Multiple Glazing Research Articles

Energy efficiency optimization of PCM and aerogel-filled multiple glazing windows

The present work numerically investigated the energy performance of ten different glazing configurations in the severe cold climate of China. Furthermore, the thermal behavior of the glass windows filled with silica aerogel or PCM was analyzed and compared with traditional glass windows filled with air. In addition, to ensure the efficient functioning and minimize the heat loss through the PCM-filled window in the severe cold climate, three configurations of the triple-glazing selected for optimization and filled with silica aerogel and PCM were evaluated based on optical properties of the glass, thickness of the silica aerogel layer and melting point of the PCM. The transient solution for the simplified models of glazing units also included the radiative heat transfer. The results show that adding PCM into the glass window results in degradation of thermal performance of glass windows in winter. However, as the silica aerogel is used together with a PCM having a suitable melting temperature in triple pane windows, the thermal comfort can be improved. On the other hand, setting appropriate optical parameters of the glass for the radiation above 2.5 μm significantly enhances the energy efficiency of the glass window coupled with the silica aerogel and PCM.

Daylighting Rule of Thumb for Room with Glazing Transmittance Variation

Since antiquity, architects have been using simple guides or easy to use calculation methods called rules of thumb for predicting daylighting performance inside buildings. These rules of thumb in daylighting continue to develop as new knowledge in science and technology evolves. In architectural practice, daylighting rules of thumb have often been expressed in terms of the percentages of window area to floor area. Such rules can be found in architectural literatures as well as in building regulations in various countries. The percentages of window glazing area to floor area suggested in the literatures and building codes often range from 10% to 35% depending on the specified visual tasks and the illumination characteristics desired. One of the most frequently cited daylighting rules of thumb is for 20% glazing to floor area allocated for habitable room or space. These rules of thumb are usually based on the standard clear glass with transmittance value of approximately 0.8 to 0.9. However, many recent buildings in tropical countries have glazing transmittance lower than this value for glare control and privacy purpose. In order to address this issue, daylighting simulations were conducted using AGi-32 to determine the effects of different glazing transmittances on indoor daylight performances and to modify existing rule of thumb. Based on the simulation data and analysis, a well-known daylighting rule of thumb by Littlefair is modified to cater for multiple glazing transmittances. This new rule of thumb presents an easy to use calculation to estimate daylight factor for interior based on glazing transmittance value.

English

English

Thermal Performance through Heat Retention in Integrated Collector-Storage Solar Water Heaters: A Review

Solar thermal systems are a long-standing technology that is receiving increased attention, in terms of research and development, due to ambitious climate change targets and the need for renewable energy solutions. Integrated collector-storage solar water heaters (ICSSWHs) are a potential contributing solution and numerous studies have focussed on the optimisation of their thermal performance and efficiency. A major drawback of these systems is the heavy heat losses experienced during non-collection periods. To combat this, various heat retention strategies have been proposed and evaluated, including baffles plates, additional insulation, multiple glazing layers, selective coatings, and phase change materials. This paper aims to bring together these studies through a systematic review of the existing literature surrounding the performance of ICSSWH systems, focusing on heat retention. This review provides a comprehensive and up-to-date point of reference on relevant research and developments for researchers in this field.

On the analytical calculation of the solar heat gain coefficient of a BIPV module

A closed-analytical expression for the solar heat gain coefficient (SHGC) of a glass-glass photovoltaic module for building-integration is constructed ab initio, from the thermal study of the general case of any number of planar parallel layers with homogeneous absorption of solar radiation. By introducing the optical model of Baenas and Machado, the expressions for the SHGC of the opaque and transparent parts of the module will be provided. The scope of the calculation and the assumed working hypothesis are in line with those of international standards for multiple glazing systems and building-integrated photovoltaic modules. The proposed model has been applied to a real case of study, showing an excellent agreement with the numerical and experimental related data.

Experimental Characterization and Energy Performances of Multiple Glazing Units with Integrated Shading Devices

Modern architecture is characterized by the use of large glazed surfaces. New technologies ensure thermal insulation by multiple glazing units so that, maintaining good solar gains, highly glazed buildings can achieve good energy performance during the heating season. More complicated is the management of the energy performance during the cooling season due to high permeability to solar radiation. External shading devices are a suitable solution but they are often neglected for functional and aesthetic reasons. Solar protection devices can be, however, introduced in the air gap of multiple glazing units, providing solar protection without interfering with the building envelope. Solar and thermal properties of several solution of glazing units with in-gap shading devices were measured with advanced experimental set-up, to be compared with conventional systems. Numerical analyses were also performed to estimate the impact of this technology on the energy performance of office buildings.

