“Modular structure based on intermodal containers” Description Technical field The present invention patent application generally relates to the field of prefabricated industrial construction and in particular to modular structures for low environmental impact and high energy efficiency infrastructures. The invention could apply to any industry where such type of device can be advantageously used, but it preferably relates to the field of recovery and reuse of intermodal containers. State of the art As known, a container is a specific equipment used for transport, especially for intermodal freight transport. It is the basic element of the “containerization” process of trade, which developed after World War II and it consists of a large box, generally made of metal, hermetically sealed, parallelepiped-shaped and with internationally standardised size, which is directly loaded into cargo ships, into open freight trains, into trailers and into large cargo planes, for accommodating goods and, therefore, be shipped across the world. In ports worldwide, for example, there are more than 300 million empty containers, ready for shipping. However, once delivered to destination, such goods containers are almost always abandoned due to the fact that basically, especially in the long trips from China to the United States, it is cheaper to build new containers to be shipped rather than return the used containers empty after shipping. Although a few decades ago containers were only used for freight transport, currently unused containers have become a new frontier of architecture, given that the latter are instead modules ideal for being transformed into comfortable homes, even luxurious ones. This revolutionary concept of architecture has actually become increasingly popular and there can be currently observed the widespread use in private construction industry. Cost-effective, light and easily available, containers have roused the imagination of many who have been able to build homes where to live. As a matter of fact, starting from the assumption that the average cost for buying a used container amounts to about 2,000 euros, it is easy to see that the easy transformation thereof into unique and low energy consumption homes, even luxurious, has become increasingly widespread worldwide. Therefore, whether built using a single container or using containers as modules to be joined to obtain larger structures, the transformation is truly amazing and always cost-effective. The metal lining acts as perfect insulation for the house, both against the ground and the external. Therefore, an important aspect is to understand the reasons that lead to building apartments starting from unused containers. The reasons that lead to constructing buildings using containers definitely include ease of construction, speed of construction and cost- effectiveness, given that containers cost up to a third less than conventional architectural solutions. Specifically, this construction is very quick to carry out, given that it is almost entirely manufactured in the factory. This means that the works are not slowed down by various setbacks including adverse weather conditions and this leads to greater certainty on the times required to construct, and therefore hand over and commissioning. Another reason, around which this choice rotates, definitely consists in a clearly identified environmental approach, i.e. choosing to recycle an element which, vice versa, would become additional waste for the planet. The idea of building homes from these containers is therefore crucial to achieving smart recycling of these elements. However, this revolutionary architectural concept, which on the one hand exploits practicability and eco-sustainability, seems quite limiting right from now if compared to the ease of use of these containers exclusively in the private building industry. The present invention tends to expand the concept according to which a container can be reutilised, by implementing new and unique use options with respect to those known up to now. The invention was generally conceived specifically to address the need of being able to use such unused containers, even for building structures other than private building structures, extending the concept of use even to actual business facilities, offices, hospitals, schools that is for building facilities where general production activities are carried out too. A further object of the present invention generally arises from the crucial need relating to the possibility to address, due to the use of suitably modified containers, sudden needs arising from immigration flows and that is sudden high concentrations of people, which could occur due to various reasons on the territory and which would often require immediate availability not only of a large number of accommodation facilities but also and above all infrastructures that are appropriate and dedicated to carrying out all logistics activities, health activities and anything else need in these events. Therefore, the object of the present invention generally consists in constructing a modular structure based on containers for temporary or permanent modular buildings where to carry out a productive activity designed to solve the aforementioned problems, as will be clearer from the detailed description of a non-limiting embodiment thereof, shown below. Summary of the invention With the present industrial invention patent, herein described and claimed is a modular structure based on intermodal containers, provided with at least a solution that is new and alternative to the solutions known up to now and in particular it sets out to overcome one or more of the drawbacks or problems referred to above and/or meeting one or more needs felt in the prior art and in particular evincible from the above. To this end, the inventors developed a temporary or permanent structure consisting of the coupling of intermodal containers capable of building a facility where to carry out productive activities. More specifically, the structure according to the present invention consists in providing a professional self-service laundry intended for the public, wherein the treatment of fabrics is carried out by setting up a professional laundry area, precisely sized according to the needs and therefore comprising washing machines and dryers, capable of guaranteeing the quality of the outcome and at the same time the