Many people put their bedrooms in their cellars. From Fengshui aspect, such arrangements are very harmful for the lucks of the household.
A cellar is a place which collects Yin energy in the house/building, therefore it is normally cold and moist. According to Fengshui, Yang energy rises up, and Yin energy falls down. Many kinds of pollutant are also Yin materials, so a cellar accumulates also much pollutant. Man spends about 1/3 of his life time in his bed room. A bed room is a place where man gets rest and recovers his energy. The environment of a bed room should be clean, comfortable and have harmonic Yin Yang relationship to be good for the health of bedroom users.
The space of a cellar is normally big. Man should not waste it. Man can use it as storeroom or other function rooms which man don't have to spend much time in. Even though man doesn't use for daily activity or resting, man should often let a cellar receive sunshine and fresh air and keep it from darkness as much as possible. Putting some auspicious things in it can also help to defuse the Yin energy in it.