Pub Date : 2023-06-01DOI: 10.1080/14733315.2023.2218424
A. Sengupta, H. Breesch, D. Al Assaad, M. Steeman
Airtight and highly insulated buildings are subjected to overheating risks, even in moderate climates, due to unforeseeable events like frequent heatwaves and power outages. Educational buildings share a major portion of building stocks and a large percentage of the energy is expended in maintaining thermal comfort in these buildings. Overheating risks in educational buildings can lead to heat-stress and negatively impact the health conditions and also cognitive performance of the occupants. In the light of increasing severity and longevity of heat waves in future climate scenarios, and associated power outages occurring during the heatwaves, measures to reduce overheating risk while limiting the cooling energy is gaining importance. Since the performance of existing buildings are not guaranteed during events like heatwaves, power outages, it is crucial for these buildings to be resilient to overheating. (Building) resilience is a method to deal with these uncertainties and is stated as “an ability of the building to withstand disruptions; and to maintain the capacity to adapt, learn and transform.” The focus of this paper is to evaluate thermal resilience for two test lecture equipped with low-energy cooling strategies like natural night ventilation (NNV) and indirect evaporative cooling (IEC) rooms, by dynamic Building Energy Simulations (BES). To assess the thermal resilience to overheating three different heatwaves (HW) files ( intense, severe, and longest) for 3 future scenarios (1) Historical (2010-2020), (2) mid-term (2041 -2060) and (3) long-term (2081-2100) and a 24h power outage (PO)scenario was simulated. Benchmarking was done with a base case- Typical Meteorological year(TMY) with no power outage. The heatwave files were developed adopting the methodology proposed by the 'Weather Data Task Force’ of International Energy Agency Energy in Buildings and Communities Programme (IEA EBC) Annex 80 “Resilient Cooling of Buildings”. This study shows, IEC has high to moderate recovery capacity in TMY period and low recovery capacity in HW period, for a power outage of 24 h. Recovery capacity is low during HW period, especially during an intense and longer HW period when outdoor temperature influences the cooling capacity of the IEC. The results also demonstrates the impact of the thermal mass on the resilience to overheating. Passive survivability assessment indicates, the lecture room with lighter thermal mass does not violate 30℃ threshold during a power outage in TMY period and additionally,. recovers faster (11% times faster) from peak temperature compared to lecture room with heavy thermal mass. There is a steep increase in unmet degree hours (occupied hours above24℃ threshold) during HW compared to TMY period. This paper gives a directive towards assessment of resilience to overheating and also points out the gap in the existing indicators to assess the resilience.
{"title":"Evaluation of thermal resilience to overheating for an educational building in future heatwave scenarios","authors":"A. Sengupta, H. Breesch, D. Al Assaad, M. Steeman","doi":"10.1080/14733315.2023.2218424","DOIUrl":"https://doi.org/10.1080/14733315.2023.2218424","url":null,"abstract":"Airtight and highly insulated buildings are subjected to overheating risks, even in moderate climates, due to unforeseeable events like frequent heatwaves and power outages. Educational buildings share a major portion of building stocks and a large percentage of the energy is expended in maintaining thermal comfort in these buildings. Overheating risks in educational buildings can lead to heat-stress and negatively impact the health conditions and also cognitive performance of the occupants. In the light of increasing severity and longevity of heat waves in future climate scenarios, and associated power outages occurring during the heatwaves, measures to reduce overheating risk while limiting the cooling energy is gaining importance. Since the performance of existing buildings are not guaranteed during events like heatwaves, power outages, it is crucial for these buildings to be resilient to overheating. (Building) resilience is a method to deal with these uncertainties and