Triple-glazed Windows Research Articles

Comparison of triple glazed windows based on long-term measurement

This paper deals with measurement of three windows suitable for low-energy or passive houses. Windows are evaluated since 2011 in the laboratory of pavilion type with constant indoor boundary conditions and real outdoor climate. There are three windows, one wooden and two plastic which differ from each other by use of thermo modules inside the frame and center seal. Temperatures and heat fluxes on the glass, sash and frame of the windows are measured continuously. Outdoor climate is measured by the mobile weather station. During the measured period - winter 2017, windows were equipped with more sensors for temperature measuring than before. Sensors were added on the glazing, on the jamb, into the space between frame and sash and also on the montage gap filled with polyurethane foam. Temperatures on the same places of different windows are compared in this paper.

Determination of total solar and visual radiation transmitted through triple glazing component with PCM layer

Modification of a glazing unit by application of PCM layer can lead to the increase of the heat capacity of the component and effective control of solar heat gains in buildings. The purpose of this study was to investigate the effect of the PCM layer on total solar and visual transmittance in solid, mushy (transition) and liquid state of PCM. The experiment was conducted in laboratory scale using triple glazed window unit sample and artificial sun as a source of solar radiation. The transmittance (total and visual) was calculated based on the results from pyranometers and illuminance meters taking into account the intensity of solar radiation at the level of 1000 W/m2. Measurements revealed that the component is almost blind in the solid state why in the liquid the transmittance is lower than for empty - traditional triple glazing. The transmitted radiation (total and visible) depends on the location of PCM layer (internal or external window chamber). The registered total solar radiation obtained in solid state was even 0 W/m2 (when material was on the inner side), while the maximum values for liquid was 142 W/m2 (material is located on the outer side). The light transmittance for more transparent case was around 1.6 klx and ten times higher in liquid than solid state.

Stressing the passive behavior of a Passivhaus: An evidence-based scenario analysis for a Mediterranean case study

This paper first reports the outcomes of a one-year measurement campaign of a passive house built in the Mediterranean climate of Cesena (Italy) in terms of thermal comfort parameters temperature and relative humidity and Indoor Environmental Quality (IEQ) parameter CO2 concentrations. The design carried out with the help of the steady state Passive House Planning Package (PHPP) was able to guarantee good comfort conditions during the heating period, but on the other hand, overheating occurrences during the cooling season have been recorded for almost 50% time according to EN 15251 Standard. Further analyses conducted with the help of dynamic simulations in EnergyPlus allowed identifying the insulation levels and ventilation mode as the key design factors to change in order to reduce overheating to less than 20% of time while keeping a comfortable indoor environment in winter.The simplifications that can be made by reducing the insulation material thickness (up to a third of the original value) on the roof and on the walls, replacing triple-glazed windows with double-glazed windows and implementing a hybrid ventilation strategy instead of using Mechanical Ventilation with Heat Recovery (MVHR) alone could also lead to economic savings. These savings, due to both lower construction costs and operational energy savings, amount to 8755 euros in terms of Net Present Value (NPV) over 30 years' time.The Passivhaus Standard can still be regarded as a good reference for designing low-energy and comfortable houses in a Mediterranean climate if some simplifications are made according to detailed building performance simulations.

Effect of Surface Thermal Resistance on the Simulation Accuracy of the Condensation Risk Assessment for a High-Performance Window

The accuracy of condensation risk assessment depends on the accuracy of the measured or calculated temperatures. The existing 2D simulation method provides sufficiently accurate results for evaluating average performance values, such as U-values. However, the accuracy of predicting the temperatures in the local areas such as the edge-of-glazing and the frame has been questioned. This study analyzes the effect of the surface thermal resistance on the accuracy of the condensation risk assessment for high-performance windows. Experiments and three-dimensional simulations were performed for a triple-glazed window. The differences in results between the basic experimental test and the simulations with several different applied boundary conditions were analyzed. The results show that, in the simulations, a small change in the surface thermal resistance has no significant effect on the accuracy of the condensation risk assessment of the center-of-glazing or the frame. However, for the edge-of-glazing, the accuracy of predicting the condensation risk was significantly improved by using the increased local surface thermal resistance with the simulation. By employing the reduced radiation and convection at the edges or junctions between two surfaces, the error between the measured and calculated temperature factors can be reduced to less than 3%.

