Evaluation of optical and thermal properties of coatings for energy efficient windows

Nilsson, Annica M.; Roos, Arne

doi:10.1016/j.tsf.2008.11.083

Cited by 20 publications

(12 citation statements)

References 5 publications

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“…To address these issues, several technologies have been developed, including internal and external blinds, transparent thermal barriers, angular selective shading systems, coatings, films, and multipane windows . The development of transparent wood as an alternative transparent material has aroused wide attentions .…”

Section: Introductionmentioning

confidence: 99%

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

Dalgo

et al. 2019

Adv Funct Materials

134

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The energy used for regulating building temperatures accounts for 14% of the primary energy consumed in the U.S. One-quarter of this energy is leaked through inefficient glass windows in cold weather. The development of transparent composites could potentially provide affordable window materials with enhanced energy efficiency. Transparent wood as a promising material has presented desirable performances in thermal and light management. In this work, the performance of transparent wood is optimized toward an energy efficient window material that possesses the following attributes: 1) high optical transmittance (≈91%), comparable to that of glass; 2) high clarity with low haze (≈15%); 3) high toughness (3.03 MJ m −3 ) that is 3 orders of magnitude higher than standard glass (0.003 MJ m −3 ); 4) low thermal conductivity (0.19 W m −1 K −1 ) that is more than 5 times lower than that of glass. Additionally, the transparent wood is a sustainable material, with low carbon emissions and scaling capabilities due to its compatibility with industryadopted rotary cutting methods. The scalable, high clarity, transparent wood demonstrated in current work can potentially be employed as energy efficient and sustainable windows for significant environmental and economic benefits.

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Section: Introductionmentioning

confidence: 99%

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

Dalgo

et al. 2019

Adv Funct Materials

134

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“…Furthermore, we also discuss the influence of these IR managing windows on temperature control and energy savings in the built environment. Inorganicbased window solutions, including metallic based reflective layers, [28][29][30][31] photochromic, [3,32,33] electrochromic, [3,8,[34][35][36][37][38][39] and thermochromic [3,[40][41][42][43] systems, plasmonic nanoparticles, [36,[44][45][46] aerogel glazing, [47] privacy windows, [48] thin film photovoltaics, [49] and even microfluidic [50] based windows have not been discussed in this review, as they have already received considerable attention and discussion. Additionally, organic based window devices and materials primarily intended to absorb and control visible light passage, including electro-, [51][52][53] photo-, and thermochromic [3] windows, are also beyond the scope of this review of infrared control materials: they have already been detailed in a number of excellent review articles.…”

Section: Introductionmentioning

confidence: 99%

Infrared Regulating Smart Window Based on Organic Materials

Khandelwal

Schenning

Debije

2017

Advanced Energy Materials

307

220

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(IR), here defined as light with wavelengths between 700 nm and 2500 nm, accounts for around 50% of the total energy emitted by the sun reaching Earth (Figure 1b), [3,4] and this light produces interior heating but is invisible to the unaided eye.The absorption of sunlight by building materials and passage of IR through transparent surfaces such as windows is responsible for much of the interior overheating of office rooms, automobile interiors, greenhouses, and other similar spaces. The use of artificial cooling and heating systems will only increase with the continued influence of global climate change, with energy used for cooling systems surpassing energy used for heating around the year 2070, and a 40 fold increase in air cooling energy use is expected by 2100. [5] By controlling the influx of radiant heat transfer, calculations show that more than 50% of the energy used in lighting, heating and cooling could be saved by deploying better control systems over only 18% of available window stock. [6] In areas with human inhabitants employing windows, more aspects must be considered than simply reducing the use of energy in the room: any switchable window used in, for example, a commercial office space has several other requirements that must be met before it may be installed. Among these requirement are reasonably fast switching speeds [7] (although for IR control, relatively longer times compared to visible light switching should be acceptable), good optical transparency with minimum haze, an acceptable device lifetime, [8] and functionality over a range of exterior temperatures. Controlling the excess of solar energy without compromising the visible transparency of the window is an important consideration for human health: maintaining inside/outside contact and daylighting are vital in retaining well-being and productivity, as well as providing economic and aesthetic gain by reducing the need for artificial lighting systems. [9,10] These are challenging goals for a window to realize.A number of materials have been developed over the past few decades to maintain indoor temperatures. Many of these focus on the opaque structural building elements like walls and roofing. [10][11][12][13] Other solutions target the transparent window, employing external mechanical shutters and blinds, [14] phase change materials (PCMs), [15] thermochromic materials, [16] aerogels, [17] trapped gas in fluid membranes, [18] and even phononic materials, [19] among other options. Indeed, controlling heat passage through the window in response to changing climate conditions is a great challenge; ideally, one would accomplish Windows are vital elements in the built environment that have a large impact on the energy consumption in indoor spaces, affecting heating and cooling and artificial lighting requirements. Moreover, they play an important role in sustaining human health and well-being. In this review, we discuss the next generation of smart windows based on organic materials which can change their properties by reflecting or trans...

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“…An alternative approach to assess the optical and energy performance of EC windows is to adopt modeling tools, such as demonstrated in recent publications by Nilsson and Roos [10], and Jonsson and Roos [11]. Nilsson et al used WinSel, a window energy simulation tool developed at Uppsala University [12] to demonstrate how optical and thermal properties of windows (including coatings) can be used to evaluate the energy performance in a specific building under specific climate conditions.…”

Section: Introductionmentioning

confidence: 99%

Modeling of optical and energy performance of tungsten-oxide-based electrochromic windows including their intermediate states

Lim

Isidorsson

Sun

et al. 2013

Solar Energy Materials and Solar Cells

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ACKNOWLEDGEMENTSWe thank Steve Selkowitz, Christian Kohler, and Rueben Mendelsberg (all LBNL) for insightful discussions. This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Building Technology, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, and by the American Reconstruction and Reinvestment Act, under contract DE-EE0003838. DISCLAIMERThis document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor The Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or The Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or The Regents of the University of California.2 Abstract Tungsten-oxide-based electrochromic (EC) windows are currently the most robust and matured dynamic windows where the transmittance of visual light and near-infrared radiation can be controlled by a small applied voltage. In its standard application, the window is commonly either in its clear or colored state. In this contribution, we study the optical and energy performance of such window in the fully bleached and fully colored state as well as when it is kept in intermediate states. Different configurations in terms of placement of the EC layer stack and possible additional low-emissivity (low-E) coating within the insulated glass unit are considered. Using optical data and software tools we find that even a small coloration has a significant effect on the energy performance because the solar heat gain coefficient is readily reduced by the absorption of the EC layer stack. We compare the performance of the EC windows to commercially available solar-control (spectrally selective) low-E windows.

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Evaluation of optical and thermal properties of coatings for energy efficient windows

Cited by 20 publications

References 5 publications

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

Infrared Regulating Smart Window Based on Organic Materials

Modeling of optical and energy performance of tungsten-oxide-based electrochromic windows including their intermediate states

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