Quantification of the fungal fraction released from various preloaded fibrous filters during a simulated ventilation restart

This study aimed to demonstrate that particles, especially those associated with fungi, could be released from fibrous filters used in the air‐handling unit (AHU) of heating, ventilation and air‐conditioning (HVAC) systems during ventilation restarts. Quantification of the water retention capacity and SEM pictures of the filters was used to show the potential for fungal proliferation in unused or preloaded filters. Five fibrous filters with various particle collection efficiencies were studied: classes G4, M5, M6, F7, and combined F7 according to European standard EN779:2012. Filters were clogged with micronized rice particles containing the fungus Penicillium chrysogenum and then incubated for three weeks at 25°C and 90% relative humidity. The results indicated that the five clogged tested filters had various fungal growth capacities depending on their water retention capacity. Preloaded filters were subjected to a simulated ventilation restart in a controlled filtration device to quantify that the fraction of particles released was around 1% for the G4, 0.1% for the M5 and the M6, and 0.001% for the F7 and the combined F7 filter. The results indicate that the likelihood of fungal particle release by low efficiency filters is significantly higher than by high efficiency filters.     

Patterns in Volatile Organic Compounds in Dust from Moldy Buildings

Abstract Of the ca. 80 volatile organic compounds (VOCs) identified from moldy building materials, 40 were identified as possible microbial metabolites or their derivatives. Thermal desorption of dust from visibly mold-contaminated rooms resulted in the identification of 55 tentative microbial VOCs (MVOCs). Principal component analysis of peak areas for 20 W O C s from dust samples allowed the classification of rooms according to their contamination by mold growth. Bacterial flora in the dust was similar for mold-contaminated and control rooms and only a few actinomycete colonies were observed. Mold flora in dust from moldy rooms was dominated by Penicillium commune(palitans), P. chrysogenum and Aspergillus versicolor. Some MVOCs (or their derivatives) from moldy building materials were also identified in dust from mold-infested rooms and from pure cultures of the three dominant mold species grown on a rich laboratory substrate.     

某非典负压病房内空气环境的技术措施分析

通过对某新建非典负压病房的空调通风系统的设计审查,施工过程监督及施工后的现场测试,总结了系统在各房间内的静压设计与压差维持、负压病房的送风量、房间的温湿度、管路保温、噪声及系统控制等方面出现的问题,并讨论了产生的原因;提出需要对负压病房的新风量大小、静压值及空调通风系统的消毒灭菌方面作进一步进行研究。另外,对类似_丁程的设计及施工也提出了建议。     

Investigation of inflammatory and allergic responses to common mold species: Results from in vitro experiments,from a mouse model of asthma,and from a group of asthmatic patients

Most studies on molds focus on Alternaria alternata and Aspergillus fumigatus. Here, we report on inflammatory and allergenic properties of more typical indoor species Aspergillus versicolor, P. chrysogenum, C. cladosporioïdes, and C. sphaerospermum that were compared to A. alternata and A. fumigatus. In a mouse model, after intranasal instillation, A. alternaria, A. versicolor, and C. sphaerospermum induced the early recruitment of neutrophils and the strong expression of inflammatory markers in the bronchoalveolar lavages fluids. A. fumigatus also induced the early accumulation of neutrophils but with lower levels of inflammatory markers. Chronic treatment induced variable response according to species: P. chrysogenum and A. fumigatus appeared strong pro‐allergenic inducers compared to A. alternata and C. sphaerospermum while A. versicolor and C. cladosporioides induced a mixed pro‐allergenic/pro‐inflammatory response. In mold‐sensitized asthmatics, mold‐specific Immunoglobulin E (IgE) were detected with an in‐house dot‐blot assay. A. fumigatus and A. alternata were the most frequent sensitizers. Altogether, P. chrysogenum, P. brevicompactum, C. sphaerospermum, and C. cladosporïoides were the “major sensitizer” (defined as the strongest response against a single mold species) for almost 30% of the asthmatics. These results show that, not only A. alternata and A. fumigatus, but also indoor species have strong inflammatory and allergic properties and a harmful potency.     

