle. The conductivty of the glass, combined with the flywheel mass effect combine to give the duty cycle. He said he was seeing a peak of around 20 watts per sq. ft. per hour at design conditions, but couldn't tell me what the AUST and MRT for his facilites were at that point.

Last Friday, at our company party, we unplugged the unit at 9:00 PM, and at 10:30, it was STILL radiating warmth. Un controlled, that could pose some minor overshoot problems...

Least of my concerns :-)

ME

Constantin

TCO has been around for a while...

... this kind of glass has been used for years in the appliance industry. How else do the doors to the deep freeze stay frost-free when you open a door in a super market freezer in Houston? Even the construction details shown on the website show the same assembly sequence as what you would find in commercial refrigerators.

Solar PV systems also frequently make use of Tin Oxide layers for conductors (top layer). So, these folk have adopted a pre-existing technology for the residential fenestration market. The PWM controller is a neat idea though.

I see this technology as a useful crutch to overcome bad design practices, i.e. the overuse of glass and the subsequent discomfort of building occupants in cold climates. It's not inexpensive on account of all the electrical connections to install, and it probably will be expensive to run if the idea is 24/7 comfort.

But in conjunction with a PWM controller and time of use control, it's a bit like a electric towel warmer...

Gordy

A lot of old news

Out there....Sometimes technology is used to fix a certain problem, with out realizing potentials in other areas. Shame on them for not following through, hurray for the one who can see the market potential, and make it better.

Its all in finding the right application, and the marketing. I think this could be huge given time.

Gordy

singh

Cool

How does this heated glass compare to triple pane?
Both in price and performance.


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Constantin

TCO is not cheap...

... costs multiples of regular float glass. The low-e coatings are comparatively cheap because there is more competition. One benefit these guys have is that they're not trying to connect solar cells where the waviness induced by tempered glass will have an performance impact.

Whether the TCO in their area is plentiful or not depends on a lot of factors - glass is usually not shipped far on account of its weight and low cost. TCO changes that equation a bit. I can't get into pricing (NDA) but I doubt that this glass will perform any better than a standard triple-pane window (R5) that also has low-e coated glass in it.

Dave Yates (GrandPAH)_8

Danged Interesting!

It'd be interesting & (I think) more accurate to perform that experiment on something bigger than a 4' square cube. Something built to mimic an actual living space.

I'm not attacking the product or the fine job you're doing by bringing this to our attention. It's just that I'm having a real hard time swallowing the notion that direct conduction heat losses are less than convective heat losses. Mono-directional radiant waves of energy? What side of the glass does this product get installed on and to what extent can a lay person interact with the 48-V DC at the window area.

Unknown

so 85% heat utilization is consistent with about an R7 to R8, if I interpret you correctly. I would expect no better than 75% here (R4) unless the window assembly itself is triple pane, low-e, all that good stuff... thoughts?

Just talking this through.... I'm not making any claims on understanding the tech and this is just how I learn.

I am absolutely seeing value in "negating" window load and its effect on comfort, etc. Maintaining the window at 70 to 80 shouldn't be that much worse than the load through the window given that room temp anyway (a bit, perhaps, but not maybe not too much..)? There are tons of applications where that could be useful, no doubt! but that's not primary heat, that's more "spot load negation" and "comfort maintenance".

To actually provide the rest of the space's heating needs, though, you elevate the window temperature. and I just don't see how that could possibly be efficient at all. If efficiency is a concern, my initial reaction would be that this is a supplement to another heating system... perhaps allowing for cheaper heating methods to achieve better comfort, and to operate more efficiently given lower load conditions... but primary heat from the window alone? No way.

Let's put this another way. If you can utilize 85% of the energy going into the window, in the field, then all windows should be replaced with these and the elements turned off if they are not needed, because you've got an R7-8 window which would cut your window loads in half compared to most windows out there today. That alone would have a dramatic increase on comfort with no further energy input. I believe Thermotech windows do this, for example. Of course, maybe they are cost prohibitive.. but I'm just talking about the thermal characteristics here. Agreed with this previous statement?

If that is not the case (the window is not an R6), then I don't see any possible way that the 85% number can be true. R2 is a 50% heat loss reduction.. R4 is 75%... R8 is 87.5%... right?

Kevin_in_Denver_2

I like that

I've been considering mini-split heat pumps to accomplish that task...they would be cheaper to run than resistance heat in the shoulder seasons .

Lurker_2

re

Thinking well above my pay grade here, but what if the effect that is seen here is because the warmer interior temp is effectively stalling the convection. IOW, the river of cold air rolling down the window isn't happening, making net transmission into the room inefficient. Convection between the panes is still happening..........

Also did I understand that the tests were done with a plywood box? wouldn't a ~R20 box be a better simulation, and wouldn't one want to do a loss test on the box without the window as a reference?

jp_2

Mark, pls return to earth....

at 136 btu/sq ft or approx 40watts/sq ft, you'd be spending about $200/sq ft for PV's?

can't see that as practical? a 10x10 window would cost $20,000 in PV panels yet would only work 6-8 hrs per winter day?

jp_2

oops

that should be approx 40watts/sq ft not 10watts

gerry gill

this could be

the greatest thing since sliced bread.

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[Deleted User]

History of electrically heated glass...

Dates back to WW2. As our bombers acheived higher altitudes, the glass frosted over from condensing the breath and perspiration ofthe pilots in the cock pits of these high altitude bombers. Hence, the introduction of electrically heated glass.

Neccessity, the mother of invention.

ME

[Deleted User]

How often are we at design condition....

and how long do we stay there. Obviously, the glass will only be at its maximum consumption for less time than you can imagine. And, then theres this time of delivery versus time of need scenario...I understand.

But it IS doable.

I'm firmly planted on the face of the earth jP...

ME

[Deleted User]

I hear ya Dave...

And I can understand your reluctance. I was too until I saw the ice forming on the outside pane of thier test rig. I kept saying, "It can't be, it can't be. It goes against everything I've been taught and am teaching..."

But, after extensive lab testing, it IS. It's kinda like the voodoo magic of the 10 MM passage ways in the Vitodens heat exchanger. It defies explanation, but it works...

THey did test a larger window with a larger gap, and they did see higher outer pane temperatures. In other words, thinner air gap is better.

We want to get a large insulated shed, and set it up outside, and put a window in there and see how it does. These guys have these things ALL over the glass plant where they are made, and they work GREAT.

ME

[Deleted User]

Not sure of your math Rob...

I looked at it like this. 136 divided by .85 = 160 btuh/sq ft per hour input.

160-136 = 24 btu/sq foot per hour back loss. (from actual tests with a 60 degree delta across the glass)

R-2 glass, exposed to a 60 degree differential uses 30 btu's per square foot per hour (A/R*delta T)

Hence, the glass loses less energy to the outside when it is powered then it would if it were NOT powered.

ME

[Deleted User]

Kevin,

The glass and the box were initially tested without the benefit of the radiant glass being on. They used 1/2" plywood to avoid any issues of inconsistent R value associated with an insualted, framed wall. The R value of solid wood is a fair constant to work with. Once they established teh energy equalibrium under those conditons. as confirmed byu the electric forced air heater in the box, they then powered the window up and watched the change in energy consumption until they again reached energy equalibrium, and the increase in MRT within the test box.

Dr Chapman stated that there would be SIGNIFICANT increase in human comfort utilizing the windows.

And boy, was he ever right :-)

ME