is stated as “an ability of the building to withstand disruptions; and to maintain the capacity to adapt, learn and transform.” The focus of this paper is to evaluate thermal resilience for two test lecture equipped with low-energy cooling strategies like natural night ventilation (NNV) and indirect evaporative cooling (IEC) rooms, by dynamic Building Energy Simulations (BES). To assess the thermal resilience to overheating three different heatwaves (HW) files ( intense, severe, and longest) for 3 future scenarios (1) Historical (2010-2020), (2) mid-term (2041 -2060) and (3) long-term (2081-2100) and a 24h power outage (PO)scenario was simulated. Benchmarking was done with a base case- Typical Meteorological year(TMY) with no power outage. The heatwave files were developed adopting the methodology proposed by the 'Weather Data Task Force’ of International Energy Agency Energy in Buildings and Communities Programme (IEA EBC) Annex 80 “Resilient Cooling of Buildings”. This study shows, IEC has high to moderate recovery capacity in TMY period and low recovery capacity in HW period, for a power outage of 24 h. Recovery capacity is low during HW period, especially during an intense and longer HW period when outdoor temperature influences the cooling capacity of the IEC. The results also demonstrates the impact of the thermal mass on the resilience to overheating. Passive survivability assessment indicates, the lecture room with lighter thermal mass does not violate 30℃ threshold during a power outage in TMY period and additionally,. recovers faster (11% times faster) from peak temperature compared to lecture room with heavy thermal mass. There is a steep increase in unmet degree hours (occupied hours above24℃ threshold) during HW compared to TMY period. This paper gives a directive towards assessment of resilience to overheating and also points out the gap in the existing indicators to assess the resilience.","PeriodicalId":55613,"journal":{"name":"International Journal of Ventilation","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89230853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-27DOI: 10.1080/14733315.2023.2198791
Benedikt Kölsch, J. Pernpeintner, Björn Schiricke, E. Lüpfert
Abstract Air leakage in building envelopes is responsible for a large portion of the building’s heating and cooling requirements. Therefore, fast and reliable detection of leaks is crucial for improving energy efficiency. This paper presents a new approach to determining air leakages in a building’s envelope from the outside, combining lock-in thermography and thermal excitation by a blower door system. The blower creates a periodic overpressure within the building, inducing periodic temperature variations of the surfaces near the leaks on the outside surface, the façade. With the temperature variations excited at a known frequency, Fourier transforms of the time-series of the thermal images at the excitation frequency result in amplitude and phase images highlighting the areas affected by leaks. Periodic excitation and detection by an IR camera is known as lock-in thermography and is widely used to characterise semiconductor devices and in non-destructive testing. Excitation is usually achieved by optical, electrical, or mechanical energy input. For this work, measurements of outside façades have been performed with three excitation cycles of a period of 40 s at a 75 Pa pressure difference, leading to a total measurement time of only 2 min. Measurements have been performed with air temperature differences of 5 to 7 K at highly variable conditions of irradiance, wind, and cloud cover. The measurements show higher detection quality and less impact from changing ambient conditions than the state-of-the-art differential infrared thermography measurements. With the method highlighting the variations in the amplitude image only at the excitation frequency, variations caused by environmental effects are filtered out. A temperature difference as low as a few Kelvin is therefore sufficient, and large façades can be examined from the outside. This amplitude image is already clearer than an image created with differential thermography. A further reduction of unwanted artefacts in the image is demonstrated using phase-weighing of the amplitude by scalar product.
{"title":"Air leakage detection in building façades by combining lock-in thermography with blower excitation","authors":"Benedikt Kölsch, J. Pernpeintner, Björn Schiricke, E. Lüpfert","doi":"10.1080/14733315.2023.2198791","DOIUrl":"https://doi.org/10.1080/14733315.2023.2198791","url":null,"abstract":"Abstract Air leakage in building envelopes is responsible for a large portion of the building’s heating and cooling requirements. Therefore, fast and reliable detection of leaks is crucial for improving energy efficiency. This paper presents a new approach to determining air leakages in a building’s envelope from the outside, combining lock-in thermography and thermal excitation by a blower door system. The blower creates a periodic overpressure within the building, inducing periodic temperature variations of the surfaces near the leaks on the outside surface, the façade. With the temperature variations excited at a known frequency, Fourier transforms of the time-series of the thermal images at the excitation frequency result in amplitude and phase images highlighting the areas affected by leaks. Periodic excitation and detection by an IR camera is known as lock-in thermography and is widely used to characterise semiconductor devices and in non-destructive testing. Excitation is usually achieved by optical, electrical, or mechanical energy input. For this work, measurements of outside façades have been performed with three excitation cycles of a period of 40 s at a 75 Pa pressure difference, leading to a total measurement time of only 2 min. Measurements have been performed with air temperature differences of 5 to 7 K at highly variable conditions of irradiance, wind, and cloud cover. The measurements show higher detection quality and less impact from changing ambient conditions than the state-of-the-art differential infrared thermography measurements. With the method highlighting the variations in the amplitude image only at the excitation frequency, variations caused by environmental effects are filtered out. A temperature difference as low as a few Kelvin is therefore sufficient, and large façades can be examined from the outside. This amplitude image is already clearer than an image created with differential thermography. A further reduction of unwanted artefacts in the image is demonstrated using phase-weighing of the amplitude by scalar product.","PeriodicalId":55613,"journal":{"name":"International Journal of Ventilation","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73289641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-23DOI: 10.1080/14733315.2023.2198793
Nima Najafi Ziarani, M. Cook, Paul D. O'Sullivan
Abstract Wind-driven single-sided ventilation (SSV) is present in many existing buildings across Europe, and with new near-zero energy building (NZEB) regulations for the refurbishment of the existing building stock, its attractiveness as a noninvasive, low-energy solution is set to continue. As a strategy, however, in addition to its air change rate capacity, the distribution of fresh air is an important evaluation criterion for its performance. Airflow guiding components located in the external opening that enhance the effectiveness of the wind-driven flow in ventilating the occupied zone could improve the quality of indoor environments. To our knowledge, the literature is sparse on the practical implications for ventilation when adopting guiding components such as louvres, an increasingly popular approach. In the present study, the performance of wind-dominant SSV was simulated using RNG and RSM CFD models, with and without louvres at three building orientations, for example, windward, parallel and leeward. The purpose of this study was to investigate whether louvres installed in the opening would improve both the effective ventilation rate and the penetration depth of the flow into the indoor space. The performance of SSV was evaluated using the age of air and interpreting the secondary air circulation inside the room affected by louvres. As a result of these investigations, a newly configured airflow guiding component was designed and compared to the other cases. Results show louvres can play a crucial role in controlling the secondary air circulation inside the room, and they could either improve or worsen the performance of SSV in terms of air-exchange efficiency. It was shown that in most cases, if louvres were the cause of incremental changes in turbulent intensity within the indoor space, then they are effective as an air-exchange efficiency improvement strategy.
{"title":"The effect of airflow guiding components on effective ventilation rates in single-sided ventilation applications","authors":"Nima Najafi Ziarani, M. Cook, Paul D. O'Sullivan","doi":"10.1080/14733315.2023.2198793","DOIUrl":"https://doi.org/10.1080/14733315.2023.2198793","url":null,"abstract":"Abstract Wind-driven single-sided ventilation (SSV) is present in many existing buildings across Europe, and with new near-zero energy building (NZEB) regulations for the refurbishment of the existing building stock, its attractiveness as a noninvasive, low-energy solution is set to continue. As a strategy, however, in addition to its air change rate capacity, the distribution of fresh air is an important evaluation criterion for its performance. Airflow guiding components located in the external opening that enhance the effectiveness of the wind-driven flow in ventilating the occupied zone could improve the quality of indoor environments. To our knowledge, the literature is sparse on the practical implications for ventilation when adopting guiding components such as louvres, an increasingly popular approach. In the present study, the performance of wind-dominant SSV was simulated using RNG and RSM CFD models, with and without louvres at three building orientations, for example, windward, parallel and leeward. The purpose of this study was to investigate whether louvres installed in the opening would improve both the effective ventilation rate and the penetration depth of the flow into the indoor space. The performance of SSV was evaluated using the age of air and interpreting the secondary air circulation inside the room affected by louvres. As a result of these investigations, a newly configured airflow guiding component was designed and compared to the other cases. Results show louvres can play a crucial role in controlling the secondary air circulation inside the room, and they could either improve or worsen the performance of SSV in terms of air-exchange efficiency. It was shown that in most cases, if louvres were the cause of incremental changes in turbulent intensity within the indoor space, then they are effective as an air-exchange efficiency improvement strategy.","PeriodicalId":55613,"journal":{"name":"International Journal of Ventilation","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89334956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-21DOI: 10.1080/14733315.2023.2198804
Vasileios Filis, K. Smith, J. Kolarik, F. Kuznik, Lucie Merlier
Abstract Humidity-controlled mechanical exhaust ventilation (RH-MEV) has been widely used in France for over 35 years, demonstrating high durability and robustness. This exhaust-only ventilation strategy is widely used as an energy-saving measure, replacing constant mechanical exhaust ventilation (Constant-MEV) systems in residential buildings. It demonstrates energy savings due to the restricted airflows, but as a downside, the building’s indoor air quality (IAQ) often deteriorates. Moreover, it is impossible to recover heat with exhaust-only ventilation systems, which means that energy consumption for space heating is still quite significant and cold supply air temperatures are frequently introduced to the heated spaces. Room ventilation units (RVUs) with heat recovery represent an alternative ventilation solution allowing simple installation through the façade and providing fresh outdoor air and exhaust ventilation to each room. This study investigates these units’ energy saving potential and indoor environmental quality performance as an alternative solution to centralized exhaust-only ventilation systems. The dynamic simulations were performed for a reference residential building under various French climatic conditions for a heating season. The three ventilation strategies investigated were Constant-MEV, RH-MEV and room-based ventilation with RVUs. The results demonstrated 61–85% savings in space heating demand with the RVUs, compared to Constant-MEV under all climatic conditions. Compared to RH-MEV, the RVUs saved 44–75% energy for space heating while the CO2 concentration and relative humidity levels were decreased due to RVUs’ constant air exchange rate. In all cases, RVUs provided considerably higher supply air temperatures due to the implemented heat recovery, which can potentially improve indoor thermal comfort.
