2. What you ask is which door picks the stars, but it is actually a question of opening a room.
3. This problem did not exist in previous residential houses and single-family houses. Now this problem is complicated because of the phenomenon of "multiple households on the first floor" or even "several doors on the first floor" in urban housing.
4. If it is a single-family house, including an independent small courtyard, it usually faces the door and takes the courtyard door as the air inlet. But the two are often the same in most cases. If the orientation of the courtyard door is inconsistent, or the fence of the courtyard door is a fence, or there is another garage door in the house, or there is a separate kitchen in the front of the house, it is necessary to take the door of the house (not the courtyard door) as the orientation and the courtyard door as the air inlet.
4. If it is a unit building or a commercial building, I think, generally speaking, it depends on whether the door of the building is consistent with the door of the residents. Accurately speaking, it depends on whether the wall where the door of the building is located is consistent with the wall where the door of the household is located. If it is consistent, it should be the entrance of the building. If it is inconsistent, it should be guided by the door of the residence. On the other hand, if the wall of the household is in the same direction as the wall of the whole building, it should also be oriented by the building door. However, some commercial and residential buildings are not square in design because of the orientation of land use or accommodation, and the four walls of some unit houses are not parallel to the four walls of the main building. At this time, they can't be guided by the door (entrance) of the building, but by the door of the resident. In addition, they can be oriented through the main wall of the residential sunrise. Because modern architecture transcends the traditional architectural pattern, there is no conclusion in this respect, and Mr. Feng Shui of Hong Kong and Taiwan Province also has his own opinions.
Some buildings have two or even three doors (entrances). If you need to use the door of the building for orientation, you should choose the main entrance, which is generally a door with many people coming in and out, rather than a door that can be opened at will.
Finally, I don't think the orientation of the flying star has any scientific basis for the "good or bad" housing. What I said above is only an introduction to the statement of Feng Shui Master (Mr. Feng Shui).