air distribution

The main purpose of this study is to analyse the effects of heat gain, airflow rate, air distribution, and the location of an infector on the airborne transmission and infection probability in a meeting room. In a six-person meeting room the droplet nuclei of an infected person were simulated with tracer gas (SF6) generated by a thermal breathing manikin. An overhead perforated duct (OPD) and low velocity unit (LVU) were used and their performance was compared.

Air and airborne contaminant mixing in building spaces is important to ventilation system design and performance, tracer gas measurements of ventilation rates, and occupant exposure to indoor pollutants. The physics of air and contaminant mixing have been studied for decades and are fairly well understood. Nevertheless, many discussions of building ventilation, air movement and indoor air quality use the term “perfect mixing” without a clear discussion of what it means or how it applies to the situation being considered.

This research aims to evaluate ventilation performance on airborne transmission in buildings, by analyzing the effect of different ventilation configurations and flow rates on contaminant removal effectiveness

Measurement method for ventilation effectiveness, more specifically, for contaminant removal effectiveness with a point source corresponding to infector is analysed in this study with tracer gas measurements and infection risk calculations. Ventilation effectiveness is needed in infection risk-based ventilation design to take into account air distribution methods deviating from fully mixing. Tracer gas measurements were conducted with two source location in six non-residential spaces.

The importance of ventilation of spaces for occupants’ health has been known for many years. Ancient Egyptians used natural ventilation to remove dust and thus to reduce respiratory diseases of stone carvers working indoors (Janssen 1999). In the past ventilation has been used to reduce airborne transmission of respiratory generated infectious agents in buildings.

Stratum ventilation (SV) is an energy-efficient solution to provide thermal comfort and improve air quality. The air distribution in rooms with SV depends on the room layout, location of supply and exhaust grills and indoor heat gains. Therefore, the commonly used methods to predict air temperatures in the occupied zone do not usually fit the indoor temperature distribution. At the same time, detailed simulations of indoor air distribution are still mainly used in complicated room layouts and research.

A smart ventilation system is able to continually adjust itself to provide the desired indoor air quality (IAQ) while minimizing energy use, utility bills, thermal discomfort and noise. A smart ventilation system is also responsive to e.g. occupancy, outdoor conditions, direct sensing of contaminants and can provide information about e.g. IAQ, energy use and the need for maintenance or repair. Technically, all components for such systems are available in the market.  

A literature review has revealed that there is a very limited number of numerical or experimental studies of the air flow for mechanically ventilated large occupied rooms. Existing literature suggests that a room with more than 5 meters floor-to-ceiling height can be considered as a large space. The aim of this paper is to present a set of detailed air temperature and velocity measurements in a large open plan office located in south England.

When planning ventilation systems for energy efficient housing, an appropriate design of the overflow elements between rooms is important as it influences ventilation losses, indoor air quality and sound attenuation between rooms. Based on calculation results of the natural in- or exfiltration rates through the building envelope as a function of the overflow element’s flow resistance, this work proposes a maximal pressure drop of 2-3Pa for overflow elements in energy efficient buildings.

On the basis of modelling with similarity theory and by using the Archimedes number, Ar, as the similitude parameter, this paper analyzes the air distribution of a busbar corridor in a hydropower station by using the Particle Image Velocimetry (PIV) measurement technique.