I should include that this is in a condo ... the new windows must approximately match the existing double hung windows.

The rough opening size is about 36 in. wide x 48 in. tall. (tape measure guess) so it should be a readily available size. You know when they built these things that they didn't do anything custom.

The existing window opening (push one sash up) is just shy of the minimum required 5.7sq. ft. so they told me the only option is to put in a window that allows the entire window (both top and bottom) to swing in, creating an opening big enough for King Kong to pirouette through.

Some companies such as Simonton make what's called a Colonial Casement. It is made to look like a double hung but will solve your egress issues but still conform to HOA rules and qualify for the tax credits.

Here is a link that might be useful: Simonton Colonial Casement Window