Uncertainty in airflow rate calculations due to the use of surface-averaged pressure coefficients

Cóstola, D Daniel; Blocken, Bje Bert; Ohba, Masaaki; Hensen, Jlm Jan

doi:10.1016/j.enbuild.2009.12.010

Cited by 62 publications

(36 citation statements)

References 16 publications

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“…This non-convergence was caused by the introduction of new terms for uncertainty analyses that were uncorrelated to previously existing terms. Cóstola et al [6] investigated the effect of uncertainties in wind-pressure coefficients (Cp) on air infiltration and ventilation simulations. Breesch and Janssens [7] conducted uncertainty and sensitivity analyses in climate and design-related parameters for thermal comfort evaluations of passive cooling in office buildings.…”

Section: Introductionmentioning

confidence: 99%

Uncertainties in energy consumption introduced by building operations and weather for a medium-size office building

Wang

Mathew

Pang

2012

Energy and Buildings

146

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Deviations between predicted and actual building energy consumption can be attributed to uncertainties introduced by four components of such projections: (1) the accuracy of the underlying models in simulation tools, (2) the accuracy of input parameters describing the design conditions of building envelope and HVAC systems, (3) actual weather, (4) variations in building operation practices. This study investigates uncertainties in energy consumption due to actual weather and building operational practices, using a simulation-based analysis of a medium-size office building. The combined effect of poor practice in building operations across multiple parameters results in an increase in energy use of 49-79% across four selected cities, while good practice reduces energy use by 15-29% across the cities. The impact of year-to-year weather fluctuation on energy use ranges from -4% to 6%. To determine the uncertainty distribution profile for annual energy use, a Monte Carlo method is applied to sample the possible combinations. This study finds that the uncertainty distribution in annual energy consumption approximately follows a log-normal distribution, and shows that the uncertainty range due to operational factors even at an 80% confidence level can dwarf the impact of design features.

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Section: Introductionmentioning

confidence: 99%

Uncertainties in energy consumption introduced by building operations and weather for a medium-size office building

Wang

Mathew

Pang

2012

Energy and Buildings

146

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“…[6,7,9,10,13,[19][20][21][22][23][24][25][26][27][28][29]), analytical and/or semiempirical formulae (e.g. [9][10][11]13,15,[30][31][32][33][34]), simulations with zonal and multizone network models (e.g. [35][36][37][38]) and Computational Fluid Dynamics (CFD) models (e.g.…”

Section: Introductionmentioning

confidence: 99%

CFD simulation of cross-ventilation for a generic isolated building: Impact of computational parameters

Ramponi

Blocken

2012

Building and Environment

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450

271

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• Extensive literature review on numerical cross-ventilation studies in overview table.• Detailed sensitivity analysis for CFD simulations of a cross-ventilated building model.• The SST k-ω turbulence model shows the best agreement with PIV measurements.• The turbulent kinetic energy strongly influences the convergence and the results.• The prediction of the outdoor standing vortex largely affects the indoor airflow. AbstractAccurate CFD simulation of coupled outdoor wind flow and indoor air flow is essential for the design and evaluation of natural cross-ventilation strategies for buildings. It is widely recognized that CFD simulations can be very sensitive to the large number of computational parameters that have to be set by the user. Therefore, detailed and generic sensitivity analyses of the impact of these parameters on the simulation results are important to provide guidance for the execution and evaluation of future CFD studies. A detailed review of the literature indicates that there is a lack of extensive generic sensitivity studies for CFD simulation of natural cross-ventilation. In order to provide such a study, this paper presents a series of coupled 3D steady RANS simulations for a generic isolated building. The CFD simulations are validated based on detailed wind tunnel experiments with Particle Image Velocimetry. The impact of a wide range of computational parameters is investigated, including the size of the computational domain, the resolution of the computational grid, the inlet turbulent kinetic energy profile of the atmospheric boundary layer, the turbulence model, the order of the discretization schemes and the iterative convergence criteria. Specific attention is given to the problem of oscillatory convergence that was observed during some of these coupled CFD simulations. Based on this analysis, the paper identifies the most important parameters. The intention is to contribute to improved accuracy, reliability and evaluation of coupled CFD simulations for cross-ventilation assessment.

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“…This includes the work of de Wit (2002) and Macdonald (2002). More uncertainty studies related to ventilation can be found in Wouters et al (2004), Hyun et al (2008) and Costola et al (2010). However, uncertainty quantification analysis has not been widely used in the performance calculation of the HRVS and no overall assessment framework that considers these uncertainties has yet been established.…”

Section: Introductionmentioning

confidence: 99%

Performance of Counter Flow Heat Recovery Ventilation Systems in Dwellings Considering the Influence of Uncertainties

Yang

Cauberg

Tenpierik

2012

International Journal of Ventilation

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Both critical and optimistic claims have been made regarding the performance of heat recovery ventilation systems (HRVS) in dwellings. Such arguments are raised partly because two key aspects are not fully clarified, i.e. the performance criteria and the influence of uncertainties. In the current paper, an assessment method for HRVS considering the influence of uncertainties is described. This includes adequate assessment criteria, the method of identifying the uncertainties, and the method of addressing the influence of such uncertainties. The performance criteria consider the airflow performance, supply air quality and energy performance. Uncertainties in four aspects, including ventilation component, building properties, outdoor environment and occupant behaviour, are defined and related to five uncertainty sources ranging from the design phase to usage phase, i.e. design alternative, specification uncertainty, production deviation, modelling uncertainty and stochastic process. The estimation methods are given for each type of uncertainty based on the sources. Then, the method of carrying out the uncertainty analysis is introduced. This includes the calculation steps under a given commissioning status of the ventilation system, the uncertainty quantification techniques and the calculation steps. Afterwards, the method is applied to a case study of a counter flow heat recovery ventilation system in a reference Dutch house with the aid of simulations. Generally speaking, the method proposed in this article can provide an adequate framework for analysing or assessing the performance of HRVS in houses. As such it may contribute to a better understanding and a better design of this type of ventilation system.

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Uncertainty in airflow rate calculations due to the use of surface-averaged pressure coefficients

Cited by 62 publications

References 16 publications

Uncertainties in energy consumption introduced by building operations and weather for a medium-size office building

Uncertainties in energy consumption introduced by building operations and weather for a medium-size office building

CFD simulation of cross-ventilation for a generic isolated building: Impact of computational parameters

Performance of Counter Flow Heat Recovery Ventilation Systems in Dwellings Considering the Influence of Uncertainties

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