Facade systems with variable solar control using thermotropic polymer blends

Raicu, Alexandra; Wilson, Helen Rose; Nitz, Peter; Platzer, Werner; Wittwer, V.; Jahns, Ekkehard

doi:10.1016/s0038-092x(01)00093-7

Cited by 39 publications

(31 citation statements)

References 7 publications

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“…Simulation studies and prior field measurements have been used to evaluate the energy savings potential of this technology and to provide guidance to the material science community as to which properties increase energy efficiency [6][7][8]. Saeli et al [7] used the EnergyPlus building energy simulation program to evaluate the energy savings potential of actual and ideal thermochromic films in a daylit office zone, showing that coatings with broad NIR switching and a low critical switching temperature (20°C) produced significant energy savings in warmer climates compared to conventional glass.…”

Section: Introductionmentioning

confidence: 99%

An empirical study of a full-scale polymer thermochromic window and its implications on material science development objectives

Lee

Pang

Hoffmann

et al. 2013

Solar Energy Materials and Solar Cells

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Large-area polymer thermochromic(TC) laminated windows were evaluated in a full-scale testbed office. The TC interlayer film exhibited thermochromism through a ligand exchange process, producing a change in solar absorption primarily in the visible range while maintaining transparent, undistorted views through the material. The film had a broad switching temperature range and when combined to make an insulating window unit had center-of-glass properties of Tsol=0.12-0.03, Tvis=0.28-0.03 for a glass temperature range of 24-75°C. Field test measurements enabled characterization of switching as a function of incident solar irradiance and outdoor air temperature, illustrating how radiation influences glass temperature and thus effectively lowers the critical switching temperature of TC devices. This was further supported by EnergyPlus building energy simulations. Both empirical and simulation data were used to illustrate how the ideal critical switching temperature or temperature range for TC devices should be based on zone heat balance, not ambient air temperature. Annual energy use data are given to illustrate the energy savings potential of this type of thermochromic. Based on observations in the field,a broad switching temperature range was found to be useful in ensuring a uniform appearance when incident irradiance is non-uniform across the facade. As indicated in prior research, a high visible transmittance in both the switched andunswitched state is also desirable to enable reduction of lighting energy use and enhance indoor environmental quality.

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Section: Introductionmentioning

confidence: 99%

An empirical study of a full-scale polymer thermochromic window and its implications on material science development objectives

Lee

Pang

Hoffmann

et al. 2013

Solar Energy Materials and Solar Cells

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“…Several studies have been performed on electrochromic [19][20][21][22] and thermotropic [23][24][25] systems suggesting that such systems can significantly reduce the overall energy demand and enhance overall building energy performance. The advantage of a thermochromic system based on VO 2 compared to these systems is that there is no change in the visible portion of the spectrum, only in the infrared portion [7].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Transition Hysteresis Width in Thermochromic Glazing Systems

Warwick¹,

Ridley²,

Binions³

2013

OJEE

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Thermochromic glazing theoretically has the potential to lead to a large reduction in energy demand in modern buildings by allowing the transmission of visible light for day lighting whilst reducing unwanted solar gain during the cooling season, but allowing useful solar gain in the heating season. In this study building simulation is used to examine the effect of the thermochromic transition hysteresis width on the energy demand characteristics of a model system in a variety of climates. The results are also compared against current industry standard glazing products. The results suggest that in a warm climate with a low transition temperature and hysteresis width energy demand can be reduced by up to 54% compared to standard double glazing.

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“…alter solar and visible light transmittance and reflectance based on window temperature, 11 they have the potential to reduce solar heat gains and subsequently reduce cooling loads 12 when the external conditions exceed those required for occupant comfort. Conversely when 13 the external conditions fall short of those required for occupant comfort, they maintain a 14 degree of optical transparency thus promote the potential for passive solar gain.…”

mentioning

confidence: 99%

“…'Switchable glazing' however is designed to 10 regulate the amount of transmitted solar and long-wave radiation (300-3000nm) and is 11 therefore far more adaptive in nature. By responding to an applied stimulus; heat 12 (thermochromism), electricity (electrochromism) and light (photochromism), these 13 technologies have demonstrated significant potential to reduce energy consumption in 14 buildings [2]. 15 Thermotropic (TT) windows are a type of thermochromic (TC) glazing that features 16 reversible transmission behaviour in response to heat.…”

mentioning

confidence: 99%

“…It was found that in a warm climate with a low 7 transition temperature and sharp hysteresis gradient, energy demand can be reduced by up 8 to 51% compared to conventional double glazing. 9 10 In the project presented here, a new type of thermotropic window has been developed 11 where the thermotropic layer is sandwiched as a membrane between two conventional 12 glazing panes. Made from hydroxypropyl cellulose (HPC), three concentrations of HPC 13 (2wt.%, 4wt.% and 6wt.%) were tested for solar and visible light transmittance and 14 reflectance using a spectrometer.…”

mentioning

confidence: 99%

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