Natural ventilation - A new method based on the Walton model applied to cross-ventilated buildings having two large external openings

TL;DR

This paper introduces a new natural ventilation modeling method based on the Walton model, extended for large external openings, to improve prediction accuracy in cross-ventilated buildings with low energy consumption.

Contribution

A novel building-dependent coefficient is developed to enhance Walton's model, better capturing turbulent phenomena near large openings for natural ventilation prediction.

Findings

The new model improves the representation of turbulent flows near large openings.

Discharge coefficient alone is insufficient for accurate pressure and flow predictions.

Comparison with CFD shows the model's enhanced predictive capabilities.

Abstract

In order to provide comfort in a low energy consumption building, it is preferable to use natural ventilation rather than HVAC systems. To achieve this, engineers need tools that predict the heat and mass transfers between the building's interior and exterior. This article presents a method implemented in some building software, and the results are compared to CFD. The results show that the knowledge model is not sufficiently well-described to identify all the physical phenomena and the relationships between them. A model is developed which introduces a new building-dependent coefficient allowing the use of Walton's model, as extended by Roldan to large external openings, and which better represents the turbulent phenomena near large external openings. The formulation of the mass flow rates is inversed to identify modeling problems. It appears that the discharge coefficient is not the only or best parameter to obtain an indoor static pressure compatible with CFD results, or to calculate more realistic mass flow rates.