Nature fumigation did not correlate literally with energy usage. But a fumigation system should cost substance and energy to implement. Traditional fumigation, such as book fumigation, should close the whole library to spray fumigant toxicity. This way is not environmental protection, also cost time and labors.
Nature fumigation adopts to inject high density nitrogen into a gas tight room. The nitrogen is from our air. After fumigation, the nitrogen can be release to the air without any chemicals and have no any pollution with the environment.