An incubator is fitted with an enclosure which surrounds the incubator. A cold air generation system supplies relatively cold air to a space formed between enclosure and the incubator. The system supplying the cold air can be embodied in a cart or base upon which the incubator sits. The enclosure is also placed on the base in a manner such that it substantially envelops the incubator. The top of the cart has openings for egress of cold air and return of air so that air may circulate in a closed loop. The incubator, cold air supply system and enclosure present a solution for incubating samples in a nominal 20-25°C temperature environment. The enclosure, which is preferably insulated, may include a void or opening which exposes doors or other access device of the incubator, allowing direct access to the samples in the incubator while the rest of the incubator is enveloped by the enclosure.