Exterior Windows Research Articles

Prediction of an Efficient Energy-Consumption Model for Existing Residential Buildings in Lebanon Using an Artificial Neural Network as a Digital Twin in the Era of Climate Change

Environmental factors, such as climate change, have serious consequences for existing buildings, including increased resource consumption and footprint, adverse health effects, and reduced comfort for the occupants. To promote sustainability and address climate change, architecture must embrace digitalization. Buildings can be built digitally, analyzed in real time, optimized for energy consumption, and utilized to reduce carbon emissions and achieve zero energy consumption using digital twin technology. Currently, Lebanon’s residents are turning to solar power to generate renewable energy as a result of a lack of energy supplied by the government. In this study, a digital twin model was designed using an artificial neural network (ANN) to investigate the energy consumption of residential buildings. The main idea was to assist architects and engineers in forecasting energy consumption for different design materials by selecting the most effective alternate design for materials with building envelope characteristics, such as exterior walls, roof insulation, and windows, to minimize the consumption of energy in a residential building, hence resulting in a green building. The data simulations used in the digital twin model were carried out using Quick Energy Simulation Tool (eQuest) software; 1540 simulation results were used for different thicknesses of insulation material, values of conductivity, and window types. The digital twins were designed using an artificial neural network model. The results of the investigation and the accompanying eQuest output results were found to be precise and very similar.

Pyrolysis and combustion characteristics of typical sealing materials for exterior building windows

Seals play a crucial role in preventing flame penetration through building exterior windows. However, as urban renewal accelerates, the number of discarded seals is also gradually increasing, which is not in line with the concept of green, energy-saving sustainable development. To gain a better understanding of the pyrolysis and combustion characteristics of sealing strips and facilitate their effective resource utilization and conversion into value-added fuels, we employed thermogravimetry, cone calorimetry, and flue gas spreading test equipment. Typical sealing and filling materials used for external windows of buildings, including EPDM ordinary adhesive strips (EPDM-O), EPDM flame-retardant adhesive strips (EPDM-R), as well as 20-fold expanding graphite strips and 30-fold expanding graphite strips (EG-20 and EG-30), were investigated. Comprehensive evaluations of their pyrolysis behaviors, kinetic parameters, and combustion characteristic parameters were carried out. The results showed that EPDM exhibits good thermal stability, while EG had better demonstrates favorable pyrolysis properties and expansion densification. Average activation energies of EPDM-O and EPDM-R in the combustion phase were 68.35 kJmol−1 and 92.40 kJmol−1, respectively. Moreover, the average activation energies of EG-20 and EG-30 in the expanding combustion phase were 67.42 kJ·mol−1 and 68.62 kJ·mol−1, respectively. The reaction rate of combustion stage is faster than that of pyrolysis stage. Furthermore, For the combustion, the flame growth index (FGI) of EPDM is greater than that of EG, whereas the flame spread index (FPI) is lower than EG. When EPDM burns, the flame spreads rapidly, while EG expands and generates a large number of wormlike substances, effectively preventing the high temperature from spreading to the interior of the material. Analyses of smoke spreading tests have shown that both EPDM and EG can produce irritating flammable fumes at high temperatures, affecting the environment. These results provide a basis for the development of new materials and contributes to fire safety, smoke management, and personnel escape planning.

Field measurement of the impact of natural ventilation and portable air cleaners on indoor air quality in three occupant states