{"title":"The indoor environmental quality and energy savings potential of room ventilation units compared to exhaust-only ventilation systems in France","authors":"Vasileios Filis, K. Smith, J. Kolarik, F. Kuznik, Lucie Merlier","doi":"10.1080/14733315.2023.2198804","DOIUrl":"https://doi.org/10.1080/14733315.2023.2198804","url":null,"abstract":"Abstract Humidity-controlled mechanical exhaust ventilation (RH-MEV) has been widely used in France for over 35 years, demonstrating high durability and robustness. This exhaust-only ventilation strategy is widely used as an energy-saving measure, replacing constant mechanical exhaust ventilation (Constant-MEV) systems in residential buildings. It demonstrates energy savings due to the restricted airflows, but as a downside, the building’s indoor air quality (IAQ) often deteriorates. Moreover, it is impossible to recover heat with exhaust-only ventilation systems, which means that energy consumption for space heating is still quite significant and cold supply air temperatures are frequently introduced to the heated spaces. Room ventilation units (RVUs) with heat recovery represent an alternative ventilation solution allowing simple installation through the façade and providing fresh outdoor air and exhaust ventilation to each room. This study investigates these units’ energy saving potential and indoor environmental quality performance as an alternative solution to centralized exhaust-only ventilation systems. The dynamic simulations were performed for a reference residential building under various French climatic conditions for a heating season. The three ventilation strategies investigated were Constant-MEV, RH-MEV and room-based ventilation with RVUs. The results demonstrated 61–85% savings in space heating demand with the RVUs, compared to Constant-MEV under all climatic conditions. Compared to RH-MEV, the RVUs saved 44–75% energy for space heating while the CO2 concentration and relative humidity levels were decreased due to RVUs’ constant air exchange rate. In all cases, RVUs provided considerably higher supply air temperatures due to the implemented heat recovery, which can potentially improve indoor thermal comfort.","PeriodicalId":55613,"journal":{"name":"International Journal of Ventilation","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79732830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-18DOI: 10.1080/14733315.2023.2198800
Giobertti Morantes, Benjamin Jones, M. Sherman, Constanza Molina
Abstract Common metrics used for assessing air quality are based on guidelines and/or standards for regulating concentrations that should not be exceeded over a period. Exceeding those values would represent problematic situations. A lack of agreement on appropriate norms or standards deems this approach sub-optimal. Moreover, this approach does not relate a proportion of exceedance to specific health outcomes. A need to develop health-centered IAQ metrics that can quantify burden of disease in terms of epidemiological evidence of population morbidity and mortality supported by the best knowledge of health effects, is pressing. This work proposes an approach that harnesses the advantages of using disability adjusted life years (DALYs) as a valuable metric to quantify and rank the burden of household air pollution, as a global perspective. Two methods were used to compute DALYs, one mainly based on incidence data and another mainly based on effect factors (i.e. DALYs per unit-intake of contaminant of interest). The methods are based on the following parameters: risk estimates, baseline incidence rates, damage factors, indoor air contaminant concentrations, human toxicological & epidemiological effect factors, dose–response factors, cancer-related variables and breathing rates. Systematic searches and reviews of peer-reviewed literature (including systematic reviews and meta-analyses) were performed to find information on said input parameters. Meta-analysis was used to pooled and synthesise data from different studies. A Monte Carlo approach was used to model results in DALYs lost. Over 1000 articles were revised and overall ∼200 unique sources were used as sources of data. Ten contaminants were accounted for with specific risk estimates and damage factors data, for which human epidemiological effect factors were derived. Representative concentrations of 45 contaminants were calculated. Thirty-nine contaminants were accounted for human toxicological effect factors. Total pooled DALYs were estimated per 100,000 exposed population with corresponding uncertainty intervals. Estimated population-averaged annual cost, in DALYs lost, of chronic air contaminant inhalation in dwellings indicate that the contaminants with highest median DALY loss estimates are PM10 and PM2.5 (magnitudes of 103); PMcoarse, formaldehyde and NO2 could be found with magnitudes of 102; contaminants with magnitudes of 101 include radon and ozone, finally SO2 and acrolein would have magnitudes of 10°; mould-related bioaerosols could be of interest as well. The updated strategies allowed for the quantification of contaminants and health outcomes that were not accounted for in previous works. Computed DALYs have lower uncertainty intervals than those previously proposed. The updated methodology presented in this study may be used to assess cumulative health impacts of indoor air contaminants.
{"title":"A preliminary assessment of the health impacts of indoor air contaminants determined using the DALY metric","authors":"Giobertti Morantes, Benjamin Jones, M. Sherman, Constanza Molina","doi":"10.1080/14733315.2023.2198800","DOIUrl":"https://doi.org/10.1080/14733315.2023.2198800","url":null,"abstract":"Abstract Common metrics used for assessing air quality are based on guidelines and/or standards for regulating concentrations that should not be exceeded over a period. Exceeding those values would represent problematic situations. A lack of agreement on appropriate norms or standards deems this approach sub-optimal. Moreover, this approach does not relate a proportion of exceedance to specific health outcomes. A need to develop health-centered IAQ metrics that can quantify burden of disease in terms of epidemiological evidence of population morbidity and mortality supported by the best knowledge of health effects, is pressing. This work proposes an approach that harnesses the advantages of using disability adjusted life years (DALYs) as a valuable metric to quantify and rank the burden of household air pollution, as a global perspective. Two methods were used to compute DALYs, one mainly based on incidence data and another mainly based on effect factors (i.e. DALYs per unit-intake of contaminant of interest). The methods are based on the following parameters: risk estimates, baseline incidence rates, damage factors, indoor air contaminant concentrations, human toxicological & epidemiological effect factors, dose–response factors, cancer-related variables and breathing rates. Systematic searches and reviews of peer-reviewed literature (including systematic reviews and meta-analyses) were performed to find information on said input parameters. Meta-analysis was used to pooled and synthesise data from different studies. A Monte Carlo approach was used to model results in DALYs lost. Over 1000 articles were revised and overall ∼200 unique sources were used as sources of data. Ten contaminants were accounted for with specific risk estimates and damage factors data, for which human epidemiological effect factors were derived. Representative concentrations of 45 contaminants were calculated. Thirty-nine contaminants were accounted for human toxicological effect factors. Total pooled DALYs were estimated per 100,000 exposed population with corresponding uncertainty intervals. Estimated population-averaged annual cost, in DALYs lost, of chronic air contaminant inhalation in dwellings indicate that the contaminants with highest median DALY loss estimates are PM10 and PM2.5 (magnitudes of 103); PMcoarse, formaldehyde and NO2 could be found with magnitudes of 102; contaminants with magnitudes of 101 include radon and ozone, finally SO2 and acrolein would have magnitudes of 10°; mould-related bioaerosols could be of interest as well. The updated strategies allowed for the quantification of contaminants and health outcomes that were not accounted for in previous works. Computed DALYs have lower uncertainty intervals than those previously proposed. The updated methodology presented in this study may be used to assess cumulative health impacts of indoor air contaminants.","PeriodicalId":55613,"journal":{"name":"International Journal of Ventilation","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80018068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-18DOI: 10.1080/14733315.2023.2198788
G. Rojas, Andreas Greml, Rainer Pfluger, P. Tappler
Abstract In Austria the lack of guidelines or standards has caused many discussions and disputes on the question if “sufficient ventilation” can be ensured with window airing only, in particular in newly constructed, airtight residential buildings. This work presents the development of a calculation method aiming to provide a simple-to-use tool to estimate the risk of mould growth and the window airing interval required to ensure good indoor air quality assuming a range of different boundary conditions and occupant behaviours. The method implements a Monte Carlo approach calculating 1000 single zone mass balances for carbon dioxide (on a room level) and water vapor (on a housing level). Air infiltration through the building envelope is accounted using the so-called LBL-model. The time interval between window airing required to comply with CO2 limit value is estimated by calculating the time evolution of the CO2 concentration for 1000 different parameter combinations. The mould risk is estimated by a 1000-fold calculation of the daily averaged indoor air humidity and the resulting water activity on critical wall surfaces. The results are displayed as probability distributions providing information on the risk that the queried situation can or cannot ensure “sufficient ventilation”. Exemplary calculations for bedrooms of new multifamily buildings estimate that intervals between window airing events (to keep time-averaged CO2-concentration below 1000 ppm), will vary between 23 and 190 minutes (representing the 5th and the 95th percentile). This is clearly below an acceptable intervention interval for bedrooms. For living rooms, the assessment shows a strong sensitivity on the “accessible” air volume. The humidity assessment for this type of housing suggests that mould growth could occur in about 17% of the cases even though air exchange corresponding to two airing events per day were assumed. An additional outdoor air exchange of up to 40 m³/h would be required to reduce the mould risk fraction to <1%, suggesting the need for mechanical ventilation concepts in residential housing to enable healthy indoor environment independently of occupant behaviour.
{"title":"Assessing the “sufficient ventilation” requirement for Austrian buildings: development of a Monte Carlo based spreadsheet calculation to estimate airing intervals and mould risk in window ventilated buildings","authors":"G. Rojas, Andreas Greml, Rainer Pfluger, P. Tappler","doi":"10.1080/14733315.2023.2198788","DOIUrl":"https://doi.org/10.1080/14733315.2023.2198788","url":null,"abstract":"Abstract In Austria the lack of guidelines or standards has caused many discussions and disputes on the question if “sufficient ventilation” can be ensured with window airing only, in particular in newly constructed, airtight residential buildings. This work presents the development of a calculation method aiming to provide a simple-to-use tool to estimate the risk of mould growth and the window airing interval required to ensure good indoor air quality assuming a range of different boundary conditions and occupant behaviours. The method implements a Monte Carlo approach calculating 1000 single zone mass balances for carbon dioxide (on a room level) and water vapor (on a housing level). Air infiltration through the building envelope is accounted using the so-called LBL-model. The time interval between window airing required to comply with CO2 limit value is estimated by calculating the time evolution of the CO2 concentration for 1000 different parameter combinations. The mould risk is estimated by a 1000-fold calculation of the daily averaged indoor air humidity and the resulting water activity on critical wall surfaces. The results are displayed as probability distributions providing information on the risk that the queried situation can or cannot ensure “sufficient ventilation”. Exemplary calculations for bedrooms of new multifamily buildings estimate that intervals between window airing events (to keep time-averaged CO2-concentration below 1000 ppm), will vary between 23 and 190 minutes (representing the 5th and the 95th percentile). This is clearly below an acceptable intervention interval for bedrooms. For living rooms, the assessment shows a strong sensitivity on the “accessible” air volume. The humidity assessment for this type of housing suggests that mould growth could occur in about 17% of the cases even though air exchange corresponding to two airing events per day were assumed. An additional outdoor air exchange of up to 40 m³/h would be required to reduce the mould risk fraction to <1%, suggesting the need for mechanical ventilation concepts in residential housing to enable healthy indoor environment independently of occupant behaviour.","PeriodicalId":55613,"journal":{"name":"International Journal of Ventilation","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86808953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-07DOI: 10.1080/14733315.2023.2198780
Kevin Verniers, Frederik Losfeld, I. Pollet, J. Laverge
Abstract Residential ventilation systems target in an energy efficient manner an indoor atmosphere fulfilling people’s desired comfort requirements with regard to CO2, temperature, and RH. However, the reach of an indoor atmosphere is not limited to comfort only. Ensuring a healthy indoor atmosphere reducing the risk of acute and chronic diseases caused by the inhaled air is also of importance. A number of elements contribute to indoor air pollution, such as: Volatile Organic Compounds (VOCs), infectious aerosols, and Particulate Matter (PM). These elements combined with the larger proportion of time spent indoors by humans put an emphasis on creating healthy spaces indoors. This investigation treats and discusses in-situ indoor measurements with the Renson Sense of PM1,2.5,4,10, and VOCs caused during the following activities: induction cooking of a typical European meal, vacuuming, and burning of regular and scented candles. All activities were carried out according to a fixed schedule. Both PM and VOC were measured in several rooms of a single, airtight dwelling in Belgium while the following ventilation options were considered: no ventilation, window ventilation, intensive ventilation via a cooker hood, Mechanical Extract Ventilation (MEV = natural supply, mechanical exhaust), and Mechanical Ventilation with Heat Recovery (MVHR = mechanical supply and exhaust). The exhaust flow rate of both MEV and MVHR was set identical to avoid the impact of different air exchange rates on building level. The following main findings were derived from the results. Particle diameters <1 µm (PM1) were dominantly present during all activities and for all considered ventilation options, possibly due to the sensor technology. The spread of cooking-related PM was confined to the floor where the activity took place, and a cooking hood was most effective in reducing PM, as could be expected. Furthermore, no ventilation exhibited logically the slowest decay of PM1, whereas this was most pronounced for window ventilation followed by an equal decay for MEV and MVHR. Burning scented candles led to higher PM levels compared to regular candles, while the PM peak was observed for both when extinguishing the candle. The spread of PM from burning candles was also restricted to the floor where the activity took place, window ventilation clearly reduced the spreading throughout the floor compared to the other ventilation options. Vacuuming activity created much lower PM levels compared to induction cooking and burning candles and therefore the spread of this PM throughout the dwelling was generally non-significant. Regarding VOC, the impact from induction cooking and burning candles was apparent in contrast to vacuuming for all considered ventilation conditions. Next to this, the spread of VOC throughout the building was more limited compared to PM.
{"title":"Impact of ventilation type on indoor generated PM and VOC levels for different indoor activities","authors":"Kevin Verniers, Frederik Losfeld, I. Pollet, J. Laverge","doi":"10.1080/14733315.2023.2198780","DOIUrl":"https://doi.org/10.1080/14733315.2023.2198780","url":null,"abstract":"Abstract Residential ventilation systems target in an energy efficient manner an indoor atmosphere fulfilling people’s desired comfort requirements with regard to CO2, temperature, and RH. However, the reach of an indoor atmosphere is not limited to comfort only. Ensuring a healthy indoor atmosphere reducing the risk of acute and chronic diseases caused by the inhaled air is also of importance. A number of elements contribute to indoor air pollution, such as: Volatile Organic Compounds (VOCs), infectious aerosols, and Particulate Matter (PM). These elements combined with the larger proportion of time spent indoors by humans put an emphasis on creating healthy spaces indoors. This investigation treats and discusses in-situ indoor measurements with the Renson Sense of PM1,2.5,4,10, and VOCs caused during the following activities: induction cooking of a typical European meal, vacuuming, and burning of regular and scented candles. All activities were carried out according to a fixed schedule. Both PM and VOC were measured in several rooms of a single, airtight dwelling in Belgium while the following ventilation options were considered: no ventilation, window ventilation, intensive ventilation via a cooker hood, Mechanical Extract Ventilation (MEV = natural supply, mechanical exhaust), and Mechanical Ventilation with Heat Recovery (MVHR = mechanical supply and exhaust). The exhaust flow rate of both MEV and MVHR was set identical to avoid the impact of different air exchange rates on building level. The following main findings were derived from the results. Particle diameters <1 µm (PM1) were dominantly present during all activities and for all considered ventilation options, possibly due to the sensor technology. The spread of cooking-related PM was confined to the floor where the activity took place, and a cooking hood was most effective in reducing PM, as could be expected. Furthermore, no ventilation exhibited logically the slowest decay of PM1, whereas this was most pronounced for window ventilation followed by an equal decay for MEV and MVHR. Burning scented candles led to higher PM levels compared to regular candles, while the PM peak was observed for both when extinguishing the candle. The spread of PM from burning candles was also restricted to the floor where the activity took place, window ventilation clearly reduced the spreading throughout the floor compared to the other ventilation options. Vacuuming activity created much lower PM levels compared to induction cooking and burning candles and therefore the spread of this PM throughout the dwelling was generally non-significant. Regarding VOC, the impact from induction cooking and burning candles was apparent in contrast to vacuuming for all considered ventilation conditions. Next to this, the spread of VOC throughout the building was more limited compared to PM.","PeriodicalId":55613,"journal":{"name":"International Journal of Ventilation","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91314827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-20DOI: 10.1080/14733315.2023.2188346
Sarah Truchet, A. Jay, E. Wurtz, J. Anger, A. Brun, P. Bernaud
{"title":"Impact of thermal inertia coupled to natural night ventilation. A case study for a high performance building in continental climate","authors":"Sarah Truchet, A. Jay, E. Wurtz, J. Anger, A. Brun, P. Bernaud","doi":"10.1080/14733315.2023.2188346","DOIUrl":"https://doi.org/10.1080/14733315.2023.2188346","url":null,"abstract":"","PeriodicalId":55613,"journal":{"name":"International Journal of Ventilation","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74141553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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