I'm looking into windows for a customer. The budget is fairly limited, so we are looking for the best windows for the money. We don't want junk, but unfortunately can't get top of the line. One local supplier deals in Atrium windows. Does anyone have anything to say about these? I was leaning toward Andersen 400's or the comparable line from Marvin. Any suggestions?

I looked at Atrium windows several years ago at the local lumber yard. They seemed like standard builder grade vinyl windows. The same lumber yard also carried another brand of vinyl windows which were a step above the Atrium windows, but I don't recall the brand and the lumber yard has since went out of business.

Do you have a WeatherBarr window dealer in your area. They are a quality vinyl window at a low to moderate cost. I was looking at them initially, but they don't offer the high solar heat gain glass I wanted. I also shifted my focus to fiberglass framed windows and have since elected to go with Marvin Integrity All Ultrex windows which are about 50% more cost than comparable vinyl frame windows I have found.

http://www.weatherbarr.com/

If you are getting a vinyl window it MUST have a steel reinforced channel running through the inside frame of the vinyl/pvc. Otherwise you are going to have problems with the vinyl expansion and strength. Quality European pvc windows all have steel reinforcement in them. Another important item is that the windows glazing unit MUST NOT be sealed with silicone or double sided adhesive tape to the pvc frames. The reason is simple; the glazing will thermally expand/contract at a much lower rate then the vinyl will. What happens is that the seals will break and fail, it's inevitable.

To be blunt, if they don't have steel reinforcement and if they don't feature separated window gaskets/seals, they are junk and the window will deform and seals will fail within a few years. Unfortunately US made vinyl windows fall into the poorly engineered category. The pvc frames are thin, they are not steel reinforced, they don't feature floating gaskets between the glazing and vinyl frames and the vinyl is of a cheaper quality.

Posted By Lbear on 21 Mar 2013 05:05 AM
If you are getting a vinyl window it MUST have a steel reinforced channel running through the inside frame of the vinyl/pvc. ...

You don't have to have steel reinforcement.  There are other options that offer advantages over steel in this application.  Take for instance the Weatherbarr Heritage series windows that have the following reinforcement inside the vinyl (this is a cut-and-paste from their website):

1. The Tri-Beam composite, low conductive, structural reinforcement system:
• Insulates 730 times better than aluminum and 191 times better than steel.
• Composite material is recyclable and sustainable.
• Exceptionally strong material without the thermal and deteriorating drawbacks of metals.

Posted By arkie6 on 21 Mar 2013 08:27 AM

Posted By Lbear on 21 Mar 2013 05:05 AM
If you are getting a vinyl window it MUST have a steel reinforced channel running through the inside frame of the vinyl/pvc. ...

You don't have to have steel reinforcement.  There are other options that offer advantages over steel in this application.  Take for instance the Weatherbarr Heritage series windows that have the following reinforcement inside the vinyl (this is a cut-and-paste from their website):

1. The Tri-Beam composite, low conductive, structural reinforcement system:
• Insulates 730 times better than aluminum and 191 times better than steel.
• Composite material is recyclable and sustainable.
• Exceptionally strong material without the thermal and deteriorating drawbacks of metals.

I'm sorry but it's all marketing word games. There are no advantages to eliminating steel reinforcement in pvc windows except it saves them money and they produce and inferior window that is doomed to fail. Can they make a pvc residential window that is 10 x 9 in size (90 sqft) and still get a DP70 rating? Unfortunately they cannot make such a window size because their "tri-beam composite" is not strong enough of a vinyl frame to support such a glazing size. You can't violate the laws of physics here. Vinyl can only carry so much weight on its own and the thermal expansion rates of vinyl are high. With a European steel reinforced pvc window, not only can you make such a large window size but it can be triple pane glazing which adds even more weight.

Again, how do they attach the glazing to the pvc frame? It's not by a floating gasket design so it's inevitable that the seal between the glazing and pvc frame will eventually fail due to differing thermal expansion rates. When the glass and pvc frames are expanding at 2 totally different rates, all throughout the day and night, 365 days a year, that non-floating gasket design is doomed to fail.

