During the second year of the project, the ENVISION consortium focused on the design, development and evaluation of the innovative key enabling technologies to be used for the implementation of the facade energy harvesting solutions for both the opaque and the transparent part of the building envelope.

The Akzo Nobel team has developed a coating technology that enables the absorption of solar heat, even for light colors.

The heat absorbing technology has shown to be robust and is forecasted to be durable.

TNO and Pilkington have been working on esthetical colored interference coatings for covered thermal collectors. The approach was to reduce the costs of the coating by reducing the numbers of layers in the colored system and to investigate whether sol-gel processing compared to magnetron sputtering is a cheaper and better alternative for the production of these coatings. The colors tomato red, signal blue and yellow green were selected. Based on the input data for the three colors a number and thicknesses of high (TiO2) and low (SiO2) refractive index layers were calculated as a function of angle dependency. Based on the modelling results the colored coatings onto glass
substrates were prepared by magnetron sputtering and sol-gel processing. Both techniques have proven to fulfill the requirements in relationship to the hardness of the coating, even though the solgel coatings appear to be slightly better.

BGTEC developed the concept of an innovative window module provided with additional features that enable the harvesting of heat and the recirculation of heated air, thus supporting domestic hot water (DHW) production (in summer) and internal environment heating
(in winter). The proposed solution is based on integration of a NIR (Near Infrared Radiation) absorbing glass layer in a traditional triple
glazed unit, with the ventilated chamber enabling circulation of air. Two full scale prototypes have been assembled for monitoring purposes, while a first set of numerical activities (CFD) have been performed to provide a detailed simulation of the thermo-fluid-dynamic behaviour of the window. Prototyping and modelling activities performed so far enabled to investigate possible alternative solutions and eventual modifications before the final optimization of the system.

The Pilkington project team developed a variation of the Building-integrated photovoltaics (BIPV) technology Pilkington Sunplus™ BIPV, with a higher level of transparency, that provides power-generating, architectural glass solutions for both vertical and horizontal applications, allowing building proprietors and developers to turn buildings into power generating assets. A laminating process was developed for the incorporation of semi-transparent monocrystalline PV strings in laminated safety glass for use in windows starting from small scale lab experiments and finishing with plant trials in actual manufacturing sizes.

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