The lower the thermal conductivity of the same insulation material, the thinner the design thickness, the lower the cost, and the fewer design problems of the joints. If the thermal conductivity is greater, the required thickness is greater, the possibility of molding products is smaller, and the cost is higher. External wall insulation materials should have good stability. If used in engineering, the board is prone to warping and deformation, which is easy to cause cracking and leakage of external wall decoration. Such as rock wool composite board, extruded polystyrene board, phenolic board, polyurethane insulation board, etc., the board must be obtained to achieve a reasonable aging cycle to avoid the board deformation caused by cracking and shedding of the system to the maximum extent

When the external wall insulation material absorbs water, the insulation performance will be greatly reduced. Therefore, the insulation material used in this project should have low water absorption. At present, rock wool board, phenolic board and traditional insulation mortar are all highly absorbent materials, and the actual insulation performance is far from the theoretical effect. It is conducive to improving the quality of the room temperature environment. Due to the large heat capacity of the internal solid wall, the change of indoor temperature can be slowed down after adding the insulation layer. Stability at room temperature is conducive to energy saving. In summer, external insulation can reduce the heat transfer from the sun and the impact of high outdoor temperatures, making the building warm in winter and cool in summer.

In order to prevent condensation, the inner insulation layer should be provided with an air layer, the outer insulation layer should be free of air layers, and the insulation material is protected from moisture under the protection of the outer wall surface layer. At the same time, the outer insulation layer raises and lowers the overall wall temperature of the structural layer, and its humidity increases the thermal insulation performance of the wall. Outside the exterior wall insulation material, the commonly used asbestos fiber and cement mixture is used as a protective layer of the asbestos cement shell. Its function is to protect the exterior wall insulation material and prevent moisture from entering the exterior wall insulation material. The waterproof layer is usually made of felt, iron or oiled glass cloth.

Commonly used insulation materials in exterior wall insulation material projects include asbestos, rock wool, perlite, glass wool, foam rubber, polyurethane rigid foam and other products. The thickness of the exterior wall insulation material varies with the diameter of the insulation pipe. For example, the thickness of the exterior wall insulation material of the air conditioning duct is usually 20mm thick. At the same time, the insulation thickness of the insulation pipe should meet the design requirements, and the thickness tolerance is 5-10%.

The calculation formula in the "Guidelines for Insulation Design of External Wall Insulation Materials" is determined. This standard clearly stipulates that in order to reduce the heat loss of the insulation structure, the thickness of the external wall insulation material layer should be calculated according to the economic thickness method. Taking into account the two factors of capital investment in the pipeline insulation structure and the annual operating cost of the pipeline heat loss, the economic thickness is the insulation when the annual cost of the insulation structure is the minimum. Thickness. The optimal insulation thickness corresponding to the minimum time is the economic thickness. In Zhongdu, the insulation layer is thinner, the annual heat loss cost increases, and the total investment cost of the insulation structure decreases.

The external wall insulation material laid outdoors and in the trench has good waterproof and moisture-proof properties to prevent heat loss. In the design, it should also be considered that the thickness of the insulation pipe increases with the increase of the heating area of the pipe network.