You are better off going with fiberglass windows than a non-steel reinforced pvc window. Fiberglass frames are much stronger than any non-steel reinforced pvc frames and fiberglass doesn't have the same thermal expansion rates like pvc does.

If you want quality windows that last a long time, either get American made aluminum clad/wood frame windows or fiberglass windows. If you want a quality vinyl window that will last a long time, get European pvc windows like Intus. All American made vinyl windows are inferior to a European steel reinforced vinyl window. Go on Green Building Advisor and nobody will recommend an American made vinyl window. I'm sorry but American made vinyl windows are a flawed design and doomed to have early failure. The warranties are worthless because 5 years down the road when the glazing seals fail and the vinyl distorts, the fine print will rule where it states that wear & tear is not covered by warranty.

I would bet that these composite reinforcement beams cost far more than stamped/rolled steel. The advantage they offer is much lower thermal conductivity than steel. As far as strength goes, Soft Lite windows claims that their K-Beam composite reinforcement with kevlar is 5 times stronger than steel.

Posted By arkie6 on 21 Mar 2013 03:18 PM
I would bet that these composite reinforcement beams cost far more than stamped/rolled steel. The advantage they offer is much lower thermal conductivity than steel. As far as strength goes, Soft Lite windows claims that their K-Beam composite reinforcement with kevlar is 5 times stronger than steel.

The pvc frames on a steel-reinforced European window like Intus are rated at U-Value of 0.16 and the triple glazing is around U-Value of 0.08. The steel within the PVC framing is thermally broken as it is surrounded by pvc. Intus windows achieve a total U-Value of 0.13 or a R-7.

Are we talking about a different vinyl window? You now mentioned "Soft Lite" windows. Either way, if they claim their "kevlar reinforcement" is 5x stronger than steel, the proof is going to be in their tested strength. If they can produce a pvc 10x9 window in triple pane and achieve DP70 ratings with <0.03cfm of air leakage, they then can compare themselves to a European pvc window.

I've done a lot of research on windows and all the GBA experts agree, if you are looking for a quality high-performing pvc window, you go to Europe or even Canada, not the USA. They make good quality American windows but they are aluminum clad/wood and in double pane. Marvin makes decent fiberglass windows but they are not the highest performing and they cannot make large sizes because of the frame limits. Canadian fiberglass windows perform better.

But again, I keep repeating this but it is a must to have a floating window glazing unit within the pvc frame. The glazing and frame cannot be sealed using silicone or double sided adhesive as the expansion rates of the two materials are so different that the seals will eventually fail. A rubber EPDM gasket that allows movement without compromising the seal is mandatory in a pvc window, as shown below:

"The pvc frames on a steel-reinforced European window like Intus are rated at U-Value of 0.16..."

For the Intus tilt-turn windows certified by the NFRC, the lowest U-values that I see at the NFRC site http://search.nfrc.org/search/cpd/cpd_search_detail.aspx?cpdnum=IWW-M-2 are listed as U=0.17. The solar heat gain coefficient (SHGC) for these windows vary between 0.16 and 0.31. These SHGC are so low that they might be a suitable choice for cooling dominated climates, but definitely not for heating dominated climates unless there is little sunlight to work with at the desired location. The visual transmission (VT) for the windows with the SHGC of 0.16 is about 0.28 or 0.29, so very low.

Posted By Lee Dodge on 21 Mar 2013 09:26 PM
"The pvc frames on a steel-reinforced European window like Intus are rated at U-Value of 0.16..."

For the Intus tilt-turn windows certified by the NFRC, the lowest U-values that I see at the NFRC site http://search.nfrc.org/search/cpd/cpd_search_detail.aspx?cpdnum=IWW-M-2 are listed as U=0.17. The solar heat gain coefficient (SHGC) for these windows vary between 0.16 and 0.31. These SHGC are so low that they might be a suitable choice for cooling dominated climates, but definitely not for heating dominated climates unless there is little sunlight to work with at the desired location. The visual transmission (VT) for the windows with the SHGC of 0.16 is about 0.28 or 0.29, so very low.

Not to hijack this thread since it is supposed to be about vinyl window frame quality but I will address the above:

As you are aware since you read and post comments on the Green Building Advisor webpage, the European manufacturers have different calculation methods but most importantly is that they did not turn in all their window glazing options to the NFRC for testing.