Study on develop crawling patterns though multiple glazing

Study on develop crawling patterns though multiple glazing

KS L 9107에 의한 태양열 취득률(SHGC) 측정장치 개발 및 평가

Abstract Recently, multiple glazing units, frames, complex fenestration systems, and windows with shading devices havebeen developed to save cooling energy in buildings. However, very little work has been conducted on developing a directexperimental test method of the solar heat gain coefficient(SHGC) for new fenestration techniques. This study aims to developand evaluate a test apparatus to measure the SHGC, according to the KS L 9107 test method. The performance of thesolar simulator was class A, B, and A, for spectral match, non-uniformity, and instability irradiance, respectively. The differences between the measured and calculated SHGC values were found to range between 0.001 and 0.011, and for all test specimens they agreed within 4%. These results establish the validity of the test apparatus. This system is thus expectedto be useful in assessing the energy performance for various types of fenestration. Key words KS L 9107, SHGC(태양열 취득률), Fenestration(창호), Cooling energy (냉방에너지), Test method(시험법)†Corresponding author, E-mail:

Study of cross-linking parameters of polyacrylic acid hydrogels

Swelling of modified polyacrylic acid hydrogels under conditions of a photoinitiated polymerization of acrylic acid to give a sealing hydrogel for fireproof multiple glazing units was studied. Mechanisms by which cross-links are formed in the gel are suggested and the possibility of controlling the degrees of swelling and cross-linking is discussed.

Analysis of the performance profile of the NCERD thermosyphon solar water heater

The work reported here is the performance profile of a thermosyphon solar water heater developed by the National Centre for Energy Research and Development (NCERD), University of Nigeria, Nsukka. The performance evaluation was based on the mathematical models that describe the test system and some measured experimental data. The effect of some of the design and operating parameters that have been shown to affect the system’s performance was investigated. The parameters considered included the number of glazing covers, glazing cover thickness, tube spacing and the nature of absorber plate material. The performance results indicate that the test system has a maximum average daily collector efficiency of 0.658 and a mean system temperature of 81oC. The efficiency of the collector drops to an average seasonal value of 0.54 with a negligible variation across the three climatic seasons was covered in the study. With a tube spacing not exceeding 10 cm, the performance of the system is optimized irrespective of the nature of the absorber plate material. We found that the number of glazing covers affects the top-loss coefficient of the system depending on the type of absorber plate used. Multiple glazing shows a negligible contribution especially for low temperature application. The glazing cover thickness does not affect the performance of the system significantly.

Experimental and numerical determination of the total solar energy transmittance of glazing with venetian blind shading

In response to the increased occurrence of overheating problems in glazed buildings in recent years, EMPA has focussed on the determination and modelling of the total solar energy transmittance (TSET) of multiple glazing combined with different shading systems. Measurements were performed in a calorimetric outdoor test facility near Zurich, Switzerland. In the first phase, average TSET-values related to the incident global solar radiation were identified for various Venetian blind configurations with a measurement period of a few days each. As expected the results strongly depend on the slat tilt angle as well as on the solar reflectance of the slat surface. The influence of the directional distribution of the incident radiation is demonstrated by comparison of results from different measuring periods with the identical shading–glazing configuration. An extended identification model accounting for the angle-selective transmittance is presented. The experimental results are also compared with weighted g-values from numerical modelling, which are based on a view factor method extended for curved slats in a louver type shading device. In general, the agreement between the measured and calculated results is satisfactory. Some deviation is explained by a significant non-diffuse albedo component in the hemispherical radiation field.

Combined nongray radiative and conductive heat transfer in multiple glazing taking into account specular reflection and absorption

AbstractThe problem of combined nongray radiative and conductive heat transfer in multiple glazing subjected to solar irradiation is analyzed. A spectral solar model proposed by Bird and Riordan is used to calculate direct and diffuse solar irradiance. The radiation element method by ray emission model, REM2, is used to analyze the spectral dependence of radiative heat transfer. Specular reflection at boundary surfaces is taken into account. The spectral dependence of radiation properties of glass such as specular reflectivity, refraction angle, and absorption coefficient is taken into account. The steady‐state temperature and heat flux distributions in the glass layer are obtained and the insulating efficiency of multiple glazing is examined. The overall heat transfer coefficients predicted by the present method are compared with those based on the JIS method. The values obtained by the present method are slightly lower than those obtained by the JIS method. To investigate the spectral variation of radiative heat flux attenuated in the glass layer, the spectral heat flux at the room‐side surface and incident radiation are compared. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(8): 712–726, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10125

自然室温による日本各地の戸建住宅の熱性能評価に関する研究

This study proposed a evaluation method of the thermal performance of detached houses using natural room airtemperature. The numerical simulations were performed to clear the effects of techniques such as wall insulation, multiple glazing, south-facing large windows and air tightness of the house as well as summer solar shading and natural ventilation on the natural room air temperature. The scheme of high-performance houses that exceed the assumed criterion of the natural room air temperature were presented for 10 cities in Japan.

Combined Nongray Radiative and Conductive Heat Transfer in Multiple Glazing Taking Into Account of Specular Reflection and Absorption.

Combined nongray radiative and conductive heat transfer in multiple glazing subjected to solar irradiation is analyzed. A spectral solar model proposed by Bird et al. is used to calculate direct and diffuse solar irradiance. The radiation element method by ray emission model, REM2, is used to analyze spectral radiative heat transfer. Specular reflection at boundary surfaces is taken into account. Spectral dependence of radiation properties of glass such as specular reflectivity, refraction angle, and absorption coefficient is taken into account. Steady-state temperature and heat flux distributions in glass layer are obtained and insulating efficiency of multiple glazing is examined. Overall heat transfer coefficients predicted by the present method are compared with those based on the JIS method. The values obtained by the present method are slightly smaller than those obtained by the JIS method. To investigate the spectral variation of radiative heat flux attenuated during glass layer, spectral heat flux at room side surface and incident radiation are compared.

Thermal transmittance of multiple glazing: computational fluid dynamics prediction

Computational fluid dynamics (CFD) is applied for predicting the convective heat transfer coefficient, thermal resistance and thermal transmittance for a double glazing unit. The predicted thermal resistance of glazing is compared with reference data and good agreement is achieved. The convective heat transfer coefficient and thermal transmittance vary with the air space width and the temperature difference across glazing. The CFD technique can be used to gain insight into multiple glazing performance and also optimise the design and operation of novel multiple glazing systems such as air flow windows or double skin facades in terms of energy efficiency and thermal comfort.

Sound transmission through single, double and triple glazing. Experimental evaluation

Experimental results on sound insulation of glazed openings are reported in this work. The laboratory experiments were performed placing the text specimens between two relatively small rooms. The number of glass panels, their thickness, the air gap thickness between the panels and the type of fixing frame are the variables considered. The insulation conferred by the glazed opening is characterised, identifying the localisation of the dips of insulation in the frequency domain with those related to its own natural dynamic vibration modes and those related to the natural modes of vibration of the rooms. Since the full mathematical description of the acoustic insulation conferred by glazed panels is extremely complicated, simplified theoretical models are frequently used. In this work, the experimental insulation curves obtained are compared with those predicted by the simplified analytical models. This analysis shows that the predictive models, particularly when applied to multiple glazing windows, exhibit marked differences when compared with the experimental data.

Improving Thermal Performance Of Multiple Glazing

A current topic is the possibility of raising the thermal protection offered by multiple glazing by using layers of foil between the panes.Measurements, both predictive and practical, carried out at the Fraunhofer Institute of Building Physics, Stuttgart, are reported here. The concept is feasible, it is slated, and improvements can be achieved, but much existing data is over-optimistic. In practice it would seem that the air spaces must be at least 20 mm, and further attention must be given to the durability and ageing behaviour of such techniques.

Correlation between absorption changes and electron transport in photosynthesis : Rumberg, B., P. Schmidt-Mende, J. Weikard and H. T. Witt, reprinted from Photosynthetic Mechanisms of Green Plants, Pub. 1145, National Academy of Sciences, National Research Council, received August 19, 1964, 34 pgs, illus.

In response to the increased occurrence of overheating problems in glazed buildings in recent years, EMPA has focussed on the determination and modelling of the total solar energy transmittance (TSET) of multiple glazing combined with different shading systems. Measurements were performed in a calorimetric outdoor test facility near Zurich, Switzerland. In the first phase, average TSET-values related to the incident global solar radiation were identified for various Venetian blind configurations with a measurement period of a few days each. As expected the results strongly depend on the slat tilt angle as well as on the solar reflectance of the slat surface. The influence of the directional distribution of the incident radiation is demonstrated by comparison of results from different measuring periods with the identical shading–glazing configuration. An extended identification model accounting for the angle-selective transmittance is presented. The experimental results are also compared with weighted g-values from numerical modelling, which are based on a view factor method extended for curved slats in a louver type shading device. In general, the agreement between the measured and calculated results is satisfactory. Some deviation is explained by a significant non-diffuse albedo component in the hemispherical radiation field.