A fan is attached to the roof for ventilation purpose on a sunny day! When we first step into the long roofed house, I felt that the interior of the house is cooler compared to the exterior and the fan was not even ON! I think it is because of the materials that were used to built the house itself and also the ceiling of the roof is high enough that it provides maximum ventilation. There are also lighting attached to the house for night usage when there is no natural lighting.