Storm Window over Thermopane?

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  #1  
Old 12-07-04, 08:47 AM
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Storm Window over Thermopane?

We have a guest bedroom that has a window facing north and a window facing west. Both windows are about 4'x6'.
Both windows are thermopane windows.
We live in the Midwest with cold weather.
Here is the problem....This room is consistently 4 degrees cooler in the winter weather than the rest of our house.
My question is: Can storm windows be installed over these thermopane windows? If yes, can you approximate the cost to install storm windows over these two windows?
I may even try plastic on the interior of these windows first to see if that helps bring the room temperature up.
Any suggestions will be appreciated.
 

Last edited by whynotme; 12-11-04 at 03:42 PM. Reason: delete post
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  #2  
Old 12-07-04, 09:28 PM
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If this room is 4 degrees cooler than the rest of the house, I would go looking for the reasons WHY and address them. (Storm windows are 'old tech', and won't correct the problem.)

Is this room a second story room, over an unheated garage or basement? Is the HVAC duct to this room undersized, broken, or clogged? (Is the register open??) How much attic insulation is above this room, as compared to the rest of the house? Are the walls insulated?

IF everything I mentioned checks out, then I would replace the IG units of these windows with IG units that have low-E or low-E squared glass. That will do a lot more for you than storm windows ever thought of!
 
  #3  
Old 12-08-04, 12:01 PM
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Whynotme

Thanks for your comments. The insulation on walls and above the room check out ok. We just had the ducts in the house sealed by Aeroseal.
I believe the cause of the degree drop in this room are the windows.
Can I ask....what is the meaning of !G and low E ?
 
  #4  
Old 12-08-04, 12:42 PM
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OK, you seem to have eliminated some of the possible cases I mentioned. It's starting to look like it could be the windows.

An "IG unit" is the glass in your windows. You replace both panes as a sealed unit. You can order them from any glass shop, and you would have them in about a week.

Low-E or Low-E squared is a low emissity coating that is sprayed on a pane of glass, then that pane is used to make an IG unit. The Low-E coating simply blocks the transfer of heat. In the winter, it's keeping the heat in the room (not allowing it to pass thru the glass to the outside), and in the summer, it's keeping the outside heat from entering the room thru the glass.

Replacing the IG units in your windows with ones with Low-E glass would certainly help with your heat loss, and may even cure it. Less expensive to replace the IG units than it would be to retrofit the windows, but retrofitting the windows would reduce your heat lose even more. And there may be incentives from your local utility available if you were to retrofit the windows, in the form of a rebate. And, your house would be more comfortable, and you would save 10%, 15% maybe even 20% or more on your utility bill.
 
  #5  
Old 12-08-04, 01:27 PM
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Assuming the windows are fairly new, I don't think changing the glass or installing storm windows is cost effective and I don't think you will raise the room temperature 4 degrees. What type of heat do you have throughout the house? Steam, Hot Water, Forced Air or another type?
 
  #6  
Old 12-08-04, 01:32 PM
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Thanks for your suggestions.
We have forced air heat thoughout the house. It is a Ranch, all on one level.
The room I reference is the furthest room from the Furnace which is in the basement.
 
  #7  
Old 12-08-04, 04:09 PM
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There's your answer.............I also have forced air heat and my bedroom is the furthest from the furnace and the coldest room in the house. You can try a booster fan in the duct or register.
 
  #8  
Old 12-08-04, 04:20 PM
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If you are dealing with vinyl framed windows you will void any warranty they have as too much heat can buiuld up between the window and storm and cause frame to warp and lose seal.

I would venture to say that even with the latest greatest in window pane technology, the simple fact of the matter is you have 2 4'x6' windows. These windows will radiate coolness regardless, how much does depend on quality of panes currently in window. I bought this house of ours last year and installed all new windows/siding/roofing, walls are 2x6 fully insulated and bought the best of the best for windows that I sell. Our bedroom is located on the north side of the house and I ommited the 4'x3' window on the north wall, and shrunk down the window on the east side to 10'x5'-it was 12'x6' LOL.

