This diagram shows how the 100% of energy used by a best-in-class lighting fixture is converted into heat and light. Convection heat radiates upwards and does not affect the crop. A certain amount of energy is converted into radiation heat. High levels of radiation heat can stress or even burn the plants. LED toplighting has low levels of radiation heat, and is therefor ideal for growing cold-loving crops like lettuce and herbs, for warm dark regions and for use in low greenhouses.