super good thermally-broken storefront windows: suggestions?

Hey Guys:

I've searched the forum and not found any helpful threads.  I'm looking for:

a really well-broken thermal storefront

(how does one state that?)

a really well-thermal-broken storefront

a storefront system with excellent thermal breakage

a storefront replacement window system that won't condense in a cold Midwestern climate


I think you get what I mean.  Suggestions? This is to replace existing 20-year-old aluminum storefront in a limestone surround.

Nov 8, 12 9:33 am

i'll go ahead and start with a simple kawneer frame:

i don't know if i would say that's "super good" but it appears to be a thermally broken system that, if installed properly, will help prevent condensation.

get decent installers.  if the glass isn't glazed into the frame right or they don't caulk joints (even when it's slightly inconvenient to get a caulk gun into a corner or behind a door closer) it's not really going to matter how good the system is.

did i say that right with "glazed in?"  i have a picture in my head of a little black thing not pushed in right, but i'm not a glazing industry person so i'm not positive.

this might be what they ve down to.  i suspect it is not as good:

Nov 8, 12 10:13 am

You need a system that states it is actually thermally broken, not thermally improved. Most reps won't know the difference and will try to tell you that thermally improved is the same--it is not. One of the problems with storefront systems is that there will most likely be sub-sill flashing which extends from the exterior to the interior; "short circuiting" any thermal break that the sill section has.

Perhaps the condensation issue could be helped by washing the windows with warm air or lowering the humidity of the space? Or what about using a steel system instead (steel is a little better thermally than aluminum)?

I know EFCO has started to add PVC filler pieces to the glazing pocket of the jambs of their curtainwall systems which greatly improves the thermal performance…but that's curtainwall, not storefront.

I just looked at their 960 series storefront which looks to have a pretty substantial thermal break and seems to work more like a curtainwall system (separate mullion and cap).

The images below illustrate the difference between a thermally broken system versus a thermally improved system (it's curtainwall but the concept is the same). I'm not an EFCO rep--I just happen to have these images handy because we were looking at using one of their systems.

Nov 8, 12 10:34 am

Also--you could look at using a thermally broken spacer in the glazing unit.

Here's one by Solar Seal:


Argon gas-filled glazing units may have great thermal properties and help get you LEED points; however, the argon leaks out of the unit rather quickly rendering the unit no better than a "regular" insulated glazing unit.

Nov 8, 12 11:06 am

what curtham and piggins said.

Kawneer, EFCO, TRACO, Tubelite, Vistawall, Trulite. Be weary of of manufacturers  outside that list. 

Other than that, a single pane framed or all-glass storefront should not show condensation if the components were not installed by a midwestern cow. 

Nov 8, 12 12:49 pm

unfortunately, in kentuckiana, midwestern cows are often the lowest bidder. 

Nov 8, 12 1:34 pm


Donna, here are a few systems to look into. 

thermally enhanced/broken:

  • Arch Aluminum, Thermalfront III System.
  • Efco, System 433T
  • Kawneer, Trifab VG 451T Thermal.

Thermal barrier systems:

  • Arch Aluminum, IGS 450, Thermal.
  • Efco, System 403T
  • Kawneer, 451T Thermal.

Thermally improved (cheaper)

  • Efco, System 960
  • Kawneer, EnCore.
  • Arch Aluminum, NRG

There are others of course. Your performance criteria (a really well-thermal-broken storefront) needs some massaging :)

Nov 8, 12 1:59 pm

What Steven said. But do you think a California cow could do a better install?!  All they do is surf and smoke pot all day!


Thank you everyone! I love those close-up profile pictures, Russell Higgins. Aluminum extrusions are dreeeeeamy.

Nov 8, 12 3:56 pm
t a z

An an argon filled IGU with a  thermoplastic spacer (TPS) and a thermally broken frame will give you the best performance but will be the most expensive configuration.

A program called THERM (free from LBNL) is pretty much the industry standard to review thermal performance of glazing details and assess condensation risk (based on the dew point temperature).

You'll usually see pretty rainbow colored contour diagrams in company literature to boast how good this or that product is.  That's usually THERM results.

Nov 8, 12 7:25 pm

annnnd.... bookmarked.  I love these kinds of threads.  Thanks for posting Donna, and thanks for contributing knowledge, everyone!

Nov 9, 12 1:38 pm

YKK AP America Inc. has an excellent high thermal performing Storefront. Our enerGfacade YES 45 XT will achieve a 0.36 U-factor using a Center of Glass (C.O.G.) U-factor of 0.29. (IP Units). Thus storefront has a daul thermal break, which utilizes Azon USA's MLP Technology to maintain the structural performance of a single pour and debridge type storefront. Please contact David Warden at 1-800-955-9551 for further imformation of visit and look in the commercial products tab for YES 45 XT Storefront.

Nov 9, 12 4:33 pm

Oh! yah! Here is the link to enerGfacade

Nov 9, 12 4:36 pm

another option...

Nov 9, 12 5:01 pm

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