• Ventilation strategies are proposed in the state of unoccupied, sleep and leisure. • A strategy of natural ventilation combined with portable air cleaners is proposed. • The exterior window should not be completely closed when running PAC. • It is recommended to open the windows during sleep to reduce the CO 2 concentration. • Opening the residential inner door can result in a uniform indoor environment. Natural ventilation (NV) has been considered a simple and effective method of ventilation. However, the introduction of NV does not achieve better indoor air quality (IAQ) when the outdoor atmospheric environment is polluted. Therefore, portable air cleaners (PACs) are increasing in use in recent years, but their effectiveness is highly dependent on the residents' habits. A typical residence in Xi'an, China was selected to examine the effects of the use of NV alone and the use of NV and PACs together on IAQ in the three occupant states, i.e., unoccupied, sleeping and leisure. Parameters, such as temperature, relative humidity, CO 2 , and PM 2.5 concentration were measured when changing the window opening and the position of the PAC. The results showed that in the unoccupied state, opening the inner door can promote a more uniform thermal and humid environment. In the sleeping state, the I/O ratio of the PM 2.5 concentration was the lowest when the window opening of the bedroom was 1/2 or 3/4, with a mean value of 0.3. In the leisure state, only using NV, when the purification rate reaches 90%, the mean purification time of each window opening in the living room is 87.5 min. The mean purification time was reduced to 25 min when both NV and PAC were used. The on-site purification efficiencies were 91.0% and 94.5%, when the window opening was 1/2 (i.e., the PAC was placed in the center of the room) and 3/4 (i.e., the PAC was placed away from the outer window), respectively.

Between Fancy and Functionality: Comparative Thermal Performance Analyses of Selected External Building Shading Elements in Tropical Building Design

Tropical region is characterized by high temperature, arising from high solar radiation. Incoming near-infrared energy emanating from excessive direct sunlight leads to increase in the indoor temperature with its attendant indoor thermal discomfort. Thus, there is the need for protection of the interior from this excessive direct heating. One of such protective approaches is the introduction of exterior shading elements to block the incoming solar energy. To achieve this in a typical tropical city of Ogbomoso, Nigeria, several forms of exterior window shading elements are adopted predominantly based on individual preferences, fancies, etc., without scientific consideration for their effectiveness. This study therefore investigated performance effectiveness of each type, with a view to identifying the most effective shading element in the study area. The study adopted the use of multiple/iterative building performance simulation tool, DesignBuilder for evaluating indoor thermal performance of a typical three-bedroom residential building, with regard to four predominantly adopted fixed external shading elements in the study area. Virtual models of five variants of the building were subjected to energy performance simulation analysis, using weather data for Ogbomoso. While the first building tagged Building I was modelled without any shading element, to serve as the control building, the remaining four tagged Building II, Building III, Building IV and Building V were modelled with overhangs, side-fins, hybrids and louvres shading system respectively. Building V recorded highest reduction (56.55%) in the indoor solar gains. This was followed in the order of Building IV (23.90%), Building II (16.00%), and Building III (7.63%). Thus, effectiveness of external louvres system as an external shading device over side-fins and overhangs in the study area could be established. This research is necessary to minimize additional active energy required to reduce the indoor thermal discomfort arising from solar gains (through reduced annual space cooling loads). This will increase building energy efficiency and reduce carbon emissions for overall clean and safe global environment

An Empirical Study of a Passive Exterior Window for an Office Building in the Context of Ultra-Low Energy

An Empirical Study of a Passive Exterior Window for an Office Building in the Context of Ultra-Low Energy

Influence of Opposing Exterior Window Geometry on the Carbon Emissions of Indoor Lighting under the Combined Effect of Natural Lighting and Artificial Lighting in the City of Shenyang, China

