The current authors carried out a field measurement survey on indoor thermal environment in nine Chinese cities. Based on this investigation, the purpose of this present study is to develop a database of actual indoor humidity conditions for moisture moderate design, through which the characteristics of indoor humidity environment in Chinese residential houses can be identified and clarified.
The results demonstrated that the indoor humidity level is too low with the relative humidity falls below 20 % in some cities where residences equipped with central heating system in winter. On the other hand, indoor humidity is very high with the relative humidity beyond 80 % in some cities where residences have inadequate heating and high outside humidity ratio in winter. The severe indoor humidity environment indicated that the moisture level in the residential houses of China should be mitigated and controlled in order to achieve a sustainable and healthy indoor environment.