When it comes to bulbs most of the energy is lost from the tip which is why for instance in the low pressure sodium ( most effecient light at 200 lumens per watt) Phillips in the Netherlands puts on a IR coating on the tip insulating iit. They used to use tin back in the day which produces a blue spectrum but the IR coating according to them produces a 15% red with the pure yellow of the gas

Any clue way each day I am having posts erased?