The indoor air climate of a church, with a total building volume of 9500 m^{3, was investigated from January to October, 2008. During this time, infiltration and ventilation measurements were performed at four periods ranging from 17 to 45 days. The local mean age of air was determined in several locations at different heights using passive samplers and homogeneous emission of PFTs. In addition, the temperature and relative humidity was measured at selected locations. The total infiltration of fresh air into the church was found to be mainly driven by the difference between indoor and outdoor temperature. The rate of infiltration ranges from 780 m3/h (deltat=14.8 degrees C) in January to 240 m3/h (deltat=3.5 degrees C) in August. The local mean age of air in the upper and lower air volumes were found to be roughly equal, both during the heating season and in the summer. This indicates that the air volume in the church is well-mixed throughout the year. Transient measurements to assess the effects of doors opening in the summer were also performed using pumped sampling.}

Using a passive tracer gas technique, 1 and 2 week averages of local mean ages of air have been estimated in an occupied detached single family house in mid-Sweden during one year. In this paper the measurement result is compared with the result of transient simulation of ventilation using the CONTAM program. The simulation shows that the whole-house air change rate is dominated by the infiltration due to mechanically created pressure difference as long as the outdoor temperature difference exceeds approx. 10 °C. At lower outdoor temperature, the natural driving force becomes increasingly more important increasing the local air change rate (local ACH) in the basement. However, the local ACH on the ground floor is almost independent of indoor-outdoor temperature difference and completely dominated by the mechanical extract. The result from the simulation can reproduce the result of the measurement in satisfactory detail without using wind pressure data.

High local concentrations of a pollutant can be the result of high local emission rates of the pollutant or insufficient ventilation. Using tracer gases to map the ventilation in multi-zone buildings combined with measurements of the local pollutant concentration provide the means to discriminate between these causes. In a similar manner, the propagation rate of pollutants from a source to a target zone and the emission rate of the pollutants at the source may be determined quantitatively.

The paper presents both the theoretical framework for the techniques and experimental examples of the proposed methods.

Portugal has technical recommendations and standards regarding ventilation rates in natural ventilation systems. However these ventilation rates have not been fulfilled in most residential buildings recently erected in Portugal. We believe that natural ventilation systems alone are unlikely to guarantee the recommended ventilation, and so we characterized the performance of a mixed ventilation system consisting of an air inlet through self-adjustable inlets in bedrooms and living rooms, natural exhaust in bathrooms and fan exhaust systems in kitchens. We measured ventilation conditions in a residential complex of 94 apartments in the Porto area using the passive tracer gas method, more precisely the PFT technique. The study evaluates the façade’s permeability and the respective air exchange rates per compartment using the PFT technique. Seven flats were analyzed, six of which have a mixed ventilation system (continuous exhaust system in the kitchen and natural exhaust in the bathroom). The seventh flat has a natural ventilation system, enabling the performance of the two systems to be compared. The experimental results allow, namely, the evaluation of the influence of insulation, a grid with low head loss and a static ventilator in the duct of the bathroom and the continuous exhaust ventilation in the kitchen.

The objective of this study is to investigate how measured ventilation rates in dwellings vary over the heating season in a Nordic climate. The aim is to draw conclusions about the possibility to transform a measurement result obtained during a relatively short period of time into one which would have been expected as an average over a whole season. If such normalisation of measurement data is not possible, dwellings may be misclassified as under- or over-ventilated, a matter which may dilute a possible relationship between health and air quality in epidemiological studies.

Passive tracer gas measurements of ventilation were performed in a detached single-family house and in a flat (apartment) in Stockholm during four consecutive winter seasons. Measured averages of air change rate data are reported for 47 two-week periods for those two naturally ventilated dwellings. Another measurement using two different tracer gases was performed in an airtight, extract ventilated detached house over one year. The variation of ventilation is discussed in terms of variation in the ventilation driving forces induced by inside-outside temperature differences. The naturally ventilated house shows a slightly better correlation between air change rate and indoor-outside temperature difference than the town flat. It is concluded that the correlations are not good enough for predictive use for either dwelling. Therefore it does not seem possible to “normalise” ventilation measurement data. A slightly better possibility to predict the weather influence exists for the airtight, extract ventilated house. A possible reason for the lack of good correlation between air change rate and natural driving forces is a highly variable influence from occupant behaviour.

Passive tracer gas measurements of ventilation were performed in a single-family house and in a flat in Stockholm during four consecutive winter seasons. Measured averages of ACH data are reported for 47 two-week periods for the two naturally ventilated dwellings. The variation of ventilation is discussed in terms of variation in the ventilation driving forces induced by inside-outside temperature differences. The detached house shows a slightly better correlation between ACH and indoor-outside temperature difference than the town flat. It is concluded that

the correlations are not good enough for predictive use for either dwelling. Therefore it does not seem possible to “normalise” ventilation measurement data, obtained during one time period with a specific weather condition, to what would be expected during a period with “normal” weather conditions. A possible reason for the lack of good correlation between ACH and natural driving forces is a highly variable influence from occupant behaviour.

This paper describes tracer gas measurements at the National Museum of Fine Arts in Stockholm. The building was erected 1850-1860 and the architect was Friedrich August Stüler. He created several museums of Fine Arts, among them Neues Museum in Berlin. The museum building in Stockholm has a volume of almost 90 000 m3 and the number of registered objects of art is well over 600 000. The collection includes one of the world’s most prestigious collections of drawings and graphical prints. In this case study the aim was to determine the infiltration through the main entrance and stairwell, through windows and outside walls. The measurement technique used was the Homogeneous Emission Technique added with a 2-zone set up, by using two different tracer gases. Several interesting results were obtained. One result was that more airtight entrance doors would decrease the infiltration into the main stairwell with 40 %. Another result of interest was that the very dry outdoor air was mixed with the indoor air quickly, and that the

mechanical ventilation system with filters and humidifying units has to be upgraded to compensate for the outdoor air infiltration.

Tracer gas sorption in and permeation through building materials influence tracer gas ventilation measurements. The permeation of the commonly used tracer SF6 through three different building materials (gypsum board, wood particle board and MDF-board) with and without paint has been experimentally investigated. The results show that the tracer diffuse through untreated boards and that gypsum board has the largest permeability towards SF6. However, the diffusion rate of tracer is effectively reduced when the boards are coated with two layers of latex paint. Caution should therefore be exercised when using tracer gas measurements in rooms with walls of untreated porous materials.