Modern buildings are associated with a lot of shortcomings, such as consumption of an excessive amount of non-renewable energy and resources, environmental pollution and depletion of natural landscapes, etc. Vernacular buildings can be argued to help in reducing environmental problems for local society. Libya, as a developing Arab country, has also faced several urbanization problems in recent years. However, the country has a remarkable span of vernacular architecture patterns. Vernacular architecture that the country owns may be a solution to combat such challenges. There are three types of traditional vernacular dwellings in three regions of the country as underground housing (the mountain region), compact dwelling (the desert), and the courtyard house (coastal region). Thus the aim of this study is to make a comparison between underground and modern housing in Gharyan, Libya, with regards to thermal performance and humidity. Thermal performance in both underground and above ground houses was measured with an instrument called a hygrometer. The result from the thermal measurement that was done in one month of the winter season (21/01/2019-18/02/2019) demonstrates that the underground house has an indoor mean temperature and humidity of 16.12°C and % 62.07 RH while the other house type has an indoor temperature and humidity of 12.70°C and % 70.13 RH. The underground house seems to have a relatively reasonable and stable indoor temperature compared to the modern house indoor. In addition, the underground house seems to be relatively less humid compared to the modern house for indoor environment in particular.