Effect of heat preservation and energy-saving by applying multi-layer thermal screen in greenhouse

The greenhouse was designed and constructed by reducing heating space measure. The ethylene-vinyl acetate copolymer(EVA)film and knitted glass mat as the material for heat preservation were selected. In the night，the temperature was measured in the greenhouse heated by water source heat-pump under different heat preservation measures. The effects of energy-saving were compared respectively in the parameters, temperature difference between inside and outside of the greenhouse, relative energy-saving ratio at the different heat preservation measures. The result showed: adding the first horizontal thermal screen layer(EVA) inside the greenhouse, the temperature difference between inside and outside of the greenhouse was increased by 1.9℃, and the temperature difference was increased by 1.7℃, 1.6℃ respectively by adding the second(EVA) and the vertical thermal screen layer(knitted glass mat) inside the greenhouse wall. Comparing with the condition without any thermal screen inside the greenhouse, the relative energy-saving ratio of the three kinds of heat preservation measures were increased by 20.34%, 31.78% and 40.53%, respectively and the return efficiencies of the investment of the three kinds of heat preservation measures were greatly higher than that in the modern agriculture industry.