Simulation research on the dynamic thermal performance of a novel triple-glazed window filled with PCM

The window energy consumption plays an important role in the building energy consumption. Recent researches on the double-glazed window filled with PCM (DW + PCM) show that in summer, the released unwanted heat into the room in the discharge period of PCM in summer night is considerable as well as the overheating phenomenon from the completely melted PCM is non-ignorable, both of which have an adverse effect on the building insulation performance. In order to solve the problems, a configuration of triple-glazed window filled with PCM (TW + PCM) is proposed and the mathematical model is established in this paper. Through the simulation, the dynamic thermal performances of the TW + PCM are obtained. The results show that in typical sunny summer day, the temperature decrement factors are 0.75 and 0.63 respectively, and the energy consumption of TW + PCM is reduced by 21.30% and 32.80% respectively, compared with DW + PCM and triple-glazed hollow window (TW). In addition, the TW + PCM shows a good performance under the typical winter conditions. In conclusion, TW + PCM can avoid overheating phenomenon effectively and has advantageous performance on heat preservation and insulation.

Nonlinear benefit-cost optimization-based selection of insulation material and window type: A case study in Turkey

In this study, we maximize the energy savings of a hypothetical household by choosing an optimal insulation material with its optimal thickness and also the optimal window type. We develop a nonlinear mixed integer optimization model that maximizes the net present value of the benefits obtained by insulation over the lifespan of the house. Savings are calculated based on the gains from the electricity usage for air conditioning during cooling-required days and the fuel usage for heaters in heating-required days. The heat transfer calculations consider conductive, convective, and radiative components simultaneously. The optimization model takes the climate conditions of the region where the house is located, the consumer's desired indoor temperature, and the properties of the insulation options; then, it returns a combination of selected insulation materials with its optimum thickness and window type as output. We applied the optimization model developed to hypothetical houses in four different climatic regions of Turkey for different lifespans. For all reasonable lifespans, the model choses stonewool as the ideal insulation material. For high interest rates, single windows or double-glazed windows are preferable, but as the interest rate decreases and the net present value of the energy-savings increases, the model prefers triple-glazed windows as the ideal material. Erzurum, a city in climatic region 4, characterized by very cold winters and cool summers, was found to require the highest optimum insulation thickness, and the economic return resulting from the above-mentioned energy-saving actions was also found to be the highest in the case of Erzurum. In all the regions, the energy-saving investments were found to be feasible via applying the feasibility assessment techniques of net present value and payback period. The model developed in this study is applicable to any household as long as the required input data are available.

Experimental characterization of glazing with glass prisms

The principles of design for two types of prismatic elements have been studied. The theoretical approach has been used for design of the glass prisms to optimize their function for given application and geographic location. The two manufactured prismatic glass elements have been applied in triple glazed window samples with a low emissivity coating and experimentally tested to determine the realistic angular selective optical properties. A specific test stand for glass prism transmittance measurement has been developed and applied. The results have been compared with conventional triple glazing with clear glass panes and triple glazing with solar control pane applied, both alternatives with the identical low emissivity coating. Significant advantages of transmittance selectivity (low transmittance for high solar altitude – summer condition, high transmittance for low solar altitude – winter condition) have been proved especially for triple glazing with reverse symmetrical prism. The results open the possible application of the prismatic structures in modern façade envelopes, e.g. curtain walling facades or greenhouse walls as low-cost alternative to other types of shading devices.

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.