According to relevant statistics, the electricity consumption for lighting in university buildings accounts for 20 to 40% of the total energy consumption of the buildings. Lighting energy saving is a key influential factor in achieving a low-carbon campus construction. The electricity consumption for lighting is simultaneously affected by the utilization of natural daylight and artificial lighting schemes. Currently, there is a lack of research regarding the dynamic quantitative correlation between the geometric design of external windows affecting the utilization of natural daylight and carbon emissions. Also, research on the dynamic synergistic impact between natural light utilization and artificial lighting on carbon emissions has not been observed. Hence, there is a lack of quantitative carbon impact prediction and guidance in the early design and actual operation of such spaces. This study took the professional drawing space of a university in the severe cold regions of Shenyang as a prototype. Daylight factor (DF) and spatial daylight autonomy (sDA) were determined using Rhino + Grasshopper and Ladybug + Honeybee for window geometry. DIALux evo simulation was used to analyze the carbon emissions of space operation, followed by correlation analysis and multiple linear regression analysis using SPSS to determine the degree of influence of each window design parameter on the carbon emissions. The window-to-floor ratio (WFR), window-to-wall ratio (WWR), windowsill height (Hws), window width (Ww), and window height (Hw) had inhibitory effects on carbon emissions from daylight-responsive artificial lighting (C), and the influence of different orientations was different. Under the condition of an opposing window, the overall C trend of the professional drawing space was west < east< south < north, and the C of the morning period in each orientation was significantly lower than that in the afternoon period. Taking the frame structure system space with a floor-to-floor height of 4.2 m as an example, within the requirements of WFR and WWR, the C of the west-facing professional drawing classroom with 2.55 m for Hw, 0.75 m for Hws, and 9.6 m for Ww was the smallest. To a certain extent, opening large windows and opening high windows can reduce the C of the space.

Construction of Building an Energy Saving Optimization Model Based on Genetic Algorithm

The building envelope structure is the cause of a major part of energy consumption, with exterior walls and windows being the main energy-consuming components. Traditional building energy conservation measures often overlook the demand for human comfort, especially in areas characterized by hot summers and warm winters. For this paper, the authors concentrated on indoor comfort, with a focus on optimizing the heat transfer coefficient of windows and exterior walls using a genetic algorithm. They used a genetic algorithm to explore the performance optimization of exterior walls and windows in the enclosure structure. To aid this effort, they constructed a building energy-saving optimization model. In addition, they created an optimization model in an attempt to reduce building energy consumption. They took the heat transfer coefficients of the outer window and the outer wall as the optimization parameters of the established model, and they compiled the optimization program using MATLAB. The experimental results showed that the heat transfer coefficients of exterior walls and windows in cold regions are 0.4459 and 2.7875, respectively, while the heat transfer coefficients in warm winter and hot summer regions are 0.66, 1.98, 1.026, and 1.59. The conducted work provides a reference for the optimization design of the heat transfer coefficient of external walls and windows as a measure to enhance building energy efficiency.

Research on the Evaluation of Green Technology Renovation Measurement for Multi-Storey Houses in Severe Cold Regions Based on Entropy-Weight-TOPSIS

In the context of global warming and the energy crisis, a large amount of energy consumed by the construction industry has a negative impact on climate change. Green retrofitting for older multi-story houses can significantly reduce energy consumption and pollutant gas emissions. However, a comprehensive evaluation method is needed to select suitable retrofitting methods. This paper established a green renovation evaluation system, including five dimensions from the green concept, and 16 evaluation indexes. Making an old multi-story house in Shenyang the research object, 16 transformation plans were generated through orthogonal experiments. The total weights of each index were derived through entropy weighting and expert scoring, and then the best retrofit solution was selected using the improved TOPSIS method. The best retrofit solution was evaluated to reduce energy consumption by 3016.4 kWh/m2 and pollutant gas emissions by 3934.3 tons over the remaining 35 years of its life cycle while generating an economic benefit of approximately 1.58 million yuan. These study results show that the retrofitting of external walls significantly affects the building’s energy consumption; exterior windows present the most negligible impact. The photovoltaic facilities provide significant energy savings.

