<p> The aim of this study is to verify the annual characteristics of indoor environments in facilities for the elderly in cold regions. The temperatures, humidity and CO₂ concentrations were measured in rooms and common spaces of 4 facilities for the elderly in Finland Espoo and 4 facilities for the elderly in Hokkaido Sapporo through a year. At first, the daily characteristics and the annual characteristics of indoor environments were analyzed. Secondly, the required humidification rate to control the indoor relative humidity to meet 40RH% (SEHMB: Standard for Environment and Health Management of a Building) were calculated using the results of the long-term measurements. The required humidification rates on condition that carbon dioxide concentrations are same as the measured concentrations and the rate on condition that the concentration controlled to 800ppm were calculated and the results of Finnish facilities and those of Hokkaido’s facilities were compared. Thirdly, the energy loads for ventilation and humidification and the influenza concentrations were calculated with these conditions on ventilation. The results showed the followings.</p><p> 1. In winter, the outdoor temperatures of Finnish facilities are not so different from those of Hokkaido’s facilities. However in mild or cooling seasons, the outdoor temperatures and absolute humidity are higher in Hokkaido than in Finland.</p><p> 2. Temperatures are well controlled in winter by floor heating systems in both Finnish facilities and Hokkaido’s facilities.</p><p> 3. Even if the portable humidifiers were used in Hokkaido’s facilities, the humidity is lower than the standard 40RH% .The indoor humidity is lower in Finnish facilities and the indoor absolute humidity is same as the outdoor in Finnish facilities where humidifiers are not used at all.</p><p> 4. In summer, the absolute humidity decreases in Hokkaido’s facilities where cooling systems were used in the common spaces. However the absolute humidity did not decrease in Finnish facilities.</p><p> 5. The concentrations of carbon dioxide were enough lower than the SEHMB 1000ppm in all facilities. The concentrations change with the dwellers behaviors especially in Hokkaido’s facilities where they open windows and operate ventilation fan in order to control smell and risk of influenza infection.</p><p> 6. Because the ventilation rate are kept higher in Finish facilities, the risk of influenza infection is lower in Finish facilities than in Hokkaido’s facilities.</p><p> 7. Because heat recovery systems are used in Finish facilities, the energy load of humidification and ventilation is kept lower in Finish facilities.</p><p> These results showed that it is necessary to control both ventilation and humidification considering energy loads and influenza infection risks.</p>