Evaluation of the thermal and optical performance of thermochromic windows for office buildings in China

Liang, Runqi; Sun, Yanyi; Aburas, Marina; Wilson, Robin; Wu, Yupeng

doi:10.1016/j.enbuild.2018.07.009

Cited by 72 publications

(27 citation statements)

References 39 publications

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“…Many efforts have been made to improve the building performance of window systems, and these are mainly in two directions: (1) for increased thermal resistance, such as using inert gases as cavity fill, multiple glass panes, low emissivity coatings, vacuum glazing and aerogel glazing; and (2) controlling solar radiation and daylight entering the room by introducing tinted coatings, reflective coatings, shading devices and switchable glazing (e.g. electrochromic (EC), thermochromic (TC) and gasochromic (GC)) (Sun et al 2018;Zhang et al 2016;Peng et al 2015;Liang et al 2018). Amongst all the technologies that control solar radiation, switchable glazing shows advantages as their thermal and/or optical properties are variable, which makes them capable of reacting to environmental changes.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Mg-Y coated gasochromic smart windows for building applications

et al. 2018

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In the purpose of improving indoor comfort and achieving building energy conservation, significant efforts have been made to improve the performance of window systems. Smart windows have been increasingly considered as an efficient technology with adjustable control of their thermal and/or optical properties in response to instant changes of the environment. This paper explores the potential of using a durable Mg-Y based switchable mirror gasochromic (GC) material for building window applications. The selected Mg-Y based GC window provides a degree of flexibility to reflect the undesirable incident solar radiation rather than the other types of GC windows, which absorb the solar heat that might eventually go into the indoor space through convective, conductive and radiative heat transfer. Building simulations were carried out for a typical office with Mg-Y GC window applied using EnergyPlus. The characterization of the selected gasochromic smart window and its impact on building performance was comprehensively studied under 5 diverse climates in China. In addition, various control strategies in response to different environmental conditions or indoor comfort criteria are also considered. The results indicated that Mg-Y based films with excessively low transmittance at the reflective state are not beneficial from the perspective of building energy conservation, while potentially developed Mg-Y windows with relative higher transmittance and larger transmittance modulation can yield energy conservation of up to 27% when compared with standard double glazing. Overall, the work presented in this paper may be seen as offering potential advice and guidance on further development of switchable mirror GC material that seek to be applied into building windows for amplifying improvements in energy efficiency and occupant comfort.

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Section: Introductionmentioning

confidence: 99%

Investigation of Mg-Y coated gasochromic smart windows for building applications

et al. 2018

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“…A validated building simulation model developed in EnergyPlus has been applied for this study [23,36]. A typical single office room was used to carry out the prediction of building performance affected by different TCs under three different climates.…”

Section: Methodsmentioning

confidence: 99%

“…Currently, the above-mentioned technologies are either at the stage of lab study or small-scale product development (e.g. PC glass for sunglasses), and their potential for regulating daylighting and solar heat gain in buildings continues to be studied [23,24]. Electrochromic (EC) glazing systems have been widely investigated as well as commercially produced; their reversible switching process is via.…”

Section: Introductionmentioning

confidence: 99%

An exploration of the combined effects of NIR and VIS spectrally selective thermochromic materials on building performance

Liang

Sun

Aburas

et al. 2019

Energy and Buildings

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Thermochromic (TC) windows are able to adjust solar radiation transmitted into buildings in response to varying window surface temperature. Vanadium Dioxide (VO2) is the most common TC material used for TC windows, as it can reduce near infrared (NIR) solar transmittance to block undesirable solar heat gains during hot days when window surface temperature rises above a particular transition temperature. However, few have studied the effect of TC windows on the indoor luminous environment. In order to improve the daylighting control, an innovative Iron-liquid based TC window film which can control the visible (VIS) spectrum was introduced and applied alongside a VO2 based TC material in this study. The combined performance of these two types of TC materials was discussed under three climatic conditions within China: Beijing, Shanghai and Guangzhou. The results show that enlarging either NIR or visible change, which is the transmittance difference before or after switching, is beneficial for thermochromic performance, the maximum energy saving increased from 11% to 18%, and UDI500-2000lux is increased by up to 27%. Combined application of NIR and visible spectral selection results in more significant balance between energy and daylighting in demand. While their energy saving potential and daylighting regulating capability affected by the combined implementation is highly dependent on the climate conditions of the TC windows.

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“…Studies by Papaefthimiou et [17][18][19][20][21] show that thermocromic coatings are best suited for hot climates. The study by Saeli et al shows that coatings with low transition temperature are more suitable for fenestration [19].…”

Section: Introductionmentioning

confidence: 99%

Thermal Performance Optimization of Double and Triple Glazing Systems for Slovenian Climate Conditions

Brdnik

2021

Sustainability

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Glazing elements are an important part of the thermal envelope of a building. Therefore, good thermal performance of glazing elements can improve indoor comfort and reduce annual maintenance costs and CO2 (carbon dioxide) emissions by reducing heat loss. Reducing heat loss through glazing elements during the heating season can be achieved by combining low thermal transmittance with high solar heat gain. Using standardized calculation methods and measured climate data for three Slovenian locations representing typical continental, mountainous and Mediterranean climates, this study predicts the best combination of optical properties (emissivity, transmittance and reflectance) of glass panes in double and triple glazing systems that contribute to minimal heat loss. It was found that for the double glazing system, the minimum heating and cooling demand for buildings with low solar gains or high solar gains and applied shading is achieved by an inner pane with high transmittance without low-emissivity coating, and an outer pane with low-emissivity coating with minimum possible emissivity. In Maribor and Portorož climatic zones, the panes with low emissivity coating should be used as inner panes in buildings with high solar gains. For triple glazing, the minimum heating and cooling requirements are achieved with two or three panes with low emissivity. For buildings with low solar gains, an emissivity of the coating of 0.03 is preferable, but for buildings with high solar gains, lower emissivity values should be used.

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Evaluation of the thermal and optical performance of thermochromic windows for office buildings in China

Cited by 72 publications

References 39 publications

Investigation of Mg-Y coated gasochromic smart windows for building applications

Investigation of Mg-Y coated gasochromic smart windows for building applications

An exploration of the combined effects of NIR and VIS spectrally selective thermochromic materials on building performance

Thermal Performance Optimization of Double and Triple Glazing Systems for Slovenian Climate Conditions

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