English

Wind pressure coefficients (Cp values) are among the basic data required for ventilation and air infiltration calculations and modelling. More than two years of systematic wind tunnel testing in ETI of some of the most frequent building shapes has resulted in a database that has been provided with a handling program. This package is available from ETI, for IBM XT/AT and compatible PC's.

In the field of ventilation engineering the understanding of jet types of flow is well established. However, the behaviour of buoyant flows with high initial Archimedes numbers has been much less explored. The aim of this short note is to highlight some of the differences between ordinary jet flow and the discharge from low velocity air terminals. Results are presented both from tests carried out in a full scale mock up and from model tests with water as operating fluid.

In this note we discuss the problem (concealed by the latter statement) of calculating the inside air temperature which varies with time and is, when not measured directly, in general not known. The inside air temperature (Tin), which is in betwe

In buildings with mechanical ventilation there are spaces with substantial pressure differences, which bring exfiltration, infiltration and transferred air between the rooms. For such buildings we have converted a multiple cell theory to a quadratic programming problem, and developed a computer programme, MCSPID for airflow identification. Today MCSPID is inpractical use to simultaneously determine flow rates for airsupply, exhaust air, transferred air, infiltration and exfiltration with a single tracer gas.

As the thermal performance of buildings continues to improve, air exchange will eventually become the dominant mechanism for building heat loss. Although, therefore, an essential parameter of the energy equation, ventilation is nevertheless vital forthe dilution and removal of pollution generated within buildings. An inadequate supply of fresh air or poor air distribution will result in high levels of indoor contaminants, discomfort and a poor living environment, it could also result in more serious health related problems.

AC pressurisation is a method for measuring the airtightness of buildings. This technique, which is also called the infrasonic method, employs a reciprocating piston or bellows to impose a sinusoidal small change in volume inside the building

The Air Infiltration and Ventilation Centre is currently finalising the detailed work program for its Numerical Database. This is being developed in response to the need to establish a core of numerical data, suitable for model validation, themodelling of real buildings, assessment of standards, the effects of new building methods and the use of differing ventilation systems.

As part of its new operating programme, the Air Infiltration and Ventilation Centre is establishing a numerical database to be used both in support of design studies and for the verification of numerical models. In addition to being available as a computer database, it is intended to present selected source data and simple algorithms in loose leaf form as a new volume in the AIVC's series of Application Guides.

This article briefly describes a new piece of apparatus, recently developed at UMIST, which can be used for the determination of ventilation rates in, and air movement rates between, four interconnected cells.