In regards to Intus and their Eforte line (triple pane glazing with steel-reinforced pvc frames), the glazing is tested and complies with European Union; EN410, EN673 and EN12412:2003 calculation standards. As you also know, Intus does not use Cardinal glass like the US manufacturers use. Intus uses Guardian glazing and there are substantial differences in the two, like 44mm glazing thickness, etc. Which is another topic altogether.

Intus makes a glazing unit with a SHGC with a 0.25 rating (cooling dominated climate) but it still has a VT rating of 0.45. In an area like southern AZ, that would be an ideal glazing setup. Some might even prefer a lower VT rating because it's plenty of bright out in AZ and reducing glare and daylight is commonly practiced. Everything is tinted out here to help reduce the amount of light.

Intus also makes glazing units with a SHGC with a 0.494, 0.532, 0.578, and even a 0.62 for those in the frigid heating dominated climates. So your assumption that Intus does not produce a glazing unit for heating dominated climates is far from accurate. Remember, Intus is based in Europe and the frames are produced in Germany and the windows are assembled in Lithuania. They have installed thousands of windows in very cold European and Russian climates and have utilized the higher SHGC for Passive Solar projects. Since you frequent GBA, you are aware that Intus has been used in many Passive Solar homes and they have glazing units with SHGC > 0.494 and they have VT ratings of > 0.709.

Back to the topic at hand, Intus pvc steel-reinforced frames are rated at a U-Value of 0.167 and their triple pane glazing units are rated as low as 0.088 and are in compliance with the European calculation standards that were mentioned above. NFRC doesn't have an exhaustive listing of all of Intus' glazing options, there are many options which are not listed.

Posted By Lbear on 22 Mar 2013 01:15 AM

Not to hijack this thread since it is supposed to be about vinyl window frame quality but I will address the above:

The original poster did not mention anything about window frame quality.

...snip...

Back to the topic at hand, Intus pvc steel-reinforced frames are rated at a U-Value of 0.167 and their triple pane glazing units are rated as low as 0.088 and are in compliance with the European calculation standards that were mentioned above. NFRC doesn't have an exhaustive listing of all of Intus' glazing options, there are many options which are not listed.

I believe the U=0.088 value that you mention follows the European convention of center-of-glass only, and should not be mixed in with NFRC values that include heat losses due to the frame and the spacers.  These center-of-glass values are not very useful in comparing windows, but rather, can be used in comparing glazings only.  Let us stick to whole window test results that include all losses, and since this forum is based in North American, let us focus on windows that can be installed in North America meeting all codes and, therefore, that are NFRC tested. 

Following these conventions, I repeat that the Intus windows with a U-value of 0.17 may be a good choice for cooling-only climates, but due to their low SHGC (0.28 or lower), they would be a poor choice for heating-only climates, and for some mixed climates, unless the house location, design, climate, or owner preference does not allow for any passive solar gain.  A higher SHGC might be available from Intus, but they will necessarily have a higher U-value.  These two performance criteria are coupled, for the obvious reason that a higher solar gain coating will have higher near infrared transmission, lower reflectivity, also therefore, a higher emissivity.  The physics is the same on both sides of the Atlantic.   

You might provide a reference to the NFRC table showing the test results for a high SHGC window available from Intus, and note the U-value.  If the windows are not NRFC tested and labeled, there could be a problem getting the house approved by the county inspector.   

Window choice must include house design and location, and the window function (operable or not), and should never be based solely on U-value.  Otherwise, you might end up with a window that would work fine in southern Arizona, but not so well in Montana.    

Intus, Cascadia and Inline all have tilt and turns with U values of 0.17.  Inline actually has a t/t window with a U value of  0.16. the lowest of them all.  The lowest SHGC at U.017 is Inline .14 Intus .16 and Cascadia is .18 and highest SHGC at 0.17 u value Cascadia is 0.33, Intus at 0.31 and Inline at 0.24

Cascadia and Inline are fiberglass and Intus PVC.  They only difference is price and longevity.

All are very similar when it comes to performance...

