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.

About Vision News Events Partners Internal

InDeWaG News

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.

SPECIAL SESSION 7: Achieving nearly Zero Energy Buildings with Water Flow Glazing facades

During the last two decades, all international initiatives have been aimed at reducing energy consumption as well as diminishing global warming. Energy consumption in buildings represents, worldwide, approximately one third of the total energy consumption. This percentage varies depending on the location and the systems used, such as building enclosure, where glazing has strengthened its position as an essential construction material in low energy buildings. This session focuses on Water Flow Glazing façades as an active solution for achieving nearly zero energy consumption in buildings with maximum functionality and aesthetic benefits. Water Flow Glazing façades strategically take advantage of the energy exchange between indoors and outdoors, allowing energy harvesting or energy rejection strategies. Water Flow Glazing envelopes are able to adapt to the building usage as well as the climatic conditions of its environment to achieve maximum energy efficiency together with high levels of comfort for its users.

In cooperation with researchers from the City University of Hong Kong, Partners from InDeWaG have prepared a special session on Water Flow Glazings. With Prof. Tin-Tai CHOW, a pioneer on the field of water flow glazings systems, we have been able to allure a researcher of high standing for an exchange of knowledge, experience, results not only with our own experts. Building energy experts, civil engineers, architects, researchers but also stakeholders from the industrial and public sector are invited to discuss recent works on water flow glazing facades.

Scope of the session:

  • Theoretical heat and fluid flow analysis in water flow glazing (WFG)
  • WFG materials selection and optical properties
  • Solar engineering, energy storage and services system integration
  • WFG product and system design optimization
  • Architectural design, prefabrication and site installation matters
  • Long-term reliability and life-cycle analysis
  • Operation, maintenance, and services management
  • Industrial applications and demonstration projects
  • Social and technological barriers on WFG applications


In six presentations, scientists from InDeWaG will highlight selected aspects from our reset research:

Software tool for the design of water flow glazing envelopes, J. A. Hernandez (UPM), B. Moreno (UPM)

Water flow glazing facades are considered active envelopes able to react or to adapt to the external and internal conditions of the building. The use of the building, the orientation of the facade and the location of the project are relevant inputs to determine the glazing composition as well as the energy strategy involved in the facade. A proper design of the glazing composition and the energy strategy will allow huge energy savings in the whole project.

To achieve this goal, a software tool has been developed to allow the design of a water flow glazing facade. The software tool is an open software code with a graphical user interface. It comprises (i) energy balance considerations associated to potential sun energy for specific locations, (ii) spectral properties of the glazing based on the selection of different glass layers or coatings, (iii) thermal performances of the glazing module based on the absorption properties and (iv) a thermal simulator of zones including insulated opaque facades and water flow glazing facades.

The main result of this work is a software tool to allow project engineers to design water flow glazing facades. Understanding active facades as transparent thermal collectors are carried out by thermal simulation movies. This tool allows the project engineer to determine the water heat gain during the whole year. Besides the graphical user interface, this work constitutes a complete library to simulate water flow glazing envelopes written in modern FORTRAN. This library has a documented application program interface that allows developers to integrate water flow glazing envelopes in existing energy simulators for buildings.

Link to full paper:

Commissioning process of water flow glazing facades, D. Garcia (UPM), B. Moreno (UPM), J. A. Hernandez (UPM)

The objective of commissioning is to provide documented confirmation that a facility fulfils functional and performance requirements. Commissioning recognizes the integrated nature of water flow glazing systems performance. Commissioning is carried out to prove that systems operate and perform to the design intent and specification.

To reach this goal, it is necessary for the commissioning process to establish and document project requirements, performance specifications, and system functions. It is important to verify and document compliance with these criteria throughout the design, proof of concept, construction, and the initial period of operation. The commissioning process works in conjunction with the project design team through the design stage and the construction stage. It prepares a commissioning plan and final commissioning results.

The main results of this work are the elaboration of detailed checklists for the design and the construction stages to assure that the water flow glazing facade is properly installed, started and checked out. During the installation, various tests are undertaken known as static testing. Upon completion of static testing, dynamic testing is undertaken. Generally, during the integration process, some equipment of the primary circuit is inoperative. Hence, emulation or simulation of specific equipment is needed to prove that the water flow glazing facade operates in accordance with specifications. In this work, functional tests are established to evaluate the thermal performance and operation of the equipment. Automation software and hardware platform are used to monitor thermal and comfort requirements and to expedite the commissioning process. The fulfilment of commissioning procedures for the project is recorded at the end of the construction phase.

Link to full paper:

Thickness dimensioning of water flow glazing facades, J. Escoto (UPM), B. Moreno (UPM), J. A. Hernandez (UPM)

The fluid inside water fluid glazing facades creates a linear distribution pressure along the vertical direction. Hence, the glazings must be designed to with stand pressure loads satisfying deflection and stresses requirements given by the norms and standards. The straightforward solution is to increase the glass thickness until the deflection is below the required limit. This implies an increase in weight and amount of material rising the price of the glazing, which is undesirable. Therefore, pillars or stripes can be considered as an alternative solution to limit glass deflection.

In order to ensure that the structural behaviour requirements are fulfilled, a proper mathematical model and simulation must be carried out. The elastic plate model must be sufficiently detailed to retain the most relevant physical aspects of the process but simple enough not to over dimension the problem. To solve the mathematical model it was necessary to apply a numerical method to the partial differential equations resultant. For this task, a High Order Finite Difference Method (HOFM) was implemented for both linear and non-linear models, which led to satisfactory results from the viewpoint of the accuracy of the solution.

