Airtightness Of Windows Research Articles

The effect of particle size, meteorological parameters, and building airtightness on particulate matters infiltration

Introduction: The present study analyzed the infiltration behavior of size- fractionated particles and the influencing parameters. Materials and methods: The studies were carried out in two apartments under varying conditions of airtightness, utilizing real-time surveillance of Particulate Matters (PM0.3, PM1.0, PM2.5, PM10), along with air exchange rates and meteorological factors. The seasonal variations of the indoor dissemination of particulate matters have been also discussed. Results: The analysis of correlations indicated a strong dependency of indoor Particulate Matter (PM) concentrations on outdoor levels. However, the penetration patterns varied across different particle sizes. The highest contribution to outdoor PM10 was observed for PM 2.5-10 while indoors, the predominant particle size was among the finer categories, PM0.3-1.0. Moreover, window air-tightening appeared to decrease the overall effective leakage area of the building envelope, which in turn slightly lowered the ratio of indoor to outdoor PMs as well as the infiltrability for particles of all sizes. However, this intervention did not alter the distribution of particles within indoor environments.The most penetrated particles were observed in the size range 0.3-1.0 µm and then PM<0.3 µm, and the least in the size range 2.5-10 µm. Conclusion: Particle dimensions and external sources primarily influenced the degree of particle infiltration, significantly overshading the impact of weather-related factors. The relationship between indoor and outdoor particulate matter was diminished by the airtightness of windows, particularly for larger particles. No notable difference was observed in the infiltrability and indoor distribution of particles of varying sizes between the winter and fall seasons.

Comparison of infiltration of different particle sizes and influencing parameters

The size fractional distribution of indoor and outdoor particles was investigated to understand how particle size, air change rate, building airtightness, and meteorological parameters affect particle infiltration behavior. The experiments were performed for two apartments, one without airtightness intervention and the other after sealing the window gaps. Although the correlation analysis showed that the indoor PM trend was highly dependent on outdoor conditions, different penetration behavior for different particle sizes was noticed. Despite the absence of indoor sources, the size fractional distribution of particles in the indoor and outdoor environment did not follow the same pattern. Moreover, airtightness somehow reduced the envelope effective leakage area and slightly decreased the indoor/outdoor ratio and infiltration factor for all particle sizes; however, it did not affect the relative infiltrability. The highest penetration rates were observed in the size range of 0.3–1.0 μm and the lowest rates were in the 2.5–10 μm range. Although with particles greater than 0.3 μm, the infiltration of fine particles was higher than that of coarse particles, the infiltrability of PM < 0.3 was slightly lower than PM0.3-1.0, probably due to the penetration dominated by the concentration gradient. Particle size, envelope airtightness, and outdoor source were the main factors that governed fractional particle infiltration, overshadowing the effect of meteorological parameters. Furthermore, window airtightness decreased the indoor-outdoor PM correlation, especially for coarser particles. It caused approximately a 1-h lag-time between the indoor and outdoor PM trend, a positive point in case of accidental increase of outdoor levels.

The Required Amount of Ventilation Air for the Classroom and the Possibility of Air Infiltration through the Windows

The majority of education buildings in Poland are equipped with natural (gravity) ventilation, where the air inflow depends on the level of window airtightness. A complete statistical urban population of 50 school buildings in Czestochowa have been examined. The main issue to be clarified is the answer to the following questions: Is it theoretically possible to supply enough air to meet the ventilation requirements with gravity ventilation? What is the airtightness of the windows at which it will be possible? The average technical conditions of windows in the analysed buildings were bad. However, only in the case in which high external air leakage coefficient a = 7.0 m3/(h m daPa2/3) (q100KL = 32.4912 m3/(h m) is the amount of air passing through the leaks similar to the quantitative ventilation requirements for classrooms. The quantity of air flowing from the outside through modernized windows that meet the technical requirements (a = 0.6 to 1.0 m3/(m h daPa2/3)) covers on average only about 12% and about 21% of the ventilation needs. Without installing additional vents in the rooms, or better yet, installing mechanical ventilation with heat recovery, meeting the ventilation norm requirements will be impossible.

