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Simulated Performance of Natural and Hybrid Ventilation Systems in an Office Building



Steven J. Emmerich, J Crum


A key finding of past research on natural ventilation is that the potential application of pure natural ventilation systems may be limited in the United States by issues such as climate suitability, humidity control, and reliability. However, hybrid (or mixed-mode) ventilation systems offer the possibility of attaining energy savins in a greater number of buildings through the combination of natural ventilation systems with mechanical equipment. Although a recent surge of interest in Europe has advanced natural and hybrid ventilation technology, much work is needed to identify and realize its potential in the United States. Innovators in this field are learning by doing, but there is only limited design and analysis data available-partially due to a lack of adequate engineering methodologies and tools. The objective of this study is to investigate the potential energy and indoor environmental performance of natural and hybrid ventilation alternatives in low-to-mid rise US commerical buildings in a variety of US climates. In this effort, NIST reviewed hybrid ventilation approaches and existing applications and conducted simulations to predict and compare the indoor environmental and energy performance of natural, hybrid, and mechanical systems in an otherwise similar building. Limitations of this study include the simulation of only one building with only one system of each type. Additionally, some important issues were not evaluated, such as indoor air quality impacts of outdoor and indoor sources of contaminants, purchased builidng energy, and humidity control.
NIST Interagency/Internal Report (NISTIR) -


21 CR, analysis, ARTI, design, energy efficiency, hybrid ventilation, indoor air quality, modeling, natural ventilation


Emmerich, S. and Crum, J. (2005), Simulated Performance of Natural and Hybrid Ventilation Systems in an Office Building, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed June 12, 2024)


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Created February 1, 2005, Updated February 19, 2017