Double Glass Window Research Articles

Mitigating undercooling and overheating risk in existing desert schools under current and future climate using validated building simulation model

In Palestine and neighboring regions, buildings are constructed without insulation and mechanical heating and cooling systems, leading to significant thermal discomfort for occupants. To address this issue, the paper introduces a robust methodology that utilizes a validated building simulation model (BSM) created based on hourly indoor air temperature to assess indoor thermal comfort during winter and summer seasons under both current and future climates. This methodology is applied to an existing school built in 1990 in Jericho-Palestine, which has a hot desert climate. Classrooms rely on the thermal mass to increase the indoor temperature in the winter, and natural ventilation to reduce it in the summer. The effect of climate change on indoor thermal conditions is evaluated using typical warmer and colder future years based on the latest SSP5-8.5 scenario. The results showed that the calibrated and validated BSM achieved a highly accurate prediction of indoor air temperature compared to indoor air measured temperature. The validated BSM showed extreme cold for 880 h (91% of wintertime) and excessive heat for 90 h (19% of summertime) during school days. Passive winter measures, including high insulation and airtightness level, and using double glass windows, reduce undercooling to less than 40 h but increase overheating to 180 h. Passive summer measures, including night cooling and exterior shading, are necessary to reduce overheating to around 40 h. These measures are still effective in resisting the cold future years, but more creative passive summer measures and/or a mechanical cooling system are needed.

Energy Audits and Energy Modeling as a Tool towards Reducing Energy Consumption in Buildings: The Cases of Two Multi-Unit Residential Buildings (MURBs) in Toronto

This research is based on an energy audit of two multi-unit residential buildings (MURBs) located in Toronto, Canada. Energy consumption (gas and electricity) data were extracted from the energy bills of the two buildings for a consecutive period of three years. The data were then normalized to account for variations in weather conditions. Conclusions were drawn from correlation analyses between kWh, cooling degree days (CDDs), and heating degree days (HDDs), which were then compared to the energy consumption benchmarks of MURBs within the GTA. An energy simulation using e-Quest v.3.64 was performed, utilizing the advantages of the e-Quest building modeling tool to create a virtual 3D model of the audited buildings. A baseline model was constructed to reflect the actual buildings and was used to simulate the outcomes and calculate the projected energy savings from window replacements with a higher energy efficiency than the existing ones. The simulation results revealed that triple low-E glazing outperformed single- and double-glass windows, achieving reductions of 38% and 34% in gas consumption, respectively. The building envelope simulations showed that enhancing insulation reduced gas consumption by 4%, while an insulation upgrade demonstrated no discernible savings. Reducing the window area by 20% (north/south sides) led to a 6% decrease in gas consumption, while a 30% reduction resulted in approximately 9% of energy savings.

HPC-PAA hydrogel smart windows with and without Cs0.32WO3: High solar modulation ability and luminous transmittance

Hydroxypropyl cellulose (HPC) hydrogel is a promising material for fabricating energy saving smart windows. However, its lower critical solution temperature (LCST = 42 °C) is much higher than comfortable room temperatures. In this work, we applied surface polymerization of acrylic acid (AA) monomers on HPC chains and synthesized HPC-polyacrylic acid (PAA) hydrogels with precisely controllable LCST in the range of 23.0–42.0 °C. The fabricated HPC-PAA hydrogel smart windows exhibited excellent Tlum,22 °C of 91.8% and ΔTsol,22–40 °C of 73.7%, outperforming VO2 hydrogel composites and photothermal nanoparticles doped hydrogel smart windows. Meanwhile, cesium tungsten bronze (Cs0.32WO3) photothermal nanoparticles can be introduced to the HPC-PAA hydrogel matrix, and the near infrared (NIR) shielding ability of Cs0.32WO3 allowed significant reduction of NIR transmittance of the smart windows from 81.7% to 41.6% at 22 °C, and from 19.3% to 3.6% at 40 °C. Temperature regulation tests in model houses revealed outstanding heat-shielding performance of Cs0.32WO3 (0.4 wt%)/HPC-PAA hydrogel smart windows, especially compared with ordinary double-glass windows. Furthermore, the HPC-PAA hydrogel and Cs0.32WO3 (0.4 wt%)/HPC-PAA hydrogel are non-toxic, biocompatible, low-cost, suggesting their suitability for energy-saving smart window applications.

