How to do external wall insulation of buildings?

1, insulation is very difficult to do, and it is even more difficult to do it inside. You still need to find a professional to do it. And it won't save you much money on heating and air conditioning. Even, the money you spend on heat preservation is enough for your heat preservation or air conditioning electricity bill 10 years. 2, insulation, the key is that the wall thickness is enough, you use light insulation profiles to do it indoors, which will inevitably lead to a decrease in the available area. 3. The big window is the biggest challenge of heat insulation. If you really want to keep warm, first make the window smaller, and then use hollow low-e glass, which can reduce the temperature transfer. 4. There is no need for thermal insulation between neighbors. Thermal insulation is aimed at external walls. 5, insulation layer, should be the construction stage, now the construction in the outer wall, it is of little significance. In particular, thermal insulation materials are not environmentally friendly, and if they are done indoors, the harm to the human body will be less. Therefore, indoor thermal insulation materials are not recommended. At most, you can put the outer wall inside and build a brick, but this will reduce the space too much.