Disinfection by in-duct ultraviolet lamps under different environmental conditions in turbulent airflows

In this study, we investigated the effects of environmental factors such as airflow velocity, relative humidity (RH), temperature, and duct reflectance on the performance of in-duct UVC lamps. Staphylococcus epidermidis, Pseudomonas alcaligenes, and Escherichia coli were used as the test bacteria. The UV irradiance, disinfection efficacy, and UV susceptibility constant (Z value) of the test bacteria were experimentally determined. The results showed that the UV disinfection efficacy decreased as the airflow velocity and RH increased. The maximum UV disinfection efficacy was obtained at temperature of 20-21°C compared with the performance at lower temperature (15-16°C) and higher temperature (25-26°C). When the RH increased from 50% to 90%, the Z values of airborne bacteria reduced by 40%, 60%, and 38% for S epidermidis, P alcaligenes, and E coli, respectively. Besides, susceptibility constants had lower values under both cooling temperature (15-16°C) and heating temperature (25-26°C) compared with that under the temperature of 20-21°C. It was observed that S epidermidis generally had the highest resistance to the UV irradiance. The results also showed that the UV disinfection efficacy was lower in the duct with a black surface than in the clean duct.     

Characterization and pro‐inflammatory responses of spore and hyphae samples from various mold species

Mold particles from Aspergillus fumigatus, Penicillium chrysogenum, Aspergillus versicolor, and Stachybotrys chartarum have been linked to respiratory‐related diseases. We characterized X‐ray‐inactivated spores and hyphae fragments from these species by number of particles, morphology, and mycotoxin, β‐glucan and protease content/activity. The pro‐inflammatory properties of mold particles were examined in human bronchial epithelial cells (BEAS‐2B) and THP‐1 monocytes and phorbol 12‐myristate 13‐acetate (PMA)‐differentiated THP‐1. Spores from P. chrysogenum and S. chartarum contained some hyphae fragments, whereas the other preparations contained either spores or hyphae. Each mold species produced mainly one gelatin‐degrading protease that was either of the metallo‐ or serine type, while one remains unclassified. Mycotoxin levels were generally low. Detectable levels of β‐glucans were found mainly in hyphae particle preparations. PMA‐differentiated THP‐1 macrophages were by far the most sensitive model with effects in the order of 10 ng/cm². Hyphae preparations of A. fumigatus and P. chrysogenum were more potent than respective spore preparations, whereas the opposite seems to be true for A. versicolor and S. chartarum. Hyphae fragments of A. fumigatus, P. chrysogenum, and A. versicolor enhanced the release of metalloprotease (proMMP‐9) most markedly. In conclusion, species, growth stage, and characteristics are all important factors for pro‐inflammatory potential.     

Ultrafine particle removal by residential heating,ventilating, and air‐conditioning filters

This work uses an in situ filter test method to measure the size‐resolved removal efficiency of indoor‐generated ultrafine particles (approximately 7–100 nm) for six new commercially available filters installed in a recirculating heating, ventilating, and air‐conditioning (HVAC) system in an unoccupied test house. The fibrous HVAC filters were previously rated by the manufacturers according to ASHRAE Standard 52.2 and ranged from shallow (2.5 cm) fiberglass panel filters (MERV 4) to deep‐bed (12.7 cm) electrostatically charged synthetic media filters (MERV 16). Measured removal efficiency ranged from 0 to 10% for most ultrafine particles (UFP) sizes with the lowest rated filters (MERV 4 and 6) to 60–80% for most UFP sizes with the highest rated filter (MERV 16). The deeper bed filters generally achieved higher removal efficiencies than the panel filters, while maintaining a low pressure drop and higher airflow rate in the operating HVAC system. Assuming constant efficiency, a modeling effort using these measured values for new filters and other inputs from real buildings shows that MERV 13–16 filters could reduce the indoor proportion of outdoor UFPs (in the absence of indoor sources) by as much as a factor of 2–3 in a typical single‐family residence relative to the lowest efficiency filters, depending in part on particle size.     

外墙外保温系统中耐碱网格布的检测

耐碱玻纤网格布是一种广泛用在外墙保温面层的一种玻纤增强的装饰类材料。由于这种材料的用途广泛，其技术指标的优劣就显得尤为重要。文章从实验室检测耐碱玻纤网格布的方式与方法进行讨论说明，提出正确的检测操作方法。并得出结论。     

Hygrothermische Beanspruchung und Lebensdauer von Wärmedämm‐Verbundsystemen

Hygrothermal loads and service life of external wall insulation systems. Service life and aging behaviour of external wall systems depend on their hygrothermal loads. Apart from the fluctuating climatic conditions temperature, solar radiation and humidity there are often additional exterior or interior sources of moisture, e.g. driving rain, construction moisture or surface condensation acting on facades. External wall insulation systems (ETICS = E xternal T hermal I nsulation C omposite S ystems) are especially affected due to their low mass. However, the long‐term observation by repeated inspections of the same objects over a period of 30 years proves that ETICS show not more damage than traditional facades. Apart from minor esthetical problems due to soiling or microbial growth their long‐term behaviour is very encouraging. Maintained at normal intervals ETICS are as durable as traditionally rendered masonry walls.     

