Ventilation Systems

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Why climate control?

Thanks to the effects of new work safety regulations, natural ventilation systems are surely making a name for themselves, primarily in Northern European countries. But legislators are not the only ones taking an interest in climate conditions in production facilities. It is now clear that a comfortable environment increases safety, productivity and the quality of work produced. Several different independent research studies have confirmed that work performance improves when temperature and humidity are kept within determinate value levels.

This simulation demonstrates the benefits that can be obtained from the proper design of natural ventilation systems and natural light within a building: internal temperature, maintenance costs, productivity, energy consumption and comfort were the parameters taken into consideration.

Natural ventilation

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Inside an industrial building, the hot air produced by working machinery or internal radiation rises up, driven by thermo-convective motion, and stratifies spontaneously due to the effects of temperature.

This produces significant effects in large-scale warehouses, which typically host activities like steelwork, animal production, plastic material production and in general wherever production processes contribute significant heat generation.

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This means that an effective solution to the problem of industrial ventilation can be achieved, on one hand, through the availability of models that make it possible gain a sufficiently detailed understanding of spontaneous air movement, and on the other through the choice of appropriate technical elements that can take best advantage of the laws of thermal motion. Often the problems that beset large constructions are determined by the use of technical and architectural solutions that don’t pay close enough attention to the two conditions mentioned earlier.

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The significant height of certain industrial environments is precisely what gives air stratification: the characteristic of heat engines capable of moving large air masses, taking advantage of nothing more than ascending currents. In order to best utilize these effects, however, you need ventilation systems that respect several conditions connected with efficient parts exchange, minimization of interference, as well as the size and positioning of elements within the system.

Therefore the design aspect is of crucial importance for creating a good, effective natural ventilation system. The initial design provides the best expression of a philosophy based on energy savings, environmental impact, rationality in realization and economic value. As already said, the solutions are relatively well known and widely used, especially in Northern Europe.

Assisted Natural Ventilation

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Under certain conditions it may prove necessary to assist the inherent dynamics of air masses, providing make-up air through fans and ducts. This can happen when the geometric characteristics or the ways the space is used, limit opportunities to take advantage of natural movements. For example, a limited ceiling height that doesn’t allow for an adequate thermal difference; or significant horizontal development of the building, which in turn blocks the inflow of outside air through the main volume; or small air losses distributed along the exterior walls, the sum of which interferes with a natural exchange of fresh air, blocking air flow in the lower part of the architectural volume.

In these cases it may be necessary to include some active air adduction or treatment systems in the overall project design. These should be appropriately sized with an eye to taking full advantage of the facility’s original, natural layout. In cases like these, employing active systems alongside natural ventilation must be understood as an auxiliary solution aimed at perfecting the efficiency of a natural solution, rather than substituting it, in order to conserve the economic advantages inherent to natural ventilation systems.

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It’s possible to create forms of make-up air and distribution at the center of the space, ultimately going so far as to integrate active cooling devices. One good solution is evaporative cooling, otherwise known as adiabatic cooling. This technique blends perfectly with natural ventilation from the point of view of thermal efficiency, as well as proving considerably more economical with respect to traditional air conditioning.

invernoIn many cases, natural ventilation can offer a solution, or at least make a contribution to, offsetting difficulties during the cold season as well. For example, by regulating as necessary the reintroduction of warm air mixed with colder air from outside it’s possible to realize (in addition to the exchange of air requested) a good level of environmental heating, thereby establishing a solution that’s valid year-round. In these cases, detailed calculations make it possible to identify the feasibility and technical effectiveness of the solution, while economic convenience is almost always guaranteed, since moving air masses is always less expensive than heating or cooling those same masses.

In the event the requirements for exchanging air should prove incompatible with maintaining indoor temperatures during the winter season, it’s possible to investigate integration with local forms of heating, which minimize heat dispersion due to exchanging air volumes.

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The design development of the solutions mentioned earlier is usually conducted by degrees, in part because the complexity of materials requires constant comparison with measurements taken on site, which in turn provide key indications for the next steps to take. In this manner, the final, definitive solution is often achieved by successive approximations. Among other things, this approach makes it possible to rationalize the investment appropriately.

More than a univocal technique, natural ventilation consists of a range of solutions which, blended together to a greater or lesser degree, make it possible to deal with the entire range of problems concerning air climate control in the workplace, all with an eye to optimizing energy resources.

The conditions necessary for an effective solution are, as always, the availability of real, truly representative calculation models and a detailed knowledge of the thermal conditions of the environment in question.

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