During the winter the main goal is to reduce heat transfer from the inside to the outside. The building elements (windows, roof, floor, foundation, walls, etc.) are all important sources of heat loss. These losses are treated with low thermal permeability windows (Uw < 1.6 w/m2K) and insulating materials with high thermal insulation (R > 2.2 m< sup>2K/W) for the rest of the structural elements of the building (roof, roof, external masonry, etc.).
In areas with strong sunshine, the largest source of heat energy is solar radiation which may enter directly through windows or may heat the building elements to a higher temperature than the environment, increasing heat transfer through the building elements. Solar heat transmission can be reduced by adequate shading, with energy (Low-E) glazing in the frames (Ug < 1.1 w/m2K), with light-colored roofs and reflective colors on the walls.