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Estimating Interzonal Leakage in a Net-Zero Energy House



Lisa C. Ng, Lindsey Kinser, Steven J. Emmerich, Andrew K. Persily


The Net Zero Energy Residential Test Facility (NZERTF) was constructed at the National Institute of Standards and Technology (NIST) to support the development and adoption of cost-effective net zero energy designs and technologies. The 250 m2 two-story, unoccupied NZERTF, built in 2012, had among its design goals to establish an airtight and highly insulated building enclosure designed for heat, air and moisture control. The airtightness goal was achieved through detailed envelope design, careful construction, and during- and post-construction commissioning. The NZERTF is one of the tightest residential buildings in North America with a whole building pressurization test result of roughly 0.6 h-1 at 50 Pa measured per ASTM E779-10. No special attention was given to the airtightness of the interior floors and other interior partitions. To support airflow modeling efforts, this interior leakage was quantified through a series of interzonal pressurization tests. Both the basement and attic are considered conditioned spaces since the thermal and air-moisture barriers encompasses the basement walls and attic roof, but there are transfer grilles and other openings linking the living space to these two zones. A series of fan and partition configurations were employed to quantify the leakage values of the various interzone airflow paths. Test results showed that the interior floors were more than 10 times leakier than the exterior building envelope, and that the leakage associated with the transfer grilles between levels was less than the floor leakage
Proceedings Title
ASTM Symposium on Whole Building Air Leakage: Testing and Building Performance Impacts
Conference Dates
April 8-9, 2018
Conference Location
San Diego, CA


airtightness, interzonal leakage, net-zero house, ASTM E779-10, pressurization tests


Ng, L. , Kinser, L. , Emmerich, S. and Persily, A. (2019), Estimating Interzonal Leakage in a Net-Zero Energy House, ASTM Symposium on Whole Building Air Leakage: Testing and Building Performance Impacts, San Diego, CA, [online], (Accessed February 21, 2024)
Created November 11, 2019, Updated December 31, 2019