A greenhouse is a structure designed to provide a protected, controlled environment for raising plants indoors. It is made of glass or a clear plastic that transmits the Sun's light and traps its heat. Large commercial greenhouses raise and sell flowering plants and vegetables out of season. Often such greenhouses use sophisticated technique for controlling the levels of heat and light, both natural and artificial, and have complex systems for watering and feeding plants. Greenhouses built to supplement a home garden are increasingly popular. Situated against the south wall of a house, a greenhouse may share its heat with adjacent rooms on sunny days and borrow house heat at night. A solar greenhouse, built on an insulated foundation and equipped with a curtain to cut heat loss at night and with walls or a floor containing built-in heat storage units (such as tanks of water or heat-absorbing masonry), can heat itself solely from the Sun and can retain heat for up to a week of sunless days.
Greenhouse in tropical climate
Beside in the subtropical, greenhouse also exist in tropical climate, the function of this greenhouse may different for each climate conditions. In subtropical climate greenhouses are purposes for keep Sunlight when there is no Sun. But this propose is different when in tropical climate, in tropical sun always available even in rainy season. Greenhouse can function to detain rain avoid too much water to the plant, because some of plant don't like too much water, even died if too much water. In tropical climate greenhouse also function for detain from many pest. Greenhouse in tropical climate should use an open and closed system to release heat from inside.