Assessment of exposure risk from hidden fungal growth by measurements of air change rates in construction cavities and living areas

2017 ◽  
Vol 41 (3) ◽  
pp. 209-224 ◽  
Author(s):  
Sofie M Knudsen ◽  
Eva B Møller ◽  
Lars Gunnarsen
Keyword(s):  
Field Study ◽  
Fungal Growth ◽  
Building Envelope ◽  
Exposure Risk ◽  
Tracer Gas ◽  
Change Rate ◽  
Health Symptoms ◽  
Air Change Rate ◽  
Gaseous Pollution ◽  
Growth Assessment

The transfer of particulate and gaseous pollution from hidden fungi growing on non-visible surfaces within the building envelope to occupied rooms is limited by the separating structure. Yet, growth, even in sealed construction cavities, is known to cause annoying smells and other more adverse health symptoms among the building occupants. This study analyses limitations of air change rate measurements in inaccessible construction cavities as well as analyses of the air exchange between living areas and accessible cavities such as crawl spaces and attics. It was necessary to invent a field study technique to use the tracer gas decay method in small and inaccessible cavities. This technique allowed further investigation on the exposure risk from hidden fungal growth. Assessment of the air transfer between crawl spaces and living areas indicate that the tightness of separating structure has an influence on the exposure risk.

scholarly journals Airflow as a Possible Transmission Route of Middle East Respiratory Syndrome at an Initial Outbreak Hospital in Korea

2018 ◽  
Vol 15 (12) ◽  
pp. 2757 ◽  
Author(s):  
Minki Sung ◽  
Seongmin Jo ◽  
Sang-Eun Lee ◽  
Moran Ki ◽  
Bo Choi ◽  
...  
Keyword(s):  
Middle East ◽  
Infected Patient ◽  
Close Contact ◽  
Middle East Respiratory Syndrome ◽  
High Concentration ◽  
Tracer Gas ◽  
Long Distance ◽  
Indoor Airflow ◽  
Change Rate ◽  
Air Change Rate

In this study, the results of an airflow investigation conducted on 7 June 2015 as part of a series of epidemiologic investigations at Pyeongtaek St. Mary’s Hospital, South Korea, were investigated. The study involved 38 individuals who were infected directly and indirectly with Middle East Respiratory Syndrome (MERS), by a super-spreader patient. Tracer gas experiments conducted on the eighth floor, where the initial patient was hospitalized, confirmed that the tracer gas spread to adjacent patient rooms and rooms across corridors. In particular, the experiment with an external wind direction and speed similar to those during the hospitalization of the initial patient revealed that the air change rate was 17–20 air changes per hour (ACH), with air introduced through the window in the room of the infected patient (room 8104). The tracer gas concentration of room 8110, which was the farthest room, was 7.56% of room 8104, indicating that a high concentration of gas has spread from room 8104 to rooms across the corridor. In contrast, the tracer gas was barely detected in a maternity ward to the south of room 8104, where there was no secondary infected patient. Moreover, MERS is known to spread mainly by droplets through close contact, but long-distance dispersion is probable in certain environments, such as that of a super-spreader patient hospitalized in a room without ventilation, hospitals with a central corridor type, and indoor airflow dispersion due to external wind.

Indoor hygrothermal loads for the deterministic and stochastic design of the building envelope for dwellings in cold climates

2017 ◽  
Vol 41 (6) ◽  
pp. 547-577 ◽  
Author(s):  
Simo Ilomets ◽  
Targo Kalamees ◽  
Juha Vinha
Keyword(s):  
Field Measurements ◽  
Heating System ◽  
Building Envelope ◽  
Cold Climates ◽  
Outdoor Temperature ◽  
Change Rate ◽  
Levels Of Detail ◽  
Air Change Rate ◽  
Excess Value ◽  
Occupancy Rates

In this study, several years of field measurements of indoor hygrothermal loads in 237 dwelling units are analysed. Moisture excess is calculated from hourly values of temperature, and relative humidity measured both indoors and outdoors. Air change rate and moisture production in bedrooms are calculated on the basis of carbon dioxide measurements. It is found that indoor temperature profiles differ depending on whether a building has central heating, a stove or combined heating system. The determined average moisture excess value, 2.8 g/m3 with a standard deviation of 1.6 g/m3 for cold periods, can be used in stochastic calculations. Critical values for moisture excess at the 90th percentile, ranging from 3–8 g/m3, depending upon occupancy rates, can be used in the deterministic analysis. Averages and weekly maxima of moisture excess in the study are reported at different percentiles. Considerable deviations from the EN ISO 13788 standard are discovered, concerning the breaking point depending on outdoor temperature and moisture excess during the summer. The average and critical moisture production in bedroom is presented and insufficient ventilation determined based on measurements. During the heating period, the air change rate is relatively stable while moisture production levels increase along with the dropping outdoor temperature. Two indoor temperatures and three humidity models with different levels of detail and influencing factors are proposed. Temperature and humidity loads derived using the proposed models can be used to determine the indoor hygrothermal boundary conditions for the building envelope of dwellings in cold climates.

scholarly journals A Discussion Regarding the Measurement of Ventilation Rates Using Tracer Gas and Decay Technique

