A passive solar greenhouse can be used to grow plants year round. The green house lets delicate plants that would normally be damaged by frost or freezing temperatures to continue to grow. Instead of relying on expensive gas or propane heat, this greenhouse stores heat gathered from the sun by day to keep the plants warm and growing at night when the temperatures drop.
While gas heated greenhouses work well to keep plants from freezing, they are not well insulated and can be very expensive to keep warm enough to protect those plants from the freezing weather. Passive solar greenhouses can be built at about the same cost as a traditional greenhouse, but feature insulated walls and a large mass to store solar energy. This mass could be water, rock or concrete.
With the traditional greenhouses orientation is less important than for those that rely on passive solar heating. Since only one wall allows light and heat to enter the room, it needs to be oriented toward the sun to take the most advantage of its rays. The sun is then able to warm both the air in the greenhouse as well as the solar mass.
In the warmer months it is possible for the temperature of any greenhouse will become too warm for the healthy plants to grow. It is important that you have a ventilation system that can bring in cooler outside air. Thermostatically controlled fans can be set to turn on at a certain temperature and prevent overheating of the greenhouse.
Using a greenhouse can allow you to keep fresh produce on your table year round. You can know that all the produce is organic and has had no chemicals applied as you are in control of what has been added to your plants.
The cost to build a passive solar greenhouse is about the same as the cost to build a traditional greenhouse. The savings in energy consumption is enough to offset any additional construction costs.