InDeWaG is the acronym of title "Industrial Development of Water Flow Glazing Systems" - Innovation action project funded under Horizon 2020, a Public Private Partnership on "BUILDINGS DESIGN FOR NEW HIGHLY ENERGY PERFORMING BUILDINGS". Support for innovation is provided to actions where partners focus together and join forces to remove existing barriers through market uptake measures in order to build capacity and provide support for sustainable energy policy implementation. Their mission is to foster sustainable energy investments and the uptake of technologies relevant to energy efficiency in buildings.

InDeWaG establish new technical knowledge and explore the concept of a new improved technology and product. Demonstration activity will show technical feasibility in a near to operational environment. InDeWag project introduce a new, disruptive building envelope system which has at least 15% building cost reduction potential and could be brought to industrial ripeness. The unique approach of InDeWaG is to enable maximum use of daylight by a transparent glass façade and at the same time meet nZEB performance. The consortium will undertake a quantitative analysis of different "modular" approaches: the active fluid flow glazing will combine water as heat transfer media with compressed air and solar-thermal energy conversion with BIPV (Building Integrated Photovoltaic), to enable the optimal ZEB performance for a multitude of building types in different climates.


The ambition of InDeWaG project is to bring to industrial ripeness a façade and interior wall system based on radiant heating and cooling glass surfaces made from water and/or air flow glazing, abbreviated as WFG and AFG, which harvests solar energy for various use at large scale. Such building elements will be made ready for commercial application in the building sector and will be designed to become easy adoptable for 21st century façade and overall building technology, especially for cost effective ZEB technology with increased daylight use, variable ventilation and individual control comfort. The benefits of fluid flow glazing façade technology were proven over the past 8 years on the level of few demonstrator projects, but there are still many difficulties for the right practical implementation.

The concept for extending the State of Art in water flow glass façade systems is oriented towards a system that will be able to satisfy the cooling requirements and the hot water needs for a whole building. This is achieved through the integration of a series of transparent, translucent or opaque solar thermal absorbers which operate at different nominal temperatures, namely 30ºC for heating and seasonal energy storage, 60ºC for sanitary hot water supply and 90ºC for cooling through absorption chillers. In this way, a complete glass curtain wall façade will be able to deliver all the levels of thermal energy required by a building while retaining its architectural aesthetics. In addition, implementation of radiant surfaces inside the building will be investigated by building simulation with IDA ICE and TRNSYS. The components will be tested in Demonstrators situated in two different climate zones - Bulgaria and Spain.

A proven design method, a tested and certified façade system unit, application possibilities and a focused market analysis are crucial for the fast market uptake of the Fluid Flow Glazing. The industrial development of this exciting façade technology is the main goal of InDeWaG consortium, enabling an important step forward towards achieving nZEB standard /stated by the 2020 EU policy in the Directive 31 from May 19th 2010/.



The main objective of InDeWaG is to develop an industrial technology for fabrication of cost affordable general-purpose Fluid Flow Glazing façade elements, which give maximum daylight utilization and maximum interior comfort at energy consumption level of nZEB. In addition, also interior radiant elements will be developed. This technical development is accompanied by the development of an open access software tool for design of buildings with this new type of façade and interior radiant cooling and heating elements.

The cost reduction of at least 15% is achieved by following the LowExergy9 principle and adjustment of the temperature difference between the exterior environment and the interior to a minimum value which is relevant for significant reduction of HVAC energy demand and lighting energy consumption.

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InDeWaG News

It's done!


Fluid Flow Glazing elements are up and running since several days; Additional works on the demonstrational pavilion in Sofia had come to an end.

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Ease and Comfort


While the construction faces some problems with the northern façade, the interior of the demonstrational pavilion takes shape.

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More Than Just Façade


The Fluid Flow Glazing elements finally have been installed into InDeWaG’s demonstrational pavilion.

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A perfect Frame


While the framing elements for the fluid flow glazing arrives at the contruction site, the demonstrational pavilion takes shape.

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On the Radio


Associate Prof. Miglena Nikolaeva-Dimitrova gave an interview to the Bulgarian National Radio about InDeWaG technology and the construction of the demonstrational pavilion in Sofia

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Made of Steel!


Today, we started the assembly of the steel construction for the demonstrational pavilion on-site.

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The Arrival


The shipment of the Fluid Flow Glazing elements for InDeWaG’s demonstrational pavilion in Sofia finally reached their destination at the premise of the Bulgarian Academy of Science.

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On The Road


This afternoon, the shipment of the Fluid Flow Glazing elements for InDeWaG’s demonstrational pavilion in Sofia left the glazing factory of project partner Cerviglas.

