This refers to the action of anchoring the power of the Light in a particular place. This action, like that of baptism requires one called for the purpose. It requires that the individual performing the action be able to receive and transmit this power. Also, just like in the case with baptism, this individual cannot really be chosen by any religious organization unless he or she already comes with this gift.
Light surrounds the place consecrated and therefore prevents the encroachment of evil. If it is a place of worship, then the worshippers themselves are to contribute to the continued consecration of the place by going in there with a pure volition, never allowing evil thoughts to arise while they are in there. Such a place therefore is consecrated to the Light.