Benefitting from Solar Energy Due to Different Emissivity Levels of Multiple Glass Windows for Buildings

In the study, firstly, heat transfer coefficients of windows were calculated according to the highest and lowest emissivity values. Secondly, monthly average solar radiation values were determined. The heat transfer coefficient calculated for double, triple and quadruple glass windows. Thirdly, the solar radiation in the south, north and east/west directions of the five climatic zones were multiplied by the shading factor, surface area and the solar energy factor of discrete buildings. Thus, the solar energy gain value for the heating period and solar energy losses for cooling period was determined. Finally, passive solar energy gains are calculated during the heating and cooling period for all climate zones. It has been calculated that in the fifth climatic zone in south direction, heat loss from windows with 0.05 emissivity can be provided with passive solar energy by 167.9% in double-glazed windows, 258.7% in triple-glazed windows and 349.1% in quadruple-glazed windows.

A small-sized DSSC panel based on the Uruguayan national flower dye tested at the Antarctic Artigas Base

The construction of a small-sized panel based on anthocyanins from Erythrina crista-galli as sensitizers is reported in this work. The device, named KD12, was placed indoors at the Artigas Antarctic Scientific Base from March 2019 to December 2020. Here is released for the first time, the indoor installation of dye-sensitized solar cells based on pigments from the Uruguayan national flower at an Antarctic Base and the evaluation of their performance during nineteen months. The panel showed good stability and maintained its efficiency conversion performance over the period. The output power, voltage and conversion efficiency generated for this device mainly depended on irradiance and external factors as light reflection due to snow or artificial bulbs near the area. Additional protection was provided by the double-glass window in front of the panel, lowering lighting irradiance and changing spectral characteristics of the light incident the device. A new prospect raised here: the potential application of anthocyanins as sensitizers for indoor electricity generation in the Antarctic area with long term operability, where low temperatures are helpful considering the thermal stability of the dyes. These constitute an interesting first step of a low-cost alternative searching for clean energy generation sources, focusing on a cold region like Antarctica.

DEVELOPING STANDARD WINDOW TO FLOOR RATIO (WFR) SYSTEM FOR GREEN RESIDENTIAL BUILDINGS IN SUBTROPICS

ABSTRACT The window system is generally regarded as the most vulnerable building system for the indoor energy performance of green buildings. Window systems are given significant attention by architects and engineers, especially in areas with long summer and high solar radiation such as the subtropics. This study aims to develop a standard window-to-floor ratio (WFR) system for green residential buildings in the subtropics. Using Autodesk Revit as the interface, a real high-rise residential building was digitalized and imported into Ecotect for energy consumption analysis. Comparative analyses were conducted to determine the optimal WFR for building energy efficiency. Results demonstrated 0.23 as the optimal WFR in Xiamen, one of the typical subtropical cities in Asia. Furthermore, accompanied by a four-sidefins sunshade device and a double glass window (DGW) with clear “glass+air gap+reflective” glass, the building energy consumption was further reduced by 34.47% compared to the initial model, which successfully met the optimization target of 30%, set according to the green building standard. The results of this study are helpful to architects and building engineers when designing or retrofitting green buildings as we provide specific support for design features for energy performance.

Introducing novel configurations for double-glazed windows with lower energy loss

The energy consuming has been rapidly increased during last decades, emanated from industry and economic growth. After the energy crisis in 70 s and rising the cost of crude oil and energy, the attentions on the energy saving has been developed. However, the efforts devoted for energy consumption management should be expanded amongst all facilities related to human life. The building section characterizes with most energy loss. Considering the visual features of the buildings, the windows are exposed more heat loss in comparison with other parts of buildings. Therefore, they are required an appropriate design. In the current work, some novel configurations of double-glazed windows are introduced to have lower energy wasting in buildings. It is shown that minor, applicable and inexpensive changes in the common double glass windows make them more energy efficient. Using the proposed window configurations, it is predicted to reduce the building energy consumption about 20%. Further, through using PCM in the window’s cavity instead of air, considerable improvement in thermal performance is observed, such that the Nusselt number can be decreased by a factor of 4. This work is performed numerically and consider a hot typical day in the middle of summer.

ENERGY CONSUMPTION AND PAYBACK PERIOD ANALYSIS FOR ENERGY-EFFICIENT STRATEGIES IN GLASS TYPE OPTIONS

Cities are facing a challenge with the steady increase in energy consumption for buildings. This study aims to analyse the energy consumption and payback period of energy-efficient strategy implementation in glass type options. The energy-efficient strategy in the glass options is chosen since it affects the energy consumption the most. A study on the payback period needs to be conducted since purchasing high-performance glass materials increase the building capital cost and become a consideration for decision-maker. This study tested 5 variations, including single and double glass windows and incorporating 5 types of glass materials with various solar transmittance properties. The energy consumption then is calculated using energy simulation software OpenStudio using Jakarta weather data. The payback period is calculated to find out the length of time the energy cost saving can recoup the additional capital cost needs to purchase better thermal performance glass. The result shows that the double glass windows with low solar transmittance value reduce the energy consumption for cooling the most. Thus, cheaper glass material with similar solar transmittance value reaches the payback period fastest.