cost-effectiveness of the treatment. Therefore, the entirety to the advantage of practicability and cost-effectiveness, the present invention has the main objective of providing a room designed to serve as a laundry, obtained by coupling intermodal containers, whose single metallic load-bearing bodies are capable of easily providing a stable connection with respect to each other directly at the place of installation. Furthermore, said single metallic load-bearing bodies of each used intermodal container are suitably transformed in the factory, so as to represent the basic element on which the fixtures are installed, installations in general and be easily subjected to finishing works, insulation works and other kinds of works and so as to ensure that said containers easily become areas that are perfectly habitable and accessible for the purposes for which they were designed. Specifically, the present invention provides a laundry room consisting of the coupling preferably of three common intermodal containers of the internationally standardised size type. In particular, 2 intermodal containers of the 40Hc type, having external dimensions measuring 12192 mm long, 2438 mm wide and 2591 mm high, are coupled to each other in the longitudinal direction. Similarly, the remaining 1 intermodal container of the 10Hc type, having external dimensions measuring 2991 mm long, 2438 mm wide and 2591 mm high, will be coupled to the aforementioned intermodal container of the 40Hc type along the respective widths. Such design will actually allow to obtain a laundry room in which the entirety appears rationally distributed and well-proportioned in the overall dimensions and in those of the single compartments and characterised by the creation of three separate rooms, i.e. a room accessible to the public, machine room and installations room. The interior finishes are of ordinary type, with two-coat plaster and with painted walls and ceiling and anti-slip floor. The innovative concept on which the present invention is based consists in providing an optimal compromise, given that - on the one hand - the design will allow to obtain a laundry room that is perfectly efficient and meeting the needs of a large number of people while - on the other hand - it will be suitable to be quickly and easily installed in hospitals, barracks or in any case wherever there are high concentrations of people. Therefore, forming a specific object of the present invention is providing a modular structure to be designed as a laundry, which is actually subjected to an initial transformation and almost full manufacturing in the factory and therefore only a subsequent installation and operation on the ground, which will require very little time with respect to a conventional architecture and this will be a significant advantage in which there arises the need to be installed for a particular purpose, by way of emergency. Another advantageous characteristic lies in the economic advantage, which is obtained with the structure according to the present invention. As a matter of fact, a similar structure obtained starting from unused intermodal containers will have an overall cost amounting to about a third of the cost that would be incurred with conventional architecture. A further and not less important advantage regards the full eco-sustainability of the entire process for producing the modular structure to be used for productive activities and specifically as a laundry. In particular, there are multiple factors that make the product highly compatible with the ecological needs and above all the recovery of the unused intermodal container, which would otherwise be disposed of. Then, it should be observed that being easy to install, such structures are specifically referred to as a temporary or permanent structure and they therefore allow to be easily disassembled and therefore totally removed and recovered. Another technical characteristic which differentiates this modular structure subject of the present invention lies in the fact that the initial design and production of said products in the factory, make them particularly and easily appropriate to be manufactured with ultra-high performance, which aim to achieve sustainability and energy saving both as regards insulation and as regards the production of electricity by installing photovoltaic panels. A further object is to provide a modular structure, which significantly simplifies the transport of the various components and the manufacturing of the structure. Furthermore, the modularity and scalability of the components allow to adapt the applications to several environmental situations, same case applying to the morphology of the landscapes and to the various local needs. Another characteristic lies in the fact that the modular structure in question can be made on an industrial scale, whose components are of the standard type and perfectly available on the market and whose production is fully sustainable from an economic and environmental point of view. In the light of the above, it is clear that the most important advantages obtained have already been extensively outlined. However, other advantages will be clearer both when the invention will be implemented and from the detailed description of an exemplifying and non-limiting embodiment thereof, shown below. Brief Description of the Drawings The advantages above, as well as other advantages and characteristics of the present invention, will be illustrated with reference to the attached drawings, which are to be considered as merely illustrative and non-limiting or non-binding as pertains the present patent application, wherein: - FIGURE 1 is a partially top perspective view of the modular structure based on intermodal containers, without the top cover for the sake of clarity, according to the present invention; - FIGURE 2 is a plan view of the three intermodal modules of the modular structure based on intermodal containers of Fig. 1; - FIGURE 3 is a plan view of the three intermodal modules of Fig. 1 yet to be coupled; - FIGURE 4 is a top perspective view of the modular structure according to an alternative embodiment of the present invention with several voltaic panels installed on the top cover. Detailed description of the invention The present invention will now be described in detail with reference to the figures and to a preferred embodiment thereof shown therein, in which identical reference