2020 ◽  
Vol 5 (10) ◽  
pp. 85
Author(s):  
Ricardo M. S. F. Almeida ◽  
Eva Barreira ◽  
Pedro Moreira
Keyword(s):  
Cross Contamination ◽  
Single Family ◽  
Outdoor Temperature ◽  
Time Dependency ◽  
Tracer Gas ◽  
Large Variability ◽  
Change Rate ◽  
Air Change Rate ◽  
Ventilation Rates

The measurement of ventilation rates is crucial in understanding buildings’ performances, but can be a rather complex task due to the time-dependency of wind and buoyancy forces, which are responsible for the pressure differences that induce air movement across the envelope. Thus, assessing air change rate through one-time measurements during brief periods of time may not be a reliable indicator. In this paper, the variability in the measurement of ventilation rates using the decay technique was evaluated. To that end, two compartments of a typical single-family detached dwelling were selected as a case study and 132 tests were performed, considering two different boundary conditions (door closed and door open). This work allowed the large variability of the results to be highlighted, as the coefficient of variation ranged from 20% to 64%. Wind speed had a key effect on the results, especially because during the measurements indoor–outdoor temperature differences were not so significant. The possibility of using occupant-generated carbon dioxide as tracer gas was also analyzed, but problems of cross-contamination were identified.

scholarly journals Analysis of Wind Speed and Wind Pressure on the Facades in Frequency Domain for the Modelling of Air Change Rate

2020 ◽  
Vol 172 ◽  
pp. 09005
Author(s):  
Krystyna Pietrzyk
Keyword(s):  
Wind Speed ◽  
Frequency Domain ◽  
Wind Direction ◽  
High Frequency ◽  
Pressure Coefficient ◽  
Building Envelope ◽  
Wind Pressure ◽  
Change Rate ◽  
Air Change Rate ◽  
Air Exchange

Air exchange in buildings is driven by pressure difference across the building envelope caused by wind and difference in density between external and internal air. The evaluation of the influence of wind on the air change rate is usually limited to the analysis of the hourly mean wind speed. Wind is a random phenomenon characterized by the broad energy spectrum. The high frequency part can be responsible for the oscillation of the air through the openings resulting in the increased air exchange. Wind pressure coefficient on the leeward site mostly depends on the form characteristics of the object in relation to wind direction. The analysis of wind speed and wind pressure on the facades in frequency domain can deliver interesting data to air change rate model. Some of the results of continuous measurements carried out on a single-family house for 8 months are presented in frequency domain. The statistics of wind speed, wind direction and pressure differences across the 6 building components are calculated. The wind turbulence and the pressure fluctuations on the facades and the roof of the building are being investigated using energy spectra of their signals. Farther analysis of the experimental results is needed to be able to include high frequency wind in the infiltration model.

Stable carbon isotope labelled carbon dioxide as tracer gas for air change rate measurement in a ventilated single zone

2017 ◽  
Vol 115 ◽  
pp. 173-181 ◽  
Author(s):  
K.E. Anders Ohlsson ◽  
Bin Yang ◽  
Alf Ekblad ◽  
Christoffer Boman ◽  
Robin Nyström ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Isotope ◽  
Stable Carbon Isotope ◽  
Rate Measurement ◽  
Stable Carbon ◽  
Tracer Gas ◽  
Change Rate ◽  
Air Change Rate

scholarly journals Towards upgrading strategies for nZEB-dwellings in Norway

2019 ◽  
Vol 25 (2) ◽  
pp. 35-42
Author(s):  
Lars Gullbrekken ◽  
Berit Time
Keyword(s):  
High Performance ◽  
Building Envelope ◽  
Passive House ◽  
Ventilation Control ◽  
Ongoing Research ◽  
Change Rate ◽  
Building Regulations ◽  
Air Change Rate ◽  
Upgrading Strategies ◽  
High Performance Level

Recent work suggests that upgrading in line with the Norwegian building regulations or by upgradingto the requirements of the national passive house norm, NS3700, can enable nZEB level to be achieved.The aim of this work is to explore the typical Norwegian housing typologies and some importantcharacteristics of the building envelope for these houses from different decades. The exploration involvedsurveying the typical technical qualities of Norwegian housing and how these have evolved – providingan important foundation to work addressing strategies and methods for upgrading dwellings to nZEBlevel in the next phases of the ongoing research project. The results of this work show that the buildingnorms and practices developed throughout the years have made dwellings more moisture resilient, withan increased drying-out potential through mechanical ventilation, control of the air change rate and theuse of more vapour-open wind barriers in the building envelope. Based on this, the work to follow willsuggest strategies for upgrading to nZEB level, solutions for upgrading building envelope componentsto high performance level and a methodology for risk reduction of moisture problems in the upgradeddwellings from the different decades.

scholarly journals Developing a new passive tracer gas test for air change rate measurement

2020 ◽  
pp. 1-11
Author(s):  
Sarah L. Paralovo ◽  
Maarten Spruyt ◽  
Joris Lauwers ◽  
Rudi Swinnen ◽  
Borislav Lazarov ◽  
...  
Keyword(s):  
Passive Tracer ◽  
Rate Measurement ◽  
Tracer Gas ◽  
Change Rate ◽  
Air Change Rate
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