Would a newer double pane window save energy vs 20 year old double pane?

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So current condo I have been in for ~3 years now was I guess what I would call a 'long flip' - was never meant to be permanent home but a good starter 5-7 year flip that is in a good and desirable area. Prior owner bought new and didn't do much of anything outside routing cleaning and replacing light bulbs (all mismatched mind you - imagine a 3 light fixture with 3 different temp and wattage bulbs in it), original ceiling fan must have died because he put up a 36" fan in a living room. I stopped asking myself "why?" within a month or two of moving in.

Since I have completed all the reasonable improvement/upgrades I am now staring down the barrel of a kitchen gut and remodel, bathroom facelift and potentially windows. I have watched a number of neighboring condos windows fog up because the dual pane seals failing, it opened my eyes to the fact I am seeing more and more new windows around the community.

I don't currently have a problem with the pane seals failing, I'm certain the original sealing around them is probably failing but probably not a huge hit to my power bill. So my ? is - outside of perimeter seal aging would there really be any improvement in replacing a still sealed 20 year old double pane with a new double pane? Also has anyone tried triple pane for sound attenuation? One of my windows has a row of 3 heat pumps directly outside of it that can be noisy, I have not priced triple pane but if it has better sound attenuation it would be something I would consider if they were not stupid expensive.

Thanks in advance!
 
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I'm a real estate broker. If your seals aren't broken there's no need to replace them. Basically even if the seal is broken and you get condensation in the windows, it's considered a cosmetic defect by home inspectors. It's hard to look through a windows that's all fogged up. Bottom line is that I wouldn't bother. I hardy ever see triple pane windows. No one really puts them in.
 
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In some cases, Low-E glass can help keep heat in and keep solar heat out. I guess the gold standard is triple pane Low-E glass with multiple surfaces coated. An example of a triple pane multi coated window might transmit about 60% of visible light and block significant UV and Infrared.

Whether you'd save money or not is another very real question. A point that's missed by many people is that when we need to create a temperature differential between outside and inside, it takes energy. Insulation can help retain that temperature differential, but it won't reduce the energy required to create it. Furthermore, a perfectly sealed building is very unhealthy. There must be some exchange of air or in the case of spacecraft (ISS) scrubbing of CO2 and other toxins. This air exchange does increase energy use, as it must be heated or cooled.

The natural gas furnace in my PA house consumes a reasonably small quantity of air to support combustion. But it also consumes air and heat to promote flow up the flue. This creates a natural air exchange in the house.

"IF" I remember correctly, the air exchange rate is about 1 house worth every 5 hours when the furnace is running. That ice cold exchange air needs to be heated..... and all the insulation and sealing tricks in the world won't change that fact.
 
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Hmm, I would say if your old windows did NOT have "E glass" then maybeee it might be worth it.

E glass is the silver coating that keeps heat in during winter and heat out during summer.
 
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I replaced our widows last year. They were poor quality uncoated glass, that had lost their seal and we're foggy.

I used windows with cardinal low-e 366 glass. We see a fairly consistent 15% savings in summer elec bills. Winter about 10%.
 
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I live on the highway that goes thur town. When I put in double pane replacement windows the one thing that stood out was how quiet it got in the front room. Amazing!!!! The triple pane might be a good idea for sound deadening by those heat pumps. Oh by the way my heat bill dropped right at 33% also. Single pane loose fitting windows are worthless now-a-days.
 
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I live on the highway that goes thur town. When I put in double pane replacement windows the one thing that stood out was how quiet it got in the front room. Amazing!!!! The triple pane might be a good idea for sound deadening by those heat pumps. Oh by the way my heat bill dropped right at 33% also. Single pane loose fitting windows are worthless now-a-days.

Keep in mind we've been having mild winters. Energy savings would be minimal especially when the seals haven't failed. Usually when you install new windows you also reseal/caulk them in.
 
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Would a newer double pane window save energy vs 20 year old double pane?​



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In some cases, Low-E glass can help keep heat in and keep solar heat out. I guess the gold standard is triple pane Low-E glass with multiple surfaces coated. An example of a triple pane multi coated window might transmit about 60% of visible light and block significant UV and Infrared.

Whether you'd save money or not is another very real question. A point that's missed by many people is that when we need to create a temperature differential between outside and inside, it takes energy. Insulation can help retain that temperature differential, but it won't reduce the energy required to create it. Furthermore, a perfectly sealed building is very unhealthy. There must be some exchange of air or in the case of spacecraft (ISS) scrubbing of CO2 and other toxins. This air exchange does increase energy use, as it must be heated or cooled.

