2017 Volume 66 Issue 2 Pages 163-171
Former investigations on the indoor environment of facilities for the elderly showed that the indoor relative humidity is not satisfactory for the standard of Act on Maintenance of Sanitation in Buildings (40- 70RH%). It is important to keep humidity adequate in facilities for the elderly in order to control influenza infection. However, humidifiers are not installed in the air-conditioning system in most facilities. In order to keep humidity high, many portable humidifiers are used, but the humidity is very low. The main factor of this low humidity is thought to be high ventilation rates.
With consideration in these characteristics of indoor environments in facilities for the elderly, the index of influenza air-borne infection risk is proposed using absolute humidity and ventilation rate a person. A method is proposed to improve indoor humidity considering relationships between energy consumption and influenza air-borne infection risk. The results of estimation on these investigated facilities showed that influenza air-borne infection risks depends on ventilation rate a person, because humidity is very low and the possibility of preventing influenza infection by high humidity is also low in all facilities.
The results of studies on the improvement of indoor humidity using above estimation, highlighted the following guidelines. 1) It is necessary to reduce ventilation rate a person with the consideration of indoor pollution such as odor, and 2) It is necessary to insulate openings to prevent vapor condensation.
