Abstract
Ceiling radiation heating using solar heat system that makes use of hot water produced in a solar heat collector, kept in a heat storage tank and sent to ceiling radiation panels above a living room. Tests have been conducted not only on ceiling radiation heating but also on the joint heating with floor heating and heating by a conditioner, as the heating capacity of ceiling radiation heating dependent solely on solar heat was insufficient. The authors have obtained information on assessment of comfortableness of ceiling radiation heating by residents in an experimental house through a questionnaire.