From the development of the structural model and simulation for Water Flow Glazings thickness dimensioning two conclusions were extracted. First, the plate model was sufficient to dimension the glazings and second, the presence of pillars or stripes permits to reduce significantly the thickness dimension. Hence, introducing pillars or stripes is considered an effective solution to solve the hydrostatic pressure problem and lead to a more efficient design of Water Flow Glazings.

Automation Platform as an Advanced Energy Management System, M. A. Rapado (UPM), B. Moreno (UPM), J. A. Hernandez (UPM)

Nowadays high-rise buildings with Water Flow Glazing envelopes require the implementation of strategies based on advanced concept of energy management as well as predictive maintenance services. In order to cover these needs, a controlling and data-logging platform called AtenTTo has been developed.

This article treats the design and implementation of the AtenTTo. This Electronic Control Unit is hardware and software platform that comprises two PCB: (i) AtenTTo core, which is the brain of the system, and (ii) AtenTTo multipurpose in which the brain is plugged allowing connecting specific sensors and actuators. To facilitate AtenTTo integration, the design of the multipurpose platform adjusts to the size of a standard DIN rail box. Furthermore, and in order to facilitate the user to program the system, AtenTTo software allows configuring the system with code-less programming.

The result is a multipurpose, versatile Printed Circuit Board integrated in a standard DIN rail box for monitoring and controlling buildings. The platforms provides a graphic interface that allows programming any energy strategy considering different parameters such as, outdoor climate, HVAC system, passive material influences and user behaviour.

Industrialization of Water Flow Glazing facades by means of modular units, B. Moreno (UPM), J. A. Hernandez (UPM)

Water Flow Glazing façade is a new and disruptive technology based on variable heating/ cooling glazed modules, which enables cost efficient nZEB with glass façade. These modules allow getting maximum transparency for full utilization of daylight in buildings while achieving savings on lighting and thermal energy for nZEB. The industrialization of Water Flow Glazing facades through modular units aims to reduce the complexity of the system encapsulating the components. Hence, cost reduction potentials in building construction are also evaluated.

This article treats a full description of the Water Flow Glazing modular unit, based on its three main elements: glazing, circulator, and aluminium frame. The glazing comprises different layers and interfaces according to determined spectral and thermal properties. The circulator is a key element that allows the circulation of water inside the glazing chamber in a closed circuit, exchanging the temperature between indoors and outdoors. Finally, the aluminium frame that encloses the secondary circuit is a frame-in-frame system, which provides the structural stability and easy installation. The result is an active plug-in WFG modular unit, easy to install and operate. Each module is connected to the cloud through a wireless sensor, in charge of monitoring and controlling the main variables and parameters. The dimension of the module is configurable according to the architectural project.

Link to full paper:

Building Energy Modelling by means of BIM software. A case study with Water Flow Glazing, F. Del Ama (SVC)

Building energy modelling is an inter-disciplinary area of research that involves, among others, concepts of electrical and software engineering, mechanical engineering and also, architecture. Building energy models are used at the design stage for the purpose of energy code compliance certification. The accuracy of results depends on how well the building model has been developed and calibrated. Most of the programs available in the market take into account occupancy pattern behaviour, thermal parameters of construction elements, HVAC and lighting systems. However, the impact of thermal mass and the influence of active energy management systems have not been accurately reported. This paper presents a review of significant modelling methodologies which have been developed and adopted to model the energy behaviour of buildings. A BIM-oriented methodology for building energy modelling will be presented. This research has included case studies to investigate the feasibility of modelling active systems, such as water flow glazing. Finally, the ability of transferring data among different software is also studied

Thermal performance of water-filled double-glazing system in China, W. Liu, T. T. Chow

Water-flow glazing is an innovative multi-glazing system with a purified water layer in the window cavity. With a submerged heat exchanger as one optional design, this is able to preheat feed water for domestic hot water services, and to reduce room heat gain/loss simultaneously. In this study, a dynamic simulation model was developed based on the finite-difference nodal scheme and the Perez tilted-surface solar radiation model. The appropriateness of the computational approach was verified by consecutive-day experimental measurements. The year-round energy performances in typical cities of China were then analysed, for example, with Hong Kong in the hot summer and warm winter zone and Kunming in the warm climate zone. The results show that the best vertical façade orientation in terms of accumulative solar irradiance and the useful water heat gain are within the south-to-west quadrant. The overall energy performance can be better in Kunming than in Hong Kong, in terms of reduced energy demands on HVAC and domestic hot water services

Modelling energy performance of water-filled double-glazing with submerged heat exchanger, T. T. Chow, W. Liu

Water-in-cavity multiple glazing system is a kind of transparent solar thermal collector on building façade. It incorporates the clean and inexhaustible low-grade energy, solar energy, in buildings. Water-filled double-glazing is a new design in water-in-cavity glazing technology. With a horizontal heat-transfer tubing dipped at the top end of the water layer in the window cavity, the absorbed solar heat is directly passed onto the feed water stream, for instance, for domestic hot water preheating. The technology has wide application potential in zero-energy buildings. This paper will report the development of both steady state and dynamic simulation models of this new design. The computation was through a self-developed FORTRAN program.

The calculation of the hourly room heat gain and water heat gain was conducted with daily, monthly, until the year-round calculation. The result analysis shows that this new design is much effective than the buoyant flow method. The key parameters are also discussed.