IT'S NOT FOR SURE THAT SOMETHING THAT HAS A “ NATURAL NAME ” IS MORE ECO-FRIENDLY THAN A PRODUCT OBTAINED BY RECYCLING MATERIAL DERIVED FROM PETROLEUM.
THERMAL BRIDGES
Thermal bridge is a term that is heard more and more often and it is really worth spending a few words to deepen one of the points of strength of prefabricated houses compared to construction based on reinforced concrete structures.
Quite simply, a thermal bridge is a part of the structure of a building that has thermal properties different from those adjacent to it and is one of the main causes of heat loss in a building and the formation of condensation and mold.
Thermal bridges are usually points of the building envelope which have faster heat flows than surrounding parts. The main effect of thermal bridges is the exchange of temperature with the outside. Obviously it conducts heat during the winter from inside a house to the outside, in summer it conveys it from outside to inside. By causing a privileged way to dissipate heat, they heavily reflect on the costs for heating and air conditioning, reducing the overall comfort of the home.
It must be said clearly. Thermal bridges are not a fatality but are always construction and design errors, therefore they could be avoided a priori with a minimum of care on the part of designers and companies. The classic external insulation systems that are increasingly applied to the exterior of traditional homes aim to limit their effect, especially for those parts of the building most involved in dispersions. It is no coincidence that typical examples of thermal bridges are balconies, pillars and all protruding construction parts that are hardly or not insulated at all.
Basically they exist two categories of thermal bridges, the geometric ones and the constructive ones (sometimes a combination of both factors).
The geometric thermal bridges are discontinuities present in correspondence with changes in the direction of the parts constructive, such as corners, or projecting elements.
Thermal bridges constructive are discontinuities that manifest themselves in the points in which materials ad high thermal conductivity (reinforced concrete, metal parts) penetrate a external structural element that presents greater insulation. This is the case of protruding concrete balconies without insulation, of little or no insulated lintels, of reinforced concrete pillars that cross the perimeter masonry, with marble frames around the window holes. Discontinuities in isolation can also generate important thermal bridges. You may have seen some infrared thermographic image in which thermal bridges are usually visible from the inside as cold (blue) and hot parts on the outside (red).
Thermal bridges can be safely avoided by adequately insulating the projecting parts of a building such as balconies in concrete, lintels, reinforced concrete pillars and the like.
In a house prefabricated the absence of reinforced concrete as a building material is essential to limit their presence at the start. In a prefabricated house the external wall is an element that does not present elements of possible thermal perturbation. The pipes and flues are insulated and moved inside the house, outside the wall.
The same can be said for the plumbing systems of the bathrooms which are usually carried out in an inspectable counterwall.
The dumpster of the roller shutters (clearly one of the major critical points) is insulated or even located outside, on the facade. All the insulations, from the external coat to the insulation of the roof, are performed without joints or interruptions the main problem of traditional construction is the execution on site by the workers, especially if they are not very skilled.
In a prefabricated house the casing is made with careful control, especially as regards the junction wall-window.
Even small inaccuracies can give rise to notable ones thermal bridges that can greatly lower the overall energy performance of the building. The assembly of the window by hand on site is a very delicate phase, often underestimated by those who perform it, relying more on the good thermal qualities of the window. But even the best windows with low-emissivity glass will generate a serious flaw in the casing if it presents even minimal assembly errors. In the prefabricated house, the frame-wall coupling is tested with tightness tests and verification tests that certify its absolute precision, guaranteeing the absence of assembly errors and consequent thermal bridges.
The classic balcony with reinforced concrete slab, one of the worst tragedies from a thermal point of view, in the steelconcrete house it is often made with a structure independent of the attic of the house or connected to it with insulated joints the problem of thermal bridges has been little or nothing addressed in the past, a lot from companies, as well as from designers, and only in the last few years, thanks to the incentives on the subject of energy requalification of buildings, there has been a progressive specialization of companies and qualified technicians in terms of building efficiency. On the contrary, the prefabricated house sector has always had as its main objective the elimination of thermal discontinuities, boasting a very long and proven experience in the construction of buildings with high thermal efficiency and low energy consumption.