No window is 100% air tight, its impossible. However, always get the most air tight window you can get. You will not get anywhere in court, Castle really did nothing wrong from what I can see. if you take them to court and you lose which is very probable, you will have to pay attorney fee’s to Castle which will be very expensive and you open yourself up to a countersuit by Castle as well. By the way, I am not a big fan of Castle Windows.

Maybe your walls are not insulated?

Open the window about 4" and compare the bottom of the sash with the sill. The reveal should be even from left to right. Do the same with the top of the sash and the center rail. If the window wasn't installed square and plumb it will be prone to leak more air.

If the windows weren't properly installed, it's something that you may be able to get remedied. If the issue is the window, you're probably stuck. Air Leakage ratings are an important factor for homeowners to consider as they evaluate windows, and this is but one example of why.

At least you didn't let them replace all of your windows. When it's time for the upstairs, look at Okna, Soft-lite or Sunrise and find a contractor who doesn't use such hard sell tactics. Good luck to you.

Here is an update I just posted on my issue with Castles.

https://www.houzz.com/discussions/6221653/windows-drafts

Its amazing that your husband is still with you unless … well, never mind.

You dont have a leg to stand on regarding Castle, you will lose in court and you will be paying their very expensive attorney fees. any ambulance chasing lawyer that takes your case will only want your money.

@fridge2020 my husband doesnt like to cause waves so he justs lets me deal with things i tried to get rid of him a few rimes over the past 40 years but he wont leave 😀💕