Energy Performance of Triple Glazed Window with Built-in Venetian Blinds by Utilizing Forced Ventilated airflow

Switchable exhaust air (SEA) window consists of three glass panes, two air cavities, and built-in venetian blinds. Such a triple glazed window allows the exhaust air from conditioned room to be ventilated through the cavity between the glass panes to ambient. Part of the heat/coolth inherent in the outgoing exhaust air is able to remove the heat loss/gain through the window. An unsteady state numerical zonal model is developed and used to analyze the thermal performance of the window. The proposed model has been validated by comparing the simulation results with the experimental measurements. Numerical simulations are carried out to evaluate the annual energy performance of the SEA window in hot summer and cold winter climate region in China. The energy performance of low-e window and blinds window is also investigated for comparison. Results demonstrate that the SEA window has great application potential in hot summer and cold winter climate.

Key design features of multi-vacuum glazing for windows: A review

The use of vacuum glazed windows is increasing due to their application in mod-ern building design. Among various types of vacuum glazed windows reported in literature, thermal transmittance of single glass sheet (conventional window) i. e 6 W/m2k is reduced by 66 and 77% using air filled double glazed and air filled triple glazed windows, respectively. Using low emittance coatings thermal transmittance of double glazed windows is reduced by 53%, however it offsets the visibility by reduc-ing light transmittance by 5%. Stresses due to temperature/pressure gradients if not eliminated may lead to reduction in service life of vacuum glazed windows. Vacuum created between the glass sheets is used to reduce conductive heat transfer. Degrada-tion in the vacuum is caused by number of factors such as, permeation of gaseous molecules through glass sheets, leakage through sealing, thermal/optical desorption, and photo-fragmentation of organic species have been critically reviewed and future trends are outlined.

Solar Pond Window Technology for Energy-Efficient Retrofitting of Buildings: An Experimental and Numerical Investigation

Windows are responsible for an important proportion of heat loss from building envelope due to inadequate insulative characteristics of traditional glazing products. In this respect, advanced glazing solutions are of vital importance to mitigate energy demand of buildings, thus to reduce carbon emissions. Therefore, in this research, a novel glazing technology called solar pond window is introduced, and it is numerically and experimentally investigated for different design configurations. The optimum design of this novel glazing covers four 5-mm-thick glass panes, two 20-mm-thick water layers, and one 20-mm-thick Krypton layer in the middle. The average heat transfer coefficient (U-value) of the optimum case is found to be about 0.40 W/\(\hbox {m}^{2}\) K. If air is used as insulative gas in the interlayer, the U-value of the glazing is determined to be around 0.90 W/\(\hbox {m}^{2}\) K, which is still competitive with the U-value range of argon-filled triple-glazed windows with low-e coatings. The fabrication cost of the optimum design of solar pond window is around €120/\(\hbox {m}^{2}\). Overall, solar pond window technology is a cost-effective and energy-efficient glazing, which has a great potential to be the future of fenestration products as well as being capable of meeting the latest building fabric standards.

The acoustic and thermal characteristics of wooden triple glazed windows

Windows are the main element affecting the acoustic and thermal properties of building envelope. Therefore, research of windows properties is very important. Acoustic and thermal properties are usually studied and analyzed separately in different research. The research related to overall study of acoustic and thermal properties of windows are not common. The aim of this study was to evaluate jointly acoustic and thermal properties of wooden triple glazed windows used in sustainable energy efficient buildings in the Baltic Sea region. The calculations and laboratory measurements of Rw and Rw + Ctr (characterizes acoustic properties) and U-value (characterizes thermal properties) were performed in this study. The results have shown that thermal values vary much more than acoustic one when comparing calculated and measured values. The analyses of results have shown that there is a clear relationship between calculated acoustic and thermal properties of windows but there is no a clear relationship between measured ones.

Multi-objective optimization of building envelope design for life cycle environmental performance

The building envelope incorporates significant amount of construction materials and is a key determinant of the embodied energy and environmental impacts in buildings. It is also a mediator between indoor and outdoor environmental conditions and has significant impacts on operational energy use in many types of buildings.The present article utilizes a multi-objective optimization algorithm to explore optimum building envelope design with respect to energy use and life cycle contribution to the impacts on the environment in a low-rise office building in Seattle, Washington. Design inputs of interest include insulation material, window type, window frame material, wall thermal resistance, and south and north window-to-wall ratios (WWR). The simulation tool eQuest 3.65 is used to assess the operational energy use, while Life Cycle Assessment (LCA) methodology and Athena IE are used to estimate the environmental impacts. Also, a hybrid artificial neural network and genetic algorithm approach is used as the optimization technique. The environmental impact categories of interest within the LCA include: global warming, acidification, eutrophication, smog formation, and ozone depletion. The results reveal that the optimum design scenario incorporates fiberglass-framed triple-glazed window, about 60% south WWR, 10% north WWR, and R-17 insulation.

A smart building material for low/zero carbon applications: heat insulation solar glass—characteristic results from laboratory andin situtests

Heat insulation solar glass (HISG) is a recently developed smart building material to minimize energy consumption of building sector. HISG might be presumed to be a conventional photovoltaic glazing product; however, it is completely unique by having some characteristic features such as superior thermal insulation, which is competitive with triple-glazed windows using argon as inert gas, acoustic and thermal comfort, self-cleaning ability owing to TiO2 nano-coating on module surface and extraordinary energy saving potential in both summer and winter. In our previous works, comprehensive experimental and numerical works have been carried out for power generation and thermal insulation performance of HISG under various climatic conditions. Within the scope of this research, optical- and lighting-related performance parameters of this smart building material are evaluated through extensive laboratory and in situ tests. Shading coefficient, visible light intensity, and UV and IR penetration are investigated via the tests conducted in real operating conditions. It is achieved from the results that the shading coefficient of HISG is only 0.136, which yields almost 80% reduction in solar heat gain compared with ordinary glazing. It is also observed from the in situ tests that HISG has a %100 UV and 99% IR blocking rate, which is of vital importance in terms of human health and thermal comfort conditions. Glaring effects are totally resolved via HISG, which is still a challenge for the buildings with conventional glazing products, especially in summer.

Energy saving potential of heat insulation solar glass: Key results from laboratory and in-situ testing

HISG (heat insulation solar glass) is a recently developed multi-functional glazing technology to mitigate energy consumption of buildings. HISG can generate electricity similar to conventional PV (photovoltaic) glazing products when exposed to sunlight, however it differs from them by having some extraordinary characteristic features such as thermal insulation, which is competitive with Argon filled triple glazed windows, acoustic comfort, remarkable energy saving potential and self-cleaning ability owing to TiO2 nano coating. Within the scope of this research, latest results from laboratory and in-situ testing of HISG are presented in terms of its key role in mitigating heating and cooling demand of buildings as well as clean energy generation. Lighting and thermal comfort related parameters such as shading coefficient, UV, IR and visible light intensity are also investigated through the tests conducted in real operating conditions. It is achieved from the results that instant electricity generation of HISG is 16% higher than that of standard PV glazing owing to its nano layer reflective film. Shading coefficient of HISG is only 0.136, which provides almost 80% reduction in solar heat gain compared to ordinary glazing. Indoor air temperature measured from HISG test house in summer time is very close to the ambient temperature, whereas it is found to be 14.7 °C higher in ordinary glass test house due to greenhouse effect. Annual heating and cooling demand tests indicate that HISG provides 38 and 48% energy saving in heating and cooling season, respectively.

School of the Future: Deep Renovation of the Solitude-Gymnasium in Stuttgart

The energy efficient renovation of the Solitude-Gymnasium in Stuttgart is one of the 4 demonstration buildings within the EU 7FP project “School of the Future”. The secondary school with about 710 pupils consists of a typical configuration with a main building, a building of scientific classes, a big pavilion, a small pavilion and a gym, built between 1966 and 1975. The main building and the gym include flats for the caretakers. The total heated floor area of the buildings amounts to 8,924 m2. The exterior walls of the buildings are made of exposed concrete or brick. All buildings have flat concrete roofs that had no sufficient insulation before the retrofit. Most windows consisted of PVC-frames and double-glazing, but in some corridors and stairways single-glazed facades existed. The heating was generated centrally for all 4 buildings by two gas boilers that replaced an earlier system in 2004. Domestic hot water for the gym is generated by a heat exchanger based on the heating water. Ventilation systems without heat recovery existed for some indoor rooms, some rooms in the building of scientific classes and the gym.All 4 demonstration buildings in the School of the Future project have the same goals:•Reduction of the total energy use > factor 3, verified through monitoring•Reduction of the heating energy use > 75%, verified through monitoring•Improvement of the indoor environment quality (air, daylight, acoustic, thermal comfort) with impact on the pupils’ performance, analysed by short-term measurements and questionnairesThe building envelope renovation measures at the school in Stuttgart included external thermal insulation systems and curtainwall facades with 14-18cm polystyrene insulation, 16-22cm of expanded polystyrene on the roofs and mostly triple-glazed windows. The new heating system is a co-generation plant in combination with the existing boilers. The ventilation of the classrooms is now realised by decentralised ventilation units with 80% heat recovery (main building) or by hybrid ventilation consisting of window opening supported by actuators at the upper part of the windows that are controlled by timers and manually by the teachers. CO2 visualisation systems show the teacher when window opening is necessary. The existing ventilation system in the building of scientific classes are improved by central heat recoveries of 80% - 90% efficiency. Also the lighting system was updated by T5 compact fluorescent lamps, electronic ballasts, daylight control and presence detectors. A one-year monitoring period will show whether the energy performance goals (reduction of final energy from 225 to 58 kWh/m2yr and primary energy from 215 to 54 kWh/m2yr) and the indoor comfort goals can be achieved.

Modeling and thermal performance evaluation of a switchable triple glazing exhaust air window

A concept of switchable triple-glazing exhaust air (SEA) window is proposed. The window is characterized by two air cavities with one being a ventilation channel for exhausting indoor air to the ambient. The other cavity is enclosed and, together with the adjacent two glass panes, acts as a conventional double-glazing unit. Venetian blinds are imbedded in the ventilation cavity which is located to the outer side in summer and is switched to the inner side in winter. Such a design makes the window able to reduce its heat loss/gain by utilizing the heat/coolth inherent in the exhaust air. An unsteady state numerical zonal model is developed and validated by comparison with the measured data reported in a published literature. The model is used to calculate the temperatures of the glass layers for evaluating the hourly thermal performance of window. Numerical simulations are carried out to investigate the SEA window, double and triple glazing window at a hot-summer and cold-winter city. Simulation results show that, in comparison with the double and triple glazing windows, the SEA window reduces 73.5% and 71.9% of the heat gain in summer, respectively, and 74% and 46.8% of the heat loss in winter, respectively. Further analysis reveals that the advantageous performance of the SEA window pertains to other orientations. A discussion on the difference of using steady state model and unsteady state model for the window is included.

Simulation of the Low-Emissive Coatings Influence on Double-Glazed Windows Thermal Parameters

This paper presents a one-dimensional dynamical model, based on the heat balance equations and calculations of thermal parameters for triple-glazed windows with various low-emissive coatings. The described study was performed with the financial support of the Ministry of Education and Science of Russia. Contract ID RFMEFI57614X0034.

Energy-Efficient Technologies in the Construction of School in Hot Climates

Reduction of the costs in the operation of the building, due to energy-saving technologies, is a priority in the construction today. This article discusses some ways to reduce energy consumption of schools in hot climates such as the installation of solar collectors, using of triple-glazed windows and modern insulating materials. These methods of energy reduction are determined by the selected space-planning solutions, constructive features of the structure, financial possibilities and climatic conditions. Considering these above listed characteristics, the school was designed for the class A of energy efficiency.[1-4]

Impact of the Installed Inlet Vent Flaps in the Window Structure on the Overall Aerodynamic Properties of the Window

Aerodynamic quantification of inlet vent flaps in controlled ventilation system. The impact of installed inlet vent flaps in the window structure on the overall aerodynamic properties of conventional triple glazed window and window glazed by the triple glazing with improved acoustic properties. The methodology and results of the measurement.