Associations between illness-related absences and ventilation and indoor PM2.5 in elementary schools of the Midwestern United States

This study monitored indoor environmental data in 144 classrooms in 31 schools in the Midwestern United States for two consecutive days every fall, winter, and spring during a two-year period; 3,105 pupils attended classrooms where the measurements were conducted. All classrooms were ventilated with mechanical systems that had recirculation; there were no operable exterior windows or doors. The daily absence rate at the student level and demographic data at the classroom level were collected. The overall mean ventilation rate, using outdoor air, was 5.5 L/s per person (the corresponding mean carbon dioxide concentrations were < 2,000 ppm), and the mean indoor PM2.5 was 3.6 μg/m3. The annual illness-related absence rate at the classroom level was extracted from the student-level absence data and regressed on measured indoor environmental parameters. Significant associations were found. Every 1 L/s per person increase in ventilation rate was associated with a 5.59 decrease in days with absences per year. This corresponds to a 0.15% increase in the annual daily attendance rate. Every additional 1 μg/m3 of indoor PM2.5 was associated with a 7.37 increase in days with absences per year. This corresponds to a 0.19% decrease in the annual daily attendance rate. No other relationships were significant. Present results agree with the previously demonstrated benefits of reduced absence rates when classroom ventilation is improved and provide additional evidence on the potential benefits of reducing indoor inhalable particles. Overall, reduced absence rates are expected to provide socioeconomic benefits and benefits for academic achievements, while higher ventilation rates and reduced particle levels will also contribute to reduced health risks, including those related to airborne respiratory pathogens.

Energy savings and life cycle cost analysis of advanced double skin facade system applied to old apartments in South Korea

South Korea is one of the most densely populated countries in the world, and the population density in urban areas is much higher among others. Apartments are the most common form of residential buildings due to their high population density. More than 60% of domestic residential buildings are apartments, with more than 10 million households. The high population density is a problem that has long plagued South Korea because more than 45% of apartments are old apartments that are more than 20 years old. Old apartment buildings have low thermal performance that results in lots of energy consumption. Balconies, which worked as a thermal buffer, are also being removed by residents to expand indoor space. According to the green remodeling project supported by the Korean government, the typical retrofitting method is replacing external windows with the high-efficiency window in old apartments in South Korea. This paper proposes a retrofitting method using an extended double-skin façade (DSF) system that replaces exterior windows and acts as a thermal buffer. The simulation model is developed with the EnergyPlus simulation program to conduct energy performance analyses. The simulation model has been calibrated using actual experimental data collected between October 1, 2019, and January 15, 2020. Results show that the cooling, heating, and lighting energy can be reduced up to 44.1% by fully utilizing electric energy generated by solar PV panels integrated with the DSF system. The payback period is about 15 years based on the energy price provided by the utility company. Although the payback period is long, it has great potential of energy savings and CO2 emission reductions. The DSF system should be considered as a way of renovation, considering other factors such as increased real estate values and energy cost increases in the future.

Characteristics of office lighting energy consumption and its impact on air conditioning energy consumption

The energy consumption of office buildings has increased sharply since the 21st century with the increasing urbanization coverage. At this stage, the energy consumption of office buildings in China mainly comes from air conditioning and lighting. This paper obtains the regression equation of natural lighting illumination and radiant heat gain under different curtain conditions through experiments and simulations, and gives the theoretical calculation process of curtain regulation of office thermal and light environment and energy consumption. DeST and Ecotect software were used to analyze the thermal and light environment and energy consumption of the office. The results show that setting curtains in the room can effectively improve the indoor thermal light environment, the higher the transmittance of curtains the lower the lighting energy consumption, the higher the number of high temperature hours of natural room temperature and the greater the radiant heat gain. The room with thick curtains has the lowest energy consumption for air conditioning in summer, followed by the room with thin curtains, and the room without curtains has the highest energy consumption for air conditioning. The room without curtains has the lowest energy consumption for artificial lighting, the room with thin curtains has the second lowest, and the room with thick curtains has the highest electricity consumption for artificial lighting. The air conditioning energy consumption accounts for the main building energy consumption, followed by the lighting energy consumption. After setting curtains in the office, the air conditioning energy consumption caused by the solar radiation heat entering the room through the exterior windows is smaller than the lighting energy consumption caused by artificial lighting. Therefore, the installation of internal shading with moderate transmittance and good thermal insulation performance can make the energy saving of lighting and air conditioning energy consumption reach the optimal value.

