SIMPLIFIED METHODS FOR COMBINING MECHANICAL VENTILATION AND NATURAL INFILTRATION
During the past ten years, the means of ventilating single-family residences has received considerable attention. In many areas, the use of natural ventilation for infiltration has either come under close scrutiny, or has already been supplanted by mechanical ventilation systems. To evaluate the energy efficiency and ventilation effectiveness of both mechanical and natural ventilation strategies, both complex and simplified infiltration models are used. This paper examines the inaccuracies associated with using simplified models to compare ventilation strategies. Two simplified techniques for combining mechanical ventilation flows to the flows caused by wind and stack effects are examined. The simplified combination techniques are compared with the results obtained with an iterative flow-balance simulation. The flow-balance simulation determines the ventilation by balancing the incoming and outgoing flows under the pressure conditions resulting from the combination of wind effect, stack effect and mechanical ventilation. These comparisons result in three major conclusions: (1) the commonly used flow superposition technique (flow combination in quadrature) provides better estimates of the total flow than does a technique that takes into account measured flow exponents, (2) although flow combination in quadrature overpredicts ventilation when combining wind-induced and stack-induced flows, this is not the case when mechanical ventilation is added to the picture, and (3) a simple correction for the errors caused by the simplified flow superposition technique is not easy to achieve due to the large variations in error that occur with changes in wind direction and individual flow ratios.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- Physics Division
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 1007486
- Report Number(s):
- LBL-18955; TRN: US201106%%271
- Journal Information:
- SIMPLIFIED METHODS FOR COMBINING MECHANICAL VENTILATION AND NATURAL INFILTRATION, Journal Name: SIMPLIFIED METHODS FOR COMBINING MECHANICAL VENTILATION AND NATURAL INFILTRATION
- Country of Publication:
- United States
- Language:
- English
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