Ermittlung des Wasserdampfdiffusionswiderstandes von Baustoffen in Abhängigkeit von der Baustofftemperatur

Determination of the water vapour diffusion permeability of building materials in dependency on the temperature. Investigations concerning the correlation between the water vapour diffusion permeability (μ ‐value) and the temperature were done at two wood based panels (MDF and OSB), an external thermal insulation compound system, a plaster system and an EPS‐insulation. The investigations were made by analogy to the measurement method described in ISO 12572 but at the chosen temperature levels from –10, –5, 0, 10 up to 50 °C. Based on the measured results, it can be concluded, that the μ ‐value is influenced by the temperature.     

Laboratory-based investigation of the materials’ water activity and pH relative to fungal growth in internally insulated solid masonry walls

This project investigated fungal growth conditions in artificially contaminated interfaces between solid masonry and adhesive mortar for internal insulation. The project comprised several laboratory experiments: test of three fungal decontamination methods; investigation of development of fungal growth in solid masonry walls fitted with five internal insulation systems; and investigation of volatile organic compounds (VOC) diffusion through materials and whole insulation systems. One aim was to examine whether the alkaline environment (pH > 9) in the adhesive mortars could prevent fungal growth despite the water activity (a_w) in the interface exceeds the level (a_w > 0.75) commonly considered critical for fungal growth. The findings indicate that do-it-yourself decontamination solutions were inadequate for removal of fungal growth, while professional solutions were successful. However, the choice of decontamination method was of minor importance in the case of application of internal insulation with high pH adhesive mortar, as the high pH adhesive mortars were found to inactivate existing growth and prevented spore germination during the experimental period. The three tested VOCs were capable of diffusing through most of the examined products and could potentially affect the indoor air quality.     

Collection of biological and non-biological particles by new and used filters made from glass and electrostatically charged synthetic fibers

Synthetic filters made from fibers carrying electrostatic charges and fiberglass filters that do not carry electrostatic charges are both utilized commonly in heating, ventilating, and air-conditioning (HVAC) systems. The pressure drop and efficiency of a bank of fiberglass filters and a bank of electrostatically charged synthetic filters were measured repeatedly for 13 weeks in operating HVAC systems at a hospital. Additionally, the efficiency with which new and used fiberglass and synthetic filters collected culturable biological particles was measured in a test apparatus. Pressure drop measurements adjusted to equivalent flows indicated that the synthetic filters operated with a pressure drop less than half that of the fiberglass filters throughout the test. When measured using total ambient particles, synthetic filter efficiency decreased during the test period for all particle diameters. For particles 0.7-1.0 mum in diameter, efficiency decreased from 92% to 44%. It is hypothesized that this reduction in collection efficiency may be due to charge shielding. Efficiency did not change significantly for the fiberglass filters during the test period. However, when measured using culturable biological particles in the ambient air, efficiency was essentially the same for new filters and filters used for 13 weeks in the hospital for both the synthetic and fiberglass filters. It is hypothesized that the lack of efficiency reduction for culturable particles may be due to their having higher charge than non-biological particles, allowing them to overcome the effects of charge shielding. The type of particles requiring capture may be an important consideration when comparing the relative performance of electrostatically charged synthetic and fiberglass filters. PRACTICAL IMPLICATIONS: Electrostatically charged synthetic filters with high initial efficiency can frequently replace traditional fiberglass filters with lower efficiency in HVAC systems because properly designed synthetic filters offer less resistance to air flow. Although the efficiency of charged synthetic filters at collecting non-biological particles declined substantially with use, the efficiency of these filters at collecting biological particles remained steady. These findings suggest that the merits of electrostatically charged synthetic HVAC filters relative to fiberglass filters may be more pronounced if collection of biological particles is of primary concern.     

