I should add, we have several quotes:

1. Milgard Ultra $17K

2. Andersen E series $29K

3. Marvin clad $56.7 (gulp!)

We went with Marvin Integrity with black exterior. Our contractor likes them, we like them and the price was good. Nice slim lines. Mostly casements. I understand they're starting to offer black as an interior color. I'm impressed with the fiberglass exterior.

Thank you all for your help so far. I'm hours into my hundredth round of research trying to find a reputable all-aluminum window manufacturer (thermally broken would be great but maybe not necessary in our climate?). Just trying to figure out what to use as defining criteria, other than appearance. Seems warranty is useless in most cases anyway

Aluminum would be our preference as well, but I have come to realize that most aluminum window manufacturers can not get the U factor you specified unless you went with triple pane.

Most double pane aluminum windows I looked at have U factor around 0.45. If you want to stick to your stated number, the only double pane ones I saw that would work are tilt and turn windows

"Not necessary" in your climate probably isn't the right descriptor here. Thermally broken aluminum doesn't achieve the U-Factors that you really must get in some areas of the country that have a cold season. Even with really good glass in a thermally improved aluminum window, you can have condensation issues if you are in a climate where you have to heat the home. Aluminum is a great building material, but it has some challenges when it comes to conduction of energy.

That said, if you are in an area of the country where you rarely heat the home and even the idea of heating is to warm up the exterior air from 50 to 70, thermally broken aluminum (especially looking for a contemporary look) is a great option there.

Thank you all so much. We are basically in an area that doesn't drop below 50, even in the winter, but we do have to run the heat. I'm not sure what the "breaking point" would be for indoor vs. outdoor temperature (we'd heat to 68 indoors in the winter) to determine if aluminum could still work for us. I'm going to look at Fleetwood (which I'm sure will be comparable to Marvin prices) and Milgard again (we hadn't priced out all aluminum) and see... would love any other suggestions for all metal to get that clean aesthetic. Seems like it would also be nice and low-maintenance.

Update: just checked at Milgard doesn't have black ...

It does seem that they can meet the u-factor requirements according to the calculator on their site though. I am a little concerned about lc's comments above as, perusing the boards, it seems we're on a similar hunt but she has been on it for more than a year! info seems reliable but does that mean there's no all-aluminum option with an acceptably low u factor?

If you find some with that u factor for double pane, let me know. Both Fleetwood and Milgard have u factor over 0.40 for double pane

I will, lc - and if anyone else knows, please chime in!

Who is mandating the U-Factor in this case? The State, the county, or Energy Star?

2. Andersen E series $29K

3. Marvin clad $56.7 (gulp!)

Something is off there, as those two should be in the same zip code at the least.

Thanks millworkman - I will bring both quotes to another place and see if I can reconcile the difference. Or perhaps the Marvin one includes something the Andersen one doesn't?

WoW - U factor is from the city, state, and architect (SoCal is, let's just say, energy conscious). I'm not sure if that's something that can be adjusted by the architect? I'm assuming it's calculated based on number of fenestrations and size?

That's the hang up, though, as the all-aluminum windows struggle to meet that, as far as my (and lc's) research seems to indicate.

I think I have it down to Kolbe (can't figure out the difference between Ultra and Vistalux as both seem to be aluminum clad but maybe it's just a design thing, traditional vs modern), Marvin Ultimate (aluminum clad), Andersen E (aluminum clad) or Fleetwood (all aluminum but $$$$!). Will look at the Milgard all aluminum because it exists but I feel like it won't meet up to the quality I'm hoping to get. Just being able to list a few brands is somewhat reassuring but I'm not feeling that comfortable yet. Can't thank you all enough for your graciousness with your time and knowledge.

As I mentioned in my thread, are your plans subject to the 2016 building codes? If they are, 0.32 is the required U factor for the prescriptive method.

As for pricing quotes, Marvin Ultimate was the most expensive for me. Kolbe was slightly less. Anderson E was about 20% less. Fleetwood was about 25% less. Milgard was a lot less but couldn't make all the windows. Fleetwood and Milgard are aluminum and the others were clad and all windows are either fixed or casements.

Yeah, lc, unfortunately I hit the same data. I checked back with my architect and he confirmed the U factor is calculated and pretty black and white (not much, if any, wiggle room) and that all-aluminum windows struggle to meet that. He had no recommendations for any brands that do.

I will re-price Andersen and Marvin per millworkman's suggestion just in case I'm missing something and I'll keep this thread updated with decisions and pictures. It's the least I can do to thank you all!

millworkman - I'm embarrassed you caught my mistake! The Marvin quote included doors and the Andersen one didn't! Factoring that in, they are almost identical (hanging head).

MWM has probably quote more jobs than I can count so it would make sense that he would identify those type of variances. Good catch MWM. In that case, I prefer the Marvin.

When and how do you provide validation of the energy values in this case?

WoW, there is a title 24 inspector (I kid you not). The architectural plans first are reviewed by a separate title 24 person with calculated U-factor, SHGC for all fenestrations (including skylights, etc), HVAC, thermal envelope (insulation), etc and then the contractor should build according to those plans. The inspector will then come around and verify you built according to the approved plans (include a title 24 inspector). It's madness but for a good cause. I'm all for the environment, just wish I could get the windows I want! You can offset your windows (if your U-factor is too high) by adding insulation, changing lighting, etc. It's just that the window specs are usually easiest to meet so our architect strongly advised we try to meet those rather than altering something else. Not sure if that was your question?

The fenestrations must have the NFRC sticker (or equivalent if not rated by NFRC) on it for inspection, is my understanding.