A new building envelope – increasing daylight and energy efficiency with water flow glazing

Abstract

ABSTRACTBuilding industry is still chasing the dream of fully transparent glass facades. However, available technologies of today show severe contradictions to the main purpose of such fully glazed facades: on the one side, the clear and unobstructed view from the inside into the outside environment, on the other side enabling maximum daylight autonomy to the building users. The main reason is the inevitable requirement of solar protection to avoid solar heat gains and consequently high cooling capacities in buildings. Solar coatings, tinted glass, switchable windows and classic interior and exterior sun shading devices all have the same general effect: The quality of the views to the outside is reduced, the amount of available daylight decreases. The European Union has funded the project InDeWaG (Industrial Development of Water Flow Glazing Systems) within the framework of the European research program HORIZON 2020. During the research period of three and a half years the international consortium incorporating research institutes, industry and designers is developing a new insulation glass unit. In the cavity of this unit a water‐glycol mixture is circulating. Due to the spectral properties of water, it captures most of the infrared solar radiation: it is transparent to visible wavelengths of the sunlight but opaque to NIR wavelengths. Consequently, water flow glazing has the same natural light transmission as conventional glazing whilst reducing the heat transfer towards the interior space. Moreover, the water circulation allows to use, store or dissipate the energy captured by absorption of the waterfilled cavity.