This paper describes one of the results of the IEA-annex 8 "Inhabitants behaviour with regard to ventilation". Annex 8 has shown that the occupants can play a rather important role with regard to the ventilation rates inoccupied buildings. This paper gives some practical 'rules of thumb' for estimating air flow rates through open windows. An overview of measured and estimated ventilation rates in houses is given from which a simplified approach is derived that takes into account the air tightness of the building and the behaviour.

The actual heating load of a building differs often from the designed load. One reason for this is the uncontrolled ventilation through a building envelope. The heating load of air infiltration has, in practical calculations, been calculated according to the predicted leakage flow rate and to the indoor and outdoor air temperature difference. We suggest, however, that the value of transmission heat losses should be corrected by a factor, Nusselt number, because of the thermal interaction of leakage flows and conduction heat transfer in wall structures.

Calculation of air infiltration in a large number of cases can give information of expected variations in yearly air change and energy consumptions. As model is used the equivalent leakage area model written in a spreadsheet computer program. For a typical Norwegian house an analysis of the influence of some parameters is made. The influence of climate is found to be small, if we compare the mean yearly air change for towns in Norway. Prediction of air infiltration is made from known variations in indoor temperature, 50 Pa pressurization air change and leakage and pressure characteristics.

A simplified pocket calculator model has been developed which can simulate the air flow distribution in multizone structures. The model is based on lumped parameters and includes several assumptions to simplify the description of air flow due to wind and stack effect and their superimposition. This paper gives a brief overview of the model and describes several applications. Results obtained from a mainframe based research tool. The examples show that the simplified method can be used to predict air mass flows within reasonable accuracy for different types of buildings.

A simplified model of air infiltration has been developed at Lawrence Berkeley Laboratory, in order to expand the use of air flow calculation techniques outside the field of research. The validity of the programme must be checked. Benefit has been gained from work dedicated to the same problem in the field of building thermal analysis. Following this idea, a detailed validation methodology is proposed. Progression in the complexity of the modelled structures, use of high accuracy data are sine qua non to this task.

Measurements of the air temperature and air velocity were carried out in four buildings without air-conditioning using a newly developed anemometer whose sensitivity allows the examination of the dynamic behaviour of air movements. Recent results describing the physical reasons of draft problems were employed in order to re-examine the correlation between air movements and draft problems in a building. From the resulting evaluation criteria follows that besides, the environmental temperature and the mean air velocity, the magnitude of the turbulent fluctuations is important .

Sections include: measuring procedure air tightness of facades; evaluation of measuring air tightness in practice; infrared thermography; thermographical research in air tightness, ability to detect air tightness deficiencies with thermography; ability to quantify air leakage; architectural analysis of airtightness deficiencies; recommendations.

When controlling the performance of a ventilation system it is important to investigate how the system works together with the building it ventilates. It is the performance of the complete system which is of interest, not its individual components. This paper describes the use of a computer-controlled, tracer-gas measuring system for controlling ventilation systems. By means of 4 measuring probes the condition of the air at the intake, room injection, room extraction and exhaust is registered.

In this paper we describe the development of a multi-tracer gas system for measuring interzonal air movement in buildings. The system consists of simple and stand-alone gas injectors and sampling units. The injectors are capable of releasing up to four perfluorocarbon tracer gases in different parts of a building. Following tracer gas injection and mixing, small samples of air are collected using automatic sampling units. Each unit consists of a 16-position valve and a group of removable stainless steel tubes packed with solid absorbent.

A six channel, computer controlled, tracer gas detection system for the measurement of infiltration rates and air movement in large single-cell industrial buildings has been designed, constructed and calibrated. This has been used for over 50 sets of tracer decay measurements in five single-cell buildings ranging in size from 4000 to 31000 m³, The buildings included a sports hall, a vehicle maintenance depot, two factory workshops and an aircraft hanger. Infiltration rates and interzonal flows were derived from the tracer decay curves using methods based on multizone theory.