Choosing the door to energy-efficient home should pay attention to the rate corresponding to the thermal insulation. In the case the door is an indicator U. Most manufacturers offer door U ratio of 1.3 – 2.0 W / m2. There are, however, possibilities, with regard to the passage of heat. Better in this regard are the windows of the parameters U <0.80 W / m2. So, if you build house energy efficient, we should be to invest in the very beginning, to then be able to enjoy the savings.