Earth-air heat exchanger best way to protect animals in livestock buildings against climate change

The higher temperatures resulting from climate change will require certain measures to be taken in pig and poultry production. Without suitable cooling systems, animals kept in confined livestock buildings would face increased heat stress. That would have a negative effect on the wellbeing of the animals. And, as a result of lower feed conversion or egg production, it would also have an economic impact.

A comprehensive study conducted by Vetmeduni Vienna, BOKU and ZAMG has now shown that the usual cooling systems, such as earth-air heat exchangers or direct and indirect evaporative cooling, some of which have been established practice since the 1960s, are good choices for cooling livestock buildings. Apart from the investment costs, an earth-air heat exchanger is the most efficient system. In an EAHE, outside air flows through tubes with a length of about 40 m, buried at a depth of about 2 m. The systems works somewhat like a cellar, which is cooler in the summer and warmer in the winter.

Earth-air heat exchanger better than evaporative cooling

The heat stress on animals from temperature and humidity can be measured using the so-called temperature-humidity index. These parameters have been established for people as well as for many farm animals and they are an important factor for determining which cooling systems best protect animals kept in confined livestock buildings from heat stress.

Three common cooling systems, all of which also find use in residential situations, were examined as part of the study. One system cools the air by using the earth for heat storage, the other two systems cool via the direct or indirect evaporation of water. “These two systems function in a similar way as swearting. The indirect method, however, also uses a heat exchanger to avoid humidification,” as study director Günther Schauberger explains.

“Our calculations showed that an earth-air heat exchanger is the most efficient system for confined livestock buildings. The method cools the air accordingly during the summer. And heating the inlet air in winter significantly improves the flow rate and thus the air quality in the building,” Schauberger says. “This makes is possible to completely avoid heat stress for the animals.”
Direct evaporative cooling, on the other hand, has the disadvantage that cooling the air also results in increased humidity. The indirect method avoids this disadvantage, but the cooling is less efficient. “In the end, however, you also have to consider the investment of such an air preparation system, which we did not include in our analysis,” says Schauberger. The study was conducted as part of the Austrian Climate Research Program.

The article “Modelled performance of energy saving air treatment devices to mitigate heat stress for confined livestock buildings in Central Europe“ by Ronja Vitt, Lutz Weber, Werner Zollitsch, Stefan J. H€ortenhuber, Johannes Baumgartner, Knut Niebuhr, Martin Piringer, Ivonne Anders, Konrad Andre, Isabel Hennig-Pauka, Martin Schönhart and Günther Schauberger was published in Biosystems Engineering.

About the University of Veterinary Medicine, Vienna
The University of Veterinary Medicine, Vienna in Austria is one of the leading academic and research institutions in the field of Veterinary Sciences in Europe. About 1,300 employees and 2,300 students work on the campus in the north of Vienna which also houses five university clinics and various research sites. Outside of Vienna the university operates Teaching and Research Farms. The Vetmeduni Vienna plays in the global top league: in 2017, it occupies the excellent place 8 in the world-wide Shanghai University veterinary in the subject „Veterinary Science“.

Scientific Contact:
Günther Schauberger
Unit of Physiology and Biophysics
University of Veterinary Medicine Vienna (Vetmeduni Vienna)
T +43 1 25077-4574

Released by:
Georg Mair
Science Communication / Corporate Communications
University of Veterinary Medicine Vienna (Vetmeduni Vienna)
T +43 1 25077-1165

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