Mean Age of Air in Natural Ventilated Buildings: Experimental Evaluation and CO2 Prediction by Artificial Neural Networks

The mean age of air (MAA) is one of the most useful parameters in evaluating indoor air quality in natural ventilated buildings. Its evaluation is generally based on the CO2 monitoring within the environment; however, other methods can be found in the literature, but they have not always led to satisfactory results. In this context, the present paper is focused on two main topics: the effect of the windows airtightness and of the environmental conditions on MAA and the application of artificial neural network (ANN) for the CO2 prediction within the room. Two case studies (case study 1 located in Terni and case study 2 located in Perugia) were investigated, which differ in geometric dimensions (useful area, volume, window area) and in airtightness of windows. The indoor and outdoor environmental conditions (air temperature, pressure, relative humidity, air velocity, and indoor CO2 concentration) were monitored in 33 experimental campaigns, in four room configurations: open door-open window (OD-OW); closed door-open window (CD-OW); open door-closed window (OD-CW); closed door-closed window (CD-CW). Tracer decay methodology, according to ISO 16000-8:2007 standard, was compiled during all the experimental campaigns. A feedforward ANN, able to simulate the indoor CO2 concentration within the rooms, was then implemented; the monitored environmental conditions (air temperature, pressure, relative humidity, and air velocity), the geometric dimensions (useful area, volume, window area), and the airtightness of windows were provided as input data, while the CO2 concentration was used as target. In particular, data of 19 experimental campaigns were provided for the training process of the network, while 14 were only used for testing the reliability of ANN. The CO2 concentration predicted by ANN was then used for the MAA calculation in the four room configurations. Experimental results show that MAA of case study 2 is always higher, in all the examined configurations, due to the higher airtightness characteristics of the window and to the higher volume of the room. When the difference between indoor and outdoor temperature increases, the MAA increases too, in almost all the investigated configurations. Finally, the CO2 concentration predicted by ANN was compared with experimental data; results show a good accuracy of the network both in CO2 prediction and in the MAA calculation. The predicted CO2 concentration at the beginning of experimental campaigns (time step 0) always differs less than 2% from experimental data, while a mean percentage difference of −18.8% was found considering the maximum CO2 concentration. The MAA calculated using the predicted CO2 of ANN was greater than the one obtained from experimental data, with a difference in the 0.5–1.3 min range, depending on the configuration. According to the results, the developed ANN can be considered an alternative and valuable tool for a preliminary evaluation of MAA.

Determination of key parameters (air exchange rate, penetration factor and deposition rate) for selecting residential air cleaners under different window airtightness levels

Healthy indoor air quality is a basic standard for good living environment, and air cleaners are commonly used in residential applications, especially in China, to control indoor PM2.5 pollutions from outdoors. An accurate cleaner selection method will help keep satisfying indoor air quality, as well as reducing cost and materials of equipment. Three key parameters, namely, air exchange rate (a), particle penetration factor (P) and deposition rate (k), have been suggested as direct influence on air cleaner selection when pollutants are coming from building infiltration. In relevant standards, however, there is no method that can link the three key parameters to various airtightness levels of external windows, which may often exist in real applications. This study, therefore, has proposed a calculation method for deciding a, P and k, based on monitored indoor and outdoor PM2.5 mass concentrations, with given recommended design values under different external window airtightness levels. Results showed that both air exchange rates and penetration factors were significantly influenced by the airtightness level of windows, and both their values were found to be different from the recommended values in the current Chinese standard, providing evidence to support future standard revision and update. Meanwhile, deposition rates showed good agreement with the recommended value in the current Chinese standard (i.e. 0.2h−1). Additionally, with increased window airtightness level, the required clean air delivery rate (CADR) of air cleaners showed a downward trend, which means an air cleaner with smaller size, lower energy consumption and less material.

Study of infiltration through sliding windows with respect to closing mechanisms and their locations in a building during winter season

ABSTRACTInfiltration through windows accounts for a significant heat loss in buildings during winter, leading to the need to minimize uncontrolled air flow. Improvement of window air tightness is important for reducing heat loss by infiltration through windows. In this study, infiltration is measured for general sliding (GS), parallel sliding tilt (PST) and lift sliding (LS) windows according to ASTM E283, a standard for window infiltration measurement. Measured window infiltration data, pressure coefficients calculated with STAR-CCM+ and outdoor weather data of Seoul are used in CONTAM, a network based ventilation simulation program to estimate infiltration during winter season for three sliding window types and their locations in a building. The results show that infiltration is highest for east located general sliding type window, and lowest for west located parallel sliding tilt window. Monthly analysis shows that for an east located window, infiltration is highest during January and lowest during December.

Methodology Applied to the Evaluation of Natural Ventilation in Residential Building Retrofits: A Case Study

The primary objective of this paper is to present the use of a steady model that is able to qualify and quantify available natural ventilation flows applied to the energy retrofitting of urban residential districts. In terms of air quality, natural ventilation presents more efficient solutions compared to active systems. This method combines numeric simulations, through the utilization of Ansys Fluent R15.0® and Engineering Equation Solver EES®, with on-site pressurization tests. Testing consists of the application of the seasonal pressure gradient on the building’s envelope and the calculation of the ventilation flows in three climatic representative conditions (summer, winter, and annual average). Through the implementation of this methodology to existing buildings it is possible to evaluate the influence of the built environment, as well as key parameters (relative height of the dwelling, number of vertical ventilation ducts, and airtightness of windows) of available natural ventilation.

