Triple vs. Double - South Facing Side

Had Gorell triple pane casements installed on front of house two years ago. Doing the back side now. Former installer now recommends Sunrise over Gorell (though will still quote Gorell if I want) but now recommends double pane instead of triple pane.

Sunrise quote is for Double Pane Ultra U Plus. Doesn't mention a specific sunrise model...judging by other posts there is more than one, right?

Also have a quote for Triple Pane Double Low E Krypton Imperial LS casements with Betterview Screens; medium oak interior. Salesman mentioned Kevlar reinforcement beam thing...does that apply to casements or only double hung?

What questions do I still need to ask? Does the south facing side make a difference?

Also need a patio slider...any recommendations?

What is his rationale on double pane over triple pane?

If you are okay with the slightly darker window, triple pane is a great investment.

Triple pane will have a bigger impact on overall wall performance than most give it credit for.

Example:

A standard 2x4 (R-13) wall will have an average R-Value of about 6-8 when you figure in the thermal bridging of the studs and the and the less than optimal performance.

If you were to re-calculate the R-Value of that entire wall assembly (window included and figuring that the wall to window split is 75% - 25%), the double pane window (U-Factor of 0.30) will net and average entire wall R-Value of 5.5.

That same wall with triple pane (U-Factor 0.21) windows installed will bump it up to 6.3. That is a 15% increase in the thermal resistance of the entire wall.

In theory, you would think that a 40% increase in the window performance would only net about a 10% increase given the 25% of the wall it represents but it is not a linear relationship.

Are you bored yet.....

He says triple pane is more expensive and hard to recover the difference. We plan on staying in the house a long time. Total quote on 13 panes will go up around $1000 to go to the Sunrise triple pane.

The Imperial LS triple pane number is not too far off the Sunrise double pane quote. We are leaning towards the Imperial LS.

Still curious about the Kevlar reinforcement...does that apply to casements? The Sunrise guy said the casements aren't reinforced and that they don't need to be. We do have some rather large openings - a 3 lite around 6' x 5', a 2 lite with transom on top total opening 4' x 6'.

Appreciate your advice!

The Imperial LS is a great window.

If the triple pane numbers are that good and close to the Sunrise double pane, the decision is a no-brainer for me.

Go with the LS and the triple option.

Not sure about the reinforcements on the casements but I don't think they are in there and he is right in that they casements are a bit heavier duty and don't need the reinforcements in most cases.

The Imperial L.S. only has the K bar in the keeper rail of a double hung - not the casements. As Far as Triple pane, whether it's the south side or north side, its worth getting (depending on price - $100 per window is a fair price). The insulation is better regardless if it's daytime or night. However the Shading coefficient in the Triple pane is better (lower number) and;. therefore, will help keep the house cooler during the summer, especially on the south side.

redsoxmom, I assume that you are located in the northeast? If so, Klemmerbros advice could not be worse. You run your furnace 3/4 of the year, so your windows should reflect that. A moderate shgc is appropo. Triple pane may or nay not be worth it depending on cost (you'll never recoup $100 per window), but ultimately you want a low u value with a moderate to high shgc.
Blocking out summer heat is the least of your concerns as even the most rudimentary Low-e coatings will be sufficient in that area.

Well said about the SHGC.

If you live in a climate that has a more dominant heating season, going too low on the SHGC can be a net negative impact on the performance of the home.

Standard double pane and 2-coat low-e will cut down on the sun's radiation quite a bit off the top.

We are in Des Moines, Iowa. The heating season is slightly longer than the cooling season, but not a lot.

The Imperial LS triple pane quote is $8000 for 13 lites. The Sunrise double pane is $7500. I'll look into the SHGC for each of the windows.

Thanks!

In Iowa, the heating season is going to be a bit longer than you might think... That said, at a $500 difference for triple pane LS, it seems like a no-brainer. You might lose slightly on SHGC, but it is more than made up for by the improved U value. The Sunrise casement is very nice, but the LS would be my choice here based on the pricing and option content.

http://www.climate-zone.com/climate/united-states/iowa/des-moines/

6:1 Heating to Cooling as a matter of fact.