A survey on prototype and currently commercial dynamic tintable smart windows has been carried out. The technologies of electrochromic, gasochromic, liquid crystal and electrophoretic or ...suspended-particle devices were examined and compared for dynamic daylight and solar energy control in buildings. Presently, state-of-the art commercial electrochromic windows seem most promising to reduce cooling loads, heating loads and lighting energy in buildings, where they have been found most reliable and able to modulate the transmittance up to 68% of the total solar spectrum. Their efficiency has already been proven in hot Californian climates, but more research is necessary to validate the products for colder climates, and to improve furthermore the commercial products in order to control the indoor climate in a more energy efficient way by reducing both heating and cooling loads.
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The energy consumption in buildings contributes substantially to the worldwide energy use and greenhouse gas emissions. One of the crucial elements defining energy consumption is the ...building envelope, which in modern designs includes growing share of fenestration. Due to recent improvements of windows and walls, the thermal bridging effects occurring on their connections, become more significant. Window-to-wall connections appear to be especially important and can contribute up to 40% of the total heat loss caused by thermal bridges in building envelope. Thus, this study is investigating thermal properties of window-to-wall connections. The main scope of the work is to determine the most efficient window position in the window opening regarding minimizing thermal bridging effects. Five different wall constructions are investigated along with two windows with different U-values. The thermal simulation results show that the window position has a crucial impact on the amount of energy loss through the thermal bridges. For each wall type, the most energy-efficient position is found, resulting from detailed analysis of sill, head, and jambs construction details. For some cases placing the window in the most energy-efficient position reduces linear thermal transmittance (LTT) over 50%. Among considered positions, the temperatures on the internal surface of the assemblies are weakly influenced by the window position. Example calculations show that significant share of energy losses from the fenestration presence is caused by thermal bridge occurring on window-to-wall.
The objective of answering the growing demand of environmental comfort and the urgent need to improve energy efficiency of new and existing buildings, are determining an in-depth review of the ...features and requirements of the building transparent closures towards technological solutions that can guarantee along with a maximum thermal insulation, the possibility to regulate the incoming solar radiation or generate electrical energy.
Thanks to the huge progress in the field of materials science, a new class of highly innovative glazing systems is entering the market mostly by taking advantage of key enabling technologies such as nanomaterials or smart materials.
Among these new technologies, active dynamic glazing, by modulating the amount of entering near infrared radiation and visible light, allows significant energy savings, as well as ensuring greater thermal and visual comfort for occupants.
The article offers a thorough review of active dynamic glazing technologies on the market or in development, such as electrochromics, gasochromics, and further emerging technologies, including nanocrystal in-glass composites, electrokinetic pixels, elastomer-deformation tunable window, and liquid infill tunable window, comparing them in terms of operation, performances and building application potential, and providing relevant data to aid in understanding impacts on energy-efficiency and comfort.
•Highly innovative glazing for the building envelope is discussed.•Active dynamic glazing technologies available or in development are thoroughly reviewed.•Performance and benefits/drawbacks of different smart windows technologies are compared.•Needs for improvement and future trends of active dynamic glazing are considered.
Due to advances of hyperspectral imaging sensors many unknown and subtle targets that cannot be resolved by multispectral imagery can now be uncovered by hyperspectral imagery. These targets ...generally cannot be identified by visual inspection or prior knowledge, but yet provide crucial and vital information for data exploitation. One such type of targets is anomalies which have recently received considerable interest in hyperspectral image analysis. Many anomaly detectors have been developed and most of them are based on the most widely used Reed-Yu's algorithm, called RX detector (RXD). However, a key issue in making RX detector-like anomaly detectors effective is how to effectively utilize the spectral information provided by data samples, e.g., sample covariance matrix used by RXD. Recently, a dual window-based eigen separation transform (DWEST) was developed to address this issue. This paper extends the concept of DWEST to develop a new approach, to be called multiple-window anomaly detection (MWAD) by making use of multiple windows to perform anomaly detection adaptively. As a result, MWAD is able to detect anomalies of various sizes using multiple windows so that local spectral variations can be characterized and extracted by different window sizes. By virtue of this newly developed MWAD, many existing RXD-like anomaly detectors including DWEST can be derived as special cases of MWAD.
