In a non-empirical sense, a lightbulb produces as much heat as light. You will surely feel its warmth by sitting next to it when it is placed in the lamp. The important thing to note here is that your outlet and installation must be able to handle such a large thermal load. Just thought I could stick it in a table lamp and the switch to turn it off got too hot for a few seconds. Heat issues aside, the lamp emits plenty of light with a pleasantly warm color temperature.