Airtight Windows Research Articles

Radon levels and indoor air quality after application of thermal retrofit measures-a case study.

This study was conducted to evaluate the influence of thermal retrofit on radon levels in workrooms, and to determine whether the radon concentration in the building changes after the application of retrofit measures. In the first survey, digital Airthings Corentium Home radon detector was used for 1-month radon measurements during the heating season 2018/19. The daily averaged radon concentrations varied from 37 to 573Bq/m3 for 10 selected workrooms, while hourly averaged radon measurements showed extreme variations from 6 to 1603Bq/m3 due to radon fluctuations. In second survey, passive radon technique based on charcoal canister test kit was conducted in all basement workrooms in spring 2021. The averaged radon concentrations grouped according to flooring type in workrooms were 327Bq/m3 for parquet, 227Bq/m3 for ceramic tiles, 146Bq/m3 for vinyl flooring and 71Bq/m3 for laminate. Besides thermal insulation and airtight windows, noticeable differences in indoor radon concentration within the renovated building are primarily caused by different types of flooring. It includes various types of insulation from the ground/concrete slab: laminate, parquet (wood blocks), vinyl flooring, and ceramic tiles. Detailed analysis point out that laminate is more efficient way for radon protection than other types of flooring. An efficient ventilation system should be installed to avoid increasing occupational radon exposure and to provide healthy and comfortable indoor environment.

Effects of low-frequency noise from wind turbines on heart rate variability in healthy individuals

Wind turbines generate low-frequency noise (LFN, 20–200 Hz), which poses health risks to nearby residents. This study aimed to assess heart rate variability (HRV) responses to LFN exposure and to evaluate the LFN exposure (dB, LAeq) inside households located near wind turbines. Thirty subjects living within a 500 m radius of wind turbines were recruited. The field campaigns for LFN (LAeq) and HRV monitoring were carried out in July and December 2018. A generalized additive mixed model was employed to evaluate the relationship between HRV changes and LFN. The results suggested that the standard deviations of all the normal to normal R–R intervals were reduced significantly, by 3.39%, with a 95% CI = (0.15%, 6.52%) per 7.86 dB (LAeq) of LFN in the exposure range of 38.2–57.1 dB (LAeq). The indoor LFN exposure (LAeq) ranged between 30.7 and 43.4 dB (LAeq) at a distance of 124–330 m from wind turbines. Moreover, households built with concrete and equipped with airtight windows showed the highest LFN difference of 13.7 dB between indoors and outdoors. In view of the adverse health impacts of LFN exposure, there should be regulations on the requisite distances of wind turbines from residential communities for health protection.

Indoor Climate Performance in a Renovated School Building

Indoor climate comfort is important for school buildings. Nowadays, this is a topical problem, especially in renovated buildings. Poorly ventilated school classrooms create improper conditions for classrooms. A post-occupancy study was performed in a school building in temperate climatic conditions. The evaluation was based on the results of long-term monitoring of the natural ventilation strategy and measurements of the carbon dioxide concentration in the school classroom’s indoor environment. The monitoring was carried out in an old school building that was constructed in the 1970s and compared to testing carried out in the same school classroom after the building was renovated in 2016. Surprisingly, the renovated classroom had a significantly higher concentration of CO2. It was found that this was due to the regulation of the heating system and the new airtight windows. The occupants of the renovated classroom have a maintained thermal comfort, but natural ventilation is rather neglected. A controlled ventilation strategy and installation of heat recovery units are recommended to solve these problems with the classroom’s indoor environment. Microbiological testing of the surfaces in school classrooms also shows the importance of fresh air and solar radiation access for indoor comfort.

ОСОБЕННОСТИ ФОРМИРОВАНИЯ ВОЗДУШНОЙ СРЕДЫ В СОВРЕМЕННЫХ ЖИЛЫХ ЗДАНИЯХ

Air quality in residential premises equipped with modern airtight windows and entrance doors causes public complaints. We discussed peculiarities of air quality changes in residential buildings resulting from large-scale use of window glass units, which are characterized by increased thermal resistance and high-quality insulation, used in modern residential construction. Regulatory and law documentation are analyzed. Advisability of using mechanical supply and exhaust ventilation in residential premises, as well as special inlet devices – ventilation valves, which ensure sufficient air exchange in the apartment, unlike currently used exhaust ventilation system with natural inducement, are substantiated. It is suggested to coordinate the requirements of current sanitary standards and rules for residential premises with the requirements of engineering regulatory documents.