The near‐infrared window between 1000 and 1700 nm, commonly termed the “second near‐infrared (NIR‐II) window,” has quickly emerged as a highly attractive optical region for biological imaging. In ...contrast to conventional imaging in the visible region between 400 and 700 nm, as well as in the first NIR (NIR‐I) window between 700 and 900 nm, NIR‐II biological imaging offers numerous merits, including higher spatial resolution, deeper penetration depth, and lower optical absorption and scattering from biological substrates with minimal tissue autofluorescence. Noninvasive imaging techniques, specifically NIR‐II fluorescence and photoacoustic (PA) imaging, have embodied the attractiveness of NIR‐II optical imaging, with several NIR‐II contrast agents demonstrating superior performance to the clinically approved NIR‐I agents. Consequently, NIR‐II biological imaging has been increasingly explored due to its tremendous potential for preclinical studies and clinical utility. Herein, the progress of optical imaging in the NIR‐II window is reported. Starting with highlighting the importance of biological imaging in the NIR‐II spectral region, the emergence and latest development of various NIR‐II fluorescence and PA imaging probes and their applications are then discussed. Perspectives on the promises and challenges facing this nascent yet exciting field are then given.
The importance of the second near‐infrared (NIR‐II) spectral region (1000–1700 nm) for biological imaging is highlighted, as well as recent development of inorganic and organic exogenous contrast agents for NIR‐II fluorescence and photoacoustic imaging.
Near‐infrared (NIR) light is widely used for noninvasive optical diagnosis and phototherapy. However, current research focuses on the first NIR window (NIR‐I, 650–950 nm), while the second NIR window ...(NIR‐II, 1000–1700 nm) is far less exploited. The development of the first organic photothermal nanoagent (SPNI‐II) with dual‐peak absorption in both NIR windows and its utilization in photothermal therapy (PTT) are reported herein. Such a nanoagent comprises a semiconducting copolymer with two distinct segments that respectively and identically absorb NIR light at 808 and 1064 nm. With the photothermal conversion efficiency of 43.4% at 1064 nm generally higher than other inorganic nanomaterials, SPNI‐II enables superior deep‐tissue heating at 1064 nm over that at 808 nm at their respective safety limits. Model deep‐tissue cancer PTT at a tissue depth of 5 mm validates the enhanced antitumor effect of SPNI‐II when shifting laser irradiation from the NIR‐I to the NIR‐II window. The good biodistribution and facile synthesis of SPNI‐II also allow it to be doped with an NIR dye for fluorescence‐imaging‐guided NIR‐II PTT through systemic administration. Thus, this study paves the way for the development of new polymeric nanomaterials to advance phototherapy.
The first dual‐peak absorbing organic nanoagent with nearly identical absorbance at 808 and 1064 nm is developed from a semiconducting copolymer. Such a nanoagent not only enables deep‐tissue photothermal cancer therapy in both the first and second near‐infrared windows, but also permits a fair comparative study to reveal the advantage of shifting the laser light into a longer wavelength region for phototherapy.
Smart windows with reversible regulation on solar radiation by altering their optical transmittance in response to thermal stimuli have been developed as a promising solution toward reducing energy ...consumption of buildings. This work presents a new strategy for doping Ag nanorods (NRs) with poly(N-isopropylacrylamide) (PNIPAm) hydrogel to achieve atmospheric window full-wavelength thermal management. PNIPAm as basic material was aimed to achieve solar radiation modulation among visible, near infrared (NIR), and middle infrared region. Acrylic was grafted on PNIPAm chains to enhance mechanical strength. While Ag NRs were the major factors that affected solar radiation modulation due to its structural changes driven by PNIPAm phase transition. The hybrid hydrogel showed a relatively high solar modulation ability (ΔTsol) of 59.24% while maintaining luminous transmittance (Tlum) of 61.36% under room temperature. The infrared emissivity kept a little increase from 0.947 to 0.958 during phase transition and caused a 12.7 °C reduction in temperature observed from the water-warming experiment. The innovative combination of Ag NRs and hydrogel indicated that metal nanorods may make positive effects when combining with hydrogels. This kind of new strategy based on atmospheric window full-wavelength thermal management exhibits to be an ideal candidate for applications in smart windows.
