ProVia’s Embarq Fiberglass Entry System uses added thickness (2 1/2 inches) and foam-filled channels in the side rails and header to achieve a third-party-tested U-factor of just 0.1 (about R-10). Dual perimeter seals eliminate drafts, and four heavy-duty ball-bearing hinges support the increased weight (65 pounds). $3,900, installed. provia.com