Evaluation of the Impact of Input-Data Resolution on Building-Energy Simulation Accuracy and Computational Load—A Case Study of a Low-Rise Office Building

Building-energy consumption is the primary aim of urban energy consumption, which can aid in optimization of building operation and management techniques, creating sustainable building and built environments. However, modellers’ understanding of the relationship between building-energy modelling (BEM) accuracy and computational load is still qualitative and deprived of accurate quantitative study. Based on a bottom-up engineering methodology, this study aims to quantitatively explore the effects of building-model input data with different resolution accuracies on energy simulation results, including evaluation of computational load. According to the actual parameters of the case-study building, 108 models with varying input resolution levels were developed to estimate hourly energy usage and annual mean ambient temperature. The results demonstrated that with input parameters at low resolution levels, geometric parameters such as exterior windows, interior windows, and shading exhibited significantly lower computational loads, resulting in reduced errors in the final simulation performance, whereas the occupancy schedule, thermal zoning, and HVAC configuration parameters exhibited significant declines in simulation performance and accuracy. This study presents a methodology applicable to the majority of low-rise, rectangular office structures. Future work would concentrate on carrying out comparison tests for different building forms and types while gradually improving the automation of the process to enable use of the appropriate accuracy level in assessing the crucial issue of energy-modelling input.

Distribution of polycyclic aromatic hydrocarbons in indoor/outdoor window films and the indoor film/air partition of northeastern Chinese college dormitories

Indoor window films can represent short-term air pollution conditions of indoor environment through rapidly capturing organic contaminants as effective passive air samplers. To investigate the temporal variation, influence factors of polycyclic aromatic hydrocarbons (PAHs) in indoor window films, and the exchange behavior with gas phase in college dormitories, 42 pairs window films of interior and exterior window surfaces and corresponding indoor gas phase and dust samples were collected monthly in six selected dormitories, Harbin, China, from August to December 2019 and September 2020. The average concentration of ∑16PAHs in indoor window films (398 ng/m2) was significantly (p < 0.01) lower than that in outdoors (652 ng/m2). In addition, the median indoor/outdoor ∑16PAHs concentration ratio was close to 0.5, showing that outdoor air acted as a major PAH source to indoor environment. The 5-ring PAHs were mostly dominant in window films whereas the 3-ring PAHs contributed mostly in gas phase. 3-ring PAHs and 4-ring PAHs were both important contributors for dormitory dust. Window films showed stable temporal variation, i.e. PAH concentrations in heating months were higher than those in non-heating months. The atmospheric O3 concentration was the main influence factor of PAHs in indoor window films. PAHs with low molecular weight in indoor window films rapidly reached film/air equilibrium phase within in dozens of hours. The large deviation in the slope of the log KF-A versus log KOA regression line from that in reported equilibrium formula might be the difference between the window film composition and octanol.

Experimental and Simulation Research on the Energy-Saving Potential of a Sunspace—Taking an Apartment in Qingdao as an Example

This paper investigates the thermal performance and energy-saving potential of the sunspace of an old apartment building in Qingdao through experiments and software simulations. This study found that different modes of user behavior can have a substantial impact on the thermal performance of the studied sunspace in winter. The bedroom with a non-ventilated sunspace showed a higher average temperature than the bedroom without the sunspace. However, the bedroom with the sunspace had more heat loss than the bedroom without the sunspace when the sunspace was naturally ventilated, especially at night. In Delta temperature (DT)-controlled ventilation mode, the heating load of a bedroom can be reduced by 2.94 kWh/m2 compared with the non-ventilated mode. Simply optimizing the roof configuration of the sunspace can significantly improve the heat gain of the non-ventilated sunspace and reduce the energy consumption for heating by 26 kWh/m2. Compared with the unoptimized sunspace, the optimized ventilated sunspace can reduce the heating load of the bedroom by 38.82 kWh/m2. In addition, the overheating of the room in summer can be solved by opening the exterior windows of the sunspace for ventilation during the day and leaving the door of the sunspace open at night.