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•The hydrogel showed enhanced solar modulation abilities in atmospheric window full wavelength.•Both acrylic and Ag NRs have a significant effect on transmittance modulation.•The hydrogel was stable and with no degradation of modulation under phase transition.•Window device filled with hydrogel showed a significant temperature decrease under light condition.
In this study, an iterative method is proposed for non-linear frequency modulation (NLFM) waveform design based on a constrained optimisation problem using Lagrangian method. To date, NLFM waveform ...design methods have been performed based on the stationary phase concept which has been already used by the authors in a previous work. The proposed method has been implemented for six windows of Raised-Cosine, Taylor, Chebyshev, Gaussian, Poisson, and Kaiser. The results reveal that the peak sidelobe level of autocorrelation function (ACF) reduces about an average of 5 dB in the proposed method compared with the stationary phase method, and an optimum peak sidelobe level is achieved. The minimum error of the proposed method decreases in each iteration which is demonstrated using mathematical relations and simulation. The trend decrement of minimum error guarantees convergence of the proposed method.
Occupants often perform many types of behavior in buildings to adjust the indoor thermal environment. In these types, opening/closing the windows, often regarded as window-opening behavior, is more ...commonly observed because of its convenience. It not only improves indoor air quality to satisfy occupants' requirement for indoor thermal comfort but also influences building energy consumption. To learn more about potential factors having effects on occupants' window-opening behavior, a field study was carried out in an office building within a university in Beijing. Window state (open/closed) for a total of 5 windows in 5 offices on the second floor in 285 days (9.5 months) were recorded daily. Potential factors, categorized as environmental and non-environmental ones, were subsequently identified with their impact on window-opening behavior through logistic regression and Pearson correlation approaches. The analytical results show that occupants' window-opening behavior is more strongly correlated to environmental factors, such as indoor and outdoor air temperatures, wind speed, relative humidity, outdoor PM2.5 concentrations, solar radiation, sunshine hours, in which air temperatures dominate the influence. While the non-environmental factors, i.e. seasonal change, time of day and personal preference, also affects the patterns of window-opening probability. This paper provides solid field data on occupant window opening behavior in China, with high resolutions and demonstrates the way in analyzing and predicting the probability of window-opening behavior. Its discussion into the potential impact factors shall be useful for further investigation of the relationship between building energy consumption and window-opening behavior.
•A real-time monitoring of occupants' window behavior in an office building in China was conducted.•Some main influential factors which influence Chinese occupants' window-opening behavior are analyzed.•Environmental factors, especially outdoor air temperature and indoor air temperature have significant influence on occupants' window-opening behavior.•Some other factors that don't belong to environmental factors also influence occupants' window-opneing behavior to an extent.
•Propose a new dynamic window technology that can uncouple solar heat and light.•Build and validate an analytical model for windows with nano photothermal effects.•Explained the underlying mechanism ...of dynamic control on the solar heat gain.•Incorporate dynamic solar heat gains into parametric building energy simulation.•Demonstrate the energy-saving potentials of the reversible photothermal windows.
A variety of dynamic window and glazing systems with variable solar heat gain control features reacting to seasonal weather conditions and indoor space heating and cooling demands have been investigated in the past several decades. However, the modulation of solar heat gain has to affect the solar light transmittance in most existing dynamic glazing and window systems. In this work, a new type of dynamic window concept was proposed: reversible photothermal windows based on nanoscale solar infrared-induced plasmonic photothermal effects, which can modulate solar heat, independent of visible light conditions. This study provides the underlying technical characteristics and the thermal and optical features under solar irradiation via experimentally validated analytical models. The reversible photothermal windows exhibit a substantial ability to control solar heat gain coefficient with a range between about 0.2 and 0.6 and a stable visible transmittance of 0.32, A whole-building energy simulation demonstrates the potential for energy savings offered by reversible photothermal windows could reach over 18% in mixed climates, as compared to baseline models built using the most recent energy efficiency standards. This research illustrates technical and numerical evidence and mechanisms for energy savings that will support future research and development of this new dynamic window technology.
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