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

Title: Sub-additivity in combining infiltration with mechanical ventilation for single zone buildings

Abstract

We report that in determining ventilation rates, it is often necessary to combine naturally-driven infiltration, with air flows from mechanical systems. When there are balanced mechanical systems, the solution is simple additivity, because a balanced system does not impact the internal pressure of the space or the air flows through the building envelope. Unbalanced systems, however, change internal pressures and therefore can impact natural ventilation non-linearly in such a way as to make it sub-additive. Several sub-additive approaches are found in the literature, but they are not robust across the full spectrum from tight to leaky buildings and ranges of mechanical ventilation air flow rates. There are two approaches for combining natural infiltration with mechanical ventilation that require different solutions. The forward problem is to find the total air flow when adding mechanical ventilation to natural infiltration, and this application has been investigated in previous studies. The inverse problem finds the required mechanical ventilation in order to meet a total ventilation rate given a known amount of natural infiltration. This article 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 large datasetmore » allows for the comparison with three literature models and the development of new robust sub-additivity models. These improved models are for use with unbalanced systems appropriate for consensus standards and guidelines for both the forward and inverse problem. Finally, they reduce errors to 1% or less and work across the air tightness spectrum.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [2]
  1. Université Savoie Mont Blanc (France)
  2. 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 Science (SC)
OSTI Identifier:
1532181
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Building and Environment
Additional Journal Information:
Journal Volume: 98; Journal Issue: C; Journal ID: ISSN 0360-1323
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; Unbalanced ventilation; Infiltration; Standards; Empirical models; Superposition

Citation Formats

Hurel, Nolwenn, Sherman, Max H., and Walker, Iain S. Sub-additivity in combining infiltration with mechanical ventilation for single zone buildings. United States: N. p., 2015. Web. doi:10.1016/j.buildenv.2015.12.020.
Hurel, Nolwenn, Sherman, Max H., & Walker, Iain S. Sub-additivity in combining infiltration with mechanical ventilation for single zone buildings. United States. doi:10.1016/j.buildenv.2015.12.020.
Hurel, Nolwenn, Sherman, Max H., and Walker, Iain S. Wed . "Sub-additivity in combining infiltration with mechanical ventilation for single zone buildings". United States. doi:10.1016/j.buildenv.2015.12.020. https://www.osti.gov/servlets/purl/1532181.
@article{osti_1532181,
title = {Sub-additivity in combining infiltration with mechanical ventilation for single zone buildings},
author = {Hurel, Nolwenn and Sherman, Max H. and Walker, Iain S.},
abstractNote = {We report that in determining ventilation rates, it is often necessary to combine naturally-driven infiltration, with air flows from mechanical systems. When there are balanced mechanical systems, the solution is simple additivity, because a balanced system does not impact the internal pressure of the space or the air flows through the building envelope. Unbalanced systems, however, change internal pressures and therefore can impact natural ventilation non-linearly in such a way as to make it sub-additive. Several sub-additive approaches are found in the literature, but they are not robust across the full spectrum from tight to leaky buildings and ranges of mechanical ventilation air flow rates. There are two approaches for combining natural infiltration with mechanical ventilation that require different solutions. The forward problem is to find the total air flow when adding mechanical ventilation to natural infiltration, and this application has been investigated in previous studies. The inverse problem finds the required mechanical ventilation in order to meet a total ventilation rate given a known amount of natural infiltration. This article 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 large dataset allows for the comparison with three literature models and the development of new robust sub-additivity models. These improved models are for use with unbalanced systems appropriate for consensus standards and guidelines for both the forward and inverse problem. Finally, they reduce errors to 1% or less and work across the air tightness spectrum.},
doi = {10.1016/j.buildenv.2015.12.020},
journal = {Building and Environment},
number = C,
volume = 98,
place = {United States},
year = {2015},
month = {12}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 5 works
Citation information provided by
Web of Science

Save / Share: