The thermal adaptation of buildings and their residents is important in extreme cold climates for energy saving building design. A thermal measurement and a thermal comfort survey were conducted in traditional houses during the winter in the extreme cold climate of the Himalayan region of Nepal. Measurements were taken in 9 houses over 7 days to assess the thermal environment. Thermal comfort surveys were conducted over 4 days, and a total of 1,584 thermal responses were gathered from 36 residents. Passive heating effects were found in houses with thick brick walls and mud roofs. Residents of these houses were highly satisfied with the thermal environment, with 10.7 degrees C being the mean comfort temperature, which was related to the indoor temperature of the investigated indoor spaces. It can be concluded from these findings that people are well adapted to the thermal environment of traditional vernacular houses, as a result of which the comfort temperature is lower than the thermal comfort standards. Consequently, a significant amount of energy can be saved by passive building design and lowering the indoor temperature setting for heating. (C) 2020 The Author. Published by Elsevier B.V.