Solar-assisted desiccant dehumidification system to improve performance of evaporatively cooled window in hot and -humid climates

This study examines the performance of an integrated evaporatively-cooled window (ECW) with a desiccant dehumidification system (DDS) combined with a photovoltaic/thermal (PV/t) system. The hybrid system (ECW-DDS) is applied on a glazed building surface to reduce its temperature and the associated space-cooling load. The system performance is studied during the summer months with hot and humid conditions in which the benefits of passive cooling systems are generally restricted. Mathematical models for each system component/process were integrated to predict the system effectiveness for a case study of a typical office space located in Jeddah, Kingdom of Saudi Arabia. The integrated system effectiveness was compared to two cases where the system was not installed for a clear double glass window and where only the ECW system is employed without the dehumidification of ambient air. The hybrid system (ECW-DDS) proved to reduce the inner window temperature by 5 °C, 7 °C, 4 °C, and 5 °C for June, July, August, and September, respectively resulting in an 11% decrease of the total cooling load over the summer months. In addition, the ECW-DDS system performed much better than the ECW system when humid conditions prevailed in September. For instance, the air leaving the evaporative cooler on a typical day of September recorded a temperature reduction of 14% in the case of the ECW-DDS system compared to 1% only in the case of the ECW system.

Natural Airflow in a Reversible Double-Glass Window with Reflective Film for Building Applications

AbstractThis investigation is focused on assessing the thermal performance of a ventilated double-glass reversible window with reflective film for building applications. The window is composed of t...

Fabrication and characterization of CaCl2·6H2O composite phase change material in the presence of CsxWO3 nanoparticles

Phase change materials (PCMs) with excellent energy conservation performance have been extensively utilized in solar energy storage system. In this study, a novel kind of thermal storage composite material based on calcium chloride hexahydrate (CaCl2·6H2O) salt hydrate as core PCM and cesium tungsten bronze (CsxWO3) nanoparticles as near-infrared (NIR) light absorbent additives is fabricated. The effect of CsxWO3 nanoparticles on crystalline morphology, thermal physical behaviors and light transmittance of CaCl2·6H2O are investigated. Additionally, thermal cycle tests are conducted for stability examination. Furthermore, thermal regulating performance of double layer glass window filled with the PCM composite is tested in small chambers by being sunlight irradiated under a solar simulator. All results manifest that with the incorporation of CsxWO3 nanoparticles, the salt hydrate PCM composite exhibits large latent heat, low supercooling degree and high NIR light shielding ability as well as good thermal stability. When employed as the glazing window of a test room, the PCM panel has functions of reducing indoor temperature fluctuations and increasing thermal inertia. Hence, the salt hydrate/nano CsxWO3 PCM design in this work shows great potentials for the development of solar energy storage products in energy conservation fields.

Ventilated double glass window with reflective film: Modeling and assessment of performance

In the present study, the thermal behavior of a ventilated double glass window with a solar reflective film is numerically investigated and validated against results available in the literature. The objectives of the study are to develop a validated robust thermal model for the ventilated double glass window, make it versatile so that it can incorporate different inserts (such as reflective and absorptive films, etc.), different glass sheets and different fluids and can be integrated with other available design tools. The proposed ventilated double window is composed of two glass sheets separated by a gap forming a channel having a solar reflective film on the internal surface of outer glass sheet. The model is based on the equations of mass, momentum and the energy conservation equations in steady state. Boussinesq approximation is used to evaluate buoyancy term. The discretization of conservative equations is done using the finite volume method. A numerical code is developed and validated against available experimental and numerical results. Thermal performance of the ventilated double glass window is assessed under different conditions and the results show that in order to reduce the heat gain in the internal ambient, the optimum spacing between the glass sheets should be at least 2.5 cm. The solar reflective film in a ventilated double glass window can reduce the penetrating solar energy by about 64.7% in comparison with a traditional double glass window.

