For a humid room with low natural ventilation, what is the most economical solution?

In a humid room with low natural ventilation, the most economical solution is the installation of an exhaust fan. This is because an exhaust fan effectively removes humid air from the room, helping to lower the humidity levels. By expelling the moist air, it allows for drier air to enter, which is crucial in maintaining a comfortable environment. The exhaust fan functions continuously or on a timer, ensuring that humidity is consistently addressed without the need for additional equipment or energy-intensive systems.

Other options, while they may serve some purpose, are not as effective in this specific situation. A humidifier would actually increase humidity levels, which is counterproductive for a humid environment. A ceiling fan would circulate air but would not remove humidity, so it may not significantly improve comfort in a humid space. A ventilator can introduce fresh air but might not effectively expel the moist air or bring in sufficient air changes to significantly reduce the humidity. Therefore, using an exhaust fan stands out as the most cost-efficient and functional solution for controlling humidity levels in such conditions.