Laboratory measurements have shown that when pressure differences are applied across wall and roof elements, the majority of the pressure drop takes place across the vapour barrier . Similarly , field measurements have shown that the majority of the leakage in Norwegian buildings occurs at the joints in the vapour barrier , at wall / floor joints , around penetrations of the vapour barrier and through holes in the vapour barrier . Prior to 1980, the standard vapour barrier in Norway was 0.06 mm thick polyethylene sheeting.
The accuracy of tracer gas measurements of building air infiltration rates has been a widely discussed topic. One question that has often come up at past AIVC conferences is the ability of passive methods, such as the Perfluorocarbon Tracer (PFT) method, to accurately measure fluctuation air flow rates. A series of field studies is being conducted to compare the air infiltration measurements of the constant concentration tracer gas (CCTG) and PFT methods and provide recommendations for their proper implementation in the field.
Brookhaven National Laboratory (BNL) in the USA has developed a multiple tracergas technique called BNL/AIMS (Air Infiltration Measurement System) for determination of air infiltration rates. The technique is applicable in occupied dwellings and might be promising for wide-scale measurements. This paper discusses the main results of field measurements made by the Danish Building Research Institute with use of BNL/AIMS. The results obtained are compared with the results of parallel measurements made in the laboratory and by using computer controlled field measuring equipment.
All the findings about indoor air quality is of little use to the average citizen, if they are not applied and and translated into rules incorporated in our building codes for the design, construction, and last but certainly not least maintenance of our buildings. And scientifically based up-to-date coders are not much use if they are not backed by strict , honest, and competent building inspectors. Recommendations are made for improvements in building codes to ensure good indoor air quality by concentrating, but not exclusively, on ventilation.
The mixing system (even called the dilution system) is normally used throughout the world to supply air to a premises. In the mixing system you blow air at high velocity into the room at a temperature which gives you the wanted room temperature. If the system works perfectly, you will have the same temperature and concentration of contamination in the whole room. That is because the supplied air and the air in the room is mixed due to induction.
The constant concentration tracer gas (CCTG) technique is typically used to measure air infiltration rates in mulitzone buildings. The measurements are performed by injecting metered amounts of a tracer gas into each zone so as to keep all the zones at a target concentration. One drawback to this method is that no information is gained about the level of interzone flow rates in the building. Modified constant concentration techiques are described which allow selected infiltration and interzone air flow rates to be estimated.
The main goal of a research project on wind barriers was to get more information about the influence of wind pressure on the heat loss from wood frame constructions. The project was divided into three parts: calculations, hot-box measurements and wind pressure measurements on a rotatable test house, The theoretical studies as well as the experimental investigations in the hot-box, have been restricted to one specific type of forced convection in the thermal insulation, called "anblasning", i.e.
Summary of papers in the Proceedings of the Eighth AIVC Conference. Headings include measurement techniques, calculation techniques, design (control of the internal environment) and the positive aspects of ventilation and infiltration.
The National Bureau of Standards has undertaken a research effort to develop a general air quality simulation program for buildings. At present there exists three computer programs which can be used to analyse interzonal air movements in multizoned buildings and predict the level of contaminants due to a wide variety of contaminants. This paper will introduce the reader to the scientific and mathematical basis of the models, the preparation of building input data for these programs, and the use of the models for both residential and commercial buildings.
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