Protecting ourselves from the weather is one of the primary functions of architecture. This can be done in an active way (using heating or air conditioning equipment, for example), or passively, using solar radiation, ventilation, and materials in favor of the architecture. Although the advent of cooling and heating technologies has improved indoor conditions, they have also contributed to the creation of buildings that are poorly adapted to the environments in which they were installed, making them costly to cool, heat and enable comfort in their interiors. Office buildings with glazed facades, which are not specified with respect to local climate, relegate complex air conditioning systems to the task of maintaining a constant internal temperature.
The envelope of the building is an important part as it acts as a filter between the exterior and interior climate, and should take local climatic conditions into account when designing. In warm places, it is generally sought to ventilate the building as much as possible, with generous openings and shaded spaces. In a cold region, on the contrary, the envelope tends to allow the sun to enter the space, maintaining the heat in the building. The direction of heat flow always goes from the hottest to the coldest surface and the transmission occurs when there is a difference between the temperature of the external and internal surface.
Several pieces of research address the main forms of energy loss in a building. In general, the numbers are close to 35% for the walls, 25% for windows and doors, 25% for the roof and 15% for the floor. These heat losses occur by convection, conduction, and radiation. They will inevitably occur, but it is the architect's duty to manage how quickly heat is lost - this can be controlled through the use of appropriate building materials and techniques to establish and maintain a watertight building enclosure incorporating high levels of insulation.
At this point, it is important to address the concepts of thermal insulation and thermal inertia. Thermal insulation reduces heat loss during cold seasons and heat gain during hot seasons. Insulation materials like mineral wool, ceramic fibers, Styrofoam and polyurethane generally consist of many voids. Air or other gases captured in these voids act as an insulator. They will help reduce heat losses and gains. We have already discussed how to calculate the thermal transmittance, also called the U-value, in this article. This value allows us to know the level of thermal insulation in relation to the percentage of energy that crosses the envelope; if the resulting number is low, we will have a well-insulated surface. A high number will alert us to a thermally deficient surface. Another important concept is thermal inertia, which is the characteristic of a material to retain the heat and return it to the environment little by little. Materials with high inertia will have a delayed reaction on changes in atmospheric temperature. The thermal inertia is relevant in regions with climates with large thermal amplitudes between day and night. In coastal regions and sites where there is little temperature difference in days, the adoption of materials with low thermal inertia is adequate to prevent high temperatures from entering the spaces.