numerals were used for the same components in all the figures. With reference to the various figures, the latter show a modular structure consisting of several intermodal containers designed to obtain a room to be used for professional laundry activity intended for the public and consisting in the mutual coupling of three common intermodal containers of the internationally standardised size type. In particular, as shown in the plan view of Figs. 2 and 3, 2 intermodal containers 200 and 300 of the 40Hc type and the metallic load- bearing body of 1 intermodal container 400 of the 10Hc type with which said intermodal container 300 of the 4Hc type through respective widths, are coupled to each other by joining metallic load-bearing bodies in the longitudinal direction. Such design actually allows to obtain a room design for laundry activity, wherein the entirety appears rationally distributed and well-proportioned in the overall dimensions and in those of the single compartments and characterised by the creation of three separate rooms, that is the room accessible to the public 250 obtained in the intermodal container 200, the machine room 350 obtained in the intermodal container 300 and the installations room 450 obtained in the intermodal container 400 and in which the latter is coupled through the short side to that of the machine room 350. As regards the installation step with the relative coupling of the containers to each other, which have been previously transformed and almost entirely manufactured in the factory both as regards the cutting of the walls where the fixtures are to be installed and as regards the step for preparing for the positioning of the machines and the installations in general, it should be observed that this is easily deducible from the description outlined above and - falling within the common knowledge of the prior art - it just requires little explanation. In particular, it is provided for that the coupling between the metallic load-bearing body of the intermodal container 200 with that of the intermodal container 300, and between that of said intermodal container 300 and the metallic load-bearing body of the intermodal container 400 occurs easily both by means of a common coupling obtained by means of bolted fixing brackets and through welding means like the manual one with coated electrode (MMA), the one with submersed arc (SAW), the one with continuous wire under gaseous protection (MIG/MAG) and the one under gaseous protection and with fusible electrode (TIG). More specifically in the present invention, as observable in Figs. 1 and 2, the two coupled walls of the room accessible to the public 250 and of the machine room 350 accommodate at least 6 washing machines 500 and at least 4 dryers 600, so that the front of the machines is directed towards said room accessible to the public 250. On the opposite long wall of the room accessible to the public 250, a glass wall is installed comprising at least 5 windows 260 adapted to guarantee the required lighting and thermo-acoustic comfort. Similarly, on the other long wall of the machine room 350, there are installed - in elevated position - at least 3 openable fixtures of the transom type 360. In greater detail, on the short sides of the room accessible to the public 250 and of the machine room 350, there are installed openable fixtures of the door type 270. The machine room 350 is placed in direct communication with the installations room 450 through an aforementioned openable fixture of the door type 270 while on the long wall thereof there will be installed an openable fixture of the door type 270. Even on both two remaining walls of the installations room 450, there are installed - in elevated position - at least 1 openable fixture of the transom type 460 per single wall. It should be observed that such installations room 450 contains all installation components that are essential and comprising the boiler for accumulating water, the pumps, the autoclave, the dedicated electric panel of the power line from the low-voltage external supply point and the tank for accumulating untreated heated water from the solar panels, given that they are similar to a domestic appliance and conveyed to a well near the structure. The present invention provides for further alternative embodiments at some variants of the structure thereof and the shape of the components thereof. For example, although up to now there has been described a fully dependent modular structure as regards the electrical demand from the power line coming from the low-voltage external supply point and provided with machines with internal water pre-heating system, an alternative solution according to the present invention envisages providing a product that is compatible with the ecological needs. The pre-heating of the water allows to significantly reduce the washing times given that the water is already heated upstream. Specifically, the present invention allows to ensure that the electrical absorption of the entire installation, which is part of the modular structure, is very low. As a matter of fact, as shown in Fig. 4, the large size covering the entire structure allows an effective installation of solar panels 800, which - associated with an appropriate preparation and construction of the installation initially at the factory - allows to ensure that the room is adapted to the installation of an integrated solar thermal system and indirect heat pump capable of actuating both the heating of the water and regulating the temperature of the environment inside the structure, thus significantly reducing electrical consumption. Specifically, the solar control unit for the solar thermal plant housed in the cover is obtained in the intermodal container 400 of the 10Hc type. Obviously, the data provided herein are shown purely by way of absolutely non-limiting example of the scope of protection of the present invention, given that they exclusively place the man skilled in the art in a position to understand some possible applications and embodiments of the invention. Therefore, various obvious changes could clearly be made - by the person averagely skilled in the art - to the previous exemplifying and non-limiting embodiments described with reference to the figures, without this entailing an extension beyond the inventive concept, on which the present invention is based, as defined by the following dependent claims.