Floor heating is characterized by small horizontal and vertical temperature differences, and might be especially suitable for Japanese homes where it is customary to sit on the floor. This paper compares thermal comfort in homes while floor heating systems and air conditioning systems were in use during winter. Each dwelling had both a floor heating system and an air conditioning system, each used on alternate weeks during the survey period. Throughout the survey periods residents were asked about their current thermal sensation, thermal preference, overall comfort and foot-comfort. Air temperature, globe temperature, humidity and floor surface temperature were recorded. More than 6,000 were collected from 50 dwellings. The results showed that a floor heating system was preferred, and that it was more effective in providing a comfortable environment.