This represents a multi-task topic, because it involves several challenges arising from indoor environmental quality, building energy efficiency, and vernacular culture inheritance. Although China is proud of its vast territory and resources, it has experienced pressure from a low per-capita share of resources owing to its large population. A vulnerable ecological environment has stimulated the increase and improvement of environmentally friendly and energy-saving buildings. It is essential to inherit the vernacular culture during development of a sustainable habitat environment, rather than modifying it by building new but identical or even wacky architecture. This is an effective and widely-applicable approach to solving the above challenges, through adopting passive technology in building ultra-low energy consumption buildings. As a flexible approach, passive technology has excellent applicability in meeting demands of the environment, energy resources, and vernacular culture. This paper introduces a systematic study of passive design for ultra-low energy buildings. According to existing theory of passive design, the following two key aspects in the application of passive technology were addressed in the work. First, the feasibility of using outdoor climatic resources was investigated, to determine their upper and lower limit conditions for indoor heating and cooling, respectively. The second aspect is the development and optimization of building design strategies with the use of passive technology, to effectively use the heating and cooling capacity of outdoor climate. The fundamental concept of passive and ultra-low energy building design was conducted from these two aspects. The critical and most valuable contribution of this research is the reduction of building energy consumption by decreasing the demand for artificial heating and cooling facilities. This can be achieved by effectively narrowing the difference between human thermal comfort and outdoor climate, and enlarging the climatic interval size that the passive design technology is able to control. Regarding the practice of passive and ultra-low energy consumption buildings, through a combination of theoretical, experimental, in-situ and statistical analyses involving multiple disciplines such as architecture, building climatology and building environment engineering, we determined the regular pattern of human thermal comfort under natural climate fluctuation. We also developed a bioclimatic analysis tool based on the human thermal comfort demands, and climatic zones for passive design were defined accordingly. A thermotechnical calculation for passive solar heating design and a simplified indoor temperature calculation for nocturnal ventilation are proposed. These capabilities can quantitatively analyze problems in the Human-Architecture-Climate system. The proposed concepts and theories have been successfully applied to Western China, the Loess Plateau, an arid area of northwest Yinchuan, and the Sichuan earthquake zone. This work spreads the knowledge of passive technology and provides flagship models for further study.