skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Simplified Methods for Combining Natural and Mechanical Ventilation

Abstract

In determining ventilation rates, it is often necessary to combine naturally-driven ventilation, such as infiltration, with mechanical systems. Modern calculation methods are sufficiently powerful that this can be done from first principles with time varying flows, but for some purposes simplified methods of combining the mechanical and natural ventilation are required—we call this “superposition”. An example of superposition would be ventilation standards that may pre-calculate some quantities within the body of the standard. When there are balanced mechanical systems, the solution is simple additivity, because a balanced system does not impact the internal pressure of the space. Unbalanced systems, however, change internal pressures and therefore can impact natural ventilation in such a way as to make it sub-additive. Several sub-additive superposition models are found in the literature. This paper presents the results of millions of hours of simulations of the physically correct solution, which span a broad range of climates, air leakage and structural conditions. This wide range of data allows for the comparison of three superposition models from the literature and eight new ones. The results show that by using the appropriate model(s) superposition errors can be reduced significantly, from the 20% over-prediction of simple linear addition to 1%more » or less.« less

Authors:
 [1];  [1];  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
OSTI Identifier:
1512199
DOE Contract Number:  
AC02-05CH11231
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
unbalanced ventilation; inflitration; REGCAP simulation; empirical models; superposition

Citation Formats

Hurel, Nolwenn, Sherman, Max H., and Walker, Iain S. Simplified Methods for Combining Natural and Mechanical Ventilation. United States: N. p., 2015. Web. doi:10.2172/1512199.
Hurel, Nolwenn, Sherman, Max H., & Walker, Iain S. Simplified Methods for Combining Natural and Mechanical Ventilation. United States. doi:10.2172/1512199.
Hurel, Nolwenn, Sherman, Max H., and Walker, Iain S. Mon . "Simplified Methods for Combining Natural and Mechanical Ventilation". United States. doi:10.2172/1512199. https://www.osti.gov/servlets/purl/1512199.
@article{osti_1512199,
title = {Simplified Methods for Combining Natural and Mechanical Ventilation},
author = {Hurel, Nolwenn and Sherman, Max H. and Walker, Iain S.},
abstractNote = {In determining ventilation rates, it is often necessary to combine naturally-driven ventilation, such as infiltration, with mechanical systems. Modern calculation methods are sufficiently powerful that this can be done from first principles with time varying flows, but for some purposes simplified methods of combining the mechanical and natural ventilation are required—we call this “superposition”. An example of superposition would be ventilation standards that may pre-calculate some quantities within the body of the standard. When there are balanced mechanical systems, the solution is simple additivity, because a balanced system does not impact the internal pressure of the space. Unbalanced systems, however, change internal pressures and therefore can impact natural ventilation in such a way as to make it sub-additive. Several sub-additive superposition models are found in the literature. This paper presents the results of millions of hours of simulations of the physically correct solution, which span a broad range of climates, air leakage and structural conditions. This wide range of data allows for the comparison of three superposition models from the literature and eight new ones. The results show that by using the appropriate model(s) superposition errors can be reduced significantly, from the 20% over-prediction of simple linear addition to 1% or less.},
doi = {10.2172/1512199},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2015},
month = {6}
}

Technical Report:

Save / Share: