Chapter 6: Ventilation

Overview

Ventilation, and its allied subject Fire, has become a greater part of Wind Engineering in the last decade. This has partly come about because the heating and ventilation engineers in the profession are realising how much wind engineering has to offer.

A ventilation study usually follows a wind tunnel investigation of the pressures on a building in which the surface pressures are integrated into loads and moments for the structural engineer. In the structural study the pressure tappings have been distributed to cover the surface required, with the greatest concentration on areas where the pressure is changing most rapidly. Pressure tappings have been placed at doors and other openings so that values of internal pressure can be calculated to obtain pressure differentials across the cladding. For the ventilation study these tappings at doors and other openings are used, and a few additional tappings have to be placed at all possible inlet and outlet points of the ventilation system. It is better to include all possible positions and select those most suitable, than omit some which could have been efficient.

Forced systems can be studied as well as natural ones, although the data required is different. In this case the fan has been "sized" to pass sufficient air, but it must be established that the fan is capable of so doing against the back pressure created by the position of its inlet and outlet. The calculation to ensure a satisfactory result is detailed in Section 6.3.

In the study of...