Our room is still cooler than the rest of the house even with all my tricks of the trade done to ensure house is 110% perfect since it's my own and the neighborhood was watching when I comensed work and stuck my own sign in my yard The size of the window is partly to blame, there is just simply no way around it period, I dont care what anybodies says or tries to say, big windows WILL radiate cool into the room, even the top notch, fully accesorrized ones.

Anyways, I'm also chaulking some of it upto the fact it is a very long run from the furnace and the last branch off the main line for the heat duct in our room, I've already went through the house and adjusted the floor vents to try and force more air to the far end of the house. Next spring when I replace the furnace/air I'm going to have the guys do whatever necessary to alieveate the long run/heat loss problem, which will most likely be just insulating the duct work. This is over a unfinished basement btw that does get heated, just not as much as our main living level.
 
  #9  
Old 12-08-04, 05:25 PM
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Room position in house

Right.

And even a room's location in a house, all other things being equal, can account for a 4degree difference on any day because of ambient heating for rooms on the south and west side of a home and ambient cooling for rooms on the north and east side.

Add differences in heating and cooling because of flora and fauna, openess to wind and you will find it impossible for any room in a single home to be identically controlled unless you have individually operating thermostats and individually operating heaters Ilike electric baseboard) in each room.

This is why BTU losses and energy offsets for heating and cooling are based on the overall home and not by individual room within a home.

4 degree difference is insignificant and any additional expense in trying to equalize the temperature is probably a waste of time and money.
 
  #10  
Old 12-08-04, 08:19 PM
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whynotme,

You've gotten excellent advise right down the line.

There are things that you can do to correct the 4 degree difference, but, like Homebild is saying, they probably won't be cost effective -- the cures are going to cost some money!

IHI is right -- large windows are going to affect the temp. of the room. It's ging to be cooler in the winter and warmer in the summer. Glass, as an insulator, ISN'T!

Adding an in-line blower in the duct (johnam's idea) will work, but you only want it to run when the furnace is on. Otherwise, it'll just be blowing cold air.

Upgrading the windows will run you $400 to $500 each. Downsizing them will be more.

Maybe just add a ceiling fan to the room? Simple, but they DO work!
 
  #11  
Old 12-09-04, 08:59 AM
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I too think that the HVAC is the culprit. Is there a return air duct in the room? If not, that could be the problem, you're trying to force air into a room already full of air with no way to displace the old air. Also if the heat runs are done properly (downsizing the main duct each time an individual run comes out) in theory the last run should have as much force as the first (assuming there is a return air path)

I think Insulated drapes are your simplest answer if the problem really is heat loss through the windows. Something that will block some of the heat loss there. They were common in the 70's with big non-insulated "picture windows" all the rage, less so now with better windows. They are heavy fabric and look like they're coated with latex on the back side. you put them on a corded traverse rod and shut the windows off when you don't need it or when you're trying to keep the room warm.
 
  #12  
Old 12-09-04, 12:14 PM
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Adding an in-line blower in the duct (johnam's idea) will work, but you only want it to run when the furnace is on. Otherwise, it'll just be blowing cold air.
They come with a thermostadt that senses the temperature of the air in the duct which you can set to come on when the air is warm and turn off before the air is cold.
 
  #13  
Old 12-09-04, 05:56 PM
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A bit more on energy efficiency and window performance.

Whynotme,

Glass, by its nature, has virtually no insulating value. A sheet of double strength glass (3.0mm or 1/8"), alone, has an R-value of about .8...of course R-value for a window includes glass plus frame. With a good energy efficient frame you can get an R-value of maybe 1.3, even possible to get about 1.5, but that's it. Doesn't matter what else you do, that is about topped off.

A good dual pane IGU (Insulating Glass Unit) with a softcoat LowE coating and an argon gas infill can get about an R-6. A triple pane IGU with a krypton gas infill can achieve an R-10. These are center of glass and optimum energy measurements. They are real numbers, but like the car that is rated at 35mpg that only gets 30mpg once you buy it, they are subject to variation.

There are significant differences in products. These numbers are readily available if anyone wishes to check them out.

R-value stands for Resistance to heat flow. Heat ALWAYS goes to cold. When you touch that really cold floor with your bare feet and you feel the cold spreading over your feet and up to your ankles and higher, it is not that the cold is penetrating your body, rather what you are feeling is the heat being drawn from your body thru your feet to the cold floor. This is an excellent example of conduction.

