Traditionally, in Palestine, outdoor spaces played a crucial role in organizing and improving the living quality of the living units, while this important role in modern housing design is lost by a stark separation between internal and pri- vate external spaces (balconies, verandas and yards). This separation is disconnecting private inside and outside spaces whereas in the traditional courtyard houses there was a continuity between the inside and the outside. This paper investigates the socio-environmental criteria and characteristics of private outdoor spaces that could play an improving role in the living quality of future housing design. So, a comparative study between contemporary and traditional outdoor spaces characteristics was carried out in two different cities in two different climatic zones of Palestine. The contemporary housing was evaluated by conducting a survey over 300 dwellings of different housing typologies (detached houses/apartment flats), while the characteristics of traditional design were analyzed from the old historical part of these cities. The results of this paper demonstrate that the private outdoor space is a major contributor to enhance housing sustainability. It presents the distinctive qualities of courtyard concept, which ought to be reintroduced consciously into the design of future housing in order to improve the living quality. The paper also identifies the most important factors that ensure those qualities and forms the basis for further research.