Due to the different types of greenhouse construction materials, their thermal conductivity and insulation properties are also different. Materials with relatively high thermal conductivity are prone to heat transfer. We usually refer to areas with lower insulation performance as "cold bridges". The cold bridge area is the main channel for heat conduction and also a place where condensation water is easily generated. They are the weak link in insulation. Therefore, taking measures to reduce the heat loss of the cold bridge is a means of energy conservation and heat preservation for greenhouse. A qualified greenhouse should pay attention to the treatment of these cold bridges during construction.
The gutter of multi span greenhouse has the function of connecting the roof and collecting rainwater and drainage. Gutters are mostly made of steel or alloy, with poor insulation performance and significant heat loss. The gutter occupies less than 5% of the greenhouse area, but the heat loss is more than 9%. Therefore, the impact of gutter insulation on energy conservation and insulation of greenhouse cannot be ignored. At present, the methods for insulation of gutters include using hollow structural materials instead of single-layer metal materials, and utilizing air interlayer insulation; The second is to apply a layer of insulation on the surface of the single-layer material gutter.
Compared to brick walls, underground ring beams and the ring beams at the top of low walls are also areas that transmit heat outward. In addition, when the thickness of the wall is not large, the underground soil layer is also an important channel for heat loss at the foundation. Therefore, in the construction of greenhouse, laying insulation layer (5cm thick foam polystyrene board or 3cm thick polyurethane foam board) outside the foundation and short wall is a good measure to maintain the ground temperature in the design and construction of greenhouse in the north. For solar greenhouse or vegetable greenhouse, cold proof ditches with a depth of 0.5-1.0m and a width of 0.5m can also be dug around the greenhouse along the foundation and filled with insulation materials to cut off the loss of ground temperature.
