Ventilation is a key issue for underground facilities. The ventilation is needed to provide breathing air to personnel in the facilities, to provide good air quality by removing atmospheric contaminants such as gases and dust, to provide air conditioning (cooling/heating) for personnel in the facilities, and to provide oxygen and cooling for operating vehicles in the facilities. Electrical power to provide ventilation in an underground facility is one of the main components of the total power consumption in that facility. Depending on the surface climatic condition and the depth of the facility, air conditioning (heating/cooling) might be required. In a sub-arctic climate region such as in northern Sweden, the air has to be heated to prevent freezing airways and to provide a comfortable condition for the personnel, and when the facility is at a great depth (> 1000 m), due to high virgin rock temperature, the fresh air usually have to be cooled, like in deep mines in Australia, Canada, and South Africa. In Swedish deep mines, currently heat is not a serious issue, but it might become one in the future as the mines get deeper. The electrical power consumption can comprise up to 40% of the total underground mine power consumption, which is a significant proportion. This feasibility study consists of a survey among the mining companies and tunnel owners (such as Trafikverket) and the universities that have done research and design projects within the field. The project has identified the current knowledge within this area, and the gap between the technology/practice used currently and the available technology, and the potential for further improvements in the future. A review on ventilation system in other areas such as buildings and farms was also carried out in order to identify any of its technologies that can be employed for improving ventilation system in underground facilities.