tracer gas

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.

Buildings energy renovation is a major priority in most European countries in order to achieve a fully decarbonized building stock by 2050. In France, 7 million homes are poorly insulated and 14% of French people feel cold in their homes. The government has thus implemented an ambitious plan to scale up energy-efficient renovations of buildings to achieve carbon neutrality by 2050 while also pursuing a social objective of combating energy precarity. 

All new dwellings in England and Wales are required to undergo a model-based overheating risk assessment prior to construction. An important model input is the building infiltration rate, which is usually estimated using a conversion factor on the dwelling airtightness. There is a paucity of evidence regarding the reliability of these methods in summertime. This aim of this paper is to provide new evidence on the relationship between airtightness and infiltration during summertime.

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.

Building air infiltration rate is required as an important input in the calculation of building heat loss. Tests to directly measure infiltration rates are complex and time-consuming to perform, and are therefore usually substituted with an airtightness test as a more efficient alternative. An empirical ratio, or sometimes an infiltration model, is then used to predict the building infiltration rate from the measured airtightness value. For instance, in the United Kingdom the building air permeability measured by a steady pressurisation test and reported at 50 Pa

Measuring ventilation rates in occupied dwellings is challenging but represents the conditions that occupants experience. This paper explores the constraints of existing methods when measuring the ventilation rate of occupied buildings and proposes a new method addressing some of them.  

Air infiltration contributes to a heat loss typically representing up to one third of the heating demand of a building. The building airtightness, also quantified as air leakage, is the fundamental building property that impacts infiltration. The steady (de)pressurization method (blower door) is the widely accepted standard process for measuring building air leakage. However, this method requires the enclosure to be pressurised to a typical range of 10-60 Pa, which is not physically representative of the pressures experienced by buildings under natural conditions.

In order to provide patients with a high quality indoor environment and ensure a pleasant working place for medical care personnel, thermal environment and indoor air quality are regarded as two of the most important requirements. 

Using natural ventilation is effective to save energy, and it is essential for energy conservation and decreasing running cost [1]. However, in office buildings located in where mid- to -high-rise buildings are densely distributed, the way of ensuring stable ventilation is very important matter of natural ventilation system. In this research, we focus on the ventilation performance of an office building where the natural ventilation system is introduced by utilizing the buoyancy force through a ventilation shaft.

From the energy point of view, buildings should be as tight as possible. But lack of ventilation will result in high level of indoor pollutants, which is harmful for occupants. Numerous studies find that lack of ventilation could cause symptoms for occupants, which are characterized by World Health Organization as Sick Building Syndrome.