A method of growing plants in which the plants extend in a growing chamber can include emitting light from a light source onto a foliage of the plants, the light source being positioned within a light source conduit having an inlet and an outlet, and the emitted light being transmitted across a transparent wall of the light source conduit to the plants, circulating air in the light source conduit, the air circulating in the light source conduit absorbing heat from the light source, and transferring at least some of the heated air obtained from the outlet of the conduit to the growing chamber, thereby conditioning the temperature in the growing chamber. Other methods of handling the air medium are also presented.