Depending where you are located would determine what product I would use....Btw I dislike T/T windows with a passion.

windowrookie,
Why do you dislike T/T windows with a passion?  I thought people liked that type of window.

Posted By Alton on 22 Mar 2013 09:01 PM
windowrookie,
Why do you dislike T/T windows with a passion?  I thought people liked that type of window.

I can't speak for him but I really love T&T windows. I've had casements and the problem with them is that when opened and a wind gust of 20mph+ comes along, it can catch the window like a sail and rip the crank assembly and bust the window. In addition, casement crank assemblies always wear out.

One is then left with poorly designed single or double hung windows (which are basically sliders turned sideways) and those are notorious air leakers plus you only get 1/2 ventilation from them since the assembly never fully opens to the size of the actual window. I've seen how burglars can easily pop open most slider and hung windows with a crow bar. I've had 2 hung windows fail because of the counter balance weights/mechanism. There are always draft leaks between the sashes. For a tight home, sliders and hung windows are not a good choice.

With T&T, one gets full ventilation from the window. So a 3x5 window gets a 3x5 area of ventilation when opened. They are easier to clean and doesn't have to worry about the wind catching them like a sail when opened. In addition they seal like a bank vault when closed and one can use them in the tilt function to vent without worrying about someone breaking in through them. They have nine locking pins which keep the window in place.

A T&T is a better version of a casement. While casements seal well like a T&T window, T&T windows don't have the issues with cranks and levers and one can leave them open without worrying about the wind catching them and damaging them.

Posted By Lee Dodge on 22 Mar 2013 02:11 PM


Following these conventions, I repeat that the Intus windows with a U-value of 0.17 may be a good choice for cooling-only climates, but due to their low SHGC (0.28 or lower), they would be a poor choice for heating-only climates, and for some mixed climates, unless the house location, design, climate, or owner preference does not allow for any passive solar gain.  A higher SHGC might be available from Intus, but they will necessarily have a higher U-value.  These two performance criteria are coupled, for the obvious reason that a higher solar gain coating will have higher near infrared transmission, lower reflectivity, also therefore, a higher emissivity.  The physics is the same on both sides of the Atlantic.   

I invite you to view the Guardian website and the glazing packages they provide, your information is incorrect as one can get a glazing package in triple pane that provides a U-Value in the 0.14 range and still achieves a SHGC of 0.58 for a heating dominated climate.

I believe your argument is with Guardian glass because they clearly make glazing options that fit the bill: Guardian Glass (Click on "performance data" and look under the triple pane option)

Triple Pane:  VT = 73   SHGC = 0.58    U-Value =  0.14

These are Energy Star Qualified window glazing options.


I'm sorry if you believe NFRC is infallible but energy experts believe that the NFRC methods of testing are poorly structured. As per Alex Wilson of BuildingGreen.com states:


American window energy performance testing and modeling assume a delta-T of 70°F (0° outside and 70° inside). In Europe, however, a much lower delta-T is assumed for window energy performance modeling: just 35°F. Even in a reasonably cold Northern European climate, this much more closely reflects the average delta-T during the heating season. American windows are designed to perform well with a 70°F delta-T, and European windows are designed to perform well with a 35°F delta-T. This difference in assumptions affects the thickness of the air space in a window because a thinner window is less prone to the formation of convective loops. One can’t really fault U.S. manufacturers for building thinner windows. If they built thicker windows, they would perform worse using the testing methods that are required by NFRC. But this means that outside of northern Alaska, where you might actually see a 70°F average delta-T during the heating season, our windows don’t perform as well as European counterparts.


This means that the poorly designed NFRC testing methods dictates that American windows are designed to an inferior method. In essence, the testing module become more important then the actual real world performance of the window.

So getting back to the NFRC ratings of Intus windows. Since Intus utilizes the thicker windows as per European methods, it is penalized by NFRC and gets a higher U-Value rating than they would in Europe. Even though the Intus windows PERFORMS BETTER in real life conditions, the NRFC penalizes them with their inferior rating method.