Research on Energy Saving and Economy of Old Buildings Based on Parametric Design: A Case Study of a Hospital in Linyi City, Shandong Province

With the need for a green economy and the introduction of low-carbon policies, more and more old buildings are being transformed to improve the thermal performance of buildings and reduce energy consumption. However, people ignore the village buildings and the old public buildings. Based on the investigation of a typical health center in Linyi City, this paper proposed improvement measures using EnergyPlus simulation software and JePlus parameter chemical tools. The various factors analyze the various parts of the enclosure, and the energy-saving effect of the roof is better than that of the exterior wall: When the thickness of the insulation layer gradually increases from 0 cm to 30 cm, the unit energy consumption of the building gradually decreases from 57 kW·h/m2 to 42.8 kW·h/m2, while that of the roof is gradually reduced to 24.41 kW·h/m2. Double exterior windows effectively reduce the energy consumption of the building in all renovation schemes. The optimal scheme is selected through the parameterized design of all the overall enclosure reconstruction schemes and the initial investments. The results showed that the investment recovery of the selected scheme was between 1.36–5.28 years. Plan 5 (12 cm XPS is used as insulation material for the exterior wall and roof, and the exterior window is replaced with 6 mm medium transmittance Low-e + 12 mm air + 6 mm clear) had the highest energy efficiency (91.11%). Plan 2 (6 cm XPS is used as insulation material for the exterior wall and roof, and the exterior window is replaced with 12 mm single medium transmittance heat-reflecting glass) had the shortest investment recovery period (2.04 years).

Characteristics of PCMs-filled double glazing unit under fire: A detailed thermal structural analysis

The behavior of double-glazing unit filled with paraffin wax as phase change materials (PCMs) under fire is studied in this paper. Based on the glass fracture criterion, the mathematical model of PCMs-filled double glazing unit is established, the probability failure conditions of glass fracture under fire load are reasonably set, the thermal structure characteristics of glass structure with paraffin wax layer and hollow glass unit are numerically examined, and the heat transfer characteristics of glass envelope with paraffin wax layer under fire conditions are analyzed. The thermal deformation temperature of glass envelope with paraffin wax layer reaching the fire surface under four fixed boundary conditions and the time of reaching the limit temperature at the edge are respectively delayed by 55 s and 5 s, compared to that of hollow glass unit. The outcomes reveal that the fire resistance of the double-glazing unit filled with paraffin wax is better than that of ordinary double-glazing unit. This research has important implications for the application and popularization of PCMs-filled double glazing unit in building exterior windows.

Effect of Window Openable Area and Shading on Indoor Thermal Comfort and Energy Efficiency in Residential Buildings with Various Operating Modes

Solar heat gain and natural ventilation cooling of the indoor environment in buildings are highly influenced by the shading and openable area of windows. In addition to the ambient condition, the Heating, ventilation and air conditioning (HVAC) system’s mode of use can affect the windows’ performance, especially when multiple modes are used in combination (mixed-mode). Although many studies have investigated the mixed-mode application, their conditions for starting/shutting down HVAC equipment and controlling window ventilation are inconsistent with the relevant codes. Here, we propose a mixed-mode operation that resolves the gap between the air conditioning operation temperature and the adaptive comfort upper temperature. It investigates residential buildings’ indoor thermal environment and energy efficiency by combining the effective ventilation opening area ratio (REV) and shading design. Simulation results show that our mixed-mode can reduce the indoor overheating hours by about 50% and the building’s energy consumption by about 50%. We thereby conclude that the openable area of exterior windows in residential buildings in Chongqing should not be less than 10% of the room’s floor axis area where the exterior windows are located. In general, our study expands the existing knowledge of passive energy-saving measures and provides a method for further research on building energy design in hot summer and cold winter regions.