Heat travels in three ways: conduction, radiation, and convection. All three of these factors affect your comfort level and all three of them affect the performance of your walls and windows.

Another measure of conduction is to take an aluminum bar and hold one end in your bare hand and one end in an open flame.

Everyone reading this knows how long you have before you will drop the bar because the very sudden rise in temperature will certainly affect your ability to hold on.
Do the same with a long sliver of glass. The end of the glass that you are holding will get very hot and it will become hot very quickly. Not quite like the aluminum, but it won't take long!

That is also conduction.

Radiation or, radiant heat, is what you feel when the sun warms you as you are lying on the beach (except when you gain warmth from the sand around you, that would be conduction, again). Radiant heat is what you feel when you stand close to (but not touching) a steam radiator or a radiant heater. Radiant heaters use infrared radiation (IR) to warm you (or other objects), and IR is also the heat you feel directly from the sun.

Convection heat is warm air movement such as a forced air heating system. A convection current is set up as the warm air moves and is replaced by cooler air that is then warmed and the cycle continues.

A single window with very poor insulating values will affect ALL of those properties. Sealing the window will help against leaks (if needed, this is obviously a good idea), but it has little affect against the more significant part of energy loss which is the glass itself.

Windows are normally measured in U-values and not R-values; U-value is the inverse of R-value.
U-value measures how much heat is passed thru an object, or said another way, how much heat an object will pass; versus R-value which is resistance to heat flow. Although it doesn't sound like much of a difference, it does come into account much more when doing actual energy performance calculations.

A multiple pane IGU is designed to do two things. First, it maintains a sealed dead-air space between two lites of glass. This dead air space helps to moderate the differences between the outside air temperature and the inside air temperature. The outside lite will approach the temperature of the ambient air and the inner lite will attempt to reach the inside ambient temperature. The inner lite will not reach the interior temperature because that heat will be radiated toward the exterior lite. But, while the inner lite will not reach equilibrium with the inside air temperature, it will still be warmer than the outside lite for a net gain in room temperature and especially comfort. Additionally, the air within the IGU space will be warmer than the air outside the house because of the warmer interior lite. Again adding to the net gain of the entire unit.

One might comment that using single glazing with a storm window will accomplish the same. It MAY do so in the best of circumstances, but unfortunately the window MUST be a sealed airspace for optimum performance (otherwise heat will escape thru the leaks) and any airspace wider than about 7/8" begins to lose performance because of convection currents that form between the lites within the airspace.
The outer lite and the inner lite in an IGU have to be close enough to allow the inner lite to radiate heat to the outer lite. If they are far enough apart, not enough heat will transfer and the differences in the air temperature near the two lites will cause a convection current to form. This current will very quickly suck the heat out of the inner lite and negate much of the advantage of the multipane IGU.

You also have convection currents in your house. A single pane window, for example, will be cold...this is why it was so common (and still is common) to put heat sources directly under windows on the exterior walls. The idea was (is) that heat from the heat source will rise and will warm up the glass enough to prevent much cold air from entering the room. What is really happening is that that heat is being sucked from the room through the window itself, but if you can pump enough heat at the heat sink (window), then you can keep the room warm...you are simply overwhelming the amount of heat that nature can take out of the room.

Now, what if you could include something that would reflect the radiant energy (heat) back into the room?
That is the idea of LowE coatings.
LowE coatings reflect IR energy (they also reflect UV energy as well, but that is for another post), or heat.

A LowE coating is normally applied on the interior of the exterior lite in a dual pane IGU. The exterior of the exterior lite is called surface #1 in and IGU, the interior of the exterior lite is called surface #2, the exterior of the interior lite is called surface #3, and finally, the surface you can actually touch inside your house is called surface #4.

The best location for the LowE coating is on surface #2.
The LowE will reflect IR energy. It does not care if it is generated inside or outside. In the summer, the suns IR and UV rays will hit the glass with the LowE coating and will be reflected by the coating, yet will pass visible light. This keeps a significant amount of the heat from the sun from entering your home.

In the winter, the LowE coating will again reflect the IR (or heat) back into the house, where it started.

And the advantage of coating surface #2?

