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Abstract
Single-slope, energy-efficient solar greenhouses in China use solar energy as the sole source of light and heat for winter crop production in the region between latitudes 32°N and 43°N. The use of solar greenhouses has greatly reduced energy demand and carbon dioxide (CO2) emissions. Solar greenhouses are the best structure for growing winter horticultural crops in China, and have been adopted by countries such as Japan, Korea, and Russia. Increased proliferation of efficient solar greenhouses in China may contribute to solving worldwide problems such as the energy crisis and global climate change. This article summarizes the structure, function, application, and ecological benefits of energy-efficient, single-slope solar greenhouses in China, based on 20 years of systematic studies. We hope this technology can be applied to regions of similar climate to help reduce energy consumption and CO2 emissions.
Protected horticulture production has a long history in China, and the earliest recordation is written in the Hanshu in the Han Dynasty (206–23 BCE) (Jiang et al., 2004; Zhang, 2005). In recent years, new solar greenhouse technology has been developed in China. These greenhouses play a vital role in China's vegetable production in winter. There are several different types of solar greenhouses, including the single-slope solar greenhouse. These are built facing south. The support and insulation walls are on the north, east, and west sides. A short roof is installed on top of the north wall. The south side is supported by metal or bamboo frames or a mixture of both, and is covered with plastic film and an insulating blanket. This type of greenhouse uses solar energy as the sole light and heat source for winter crop production (Figs. 1C and 2, A and B) and is unique to northern China. These greenhouses are used to produce warm season crops such as tomato (Solanum lycopersicum) and cucumber (Cucumis sativus) during the winter without using other forms of heat, in locations at latitude 32oN to 43°N.
The light and temperature conditions in solar greenhouses are controlled by solar energy. The feasibility of using such a structure largely depends on the relative duration of sunshine in the winter and the low temperatures at the greenhouse site. Solar greenhouses are widely...