Summer and winter performance: two different needs
It is worth clarifying that all systems, such as thermal insulation, which improve comfort without the use of systems are defined as “passive”. On the contrary, “active” systems are mechanical ones, such as summer heating and cooling systems, which come into operation when the casing is not performing sufficiently or is not sufficient to guarantee the desired well-being.
Passive internal contributions, on the other hand, refer to the heat produced by sources of another nature, such as human metabolism and all electrical and electronic devices that emit heat, such as light bulbs and household appliances.
The thermal coat, therefore, represents an effective solution to mitigate the cold and sometimes even the heat. It is therefore important to distinguish between winter and summer performance, because not all insulation guarantees the same behavior in all seasons. There are materials capable of offering protection throughout the year, while others are very good against the cold but less effective against the heat. For a long time, unfortunately, priority was given almost exclusively to winter protection in thermotechnical design, neglecting the summer aspect.
Each insulator has different characteristics and performance
In general, the most balanced insulators, in different seasons, are those with high density and high specific heat, such as materials of plant and animal origin. Mineral insulators have fair performance, but with lower density and specific heat values on average. Petrochemical synthetic materials, on the other hand, are often light and have less thermal storage capacity; they are excellent in limiting winter dispersions, but less effective in combating summer heat.
Of course, the performance does not only depend on the insulation chosen, but also on the structure of the building. A massive masonry made of solid brick or reinforced concrete, for example, offers a good contribution in containing summer heat thanks to its mass, but can be less advantageous in winter. The lightened thermo-brick blocks, on the other hand, allow you to combine a fair amount of summer thermal inertia with a reduction in winter losses, also allowing you to contain the thickness of the additional insulation. In the case of wooden constructions, although this material is naturally insulating, it is necessary to combine it with other insulating materials with high mass and high specific heat, to guarantee adequate comfort. Alternatively, with lighter materials, the thicknesses will need to be increased to obtain satisfactory results.
The right choice also considers the environmental impact
So far we have mainly talked about technical and performance characteristics, but the environmental aspect of the materials cannot be ignored. Historically, projects have favored the thermo-acoustic performance, leaving the ecological impact in the background, almost always forgotten. Today, fortunately, attention towards sustainability is growing: many professionals evaluate not only the technical performance, but also the origin, renewability and overall impact of the products, also thanks to a greater awareness of climate problems, the dissemination work of ecologically conscious associations that have been engaged for years on these issues and the updating of the Minimum Environmental Criteria, which have imposed the life cycle analysis for the choice of insulation.
In conclusion, to answer the initial question regarding which thermal coat is the right one, it must be considered that the choice of insulation for a coat, whether internal or external, should be based on a set of criteria, such as low thermal conductivity, high density and specific heat, good vapor breathability, durability, adequate fire resistance, preferably without harmful additives. However, it is also necessary to consider the origin from a short supply chain, preferring renewable raw materials that have a real percentage of certified recycled product, giving preference to those that have a higher percentage.
However, it is not enough to rely on commercial declarations, it is always advisable to independently and thoroughly verify the characteristics of the proposed materials.
