English

Describes the development of a particle imaging velocimetry (PIV) measurement system for use with full-scale room airflows. Two-dimensional airflows were measured in a full-scale room in order to validate the PIV system, using two typical ventilation schemes: cross-flow ventilation and return flow ventilation. In the former, a slot air inlet and a slot air outlet were positioned on opposite walls so the ventilation air moved across the room air space.

States that zero and low wind speed occurrences are often overestimated in standard meteorological data for use by HVAC engineers because of the use of the robust, rotating cup anemometers. Therefore the data would be expected to underestimate wind-driven natural ventilation as well as pollution dispersal. A comparison of rotating cup and ultrasonic anemometers carried out for this study indicated that the former can indicate zero wind speed over many hours in the day when speeds up to 1.5 m/s can be present.

A good air quality control system ensures that the most common harmful gaseous contaminants are kept below permissible levels particularly in forced ventilated spaces. Such a system can ensure a high standard of indoor air and a healthy environment. The volume of fresh air in a room can be adjusted according to the number of occupants and their level of activity. It is important to keep a vigilant eye on the levels of the most common harmful gases, because most of them cannot be detected by human senses.

This study was based upon a laboratory comparison of two air duct cleaning methods, mechanical brushing and compressed air cleaning. These methods were compared in three types of round air ducts: a metal duct without oil residual, a metal duct with oil residual, and a plastic duct. The level of cleanliness was estimated both by using the vacuum test method and visually, and the time each method took was recorded. Two rotating speeds of the brush and various brush materials were used.

Several problems can occur if the design, installation and maintenance of HVAC systems fail to follow appropriate standards. These include excessive installation and maintenance costs as well as hygiene problems produced by dust deposition and accumulation. There is no proper set of standards for biological risk assessments to prevent ventilation system pollution. All there is are a few guidelines on limit values of bacterial and fungal air concentration.

Many occupants of a Swedish office building reported symptoms typical of sick building syndrome (SBS). Tests showed that the supply airflows were inadequate, but there was poor air movement in the rooms. Much of the supply air never reached the occupants but went direct to the exhaust system. Reducing the temperature of the supply air improved its dispersion. Instead of rising, the air sank towards the floor and then circulated through the entire room.

The importance of IAQ to Finland's society and economy has led to the realisation that nationally planned and coordinated activities are necessary to achieve reliable results. For 20 years the Finnish government has had a national policy to coordinate different governmental, local and private policies to improve IAQ in homes, schools, offices, public places etc. This program has been very successful although there are still many buildings with damp, mould and other similar problems and the quality of construction falls below that required.

During extreme weather conditions, the poor quality of windows and doors in several dwellings led to a high number of air changes. This created physical and psychical discomfort for the occupants. Recently better quality windows and doors were installed which led to the infiltration air exchange rate decreasing and heating costs falling. Unfortunately mildew formed in many apartments.

This paper is based upon the results of measuring and simulating the air change in the single apartment of 5-storey multi-family dwelling. The technique of tracer gas concentration decay was applied to be able to assess the rate of air change. The building was used as normal by occupants so the results should be very accurate. The main aim of the research was to validate simulation methods used to predict infiltration. Multiven -the authors own program - was used to achieve this aim.

Discusses how important it is to understand how the exhaust fan, stack discharge and replacement air contribute to a successful kitchen exhaust system.