BRE FB69 PDF

introduction

Computational fluid dynamics (CFD) modelling is a powerful tool that is routinely used in fire engineering and building design[1,2]. It can be used to simulate different aspects of a building's performance or its impact on the local environment.

This guide gives some of the background to the CFD methodology for non-experts such as Building Control and other regulatory authorities who have to approve or accept a design. They may be presented with the visualised results of CFD simulations in various graphical formats (including animations) that show the predicted performance. However, underlying assumptions, factors and limitations that impact on the quality of the predictions tend to be buried in detailed technical reports.

The process of reviewing CFD predictions is often dependent on the ability of the reviewer to be able to identify ‘schoolboy' errors (eg supersonic wind velocities or fire temperatures of 5000 °C!) using simple sanity checks based on their experience of the real world rather than the mathematical limits of the simulation environment. Visualisation methods often mask the difference between:

• a qualitative simulation to demonstrate the feasibility of a concept
• a quantitative simulation required to prove functionality of different aspects of the design.

This guide discusses the current capabilities and limitations of CFD for building design and gives guidance on best practice, focusing on:

• fire safety
• ventilation
• thermal comfort
• wind movement around buildings.