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European Climate, Infrastructure and Environment Executive Agency


Pioneering glass facade brings buildings’ energy performance to another level of efficiency


EU law required all new buildings to be nearly zero-energy by the end of 2020. Delaying the uptake are transparent glass windows – a weak element in energy saving strategies.

Nearly zero-energy buildings (NZEBs) have very high energy performance and produce as much energy as they use over the course of a year. The introduction of new, disruptive building envelope systems that lead to significant cost reduction for multiple types of NZEBs in different climate zones will help the EU to reach its goal of decreasing energy consumption in buildings.

Façades cause considerable thermal fluctuations in fully glazed high-rise buildings. “While in winter the building suffers from heat loss through huge glass surfaces, the heat gain during summer is often intolerably high, as elevated room temperatures provide an environment that’s uncomfortable to live or work in,” explains Dieter Brüggemann, coordinator of the EU-funded InDeWaG project. “Additionally, the extensive use of air conditioning generates massive energy demand for modern buildings, and conventional solar control systems for shading limit the use of natural light.”

Maximum daylight use and interior comfort

The InDeWaG team developed a glass façade and glass interior wall system based on cost-efficient fluid flow glazing (FFG) elements that harvest solar energy. The glazing units use circulating water in the chamber between the glass panes to capture solar radiation and transport the generated heat through a pipe system that will be used for different purposes such as heating, preheating, drinking and personal hygiene. The whole façade acts as either a heating or cooling device because heated or cooled water circulates in the window’s glass chamber. “The energy consumption level complies with NZEB standards,” notes Brüggemann. “Significant cost reductions of at least 15 % for construction and installation will be achieved, thus accelerating the implementation of FFG technology in the market.”

Specifically, project partners developed a vertical-shaped FFG modular system, a circulator that allows fast flow rates of 8 litres per minute and per window, and a modular aluminium frame that encloses the glazing and the circulator. It can be used under various climatic conditions because of the different glazing variants and an intelligent monitoring and controlling system. “The technologies will keep the product attractive for architects and their vision of open space, as well as meet requirements for current and near-future offices,” comments Brüggemann.

Using the system as a basis, the team members designed and built an experimental pavilion with a floor surface of about 50 m² at the Bulgarian Academy of Sciences in Sofia. They installed water flow glazing elements on several façades and interior walls used for additional radiant heating and cooling. 

Building energy demand goes way down

Architects don’t need undesirable sun-shading devices since all daylight enters indoor spaces without any overheating issues because of solar radiation. In addition, the increase in natural light boosts comfort and reduces the need for artificial lighting. Furthermore, by repelling solar energy, the system helps to significantly decrease the demand for cooling and ventilation.

“By contributing to ambient environmental conditions inside buildings, InDeWaG enables building owners to reduce energy demand for heating, ventilation, air conditioning and lighting,” concludes Brüggemann. “The market is ripe for the large-scale production of an FFG modular system to equip office buildings, amongst other structures.”

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