It is evident from the above picture that each varga has assigned to one direction.

For exmple let us consider Aa varga, which is assigned to East direction. 
5th one from Aa varga is not recommended to construct house.5 th one from Aa varga is ta varga which is assigned to West direction.  Hence owner having name starting with Aa varga should not construct house in West direction.

7th and 11th vargas are good to construct house. For example 7th and 11th vargas fro Aa varga are North and South. Hence Owners having name starting with Aa varga is North and South facings.

One has to apply same formulas for other vargas as-well.