Introduction: There have been several studies on the effect of housing environment on children’s health. In particular, health concerns stemming from children’s lack of physical activity and lower body temperature are becoming an issue in Japan. Because children have a larger body surface area-to-weight ratio than adults, the body temperature of children is more strongly affected by the thermal environment in houses. In this work, we examined the effect of the indoor thermal environment on children’s body temperature.

Methods: A questionnaire survey among 143 parents of children who attended a kindergarten. The questionnaire asked respondents to evaluate the indoor thermal environment in winter (living room, bedroom, dressing room) and the children’s lifestyle. In addition, we measured room temperature at kindergarten, physical activity and body temperature of the children.

Results: Children who live in warmer houses, meaning that they seldom or never feel cold, have a higher body temperature. Children who attend warmer kindergartens, such as those with no difference in temperature between rooms, have higher intensity of physical activity. Multiple regression analysis shows that improving the thermal environment in the bedroom increases body temperature by 0.07 °C.

Conclusion: The thermal environment in the home, particularly in the lavatory, affects children’s body temperature. The children whose body temperatures were low undertook less physical activity at the kindergarten than the normal body temperature group.