Blinds between glass = less efficient?

11 years ago

I can't find the straight answer--if a patio door has blinds between the glass, does this mean it will be less efficient? Our contractor is talking about a jeld-wen door. Jeld-wen's website says that the normal patio doors are low-e standard, but with blinds inside low-e is optional. I also can't tell if they can fill it with argon if there are blinds. Anyone help?

Featured Answer

Fenestration_Guru

11 years ago

The information provided is pretty good but a little incomplete. When speaking of efficiency and the way that the blinds effect the properties of the glass you are talking about two different aspects of energy efficiency; U-value v. Solar Heat Gain Coefficient. The blinds affect both properties. They will negatively impact the U-Value. There is little that can be done in a standard depth insulated glass unit to counter this with blinds. The issue is that you are putting a conductive material, usually aluminum, in between the glass panes and they will transfer the heat more quickly resulting in a higher U-value. You will have controllable SHGC with the addition of the blinds. What that means for you depends on climate and orientation to the sun. With the blinds closed you will have a much lower SHGC but also a much high U-value. This will result in a significant amount of heat energy transfer. Adding a hard coat LowE can help but will never be as good as the same unit without blinds.

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Comments (9)

millworkman
11 years ago
Probably will hurt the performance a little and in my opinion important especially since Jeldwen is not know as a good product to begin with.
HomeSealed
11 years ago
Yes and no. They will use a different type of low e coating and argon fill is not possible so technically the glass will be less efficient. That said, if the blinds are used efficiently (ie: closed in the summer sun, open in winter sun) they can mitigate that loss a bit. It also depends on where you are located in terms of climate, and the direction that the unit faces on your home.
If efficiency is a primary concern, you might expand your search to some other units. There are some out there that have air infiltration ratings under .09 and u values under .28 which are phenomenal numbers. The larger the hole in the wall, the more critical it is to have a very efficient product.
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Windows on Washington Ltd
11 years ago
+1 to HomeSealed and millworkman's comments.

In the case of JeldWen...its a crap shoot.

If used in the correct application, it could be a benefit.

Based on the fact that it will hard coat vs. soft coat Low-e and no inert gas fill, it will perform a bit lower.
CamG
Original Author
11 years ago
Thanks for the thoughts. My wife really wants the blinds, so I think we will do it. Now, low-e is a $180 add on for the patio door with blinds between the glass. Is that worth it, or if we close the blinds when the summer sun is coming through, does that make low-e redundant? Thanks!
Karateguy
11 years ago
I'd agree in large part with all of the above. In the end, homeowners look at one stat: their energy bill. U value and shgc work together to improve that all important statistic, and from what I've seen, the blinds can be either an improvement or detriment depending upon usage. Most people do not use the blinds as efficiently as they could, resulting in less efficiency as a general rule.

This post was edited by Karateguy on Wed, Mar 6, 13 at 6:53
HomeSealed
11 years ago
Thank you for the added detail FenGuru. I opted to leave out the jargon in my initial comment, but my point was essentially the same. The blinds will cause the glass to be less efficient. Much of that performance loss can be made up however by using the blinds to control solar heat gain. The extent of how effective that can be depends on several factors including climate, direction that the door faces, landscaping, the ways/times that the blinds are used, etc.
Timatroyaltech
11 years ago
Before you buy geld-wen check out royaltechwindows.com they have patiodoors with opperating blinds sealed between the glass. These doors are low-e and have argon gas yes it is possible! The blinds only add to the energy efficiency not only will the low-e and argon help deflect heat and or cold the blinds will help deflect the cold back out side. Royal-tech ships nation wide
millworkman
11 years ago
They also are made of: