Ensuring optimal conditions for day-old broiler chicks upon arrival is crucial for their welfare, growth, and global performance of the farm. One fundamental good practice to achieve this is by preheating the poultry house, which helps create a stable and comfortable environment before chick arrival. Without adequate preheating, chicks may experience cold stress, leading to poor feed and water intake, reduced growth, and increased susceptibility to disease. To implement this practice effectively, the poultry barn must be heated several hours (36 hours), and often days (3 days) before chick arrival, depending on external conditions and barn type. This ensures that not only the air but also the litter and floor reach the target temperature, optimizing the thermal comfort of the birds. To effectively implement preheating, the farmer follows a precise heating schedule to ensure a gradual and uniform temperature increase (e.g. at day-3: 25°C, day-2: 28°C, day-1: 30°C, day 0 (chick arrival): 32.5°C. This stepwise approach prevents thermal shock and ensures that both the air, the litter and the concrete floor reach a uniformed temperature. The preheating costs around €700 of gas per batch per broiler barn in winter, or an average €500 per batch per house throughout the year. This represents around €14,000 a year for the farmer (a farm with two barns of 1350 m², for 27,540 chickens each). Nevertheless, it results in a more uniform flock from day 1, more active animals, lower mortality, fewer colibacillosis (E. coli diarrhea) infections, and therefore a +10% of gain per year.