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European Conference of Renewable Energy Systems 2019


InDeWaG is proud to announce its participation on this year’s European Conference of Renewable Energy Systems (ECRES). The upcoming event marks the seventh recurrence of this conference and will be held on 10-12 June 2019 Puerta de Toledo Campus Universidad Carlos III de Madrid, Spain. The purpose of the ECRES is to bring together researchers, engineers and natural scientists from all over the world, interested in the advances of all branches of renewable energy systems. Wind, solar, hydrogen, hydro-, geothermal, solar concentrating, fuel cell, energy harvesting, and other energy-related topics are welcome.

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The Construction of the Demonstrational Pavilion with Fluid Flow Glazing Façades started in Sofia.


The construction of the demonstrational pavilion started in the campus of "Scientific Complex 2" at Bulgarian Academy of Science (BAS). Central Laboratory of Solar Energy and New Energy Sources is one of the ten partner organizations working on this project. The project is financed under the Horizon 2020 Programme for research and innovation.

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New Generation NZEB - Demonstrational Pavilion with Fluid Flow Glazing and Roof Mounted PV System

The demonstrational Pavilion, which will be built at the Scientific Campus II of the Bulgarian Academy of Sciences in Sofia, Bulgaria, is designed to achieve the Bulgarian nearly Zero Energy Building (nZEB) standard. It consists of:

  • Glass envelope - Water Flow Glazing (WFG) modules on three façades
  • Roof-mounted 4.8 kWp photovoltaic system

To simulate processes in the Pavilion, the IDA ICE software was used, which has the functionality to model sophisticated simulation applications to study the indoor climate as well as the energy consumption of the entire building. In order to enable the simulation of dynamical physical changes within the WFG façade, the software was enhanced by integrating a specific tool developed as part of InDeWaG project. The simulations were made with different combinations of glass type and position of the argon and water chambers corresponding to the three types of WFG modular units so called iThermGlass, HeatGlass and CoolGlass. The highest annual monthly average Water Heat Gain and lowest annual monthly average Internal Heat Flux are obtained for HeatGlass, which makes this module type the best choice for the local climate conditions. To estimate the effect of using WFG modules another simulation was prepared in which WFG modules are replaced by standard triple glazing windows.

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Investigation of Thermal Behaviour of Innovative Fluid Flow Glazing Modular Unit

Energy consumption in buildings is approximately one third of the total energy consumption. In modern architecture, the area of the glazing is getting bigger and bigger, and this leads to an increasing influence of the windows on energy efficiency of the buildings. A huge amount of electricity is consumed to provide a comfort room temperature through air conditioning. Instead of this advance glazing technologies and materials can be used to reduce buildings energy demands and improve indoor environment.

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InDeWaG Demonstrational Pavilion in Sofia, Bulgaria

InDeWaG project aims at bringing the water flow glazing (WFG) technology into industrial ripeness. One of the main milestones towards that goal is the construction of a pavilion with façades consisting of WFG elements. For that purpose InDeWaG partners have designed a pavilion that will serve as demonstrator for this new technology. It is shaped like a glass box with a square plan measuring 7.24 meters by 7.24 meters. The glass envelope is composed of WFG modules on the East, West and South façade, while the North façade will be opaque. The roof, floor and north façade are well insulated and will contribute to the low energy requirements of the pavilion, which is designed to achieve nearly zero energy building standard according to the Bulgarian legislation. The transparent façade elements are with a due East, West or South orientation at 3.00 m height from the floor to the ceiling.

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InDeWaG Mock-up

The approach of InDeWaG project is to enable maximum use of daylight by a transparent glass façade and at the same time meet nearly zero energy performance. The main objective of the Spanish demonstrator is to validate the strategy of "energy rejection" through a CoolGlass envelope in order to achieve nZEB. CoolGlass is a triple glazing using highly reflective coating (Xtreme 60.28) deposited on the inner surface of the outermost glass pane aiming at minimizing the energy absorption. The concept of CoolGlass is to eliminate internal heat loads by circulating cool water through the water chamber facing indoors. This cool isothermal envelope allows insulating the building from outer climate conditions.

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In an interview, published by El Media, architect Dimitar Paskalev (Architectonika) gave an insight about the innovative technology of fluid flow glazing and its application in façade building. He states that the enormous effect of this technology is reducing the energy consumption in a high-rise and office buildings, where maximum daylight utilization is ensured through the glass façade. He explained that Architectonika, along with organizations from Bulgaria, Germany and Spain participate in a Public-Private Partnership under the Horizon 2020 Programme. The EU funded project is InDeWaG, and a Demonstration pavilion with the innovative water flow glazing façade will be set-up in Bulgaria.

The article is available only in Bulgarian HERE.