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.
The CO2-concentration of room air provides an indicator for the air quality in spaces without smokers. A classroom with mechanical ventilation has been evaluated for eighteen months using such a technique. These measurements were made within the framework of the research project Gumpenwiessen. A model to calculate the CO2 concentration as a function of occupancy, activity level of the occupants and air change rate was developed. It was validated using the measurements data.
The 'Simplified Technique' is a method by which it is possible to determine approximately the infiltration and ventilation rates of large and complex buildings. The aim is to provide a reliable and easy-to-use procedure for non-specialists. This paper describes a working protocol for using this technique. Results from computer model studies are given to provide guidance on use of the technique and its potential accuracy.
In the past years the need has grown for a sensitive flowrate meter with a very low pressure drop. Such a device can be used to measure flowrates of airflows through the grilles of mechanical ventilation systems with low duct pressures. Another application would be the measurement of flowrates through the different rooms of a dwelling during a blower door test. A prototype was developed based on the very simple principle of a throttled fan. The prototype proved to be accurate and capable of measuring flows on ducts with natural ventilation.
This paper presents and discusses results of moisture transfer into timber frame constructions. The two mechanisms of transfer are diffusion and bulk air movement. Three defects in construction were monitored punctured vapour barrier, continuous path via an electrical socket and discontinuities at junctions. The study has shown that, under steady-state conditions condensation can take place, while under varying conditions both condensation and evaporation occur. This second case is typical of the building in use, and can prevent high levels of moisture existing in timber components.
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