Natural ventilation of mill buildings is a process which is complicated by several factors such as external wind pressure and local distribution of heat sources. Describes theoretical and small-scale physical modelling techniques for predicting ventilation rates. The theoretical approach using a computer for the numerical aspects allows rapid and reliable assessment of the ventilation rates for very complicated building designs under any appropriate wind conditions.
Describes a simple manual method for providing a rough calculation of the likely energy requirements of a building at an early stage in the project, before the detailed information required by established computer programs can be provided.
Provides results of research in Switzerland into window ventilation in typical rented dwellings as a function of outdoor climate, and the research support activities of the Air Infiltration Centre in the UK funded by the International Energy Agency. Describes in particular the creation of an air infiltration database, the comparison and validation of computer models of air infiltration, the development of a reporting format for measurement of air change in buildings, and the compilation of a glossary of technical terms.
Explores the various roles that mathematical models can play in the design of energy efficient ventilation systems. Uses an example (an existing terraced house) to illustrate how models may be used to investigate the energy implications and air distribution patterns of a range of mechanical andnatural ventilation options. Identifies key parameters needed for accurate results, and compares predicted infiltration rates with actual measurements taken in the house. Concludes that models of proven validity are an invaluable aid in ventilation design studies.
An air infiltration computer program, developed earlier, has been further refined by the inclusion of the effects of door openings and vent-fan usage in house air infiltration. The model has also been further verified for its accuracy and precision by comparison to actual air infiltration data from both conventional construction dwellings and also from two advance design homes. A program listing and user manual of the computer program have also been developed.
States that the calculation of building energy flow is very complex, and so validation is a vital element in the development of any model. Describes an IEA R and D project to compare 23 computer programs (from 8 different countries) both in terms of consistency between programs, and in thei relative accuracy in modelling the behaviour of a real building (the Avonbank office block in Bristol). Summarizes the major conclusions developing out of the project and discusses the most important aspects which need to be considered in the development of a reliable computer program.
Derives analytical expressions for the exchange of air across doorways or similar apertures, in terms of the temperature difference between the spaces on both sides of the opening and the net volume of air flowing through this as a result of unbalanced air supply or extract.
States that the reduction in energy losses due to reduced air infiltration is often overestimated because the effect of open windows is not taken into account.< Shows that the habits of airing are rather similar in some European countries. The proportion of windows open or ajar is inversely proportional to the indoor- outdoor air temeperature difference over a large interval of this temperature difference.< The proportionality constant seems to take a value that is independent of the building construction or the heating system of the residential building.
Presents the latest results of air infiltration research in Finland. The aim is to increase the knowledge of the influences of air infiltration on energy consumption, ventilation and indoor climate. Briefly describes the principles of a calculation model for predicting the interconnection between airtightness and air change rate. Describes improvement of air tightness in Finnish buildings, with special attention to construction details. Discusses possibilities of draughtless and controlled fresh air intake through the building envelope.
Reports on a comparative study of residential infiltration as predicted by computer model and as measured in the Mobile Infiltration Test Unit (MITU) as well as in selected test houses, both occupied and unoccupied. Sensitivity analyses were also conducted on each parameter contained in the model against data obtained from MITU.
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