Is the VT for my bow window too low?

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kmp
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Joined: Mon Sep 10, 2012 4:24 pm

Is the VT for my bow window too low?

#1 Post by kmp »

Hello,

I signed a contract with a window sales and manufacturing company in northern New Jersey to replace an old, single pane picture window in our living room with a 5 lite bow. I just got the full NFRC info from the sales agent, and am concerned that the Visible Transmittance (VT) is too low.

U-Factor: 0.24
SHGC (Solar Heat Gain Coefficient): 0.23
VT (Visible Transmittance): 0.39
Air Leakage: 0.1

The bow consists of 5 lites, each of which are dual-pane glass with low-E (magnesium and tin?) and 98% argon fill. I think each pane is double-strength glass.

From my research, it seems a large share of windows fall in the VT range of 0.4 to 0.7. I know that the VT number is for both the glass and the frame. From photos he showed us of their work, the frame size seems reasonable, which leads me to think this is very dark glass, and may be considered "tinted".

I'm worried our bay view will be too dark. I know VT is subjective, but can anybody offer thoughts?

[Start edit] The bow window is in the northern hemisphere (NJ), and faces North West. [End edit]

PS, I read through a similar post (viewtopic.php?f=1&t=5130), but didn't come to a conclusion.

Thanks.

masterext
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Joined: Mon Oct 11, 2010 11:14 am
Location: Window Pro-Serves All of Northern New Jersey. Bergen, Morris, Union, Essex, Passaic, Sussex Counties

Re: Is the VT for my bow window too low?

#2 Post by masterext »

sounds like its double pane with a hard coat lowE on the inner surface.

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HomeSealed
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Location: Milwaukee, Madison, SE Wisconsin

Re: Is the VT for my bow window too low?

#3 Post by HomeSealed »

+1. Not the ideal choice for your climate IMO, as it will be quite dark and the shgc is a little lower than what would be ideal as well. Often times, window products that are "lower end" will offer very aggressive packages like that in order to make the u-factor look impressive, while ultimately not providing ideal performance when all areas are considered. That may or may not be the case here.

kmp
Posts: 5
Joined: Mon Sep 10, 2012 4:24 pm

Re: Is the VT for my bow window too low?

#4 Post by kmp »

masterext, you are correct. This is a double pane window with a hard coat lowE on the inner surface.

HomeSealed, from my research, it does seem, as you said, that the SHGC is too low for my climate. But I believe that would make a bigger impact if this was a South-facing window.

We talked with the sales person. We will be meeting some time next week so we can see what his 0.24 and 0.30 U-Factor windows look like on a double-hung window. This will hopefully give us a better idea of the VT difference. If the 0.24 U-Factor window looks too dark, we'll hopefully switch to their 0.30 window.

Thanks for your helps.

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HomeSealed
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Location: Milwaukee, Madison, SE Wisconsin

Re: Is the VT for my bow window too low?

#5 Post by HomeSealed »

kmp,
I'm not going to ask what brand you are considering because I do not want to appear biased, but based on the choices of the .24 hardcoat offering vs a .30, it is indeed sounding more like this is not a higher-end choice that you are considering. The .1 AI is not on the higher end either... Most of the quality offerings will offer a u value between .25-.29 on a double pane with a more appropriate SHGC around .25+ , and an AI significantly lower than .1.
I know that masterext services NJ and offers more than one product that would fit that bill. I'd definitely recommend reaching out to him if you are open to more quotes.

Window4U (IL)
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Location: Sales and Installation in Chicagoland and Central Illinois

Re: Is the VT for my bow window too low?

#6 Post by Window4U (IL) »

If you have signed a contract you had better put the window on hold asap with the dealer if you are considering a change. Some factories don't allow changes at all once the order is faxed to them by the dealer.(Softlite for one)

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HomeSealed
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Location: Milwaukee, Madison, SE Wisconsin

Re: Is the VT for my bow window too low?

#7 Post by HomeSealed »

Window4U (IL) wrote:If you have signed a contract you had better put the window on hold asap with the dealer if you are considering a change. Some factories don't allow changes at all once the order is faxed to them by the dealer.(Softlite for one)
+1. Most states have a 3 day recision clause. Even if you end up staying with them, it would probably be a good idea to get your remaining questions answered first before being locked in.

kmp
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Joined: Mon Sep 10, 2012 4:24 pm

Re: Is the VT for my bow window too low?

#8 Post by kmp »

Thank you all for your comments.

The sales rep brought by his 0.24 U-Factor Double-Hung and his 0.30 U-Factor Double Hung for comparison. He said the difference is largely that the 0.24 has 2 coats of Low-E, while the 0.30 has 1 coat, resulting in the difference in VT.

Side by side, we could tell the 0.24 was a bit darker/grayer. From a logical standpoint, we thought we'd likely be happy with the 0.24 and wouldn't notice the darkness once we didn't have a lighter window sitting right next to it for reference. But to be on the safe side, we switched to the 0.30 U-Factor casement windows for our bow, with SHGC 0.25, and VT 0.45. It seems like a VT of 0.45 still isn't that great, compared to numbers I've seen thrown around online. But we think we'll be satisfied, and feel like we're not overpaying for what we're getting.

Thanks again.

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Windows on Washington
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Re: Is the VT for my bow window too low?

#9 Post by Windows on Washington »

Good luck.

Be sure to post up some pictures.

kmp
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Joined: Mon Sep 10, 2012 4:24 pm

Re: Is the VT for my bow window too low?

#10 Post by kmp »

In case anyone is interested, I took some pictures of the two windows. Sorry for the terrible lighting. And I know the pictures of the bow aren't very useful since we haven't yet cleared the shrubs in front of it.

http://imgur.com/a/VyYem

But showing you the results is the least I can offer for your help.

Thanks.

uncle eddie
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Joined: Tue Sep 18, 2012 7:52 pm

Re: Is the VT for my bow window too low?

#11 Post by uncle eddie »

I assume that you are looking for feedback on the install? The double hungs look like they were measured short necessitating use of the head expander. Not terrible, but not desired. It also looks like there is not edge banding on the edge of the bow window jamb. Again, not a necessity, but then the casing should not have left a reveal with that "layered" laminated wood look if that was the case. Exterior trim quality leaves something to be desired as well.
Overall, I guess it is probably passable assuming that you didn't pay a premium and that the unseen details of the install are up to par.

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HomeSealed
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Re: Is the VT for my bow window too low?

#12 Post by HomeSealed »

Nice pics, thanks for posting back the results. :)
Nit-picking aside, are you satisfied with the results? Ultimately, that is the most important thing as long as they are competently installed, not-leaking, etc.

kmp
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Joined: Mon Sep 10, 2012 4:24 pm

Re: Is the VT for my bow window too low?

#13 Post by kmp »

@uncle eddie. I was partially fulfilling a request for pictures, in consideration of the help I already got. And I was partially secretly hoping for more feedback, so you got me. Your comments about the edge banding are dead on. My wife and I will consider whether we feel this is worth contacting the installer, or whether we're happy as is.

Windows are straight and sealed tight from what we can tell. Overall, we're happy, though maybe it's just the bliss of ignorance ;-)

Thanks again.

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TheWindowNerd
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Location: SE PA & NJ; DFW/Metroplex

Re: Is the VT for my bow window too low?

#14 Post by TheWindowNerd »

Not bad, not great.
When there is no edge banding we leave less of a reveal so the layers are not showing, there are factors that affect that too though.
So you have some nice new windows that will do a nice job for you for the next 20 years.
Thx for posting the pics. Enjoy
TheWindowNerd...

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