Study on the Thermal Performance of a Hybrid Heat Collecting Facade Used for Passive Solar Buildings in Cold Region

Passive solar technologies are traditionally considered as cost-effective ways for the building heating. However, conventional passive solar buildings are insufficient to create a relatively stable and comfortable indoor thermal environment. To further increase the indoor air temperature and reduce the heating energy consumption, a hybrid heat collecting facade (HHCF) is proposed in this paper. To analyze the thermal performance of the HHCF, a heat transfer model based on the heat balance method is established and validated by experimental results. Meanwhile, the energy saving potential of a room with the HHCF is evaluated as well. When the HHCF is applied to places where heating is required in the cold season while refrigeration is unnecessary in hot season, the HHCF can reduce the heating need by 40.2% and 21.5% compared with the conventional direct solar heat gain window and the Trombe wall, respectively. Furthermore, a series of parametric analyses are performed to investigate the thermal performance of the room with HHCF under various design and operating conditions. It is found that the thermal performance of the HHCF mainly depends on the window operational schedule, the width and the absorptivity of heat collecting wall, and the thermal performance of the inner double-glass window. The modeling and the parametric study in this paper are beneficial to the design and the optimization of the HHCF in passive solar buildings.

An experimental study of natural convection in a distribution transformer slice model

The aim of this work is to obtain experimental information on the thermal and fluid dynamics of a distribution transformer. The transformer of interest is of the oil natural – air natural type and our interest is centered in the natural circulation that is produced in the oil volume. An experimental device was built to simulate a representative slice of the transformer and a purpose built PIV setup was used to obtain the flow velocity field. The device overall dimensions and the refrigerating oil are the same as those of commercial transformers of 1000 KVA (Tubos Trans Electric S.A. 1000 KVA Standard Distribution Transformer) Natural circulation is produced by a heating element simulating the heat produced by copper losses in the transformer. A double glass window allows visual access for flow visualization and PIV capture. The slice comprises two fins and the air side is bounded by two isolating boards, forming three air channels. Two reference powers were tested for the experiment: The power corresponding to design operating conditions and a lower power to observe the sensibility to power variations. The result reported in this work shows features of the flow pattern that give important information on the sort of turbulent mixing to be expected. The transient evolution was measured and the thermal characteristic time of the system was estimated. It was found that the convection during the start-up transient is significantly stronger than during steady state operation.

Thermal performance of a room with a double glazing window using glazing available in Mexican market

A thermal evaluation of a four configurations of double glass window (DGW) coupling to a room is presented. The DGW consists of two vertical semitransparent walls separated by a 12mm air gap. The effect of varying the ambient temperature and the incident solar radiation in the warm climate conditions in México is analyzed. Numerical simulations were conducted for four configurations; Case 1: clear glass+air gap+clear glass (Reference); Case 2: clear glass+air gap+absorbent glass; Case 3: clear glass+air gap+Low-e glass; and Case 4: clear glass+air gap+reflective glass. Optical transmittance and specular reflectance were measured individually and in one sample piece for each case. The results showed that Case 4 reduces the heat flux to the indoors by up to 73%, with respect to Case 1. Moreover, Cases 2 and 3 had a similar behavior, obtaining a reduction of indoor heat flow close to 33.5% with respect to Case 1. Case 4 is the best option for energy savings in a warm climate, where it is possible to save up to $20.29 USD per kWh per year, in comparison to Case 1. In addition, the payback period for Case 4 is 3.7years. Therefore, the use of reflective double pane window is highly recommended in Mexican warm climates.

Energy Saving Assessment for Building Envelope of Supermarket Based on EnergyPlus and Openstudio

In this paper, a supermarket model located in Kathmandu is established by simulation software EnergyPlus. As one possible approach to improving the energy performance of the commercial building, this study develops an whole building energy simulation model to investigate the influence of two types of alternative walls – a insulated wall, a brick wall with 50 mm air gap and 4 inch additional brick wall on the energy performance of Bhatbhateni department store building at Krishna Galli, Lalitpur, Nepal. Single and double glazed glasses with varies thermal properties has been analyzed. This study finds that the 1 inch insulated external walls significantly improve the performance compared to the non-insulated wall. It is also found that the double glazed glass window models Envision and Reflectasol reduces the largest amount of energy. The results of this study can be used as basis data for estimating the potential energy saving with the replacement of alternative envelope (wall and window) under similar climate and orientation of the buildings.

