Moisture Transfer in Commercial Buildings due to the Air Leakage: A New Feature in the Online Airtightness Savings Calculator
Som Shrestha, Andre Desjarlais, Laverne Dalgleish, Lisa C. Ng, Diana Hun, Steven J. Emmerich, Gina Accawi
Air leakage through the building envelope is responsible for a large amount of energy use. The US Department of Energy Windows and Building Envelope Research and Development Roadmap for Emerging Technologies states that in 2010 infiltration was responsible for 20 % of primary energy consumption attributable to fenestration and building envelopes of commercial buildings. Despite this fact, improving airtightness is not always recognized by owners of commercial buildings, as they have been slow in acknowledging and diminishing the detrimental effects of air leakage on energy use, comfort, indoor air quality, and building envelope durability. The construction industry needs a credible, easy-to-use tool that estimates potential energy and financial savings in a standardized manner so designers and contractors can give building owners compelling reasons to invest in reducing air leakage. In 2016-17, Oak Ridge National Laboratory, the National Institute of Standards and Technology, the Air Barrier Association of America, and the US-China Clean Energy Research Center for Building Energy Efficiency collaborated to develop an online calculator. The calculator is free to the public, user- friendly, and uses the simulation results of the best-in-class building energy simulation tool EnergyPlus and the whole building airflow simulation tool CONTAM. In 2018-19, the calculator was expanded to add moisture transfer calculations because air leakage through the building envelope can have a significant impact on the amount of moisture transfer and associated issues. Four more commercial building types were added to the existing database of three building types. This paper describes the procedure used to calculate moisture transfer due to air leakage and provides examples that demonstrate the moisture transfer for each of the seven commercial building types that are currently part of the calculator.