Variation of Intumescent Coatings Revealing Different Modes of Action for Good Protection Performance

Thermal insulation and mechanical resistance play a crucial role for the performance of an intumescent coating. Both properties depend strongly on the morphology and morphological development of the foamed residue. Small amounts (4 wt%) of fiberglass, clay and a copper salt, respectively, are incorporated into an intumescent coating to study their influence on the morphology and performance of the residues. The bench scale fire tests were performed on 75 × 75 × 2 mm³ coated steel plates according to the standard time–temperature curve in the Standard Time Temperature Muffle Furnace⁺ (STT Mufu⁺). It provided information about foaming dynamics (expansion rates) and thermal insulation. Adding the copper salt halved the expansion height, whereas the clay and fiberglass change the height of the residue only moderately. The time to reach 500°C was improved by 31% for clay and 15% for the other two fillers. Nondestructive micro computed tomography is used to assess the inner structure of the residues. A transition of the residue from a black, carbonaceous foam with closed cells into an inorganic, residual open cell sponge occurs at high temperatures. This transition is due to a loss of carbon; the change in microstructure is analyzed by scanning electron microscopy. Additional mechanical tests are performed and interpreted with respect to the results of the morphology analysis. Adding clay or copper salt improved the mechanical resistance tested by a factor 4. The additives significantly influence the thickness and foaming dynamics as well as the inner structure of the residues, whereas their influence on insulation performance is moderate. In conclusion, different modes of action are observed to achieve similar insulation performance during the fire test.     

Performance of a CO2 sorbent for indoor air cleaning applications: Effects of environmental conditions,sorbent aging,and adsorption of co-occurring formaldehyde

Indoor air cleaning systems that incorporate CO₂ sorbent materials enable HVAC load shifting and efficiency improvements. This study developed a bench-scale experimental system to evaluate the performance of a sorbent under controlled operation conditions. A thermostatic holder containing 3.15 g sorbent was connected to a manifold that delivered CO₂-enriched air at a known temperature and relative humidity (RH). The air stream was also enriched with 0.8-2.1 ppm formaldehyde. The CO₂ concentration was monitored in real-time upstream and downstream of the sorbent, and integrated formaldehyde samples were collected at different times using DNPH-coated silica cartridges. Sorbent regeneration was carried out by circulating clean air in countercurrent. Almost 200 loading/regeneration cycles were performed in the span of 17 months, from which 104 were carried out at reference test conditions defined by loading with air at 25°C, 38% RH, and 1000 ppm CO₂, and regenerating with air at 80°C, 3% RH and 400 ppm CO₂. The working capacity decreased slightly from 43-44 mg CO₂ per g sorbent to 39-40 mg per g over the 17 months. The capacity increased with lower loading temperature (in the range 15-35°C) and higher regeneration temperature, between 40 and 80°C. The CO₂ capacity was not sensitive to the moisture content in the range 6-9 g/m³, and decreased slightly when dry air was used. Loading isothermal breakthrough curves were fitted to three simple adsorption models, verifying that pseudo-first-order kinetics appropriately describes the adsorption process. The model predicted that equilibrium capacities decreased with increasing temperature from 15 to 35°C, while adsorption rate constants slightly increased. The formaldehyde adsorption efficiency was 80%-99% in different cycles, corresponding to an average capacity of 86 ± 36 µg/g. Formaldehyde was not quantitatively released during regeneration, but its accumulation on the sorbent did not affect CO₂ adsorption.     

Real-time determination of optimal indoor-air condition for thermal comfort,air quality and efficient energy usage

For building, “surroundings” that effect on indoor-air condition change with respect to the time. Without proper determination of the desired indoor-air condition to heating, ventilating and air-conditioning (HVAC) system, it may not be feasible to provide simultaneously occupants with thermal comfort and acceptable air quality with efficient energy consumption all the time. This paper presents an alternative methodology of real-time determination of optimal indoor-air condition for HVAC system in order to achieve such total requirements. Predicted mean vote (PMV), CO₂ concentration and cooling/heating load are used as parameter indices for thermal comfort, indoor-air quality and energy consumption respectively. The performance index of the HVAC system is then defined by summation in terms of square errors between those actual parameter indices and their desired values. This performance index is to be systematically minimized by a gradient-based technique in order to yield optimal indoor-air condition for HVAC system. A case study was chosen in 24 h operating HVAC system of a single-storey building by determining indoor-air temperature, indoor-air humidity, indoor-air velocity, and air-ventilation rate. The experiment results show that the proposed methodology can be efficiently implemented in the real-time determination of indoor-air condition to HVAC system that maintains PMV and CO₂ concentration close to the desired levels with less energy consumption when compared to those from the conventional approach.     

