Energy modelling studies of thermochromic glazing

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

“…16 The metal-insulator transition can be influenced by a variety of external parameters, and recent work have considered the effects of strain [17][18][19] and lattice misfit with the substrate, 20,21 electric field or current activation, [22][23][24][25][26][27][28][29][30][31] light irradiation, [32][33][34][35][36][37][38] ion bombardment, 39,40 and gaseous ambience. 41 Considering the wealth of possibilities to modulate the properties of VO 2 -based thin films, it is not surprising that they are discussed for a vast number of applications such as thermochromic "smart" windows for energy efficient buildings, [42][43][44][45][46][47][48][49][50] variable-thermal-emittance surfaces for thermal radiation control, 51 oscillators and switches in (opto)electronics, 25,26,34,52,53 transistors of different types, 30,54,55 microcantilevers, 56,...…”

Durability of thermochromic VO2 thin films under heating and humidity: Effect of Al oxide top coatings

“…The as-deposited film shows clear thermochromism and, in particular, the infrared transmittance at λ > 700 nm is much higher at room temperature than at 100 °C. Data of this kind have been shown many times before [2][3][4][5][6][7][8][9]. Heat treated films display very different optical properties with increased transmittance, except at room temperature and λ > 1600 nm, and no trace of thermochromism.…”

“…These properties imply that, in principle, thin films of VO 2 are of interest for energy-efficient glazings and are able to admit solar energy at low temperature in order to provide indoor heating, whereas the same film can reject solar energy at high temperature and thus avoid excessive air conditioning. TC fenestration has been discussed for several decades [2][3][4][5][6][7][8][9][10], but practical implementation has been hampered by performance deficiencies such as a too high value of τ c , too large luminous absorptance, and too small modulation of the solar energy throughput [11]. However, there has been substantial progress towards the alleviation of all of these obstacles, and it is well known that tungsten doping can decrease τ c to room temperature [11,12], that luminous absorptance can be lowered by magnesium doping [13][14][15][16], and that solar energy modulation can be boosted by invoking VO 2 -based nanoparticles rather than thin films [16][17][18].…”

Thermochromic undoped and Mg-doped VO2 thin films and nanoparticles: Optical properties and performance limits for energy efficient windows

“…The potential energy saving can be high, especially in warm climates. [20][21][22] However VO 2 needs a number of modifications in order to be useful in practical windows-related applications: thus τ c should be lowered to room temperature, and T lum as well as ΔT sol should be enhanced. 7 Doping is a well-established way to decrease τ c , 23 with tungsten as the superior dopant capable of reducing τ c by as much as ~25 °C/at.% W for well-crystallized films, made by a variety of techniques, 7 without severely deteriorating the optical performance.…”