Abstract: A growing room for providing a controlled growing environment comprises a thermally insulated, light-transmissive inner enclosure (8) for containing the controlled growing environment (4). The inner enclosure 8 encloses, in use, a controlled atmosphere for the controlled growing environment (4). A light-transmissive outer enclosure 6 surrounds the inner enclosure (8) and is arranged to protect the inner enclosure (8) from the external environment, in use. A ventilated cavity (10) is defined between the out er enclosure (6) and inner enclosure (8). The outer enclosure (6) has at least one lower ventilation opening (11) and at least one upper ventilation opening (12) for allowing controlled ventilation of the ventilated cavity (10).