Even if the door is made of insulating materials, this may mean nothing if there are gaps between it and the walls of your garage. To reduce energy loss through air leaks, it is necessary that the door has been manufactured to the correct size and the sealing correctly carried out. Having a door installed by a professional is an important step in ensuring that the product does its job.
Another aspect to consider in garage doors are windows as they could be another potential source of air leak. To avoid this transfer of temperatures be sure to choose windows with low-emissivity coatings that have, at a minimum, double glazing.