Abstract: The present invention in an energy conserving greenhouse involves an insulated and opaque structure whose inner walls are preferably formed, coated or colored to reflect visible light striking thereagainst onto plant surfaces therein, the structure utilizing a shuttered lense arrangement of minimum dimensions, that is open during daylight hours to pass sunlight from a focusing solar collector, that sunlight passing through an infra red trap to heat a material therein, that heat being removed for immediate heating of the structure and/or storage for later heating thereof, the remaining sunlight spectra, including the visible spectra passing therefrom and to a diffuser that directs and disperses it throughout the structure interior.