Survey Reveals Post-Construction Ventilation Conditions

01/25/2005 |

Over- or under-ventilating may be the cause of poor IAQ


If you're moving into a newly constructed building, you might want to check the performance of its ventilation systems. According to the analysis by the National Institute of Standards and Technology (NIST) of a recent Environmental Protection Agency (EPA) survey of 100 representative U.S. public and commercial buildings, the ventilation conditions expected based on building design are often quite different than actual post-construction ventilation conditions.

According to NIST, "The analyzed data showed frequent instances of under-ventilation, a condition that can cause poor air quality, occupant discomfort, and even illness - as well as over-ventilation, a situation that can boost energy costs dramatically." The findings reveal the importance of early testing of a ventilation system’s ability to perform according to the design’s intent and pinpoint the need for subsequent (and regular) maintenance checks, NIST researchers say. They noted instances in which building engineers could not readily access ventilation system plans or found the equipment itself to be inaccessible, and are urging building designers and operators to remedy the situations.

The primary goal of the U.S. EPA Building Assessment Survey and Evaluation (BASE) Study was to define the status of the existing U.S. building stock with respect to indoor air quality (IAQ), ventilation, and occupant perceptions of environmental conditions. In the future, both the analysis and original data will be useful for:

·        Establishing standardized protocols for IAQ studies.

·        Examining the relationship between symptoms reported by occupants and building characteristics.

·        Developing guidance on building design, construction, operation, and maintenance.


The Analysis of Ventilation Data from the U.S. Environmental Protection Agency Building Assessment Survey and Evaluation (BASE) Study, NISTIR 7145, by A. Persily and J. Gorfain, is available at (


This information was provided by the National Institute of Standards and Technology (NIST). Visit NIST online at (

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