Lbear-

So just like me, you could not find any Intus windows certified by NFRC testing suitable for high solar gain applications. So your response is to criticize the NFRC test protocol!? Unfortunately for you, the NFRC is the recognized testing standard in the U.S., and approval by the county inspector requires the NFRC stickers on the windows. I may or may not be a fan of the NFRC protocol, but that has no bearing on the county inspector approving the house and providing the Certificate of Occupancy. As my builder told me, "I'll put whatever windows you want in your house, but if the county inspector does not approve them, I'll immediately pull them out and put certified windows in to get the Cert. of Occupancy."

The link to the Guardian site shows a comparison of different glazings, not different windows. You do understand that the performance characteristics of the glazings are just one aspect of the performance characteristics of the overall windows? The SHGC for the windows will always be reduced from the SHGC of the glazings alone since the windows frames are opaque to sunlight, and the U-values for windows will be greater than the U-values for the glazings due to the frames and spacers. Since the European window frames tend to be larger than the frames made in the U.S., the SHGC reduction from glazings to overall windows tends to be greater for the European windows compared to U.S. windows. This is less of an issue in cloudy German winters than in sunny parts of the U.S.

In the link to the Guardian site, it is interesting to compare the Guardian ClimaGuard 80/70 glazing package to that for the Cardinal LoE-180 (on the opening page of your link). The specs are almost the same, except that the Cardinal package is much lower in UV transmission, 27% versus 41%, so the fabric fading due to UV radiation would be worse for the Guardian package than for Cardinal.

I'm currently leaning toward using Andersen 400s for this project. The customer really wants wood interiors, which suits me just fine. I looked at the Marvin Integrity as well, but thought the Andersens looked like a better built window for the money. This isn't really based on anything more substantial than the look of the fit and finish on the display models, so I am willing to reconsider if anyone has first hand experience.

I just did this for a passive solar. Pella, Marvin, Andersen....as long as you are looking at the same type of window in each major manufacturer's lineup, I think it is very difficult to say one is built better than another. It comes down to "look", customer service and pricing. FWIW, many architects I worked with considered Pella and Marvin to be on top, and Andersen to occupy a slightly lower rung, but I couldn't tell you exactly why. They are all significantly better than what most people put in.

Posted By Lee Dodge on 22 Mar 2013 02:11 PM

Following these conventions, I repeat that the Intus windows with a U-value of 0.17 may be a good choice for cooling-only climates, but due to their low SHGC (0.28 or lower), they would be a poor choice for heating-only climates, and for some mixed climates, unless the house location, design, climate, or owner preference does not allow for any passive solar gain.  A higher SHGC might be available from Intus, but they will necessarily have a higher U-value.  These two performance criteria are coupled, for the obvious reason that a higher solar gain coating will have higher near infrared transmission, lower reflectivity, also therefore, a higher emissivity.  The physics is the same on both sides of the Atlantic.   

   

Connecticut got its first ever certified PassivHaus and it is also the winner of the 2012 Connecticut Zero Energy Challenge. The home utilized Intus Triple Pane PVC Windows. They received their Certificate of Occupancy without any problems.

GBA Article

Connecticut PH Blog

The Intus windows had a SHGC of 0.494 with a VT of 0.70 and SHGC of 0.37 with a VT of 0.55 with glazing U-values of 0.10 and 0.08

In addition to the great energy numbers from the Intus windows, triple pane windows offer superior sound quality, this was said:

The Honigs were in the house when Hurricane Sandy struck last fall, and lived through a couple of blizzards this past winter. "The interesting thing was the quiet," Diane says. "It was eerily quiet. Where other people told me it sounded like there was a freight train coming through their house during the hurricane, we heard little tippy-tapping of rain on the windows, occasionally. It was weird. We were looking outside watching the trees blow 10 feet in each direction and we didn't hear a thing."

Why did we choose Intus?  There are no American-made windows that meet the performance requirements of our Passive House, so we had to look at European manufacturers.

But this means that outside of northern Alaska, where you might actually see a 70°F average delta-T during the heating season, our windows don’t perform as well as European counterparts.

Makes sense to me. 70F differential is where I get condensation forming on windows, and that's a far more important performance (heat loss, water damage, hvac sizing, ashp efficiency) issue to me than a little more heat loss at lower T differentials. Good job NFRC. Steel - sounds like a possible opportunity for rust.