ASSESSMENT OF ACOUSTIC AND THERMAL PROPERTIES OF AIRTIGHT WOODEN WINDOWS USED IN BALTIC AND SCANDINAVIAN COUNTRIES

Windows are the one of the most important elements of a building envelope. Windows with appropriate acoustic and thermal properties can guarantee comfort and protection of indoor environment. The sound and thermal insulation of windows are influenced by various factors and one of them is air tightness. The aim of this study was to assess if airtight typical wooden windows used in Baltic and Scandinavian countries always have both good acoustic and thermal properties. For this purpose, sound reduction index (characterizes acoustic properties), thermal transmittance (characterizes thermal insulation properties) and air permeability (characterizes air tightness) of windows were determined in the laboratory. The results showed that airtight windows have various acoustic and thermal properties. This means that there is a negligible relationship between air permeability and acoustic properties, also between air permeability and thermal properties of windows.

Severe air pollution and child absences when schools and parents respond

We examine how absences respond to particle pollution in a multi-year individual panel comprising 6500 children enrolled at international schools situated in a major economic hub in north China. These schools (and their parents) have been willing and able to respond to the dire state of air quality, by implementing defensive procedures (thresholds for outdoor play) and capital (air-tight windows and central air-conditioned filtration systems). Even in this setting, we find substantial heterogeneity in the response to ambient PM2.5. Pollution sensitivity is stronger among US/Canadian/European than Chinese, children who miss school the most, and a minority of children who depart within one year of arrival, but overall is modest compared to estimates for the US. This suggests that to some extent the school response can substitute, through defensive behavior, for the absence response. We offer a benchmark for school administrators in polluted middle-income countries, yet caution that more research is needed on the long-term implications of PM2.5 exposure.

Role of airtightness in energy loss from windows: Experimental results from in-situ tests

The rate of air leakage related energy loss from glazed areas is unequivocal especially in older and poorly installed windows. Therefore, in this research, a comprehensive experimental investigation is done to analyse the importance of air leakage on overall heat transfer coefficient (U-value) of conventional air filled double glazed windows. The tests are conducted in a typical UK dwelling of Nottingham fitted with traditional air filled double glazed windows. One sash of the test window is sealed internally with a special transparent cover to provide excellent airtightness whereas the second window sash is left as it is to represent the ordinary case. The experiments are conducted in April 2016, and dynamic co-heating test methodology is applied to evaluate the rate of enhancement in the U-value of airtight window sash. The results indicate that the airtight window sash has a notably lower U-value compared to the ordinary window sash due to the impact of airtightness and reverse heat flux during noon time owing to the greenhouse effect between transparent cover and internal glazing. The overall U-value of ordinary window sash is found to be 2.67W/m2K, whereas it is 1.79W/m2K for airtight window sash. It is observed that about 33% of reduction in heat losses can be achieved via airtight windows.

Severe Air Pollution and School Absences: Longitudinal Data on Expatriates in North China

We examine how absences respond to particle pollution in a multi-year individual panel comprising 6,500 children enrolled at international schools situated in a major economic hub in north China. These schools (and their parents) have been willing and able to respond to the dire state of air quality, by implementing defensive procedures (thresholds for outdoor play) and capital (air-tight windows and central air-conditioned filtration systems). Even in this setting, we find substantial heterogeneity in the response to ambient PM2.5. Pollution sensitivity is stronger among US/Canadian/European than Chinese, children who miss school the most, and a minority of children who depart within one year of arrival, but overall is modest compared to estimates for the US. This suggests that to some extent the school response can substitute, through defensive behavior, for the absence response. We offer a benchmark for school administrators in polluted middle-income countries, yet caution that more research is needed on the long-term implications of PM2.5 exposure.

An attempt to improve indoor environment by installing humidity-sensitive air inlets in a naturally ventilated kindergarten building

Proper values of hydro-thermal parameters and good air quality indoors are known to have a great influence on human comfort, health and performance, and children are particularly susceptible to poor indoor air quality. On the other hand, there is a tendency in developed countries to modernise educational buildings to reduce energy use, and as a result, outdoor air frequently can no longer penetrate into the buildings through thermally insulated exterior walls or through airtight window frames. This may lead to high concentrations of pollutants generated indoors, increased levels of relative humidity and, often, to overheating. Installation of extra air vents (trickle vents) is sometimes recommended as a solution. The present study focuses on a comparison of passive stack ventilation performance as well as indoor conditions before and after installation of humidity-sensitive air inlets in a kindergarten building. The comparison was based on two one-month-long series of monitoring of temperature, humidity and CO2 concentration which took place before and after the installation. The results were assessed against current recommendations, and the effectiveness of the improvement was discussed. Unfortunately, the analysis of indoor conditions and ventilation performance showed that although humidity-sensitive air inlets improved performance of passive stack ventilation, the effect was not sufficient to meet current Polish and European standards and recommendations for indoor environment in newly designed kindergarten buildings.

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.

Novel method of measurement of radon exhalation from building materials

In the era of the energy saving policy (i.e. more air tight doors and windows), the radon exhaled from building materials tends to increase its concentration in indoor air, which increases the importance of the measurement of radon exhalation from building materials. This manuscript presents a novel method of the radon exhalation measurement using only a HPGe detector or any other gamma spectrometer. Comparing it with the already used methods of radon exhalation measurements, this method provides the measurement of the emanation coefficient, the radon diffusion length and the radon exhalation rate, all within the same measurement, which additionally defines material's radon protective properties. Furthermore it does not necessitate additional equipment for radon or radon exhalation measurement, which simplifies measurement technique, and thus potentially facilitates introduction of legal obligation for radon exhalation determination in building materials.

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.

Air change rates and radon accumulation in rooms with various levels of window and door closure

Dwellings in Israel must include a residential protected room made of thick concrete slabs and walls, with an extremely airtight window and outward opening extremely airtight steel door. An inward opening regular door is applied for everyday usage. Being multipurpose, the residential protected room raised concern regarding long-term radon exposure. This article presents the stage of air change rate investigation (using SF6 as tracer gas) and radon monitoring in a multidisciplinary research performed by two teams. It comprised six residential protected rooms in a tall unoccupied building, including various scenarios of window and door closure. The teams established a common theoretical model and addressed sensitivity to differences in assumptions and methods of analysis. Similar orders of magnitude of air change rates and free surface exhalation rates were obtained, but with nonnegligible discrepancies between specific values. Tracer gas method results were more sensitive to calculation assumptions and radon monitoring results to measurement uncertainties. Measured air change rates were as follows: fully sealed residential protected room: <0.03 ACH (air changes per hour); closed window and regular door: <0.25 ACH; tilted window and closed door: 1–3 ACH; one component open and the other closed: 3–20 ACH; and both components somewhat open: 20–100 ACH. It was shown that expected maximal radon concentrations in a residential protected room under conditions of regular usage or emergency protection would not reach the limit value of 200 Bq/m3.

Dynamic of Changes in Carbon Dioxide Concentration in Bedrooms

The paper presents results of preliminary studies on indoor air quality in polish sleeping rooms. Objects in typical blocks of flats with low ventilation rates were taken into consideration. Carbon dioxide concentrations were used as an indicator of indoor air quality. Theoretical calculations, results of CFD simulations and results of conducted measurements were presented. Detected high levels of CO2 concentrations (above 3000 ppm) indicated improper ventilation and poor air quality in tested bedrooms. Airtight windows associated with modern energy-efficient construction trends were recognized as the reason of this situation. Authors of publication recommended using proper window air vents in case of buildings without mechanical ventilation. Using demand-controlled ventilation and sensory information in objects with mechanical ventilation was also suggested.

Experimental study of a semi-passive ventilation grille with a feedback control system

The diffusion of window frames with low air permeability, due to the energy saving regulations, has implied in several cases the worsening of the indoor microclimate and air quality. On the other hand, air-tight window frames imply uncontrolled and too high air change rates. The mechanical ventilation not always is a practicable solution because of economic reasons and because it implies energy waste. Various Italian and European environmental and energetic laws take into consideration and promote the use of controlled natural ventilation, though this definition is not associated to well defined and tested technical solutions. An adequate solution can be achieved by using semi-passive self adjustable ventilation devices, able to ensure controlled changes of indoor air. In this paper, a semi-passive damper with a feedback control system is proposed and its behavior is investigated by means of experimental study. The presented semi-passive grille allows to control the air flow rate, injected into the room by natural or artificial pressure gradient, more effectively than the usual passive ventilation grilles made available by the present industrial production. However, since the semi-passive grille has a one-way flow, in the natural ventilation of a flat the proper functioning of the system could be ensured with a more complex configuration, with respect to the passive self-regulating grilles, able to limit the flow of fresh air in the presence of high levels of Δp; conversely, it could have widespread use in applications requiring a more accurate control of airflow in case of mechanical ventilation plants.

Influence Of Different Surface Systems AndHumidity-controlled Ventilation Systems WithHeat Recovery On The Indoor Climate In Flats

In Austria a lot of buildings suffer from rising damp and weathering, so that a high moisture content exists in the construction. Frequently problems start after the reconstruction, because new airtight windows are built-in and the high moisture content in the walls induces mould growth and other unhealthy and uncomfortable states. Investigations are done to simulate the behaviour of rooms in buildings with moisture problems to calculate the indoor climate. By the usage of prediction tools for construction behaviour and indoor climate it is possible to evaluate methods like mechanical air change with and without heat recovery, additional heating or different surface finishes. A ventilation device with humidity regulation and heat recovery can be used successfully to guarantee a comfortable and healthy indoor climate. In the paper the interaction and influences of moisture controlled ventilation with or without heat recovery on the moisture states of the indoor air are presented. In the recent past render systems, which have a low capillary moisture transport capability, have been developed for the renovation of such buildings. Investigations about the success of those measures showed different results. A sufficient exact prediction is available using a new developed program, which is able to predict the indoor climate under a given usage and the coupled heat and moisture transfer (vapour + liquid) in constructions. The simulation gives

Cinephotomicrography of the pial circulation; a study of factors influencing vascular caliber; preliminary report.

Direct observation of the pial vessels has been carried out for over 100 years.*A window was used by Ravina20in 1811. He inserted a short cylinder of wood into a trephine hole in a dog's skull. The top of the cylinder was closed by a watch glass cemented in situ. Donders,6in 1859, devised an airtight window and made the observation that when the nose and mouth of an animal were obstructed for as short a time as 10 seconds, dilatation of many small vessels became evident. Many other experimentalists used this method of study of the pial circulation. Thus, skull windows as a means of investigation of brain circulation were carried out by Berlin,2in 1851; Kussmaul and Tenner,15in 1857; Leiden,17in 1866; Riegel and Jolly,21in 1871; Elder,8in 1897; Lewin,18in 1920, and Lee,15in 1925.

Studies of the Responses of the FemaleAëdesMosquito. Part III. The Response ofAëdes aegypti(L.) to a Warm Body and its Radiation

1. A warm object is more attractive to the female yellow-fever mosquito than a cooler object, such that the numbers touching a ball warmed to 100° or 110°F. were twice as great as those touching a ball 20°F. cooler. This attractiveness was reversed when the temperature of the warmer ball reached 120°F.2. This response is eliminated by the insertion of an air-tight window of thallium bromoiodide, despite the fact that it allows almost all of the radiation to filter through. It is therefore concluded that heat convection, which is eliminated by the air-tight window, is the factor which makes a warm object attractive to the mosquito.3. The several faces of a warm cube, differing in their radiant emissivity but identical as to surface temperature, exhibited attractancies toAëdeswhich were not significantly different one from another (except in the case of black enamel, which will be explained in a later paper). These results may be interpreted to indicate that radiation plays no part in the attraction of the mosquitos to the warm face.4. It is concluded that the failure of Parker (1948) to obtain a positive response ofAëdesmosquitos to a warm dry object was due to the fact that his apparatus allowed only the radiant heat but not the convective heat to reach the insects.5 Since the response ofAëdes aegyptito heat is eliminated by a window transparent to infra-red radiation, the theory of olfaction proposed by Beck and Miles (1947) evidently has no application to this species of mosquito.