Study on the Influencing Factors of Energy Consumption of Nearly Zero Energy Residential Buildings in Cold and Arid Regions of Northwest China

There are many factors influencing the energy consumption of buildings in complex working conditions. In order to study the factors influencing the energy consumption of residential buildings with nearly zero energy in cold and arid regions of northwest China, factors such as the roof heat transfer coefficient (KR), exterior wall heat transfer coefficient (KE), ground heat transfer coefficient (KG), exterior window heat transfer coefficient (KEW), north window wall ratio (WWRN), south window wall ratio (WWRS), east west window wall ratio (WWRWE), building orientation (BO), and ventilation times (VT) are taken as the influencing factors in this paper. Using the orthogonal test, 135 building energy consumption calculation models were built in DeST, and the influence of 9 factors on building energy consumption in 5 types of regions (severe cold region A (1A), severe cold region B (1B), severe cold region C (1C), cold region A (2A), and cold region B (2B)) were analyzed. The conclusions are as follows: in the process of realizing nearly zero energy of residential buildings in the cold and arid regions of northwest China, the KR, KE, KG, KEW, WWRN, WWEWE should be reduced as much as possible in the five regions. The 1A,1B,1C regions should increase WWEWE and VT, with BO of about 15° east of due north and VT of about 5, 8, and 10 times per hour, respectively. The WWES, BO and VT for the 2A region should be set at round 0.45, north-south, and about 10 times per hour, respectively. For the 2B region, WWES should be set at around 0.45, BO around 15° east of due north, and VT as low as possible within the scope of the ‘technical standard for nearly zero energy buildings’.

Experimental Assessment of Different Sealing Methods for Windows to Improve Building Airtightness in UAE Residential Buildings

If infiltration is uncontrolled and admits unconditioned air, the results will be undesirable. Controlling this problem will increase thermal comfort and decrease energy consumption. The aim of this paper is to assess the performance of different materials used to improve airtightness, which will increase energy efficiency. This research primarily adopted an experimental approach. A typical residential building in UAE was chosen as a case study. Current airtightness status was measured using a blower door test and infrared technique. Six commonly used materials used for airtightness in UAE were identified and applied in different zones of the building envelope, including exterior walls, door and windows. The test was run before implementing airtightness strategies, following which they were applied for one year. Overall performance and energy reduction were monitored to identify how consumption fell by which method was the most efficient. The results indicate that energy was 3% when applying the 6 different airtightness strategies. The base case energy consumption was 64,287 kWh per year. The energy consumption then decreased after applying the sealants to 62,341 kWh per year. Future recommendations are made to enhance airtightness in residential buildings in a hot and arid climate.

Enhancement in Mechanical Properties of Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Thin Films Deposited by Electron Beam Evaporation

Aluminum Oxide thin films are potential candidate for anti-reflection, anti-soiling, and self-cleaning applications for solar cell panels, solar water heating panels, exterior windows of buildings, glasses, car windows, fabrics, and clothes. This paper reports on effect of chopping during deposition on the intrinsic stress and adhesion of Al2O3thin films deposited by electron beam evaporation. The kinetics of the growth and structure of the thin films is governed by adhesion. The durability and its wear are related to the certain extent adhesion of the thin film to the substrate. Effect of ambient aging on the adhesion and the internal stress in the films are also reported. The effect of chopping the thin film growth, phase change and presence of Al2O3 studied using scanning electron microscopy (SEM) and x-ray diffraction (XRD). The accumulation of strain energy in the thin film appears as internal stress and the binding of the vapor atoms to the substrates is referred to as adhesion. In this work, adhesion of thin films measured by direct pull off method and the internal stress is measured by interferometric method.