A demonstration project in Sofia, Bulgaria, is showcasing a water flow glazing (WFG) technology that utilizes water as a transparent insulator. Referred to as InDeWaG (Industrial Development of Water Flow Glazing Systems) and developed in Madrid, the project will demonstrate and test the efficiency of the system and its ability to maximize solar in varying temperatures during both winter and summer, as well as in very different climates. [Photo courtesy InDeWaG]
The project consists of a pavilion with three walls with panes that use the WFG. The remaining wall and the floors are insulated to help achieve nearly zero energy building standards (in accordance with Bulgarian legislation).
As explained in a Bulgarian article:
“Each pane has a continuous flow of distilled water and glycol. Inside each window, there is a constant flow of 70 litres of distilled water and 30 litres of ethylene glycol, which serves as antifreeze. Each transparent panel acts as an individual solar collector. Using solar cells, the windows absorb solar radiation and turn it into thermal energy to heat the building's interior.”
"The advantage of using liquids instead of air inside the glass is that water is denser, so it absorbs infrared light in a broader range,” says Miglena Nikolaeva-Dimitrova, a physicist at the Bulgarian Academy of Sciences.
The captured solar radiation can be used for heating, preheating, domestic hot water, storage or expenditure of excess energy. Depending on the temperature of the water in the glass chamber within the window, the pane may act as either a heating or cooling unit. Temperature and humidity will be monitored consistently inside of the building and data collection for the demonstration pavilion will continue for 10 years.
Researchers believe the technology is ready to go to market for smaller homes and buildings but are also eager to prove that it can work on larger buildings.