A contribution for the quantification of the influence of windows on the airtightness of Southern European buildings

Adequate airtightness levels are fundamental for the indoor environmental quality and energy efficiency of buildings. The quantitative characterization of expected leaks of common building elements is useful for practitioners that intend to improve building enclosures for airtightness optimization. This study intends to contribute to the quantification of the permeability of windows with a focus on the Southern European context of low airtightness in heavy construction buildings, where windows play an important role.A large experimental investigation was therefore carried out in 23 spaces, establishing three possible set-ups (nothing sealed, window sealed and window and roller-shutter sealed), using the fan pressurization method. A total of 104 tests were performed.Results revealed that the windows’ permeability indices ranged from 4.8 to 96.4m3/(hm2) and from 1.2 to 30.8m3/(hm), with average values of 28.7m3/(hm2) and 8.9m3/(hm), the roller-shutter contribution can be highly variable; also the year of construction, the frame material and the opening system are the key parameters for the airtightness of windows.

Influence of Drainage Holes on Condensation Risk and Air-tightness of Windows. An Experimental Case Study of Triple Glazing PVC Windows

Triple glazing windows incorporate drainage holes on glazing beads or gaskets to provide a path for condensed water from the inside to the outside. These holes are considered to be effective for draining condensed water but may decrease the air-tightness and increase the condensation risk due to the drop in surface temperature resulting from the intake of cold outside air. In this study, the related specifications and documents on the application of drainage holes and previous studies were reviewed. For the triple glazing windows with and without drainage holes, the condensation resistance and air-tightness were evaluated and compared. Condensation resistance and air-tightness were tested in accordance with KS F 2295 and KS F 2292, respectively. The results showed that the use of drainage holes did not have a significant negative impact on the condensation resistance and air-tightness.

Investigation of Indoor and Outdoor PM2.5 Pollution Situation in Beijing

In recent years, people are facing the adverse impacts of the fine particles (referred as PM2.5) in Beijing, which will cause great harm to human health. In this study, based on a large number of indoor and outdoor PM2.5 mass concentrations field monitored data under the different air-tightness level of external windows and mathematical statistics method, a PM2.5 pollution situation with different air-tightness levels of windows is studied. Moreover, as considering of individuals spend the majority spare time indoors, the particles mass concentrations is also investigated with different window air-tightness levels under infiltration. This study can provide a reference for the optimization design and equipment selection of the ventilation purification system, as well as the operation and maintenance management of the system.

Condensation Risk Due to Variations in Airtightness and Thermal Insulation of an Office Building in Warm and Wet Climate

Condensation in a building encourages microbial growth, which can have an adverse effect on the health of occupants. Furthermore, it induces the deterioration of the building. To prevent problems caused by condensation, from the design step of a building, predictions of the spatial, temporal and causation for condensation occurrences are necessary. By using TRNSYS simulation coupled with TRNFLOW, condensation assessment of an entire office building in Tokyo, Japan, was conducted throughout the year, including when the air-conditioning system was not operated, by considering the absorption-desorption properties of the building materials and papers in the office and the airflow within the entire building. It was found that most of the condensation occurred during winter and was observed mainly in the non-air-conditioned core parts, especially the topmost floor. Additional analyses, which identified the effect of variations in the thermal insulation of the external walls, roof and windows and the airtightness of the windows on condensation, showed that the lower airtightness of windows resulted in decreased condensation risks, and condensation within the building was suppressed completely when the thermal insulation material thickness of the external walls was greater than 75 mm, that of the roof was greater than 105 mm and the windows had triple float glass.

Airtightness and watertightness of window frames: Comparison of performance and requirements

Airtight buildings require airtight windows. To date little information is available on the typical airtightness of window frames, and the aptitude of current regulatory performance levels for windows in respect to very airtight buildings is highly uncertain. Between 1997 and 2012, 437 windows were tested in laboratory conditions for certification; the most important results in respect to airtightness and watertightness are reported here. For both parameters, vinyl frames yield slightly lower performance than aluminum or wooden windows. Single windows perform best, followed by double, composed and sliding windows. Window airtightness performance levels were calculated based on various building geometries and airtightness targets. Reducing the impact of windows on the overall building airtightness to 5% is realistic and feasible, even for very airtight buildings. The test results clearly demonstrate that airtightness, watertightness and resistance to wind loads are partially correlated. A comparison of guidelines and standards on watertightness of windows shows large discrepancies and little uniformity. Most turn-and-tilt windows show good watertightness and can be applied to very exposed conditions, whereas sliding windows have a limited scope.

