Patio glass doors can be affordable and may look nice, but that usually comes at quite a high cost. Patio doors can be a major source of unwanted heat loss and gain.
If you intend to install them in your home, consider:
»» Reducing their size ;
»» Protecting them as much as possible.
»» Selecting the right glazing and frames;
Patio doors should be seen as windows, and their selection, installation and sizing should follow the same rules as windows. See: Windows Labels and Coefficients.
Avoid Common aluminum framing patio doors
Aluminum is strong, durable, non-corrosive; but aluminum is also a highly conductive material. It conducts more heat than any other construction material, which makes aluminum frames a bad choice - unless the frames are designed with built-in insulation elements. Consider other types of frames for your patio doors, namely fiberglass and high-quality PVC.
See: Windows/Doors Frames
Protect your patio doors; that's critical to reduce energy consumption
Protect as much as possible your patio doors. Use awnings, shutters, blinds, and other similar sun-screening devices. Consider the shade of trees, and pergolas… Use draperies to minimize heat loss in the winter. Consider also wind-breaks.