In the winter, the interior heat warms the interior lite. The interior lite then radiates that heat to the exterior lite (a process I mentioned earlier). BUT, there is now a difference...instead of the outer lite absorbing that heat and radiating it into the night, it reflects that heat back into the house. This does two things...first, it warms the interior lite and allows it to come much closer to the inner temperature of the room; second, the warmer interior lite also tends to warm the airspace which in turn helps to keep the interior lite warmer. See the pattern?

In summer, the IR energy is reflected by the exterior lite which allow the interior lite, and subsequently the airspace, to remain cooler and closer to the inside temperature of the house (the ability of a window to reflect the sun's IR energy is known as Solar Heat Gain Coefficient or SHGC...like UV protection, that is a subject for another post; if anyone is interested).

Does all this work? It really does, and it works very well. This is not just theory and conjecture, it has been tested thousands of times in lab environments and in the field. There are some very specific test and evaluation projects that prove without doubt that it works. But, as was mentioned in several other posts, a window, especially a large window simply will not have the same insulating capacity of an insulated wall.

If anyone has actually read this far and is still interested, I can post a couple of links to some very interesting (well, interesting to me), and specific test and evaluation sites.
 

Last edited by Oberon; 12-09-04 at 06:19 PM.
  #14  
Old 12-09-04, 06:19 PM
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Oberon,

I read that far -- EXCELLENT explaination!!

I agree that surface #2 is the best place for a low-E coating, but both of the windows I install (EPI and Amerimax) use low-E squared. They coat surface #2 and surface #3. The additional cost of the windows is minimal. Amerimax doesn't offer an option of NOT having it. Adding low-E squared to an EPI window rasies the cost of the window about 10% over the same window with clear glass, but in the spring and summer, they don't even charge for the upgrade.
 
  #15  
Old 12-09-04, 06:39 PM
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Thanks Lefty.

One quick clarification, LowE squared is Cardinal Glass's designation for their dual silver coated product.
"Regular" LowE has a single layer of silver in the total LowE coating - will be about 6 layers total of various metals and metal oxides, but silver is the part that does the energy work.
LowE squared is a 13 layer coating that has two layers of silver rather than one.
Having coatings on both the #2 and #3 surfaces really isn't all that common, but I agree that there is a bit of confusion when people use the term LowE squared in some cases to describe coatings on two surfaces, and then also use it for dual coating products from PPG and Guardian and other coaters as well (Cardinal was the first to introduce dual silver coatings, but all the softcoat guys have them now).
 
  #16  
Old 12-09-04, 06:47 PM
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So I was one of the many that was confused, and now I stand corrected AND educated. (See what I get for listening to the 'pros' at my favorite glass shop! I'll print your explaination and take it to them tomorrow.

And you're right about Cardinal -- they supply the glass for both Amerimax and EPI.

WEST of the Mississippi (and the Rockies, and just about everything else!!),

Lefty
 
  #17  
Old 12-09-04, 06:50 PM
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Hey guy's, this is getting very technical. "whynotme" wants to raise the temperature by 4 degrees.....it's a guest bedroom....two people in bed will easily raise the temperature 4 degrees. CASE CLOSED......and to all a good night!!!
 
  #18  
Old 12-09-04, 06:58 PM
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johnam,

I know, and I agree.
 
  #19  
Old 12-09-04, 06:58 PM
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LAUGHING!

Great reply! And actually, I like my bedroom cooler, so I was figuring that 4 degree difference sounded okay to me!

And you are welcome Lefty. And you are also correct about Cardinal. They are the 800lb gorilla of the residential glass industry, yet I imagine not 10% of people reading posts or asking questions about windows has even heard of them.
 
  #20  
Old 12-10-04, 06:31 AM
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Thank you all for your advice. It was a real education!
Here is what I am going to do for the winter months: I'm getting some 3M paper which I will put over the windows, use my handy little hair dryer to stretch it so you will never know it is on there, and I think the problem is solved.
This board is fantastic for gaining information. Thanks again
Whynotme.
 
  #21  
Old 01-29-07, 07:34 PM
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WhyNotMe - I read that you did Aeroseal in your house. How much was it and was it worth the investment? Did it improve anything?
 
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