VALDEMANZANAS

One of the factors that most influence the design of a farm is the ventilation system that will be installed, as well as the buildings’ structure type, as they are elements that interfere with the management and well-being of the animals. Based on this objective, the CADA team of engineers opted for an automated forced ventilation system to build the new Valdemanzanas pig farm in the Saragossa municipality of Ejea de los Caballeros. This decision, unlike the choice of natural ventilation, makes it possible to build larger buildings to optimise the cost of the structure and make the best use of the land occupied.

The other appreciated building element in the design of this animal husbandry installation is the roof. A good choice helps preserve the internal comfort parameters in terms of temperature, humidity and thermal sensation, reducing to a minimum energy losses and thus reducing air-conditioning costs. “The humidity and temperature values define the operation of the ventilation and air-conditioning system of the farm area. Inside temperature must remain within values that range between approximately 21 and 28 °C. Under the minimum level, the minimum ventilation systems must kick in to control humidity, the ventilation flow increases as the ambient temperature rises, over the maximum level, the ventilation is not sufficient and cooling must operate at 100% capacity” is the explanation given by the CADA engineers.

For this reason, they chose building materials that guarantee a good level of thermal insulation and reduce thermal bridges to a minimum. “Approximately 25% of the total area that comes into contact with the outside air corresponds to the warehouse’s envelope walls, while the roof’s surface represents 75%. In addition, there are always essential elements on the walls that interrupt the continuity of the insulation: air extraction windows, access doors, spaces for the passage of equipment, etc. This is why it is more important to have good insulation on the roof”, say the engineers.

To build the warehouse’s roofs - of a total surface of 16,000 sq.m. - the engineers opted to use ISOPAN’s ISOVETRO PLUS EXTREME system which, with a steel 5-rib panel, offers high mechanical resistance and optimal maintenance of the roof during its useful life. The insulating panels, thick by 50 mm, were arranged at a slope of between 20 and 30%. The core is in polyurethane, while the steel sheets have an outer coating adapted to aggressive environments with a high concentration of ammonia and humidity, and another for the inside, made with a fibreglass sheet. These special Isopan finishes help improve the durability of the panels against interior and exterior aggressive environments.

The sandwich panel’s assembly system makes it possible to seal the joints and, in this way, minimises losses through them, at the same time providing continuous insulation thickness on the entire surface. This ensures a good seal which stops the passage of both water and humidity and that of gas, thus contributing to the efficiency of the ventilation system. “For example”, explains CADA, “we observed that, in the early morning, the condensation water on the sheet roofs is evacuated by the air humidity. We did not observe this phenomenon in other types of roof built with more porous materials, such as fibre cement, whose part of this humidity seems to be absorbed by the roof”.

Other than meeting the project’s resistance, durability, impermeability and insulation requirements, sandwich panels have also proved profitable, as, given that they can be installed quickly, the investment in the work was recovered earlier compared to the hypothetical situation in which another material had been chosen.