HVAC
LIVESTOCK
VENTILATION
Air distribution in a heated building
with recirculation fans
CLIENT
Specialist in ventilation and heating systems for livestock buildings
CHALLENGE
Hold a minimum of 33°C through the coldest periods without cold spots, stratification or uneven ventilation
RESULT
Internal temperatures between 34°C and 40°C, effective circulation, and margin left for harsher weather outside
01
CHALLENGE
In a large livestock building the internal microclimate is not a comfort question but a production one: it governs animal welfare and the efficiency of everything that happens in the building.
Through the coldest periods the building has to hold a minimum internal temperature of about 33°C, and hold it everywhere — without cold spots, without warm air stratifying under the roof, and without the ventilation reaching one end of the building better than the other.
The system under analysis heats with a hot-air burner delivering air at around 78°C through a supply duct, while six internal fans recirculate the air through the space.
02
SOLUTION
We built a complete three-dimensional CFD model of the building, including every main component of the installation: the shell, the floor, the hot air supply duct, the return duct and all six recirculation fans.
The simulation accounts for heat exchange through walls, roof and floor, realistic external weather, and the flow field the ventilation system itself generates. Internal wall temperatures were derived from the thermal balance of the building — transmission through the envelope, with an external convection coefficient computed for moderate wind — and the floor was modelled exchanging heat with ground at 10°C.
The heating is a burner of roughly 252 kW, sized to compensate the losses through side walls, roof and floor.
The model resolves velocity, temperature and static and total pressure through the whole volume of the building. Control sections were taken along all three axes — down the length, up the height, and around the supply and return ducts — so the flow can be read where it matters rather than averaged into a single number.
03
RESULTS
The simulations show the system generating effective circulation through the building. The recirculation fans produce a flow field that mixes the hot air from the burner with the air already in the space, which is what keeps stagnant zones from forming.
On temperature: the mean internal temperature exceeds the 33°C required, the heat delivered is sufficient to hold the target conditions, and the system retains operating margin for colder weather outside. Virtual measurements taken at points through the building give temperatures averaging between 34°C and 40°C, depending on position and height above the floor.
The streamlines show the fans generating a global circulation involving the entire volume of the building rather than a set of local eddies near each unit.
The analysis confirmed that the internal ventilation distributes the air well, that the burner is powerful enough to hold the required temperature, and that the fan configuration mixes the air correctly — all of it established before installation rather than after.