Effect of Different Double Glazing Window Combinations on Heat gain in Buildings for Passive Cooling in Various Climatic Regions of India

The buildings account for more than 30% of energy consumption for cooling and day lighting in India. This paper presents the thermal performance of buildings with various double glazing window glass material combinations in four different climatic zones of India such as moderate (Bangalore), composite (Hyderabad) hot and dry (Jodhpur) and warm and humid (Vishakhapatnam) climatic zones. In this study, four double glazing window material combinations such as clear-clear, bronze-clear, green-clear and grey-clear were selected. An unventilated air space of 10 mm is maintained between the two glass layers. The spectral optical properties of four glass materials were measured experimentally using UV 3600 Shimadzu spectrophotometer from wavelengths ranging from 300 nm- 2500 nm. Total sixty four building models were designed using Design builder 4.3.0.039 and thermal analysis was carried out using Energy plus 8.1 simulation tool. From the results, it is observed that concrete buildings with double grey-clear glass window were found to be energy efficient from the least heat gain point of view among sixty four building models studied in four climatic zones of India. The results of the study help in selecting the best combination of double glazing window glass material for reducing cooling loads in buildings of four different climatic zones of India.

Simulation of District Cooling Plant and Efficient Energy Air Cooled Condensers (Part I)

In hot arid countries with severe weather, the summer air conditioning systems consume much electrical power at peak period. Shifting the loads peak to off-peak period with thermal storage is recommended. Model A of residential buildings and Model B of schools and hospitals were used to estimate the daily cooling load profile in Makkah, Saudi Arabia at latitude of 21.42°N and longitude of 39.83°E. Model A was constructed from common materials, but Model B as Model A with 5 - 8 cm thermal insulation and double layers glass windows. The average data of Makkah weather through 2010, 2011 and 2012 were used to calculate the cooling load profile and performance of air conditioning systems. The maximum cooling load was calculated at 15:00 o’clock for a main floor building to a 40-floor of residential building and to 5 floors of schools. A district cooling plant of 180,000 Refrigeration Ton was suggested to serve the Gabal Al Sharashf area in the central zone of Makkah. A thermal storage system to store the excess cooling capacity was used. Air cooled condensers were used in the analysis of chiller refrigeration cycle. The operating cost was mainly a function of electrical energy consumption. Fixed electricity tariff was 0.04 $/kWh for electromechanical counter, and 0.027, 0.04, 0.069 $/kWh for shifting loads peak for the smart digital counter. The results showed that the daily savings in consumed power are 8.27% in spring, 6.86% in summer, 8.81% in autumn, and 14.55% in winter. Also, the daily savings in electricity bills are 12.26% in spring, 16.66% in summer, 12.84% in autumn, and 14.55% in winter. The obtained maximum saving in consumed power is 14.5% and the daily saving in electricity bills is 43% in summer when the loads peak is completely shifted to off-peak period.

해석 방법에 따른 창호-벽체 접합부의 결로 방지 성능 비교

The purpose of this paper is to compare calculation results of performances of condensation resistance of joints of windows and walls according to analysis standards, simulation programs, and modeling methods and also analyze the causes. Domestic and relevant foreign criteria were reviewed, and Heat transfer simulation was conducted targeting double and triple glass windows. Also, an improved modeling plan was proposed comparing performance of condensation Resistance depending on the modeling approach. The analysis results, from different calculation methods of effective thermal conductivity of cavity spaces showed significant differences in accordance with the analysis standards. It appeared that automatic calculation of effective thermal conductivity by ISO 15099 was impossible using Physibel Bisco. Therefore, an improved and simplified modeling method using respective heat transmission coefficients for window panes and frames was proposed. It was confirmed that compared to the simple modeling, the improved modeling method decreased errors of surface temperature on joints of windows and walls by up to 10% and compared to the detail modeling, all modeling cases were within 10% or less.

Thermal evaluation of a Room coupled with a Double Glazing Window with/without a solar control film for Mexico

The thermal evaluation of a Room (R) coupled with a Double Glazing Window (DGW) with/without solar control film (SCF) under warm and cold climate conditions of an extreme weather of Mexico is presented. The right vertical wall of the room is partially adiabatic and contains the DGW. The DGW consists of two vertical semitransparent walls: glazing-1 facing the room, and glazing-2 facing the external environment. The SCF is attached to glazing-1 for cold climate condition, or attached to glazing-2 for warm climate condition. During one day, hourly simulations of the R-DGW were done using an in-house code based on the finite volume method. Three cases were defined to analyze the R-DGW system: Case C1 corresponds to the R-DGW without SCF; Case C2 and C3 correspond to the R-DGW with SCF for warm and cold climate conditions, respectively. For warm climate condition the use of a SCF is highly recommended, since the Case C2 was able to reduce ≈62% of the energy gains with respect to Case C1. When the solar control coating in double glass window is used for cold climate condition (case C3), the average temperature inside of the room is similar to the case C1.