he next principle is repairability,

he next principle is repairability, the core component of many existing buildings. It states that repairing architectures is in preference to rebuild ones. For instance, a broken wooden window can be repaired (Carroon, 2010), which is as the same as buildings. In contemporary society, few houses are torn down, people prefer to renovate buildings or transform the facades because the expenditure of rebuilding and the negative effects on surroundings are huge (Carroon, 2010). The building should be torn down at first, and then it has to be reconstructed which will make large noise to nearby residents. However, if the function of a building changes, workers could only rebuild rooms which need to be changed without changing the whole structure of the building. This is a method that can not only save the cost but also reduce the workload of workmen. From this, a new conception, ‘down-cycling’, is mentioned. It is different from cycling. Down-cycling means that a material has lost its original functions but has other basic functions with lower qualities, while cycling is the product can be reused as the same product. When being used in reality, those hard produced energy resources can be used in different ways several times with another format, such as greywater (AI-Jayyousi, 2004). Passive survivability, the last principle of eco-architecture, emphasizes that even when the energy of the whole building breaks down or the modern systems are unable to work, the building can still operate (O'Connor, 2015). There are several aspects to obey the principle of passive survivability. Natural ventilation is a requirement no matter in traditional buildings or green buildings. So buildings should not only rely on the mechanical systems, but also utilize the groups of windows and doors to get fresh air. The second is natural illumination which makes the sunlight as much as possible rather than using electric pumps to keep light. Nevertheless, an eco-building should have a homeostatic function to keep warm in night and winter and keep cool in day and summer.In contemporary society, many buildings become more friendly ecological according to the three principles. Here are three applications which reflect all the principles of eco-architecture.