Grant: Idea to Innovation

Existing greenhouse agriculture requires significant energy use for temperature control in most climate conditions because it has not been viable to use insulation for temperature moderation. The use of insulation generally blocks out sunlight, and supplemental artificial light consumes large amounts of energy that is prohibitively costly today, and will be increasingly so in the future. As a result, greenhouses today are transparent structures that let in sunlight and require significant amounts of energy for temperature control. The challenge is to develop a greenhouse that can be highly transmissive to sunlight, as well as highly insulated to maintain a desired temperature inside. We have developed an energy saving, inexpensive variable canopy system for greenhouses that can be switched between two states - in one state the system acts as a sunlight transparent window and the other state the system acts as a highly thermally insulated ceiling. This variable light transmission / thermal insulation canopy system uses readily available, inexpensive materials and the switch between the two states requires only a simple, low-cost rotation device. In this project, we will demonstrate and quantify the performance of this system to manage the internal temperature of a greenhouse within a range that is desirable for plant growth without the use of energy for heating or lighting. A full-scale system will be installed in an existing greenhouse facility and operated for one growing season and a scale-model version will be tested in a cold and sunny environment for a winter season. Together these two demonstrations will establish the potential of this system as the first truly practical and cost-effective variable light transmission / thermal insulation system for greenhouse food production.