English

"Air Movement and Ventilation Control within Buildings", held 24-27 September 1991, Ottawa, Canada, proceedings published September 1991, Volume 1, pp 141-142. #DATE 00:09:1991 in English",An overall presentation will be given of the final report from Annex 18 experts are proposing DCV-systems in various building types. The presentation will be focused on strategies and pre-requisites and on DCV-systems in the building types not presented separately.

Airflow through a building has both mean and fluctuating components due to spatial and temporal variations in wind-induced pressures. Most of the existing investigations consider the average values of wind pressures and predict steadystate solutions for airflow [1]. This paper presents some experimental results for the validation of a proposed fluctuating airflow model [2]. The new model employs spectral analysis and statistical linearization methods to model the pulsating airflow through buildings.

The International Energy Agency (IEA) task-sharing project "Air Flow Patterns within Buildings" was initiated in May 1988 for a duration of 3,5 years. Twelve nations contribute work and expertise and "share the task" specified in the project's objectives. This project and the AIVC belong to the same Implementing Agreement: The Energy Conservation in Buildings and Community Systems Program. As "Attachments" to the Implementing Agreement, they are called Annexes.

We report on four new full scale experiments that were designed to measure the influence of wind on the ventilation and/or heat loss rates through single large openings: a) test-house with horizontal slit opening, set-up to measure internal pressures and the effect of air-compressibility (CSTB, France), b) attic with window ajar, set-up to measure long term ventilation rates with varying wind and temperatures (BBRI, Belgium), c) fully open window, set-up to measure ventilation rate and cooling as a function of time (BRE, UK) d) fully open window, set-up tomeasure cooling as a function of ti

The paper describes work on simplified design methods made in connection with the International Energy Agency programme "Air Flow Pattern within Buildings", Annex 20, subtask 1. It is shown that simplified models are able to indicate design values as the maximum velocity in the occupied zone and penetration depth of a non-isothennal jet in a room. The design according to throw of an isothermal jet is a fully developed method which has a sufficient level of accuracy when it is used in regular rooms.

The subtask 2 of Annex XX (Optimization of Air Flow Patterns Within Buildings) involved a research project called "Air Flows Through Large Openings In Buildings". The scope of this project was to test the range of validity of available algorithms, and where possible to develop new ones. This paper focuses on the new interzonal airflow studies which have been carried out in this frame.

The ability to accurately predict air movement and temperature distribution in spaces offers the potential for design engineers to evaluate and optimise room air distribution systems at an early stage, leading to improved thermal comfort and ventilation effectiveness. The computer models which are used for detailed analyses are based on computational fluid dynamics [1,2] and employ sophisticated numerical algorithms to satisfy the basic laws of physics. The programs are such that they are more complex and more difficult to use than those with which design engineers may be more familiar.

This paper is based on field measurements in auditoria which were carried out in Norway and in Switzerland. In both cases carbon dioxide (CO2) was chosen as the relevant indicator to establish ventilation demand.

Air is the main transport medium for contaminants in buildings. Minimizing source strengths has first priority, second is to control air flow rates, supply and exhaust, and directions between zones in buildings. Computer simulation models forventilation and pollutant spread in buildings have been proven to give useful predictions. Large measurement campaigns for optimizing ventilation and pollutant problems are complex and expensive. They are often jammed by too many vague parameters influencing the result. The computer models are an alternative and form a supplement to measurements.

Accurate measurement of the positions of windows, skylights, vents, dampers, etc. has always been a problem for researchers. Often open/closed switches are used which do not indicate the degree of opening which has occurred. The use of Hall-Effect sensors to measure such positions was first proposed for monitoring residential passive air inlets.