A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Mitigation of hysteresis due to a pseudo-photochromic effect in thermochromic smart window coatings
The aim of thermochromic window coatings is to reduce the energy consumption in the built environment by passively switching between a high solar transmitting state at low temperatures and low solar transmitting state at high temperatures. Previous studies have highlighted the negative impact of phase transition hysteresis on the performance of refection based thermochromic flms. However in the literature, the best reported results have depended on vanadium dioxide nanoparticle composites and anti-refective structures that modulate light via changes in absorption rather than refection. In light of these factors, this work aims to demonstrate theoretically, how the efects of phase transition hysteresis and gradient difer between absorbing and non-absorbing thermochromic flms. To quantify and compare the performance of flms with diferent transition characteristics, we defne a metric based on the varying net energy fux through the window over the course of a year, including thermal energy re-radiated into the building from the flm. Specifcally, and importantly for the feld, we demonstrate that a pseudo-photochromic efect in absorbing thermochromic flms mitigates the detrimental efects of phase transition hysteresis and gradient that have been reported for refection based thermochromic flms. We fnd that for moderate hysteresis widths of 15°C, the performance of the non-absorbing case drops to ~60% of its initial value whilst the performance of the absorbing flm only drops to ~95%. As a result we fnd that the absorbing case outperforms the nonabsorbing case when hysteresis widths are greater than 8°C.
Mitigation of hysteresis due to a pseudo-photochromic effect in thermochromic smart window coatings
The aim of thermochromic window coatings is to reduce the energy consumption in the built environment by passively switching between a high solar transmitting state at low temperatures and low solar transmitting state at high temperatures. Previous studies have highlighted the negative impact of phase transition hysteresis on the performance of refection based thermochromic flms. However in the literature, the best reported results have depended on vanadium dioxide nanoparticle composites and anti-refective structures that modulate light via changes in absorption rather than refection. In light of these factors, this work aims to demonstrate theoretically, how the efects of phase transition hysteresis and gradient difer between absorbing and non-absorbing thermochromic flms. To quantify and compare the performance of flms with diferent transition characteristics, we defne a metric based on the varying net energy fux through the window over the course of a year, including thermal energy re-radiated into the building from the flm. Specifcally, and importantly for the feld, we demonstrate that a pseudo-photochromic efect in absorbing thermochromic flms mitigates the detrimental efects of phase transition hysteresis and gradient that have been reported for refection based thermochromic flms. We fnd that for moderate hysteresis widths of 15°C, the performance of the non-absorbing case drops to ~60% of its initial value whilst the performance of the absorbing flm only drops to ~95%. As a result we fnd that the absorbing case outperforms the nonabsorbing case when hysteresis widths are greater than 8°C.
Mitigation of hysteresis due to a pseudo-photochromic effect in thermochromic smart window coatings
Sol, CWO (author) / Schläfer, J (author) / Parkin, I (author) / Papakonstantinou, I (author)
2018-09-05
Scientific Reports , 8 , Article 13249. (2018)
Article (Journal)
Electronic Resource
English
DDC:
690
Optimization of Thermochromic Coatings for Smart Window Applications
| Springer Verlag | 2024
MATERIAL HAVING THERMOCHROMIC EFFECT AND PREPARATION METHOD THEREFOR, AND THERMOCHROMIC SMART WINDOW
| European Patent Office | 2021
| European Patent Office | 2018
| European Patent Office | 2016
| European Patent Office | 2024