창호 풍지판 형상에 따른 기밀성의 실험적 연구

창호 풍지판 형상에 따른 기밀성의 실험적 연구

Policies and Status of Window Design for Energy Efficient Buildings

Windows are known to be responsible for considerable portion of heating and cooling energy use in modern buildings. Many countries have tightened minimum requirements for window performance and design in building energy conservation codes and regulations. We analyzed and compared these requirements of window performance and design in building energy policies of many countries. We also investigated the status of window design of office buildings in Korea in terms of WWR, glazing types, window frames, and air-tightness, etc. Finally, some suggestions were proposed to improve Korean building energy conservation code, such as the necessity of more strengthened requirements on window air-tightness and shading devices.

The Test and Analysis of Air Tightness for Zero Energy Building in Cold Region

The window is an important retaining structure. The gap of doors and windows cooling is an important part of building energy consumption of heating. A window with high quality and advanced construction technology can greatly enhance the air tightness of retaining structure. The experiment is air tightness test based on an energy-saving windows in a zero energy building in the cold region. After the test and analyzes on the windows, the air tightness of windows reached level 8 standard prescribed by “GB/T 7106-2008 Graduations and test methods of air permeability, water tightness, wind load resistance performance for building external windows and doors.

Acoustic insulation performance of improved airtight windows

Windows are used not only for lighting and thermal insulation, but also for sound attenuation. Most window frames installed in apartments are composed of either aluminum or polyvinylchloride. In general, windows in Korea consist of an outer frame forming the opening and a window frame attached to the glass, with enough clearance at the top and bottom to join them together. This space at the top and the bottom for the sliding type is the main factor affecting thermal and acoustic performance. In addition, the precision of the fit between the frames and deterioration of the mohair attached to the window frame affect environmental performance. There is however somewhat gap because the inner frame should be installed within the outer frame in the field. The goal of this study is to improve environmental conditions in residences by increasing the airtightness of windows to counteract deterioration of performance due to aging window frames and mohair. The results indicate that these attachments can attenuate sound effectively and can be regarded to reduce energy and natural resource use by attaching them to deteriorated windows or in apartments needed to be reinforced.

Infiltration Characteristic of Outdoor Fine Particulate Matter (PM2.5) for the Window Gaps

Even if closing windows, atmospheric PM2.5 can still penetrate into indoor through gaps of windows, then causing the indoor environment polluted. In order to evaluate the influence of windows with different airtightness levels on infiltration characteristic of PM2.5, a longitudinal monitoring regarding indoor and outdoor PM2.5 mass concentrations and meteorological parameters have been carried out in two offices located in Beijing, China from 1st July to 2nd November, 2014. Research results showed that when windows and mechanical ventilation were closed and there were no obvious indoor particle sources, the indoor PM2.5 mass concentration, the I/O ratio and the air exchange rate causing of window gaps of the sample site with lower airtightness window were higher than the one with higher window airtightness. Furthermore, the I/O ratio and air exchange rate were both positively correlated with outdoor wind speed, while negatively correlated with outdoor relative humidity. The findings can provide meaningful reference to further research on influence of atmospheric PM2.5 on indoor environment and help further develop approaches to control outdoor originated indoor PM2.5.

小学校における教室内熱・光環境の空間分布の改善に関する研究

The purposes of this study is to clarify the effects of improvement of thermal and lighting environment distributions in the classroom of a newly rebuilt school, that is the rebuilt classroom, comparing to the environmental distributions in the classroom of an old school which is a typical old style, that is the old calssroom, and to indicate the effects of the planning factors on the environmental distributions. The distributions of thermal and lighting environment in classrooms of old and newly rebuilt elementary school buildings in Nagaoka-shi, Niigata were measured and pupils' environmental evaluations were surveyed by questionnaire in summer and winter, 2001. The results are shown as follows. (1) The distributions and changes of thermal environment in summer and winter are remained more uniform and stable in the rebuilt classroom than those in the old classroom as the results of providing insulation materials inserted in walls and roofs, air tightness of windows and buildings, a balcony, and pair-glass windows. Most pupils vote better evaluations for thermal enviornment in the rebuilt classroom. (2) The distribution of lighting environment in the rebuilt classroom becomes smaller than that in the old classroom because of shading incident sunshine by a balcony and additional light from illumination set at the ceiling of open space. Many pupils in the rebuilt classroom vote "very bright" or "slightly bright" in the evaluation for the lightness on their own desks.

Window air tightness and its influence on energy saving and minimum required ventilation

The first part of the paper presents a method for establishing the conditions and an acceptance criterion for window air-tightness testing, in relation to average energy (heating) saving per winter. Wind velocity data of the Israeli meteorological station of Ashdod is used in order to demonstrate the difference between various methods for the evaluation of the ‘design wind velocity’. Forty-one different typical dwellings are used in order to determine a unique criterion for the acceptable air leakage under test conditions, which ensures an average of one air change per hour in most Israeli dwellings. The second part of the paper demonstrates the energy inefficiency arising from using flueless appliances, when minimum health standards are required and translated into minimum constant ventilation requirements.