The natural gas furnace in my PA house consumes a reasonably small quantity of air to support combustion. But it also consumes air and heat to promote flow up the flue. This creates a natural air exchange in the house.

"IF" I remember correctly, the air exchange rate is about 1 house worth every 5 hours when the furnace is running. That ice cold exchange air needs to be heated..... and all the insulation and sealing tricks in the world won't change that fact.
I am not following. Seems like you just said insulation retain the temperature delta but it won't reduce the energy required to create it is conflicting each other. The heat transfer is a result of the delta and the insulation on a math equation, changing one will change the other.

Single pipe furnace using indoor air is a separate subject than windows insulation. You will replace the lost combustion air intake with outside air, reducing the inside temperature. It doesn't mean your house should be leaky so you can get enough inside air for your furnace intake, your furnace should have a way to get outside air to combust or you can end up with carbon monoxide poisoning. If the furnace is not in a garage with a open window, it should have some sort of input air from outside (like a slot on the floor to the crawl space), or its own dedicated pipe for outside air.
 

JC1

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You are in Atlanta, so I'm not sure how much you would save short term.

I would want to get one of those infra red cameras and check your walls to see hot and cold spots in the walls and address any of those that may be bad. What type of heating and cooling system does the condo have?
 
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would there really be any improvement in replacing a still sealed 20 year old double pane with a new double pane?
From the thermal imaging standpoint, if there is no heat loss currently then a like for like replacement will be a net zero benefit.

As to any cost benefit, I could not imagine one unless there currently is a draft.

If you have a question, I would recommend a thermal survey
 
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Would a newer double pane window save energy vs 20 year old double pane?​



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I think that depends on how bad the old ones are. Usually contractors put in the cheapest windows they can so in theory some of the newer windows are a little more energy efficient. But even a cheap window for me is at least $200-$250 a window. In a condo where you have to buy a specific window and use a glass company to put them in, could run you $500-$1000 to put each window in. As others said, I'm not sure you make the money back in energy savings. Especially in some condos where the heat is included in the condo fee so it's averaged out among many units. It's like those instant hot water systems, cost a couple grand extra to install but saves you like $10 a month. You might never make it back before it breaks or move as people on average move every 7-10 years for homeowners, about 3 for renters.
 

pezzy84

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Thanks everyone for the great info!

I might forego the windows until the pane seals fail then re-evaluate, I think even without fogged panes they may be red flagged on an inspection because the lift springs are not in the best condition and I have not figured out how to lubricate them. They definitely are builders grade quality, when these were new build they were definitely built to a cost.

My HVAC is strictly electric and expense is solely on my electric bill, I don't have any gas appliances so makeup air is not really too much of a concern. Heat pump was one of the first major upgrades I did ~1.5 years ago as the old unit was original and at 18 years old was starting to break down frequently.

I definitely ended up with a fixer upper, it passed inspection with just some notes on appliance age (HVAC, kitchen package) but learned that inspection seemed mainly focused on function vs good function.
 
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Thanks everyone for the great info!

I might forego the windows until the pane seals fail then re-evaluate, I think even without fogged panes they may be red flagged on an inspection because the lift springs are not in the best condition and I have not figured out how to lubricate them. They definitely are builders grade quality, when these were new build they were definitely built to a cost.

My HVAC is strictly electric and expense is solely on my electric bill, I don't have any gas appliances so makeup air is not really too much of a concern. Heat pump was one of the first major upgrades I did ~1.5 years ago as the old unit was original and at 18 years old was starting to break down frequently.

I definitely ended up with a fixer upper, it passed inspection with just some notes on appliance age (HVAC, kitchen package) but learned that inspection seemed mainly focused on function vs good function.

I've probably been on hundreds of home inspections. When the springs are weak, that never seems to come up as an issue. Basically they're just checking to see that they open and close smoothly. If they're double hung windows, check to make sure that the window is properly in the spring. Sometimes one side is off so you've only got half the spring working. The springs are trickier to replace. If you look at the top of the window, sometimes there's a sticker inside that tells you who made the window and maybe you can contact them to get a new spring. But yeah, you're probably out of luck if the spring is bad, lots of companies don't stick around for 15-20 years to get parts from later.
 
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