Humidity's Impact on Greenhouse Gas Emissions from Air Conditioning

Jason Woods, Nelson James, Eric Kozubal, Eric Bonnema, Kristin Brief, Liz Voeller, Jessy Rivest

Research output: Contribution to journalArticlepeer-review

50 Scopus Citations


The increasing need to cool the air in our built environment is both a cause and an effect of climate change. Air conditioning accounts for a large portion of global greenhouse gas emissions today, which we estimate at 3.9%; however, the role that humidity plays in these emissions is often overlooked. Here, we show that the emissions associated with reducing air humidity (i.e., removing water vapor from air) are larger than emissions associated with reducing air temperature (i.e., cooling air). We calculate these emissions for today and 2050 and show how dramatically humidity-related emissions will increase with rising cooling demand around the world. We also calculate the minimum separation energy for removing water vapor from air and find that this is at least an order of magnitude less than the processes used today.

Original languageAmerican English
Pages (from-to)726-741
Number of pages16
Issue number4
StatePublished - 20 Apr 2022

Bibliographical note

Publisher Copyright:
© 2022 Elsevier Inc.

NREL Publication Number

  • NREL/JA-5500-80903


  • air conditioning
  • buildings
  • greenhouse gas emissions
  • humidity


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