Artificial vs natural Stachybotrys infestation—Comparison of mycotoxin production on various building materials

The genus Stachybotrys belongs to filamentous fungi found in indoor environment, mostly on cellulose-rich substrates after water-damage. The major purpose of this study was to investigate the influence of different building materials in case of mold infestation on the mycotoxin production of Stachybotrys species. Fifteen Stachybotrys mycotoxins including satratoxins, phenylspirodrimanes, and recently discovered stachybotrychromenes were in the focus of the investigations. Artificial and natural infestations were compared to determine whether environmental factors, for example, time of growth, temperature, humidity, and material additives have an influence on the observed mycotoxin profiles. It turned out that mycotoxin profiles from Stachybotrys spp. on building materials can be influenced by cellulose, paints, and paste of the materials. The total toxin levels of artificially and naturally contaminated gypsum board samples ranged up to 30 µg/cm², whereas wallpaper samples showed total toxin levels in the range of 20-66 µg/cm². A naturally infested sample disclosed the conversion of the dialdehyde components to the corresponding lactone isomers under the influence of light.     

Diffusion‐controlled reference material for VOC emissions testing: effect of temperature and humidity

A polymethylpentene film loaded with toluene is being developed as a reference material to support the reliable measurement of volatile organic compound emissions from building materials using environmental chambers. Earlier studies included the measurement of the material‐phase diffusion coefficient (D) and material/air partition coefficient (K) at 23°C. A fundamental mass‐transfer model can then be used to predict toluene emissions from the reference material at 23°C, serving as a reference for validating chamber‐measured emission profiles. In this study, the effect of temperature and humidity on performance of the reference material was investigated. Reference material emissions were measured at 10, 23, and 30°C and at different relative humidity (RH) levels. D and K at different temperatures and RH were determined using an independent method. Results showed that RH does not significantly affect D and K and had no effect on emissions. However, emissions increased substantially at elevated temperatures due to the relationship between D and temperature. A statistical analysis shows good agreement between model‐predicted and measured gas‐phase concentrations, indicating that the model can accurately predict emission profiles as a function of temperature. The reference material can therefore be applied to a wide range of emission chamber testing conditions.     

Biodeterioration of sandstone under the influence of different humidity levels in laboratory conditions

Excessive moisture in building materials supports microbial growth. It has been referred that relative humidity more than 55% promotes the microbial growth. To test the effect of different relative humidity tropical chamber test was set up at 52%, 76%, 85% and 96% RH and maximum diversity of fungi was found at 85% and 96% RH. Two fungi Aspergillus sydowi and Aspergillus flavipes were present throughout the course of study from moderate to highly abundant form. It was observed that Fusarium moniliforme, Cephalosporium acremonium, Papulospora sp. proliferated at higher relative humidity (i.e. at 85% and 96.6% RH) and Fusarium roseum, Fusarium oxysporum only at 96% RH level. The relative humidity level lower than 62%, i.e. at 52% level exhibited no fungal growth on sandstone surface during two-year observations. During the study pattern it was noticed that diversity decreased gradually and dominance of particular species increased with the time factor. Analysis of sandstone after fungal colonization by X-ray diffraction and SEM showed the formation of newly formed biomineral.     

关于外墙外保温技术标准若干问题的讨论

列举了当前外墙外保温技术标准编制与内容中存在的一些问题,并对外墙外保温系统及材料性能的试验条件与试验方法、耐碱网布的材质要求、系统的"薄抹面"与"厚抹面"问题、EPS板钢丝网架外保温系统的抹面层要求,泡沫塑料保温材料的尺寸稳定性及外墙外保温系统变形缝的称谓与设置等问题进行了分析与讨论,以期引起业界人士的广泛关注,并希望在相关标准修编中予以注意.     

Simulation of Legionella concentration in domestic hot water: comparison of pipe and boiler models

The energy needed for the production of domestic hot water (DHW) represents an important share in the total energy demand of well-insulated and airtight buildings. DHW is produced, stored and distributed above 60°C to kill Legionella pneumophila. This elevated temperature is not necessary for DHW applications and has a negative effect on the efficiency of hot water production units.

In this paper, system component models are developed/updated with L. pneumophila growth equations. For that purpose, different existing Modelica pipe and boiler models are investigated to select useful models that could be extended with equations for simulation of bacterial growth. In future research, HVAC designers will be able to investigate the contamination risk for L. pneumophila in the design phase of a hot water system, by implementing the customized pipe and boiler model in a hot water system model. Additionally it will be possible, with simulations, to optimize temperature regimes and estimate the energy saving potential without increasing contamination risk.