water-filled windows
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Water-filled windows make a splash

Loughborough University’s Dr Matyas Gutai has developed a system that can allegedly save up to 72 per cent more energy than buildings fitted with traditional heating systems and double glass.

The material he uses? Water.

“Water-filled glass” (WFG) involves a sheet of water being trapped between a panel of glass. Gutai has been researching the concept for over a decade. His latest study, written with Dr Abolfazl Kheybari from the University of Kaiserslautern, demonstrates how water-filled glass can revolutionise building design and performance when used as part of a wider heating system.

According to Every Building Counts, buildings account for over 50 per cent of electricity use in Australia and almost a quarter of its emissions.

Gutai says we need to focus on improving windows.

Windows have a worse insulation capacity than a normal wall. Even though they occupy a smaller surface, making small changes can save up to 25 per cent in energy for the whole building.

Gutai created the concept of water-filled glass while studying for a PhD at the University of Tokyo, after being inspired by Japanese outdoor baths.

He developed the idea into a working design, and created two prototype buildings in different climates that use WFG as part of a larger mechanical system.

The system involves connecting the water-filled window panels to a storage tank using pipes hidden in the walls, so fluid can circulate between the two. It allows the houses to cool and reheat themselves, without needing an additional energy supply for most of the year.

When it is warm, the buildings stay cool as the water absorbs external and internal heat. The warm water is circulated to a storage tank, and can be circulated back to the walls to reheat the building if the temperature drops. Alternatively, the stored heat can be used for hot water supply.

Gutai says a heat surplus in one building can easily benefit another.

“Energy exchange is not a zero-sum game,” he says.

“For example, if you connect rooms facing north and south to exchange heat, everybody wins, while today one is heated and the other is cooled. The same principle works on a larger scale.”

The process saves energy because because water absorption and pumping take much less energy than heating, ventilation, and air conditioning systems.

Gutai says the significance of WFG is proving that this approach works globally, and that hybrid constructions like water-filled glass can make it possible.

For more information please click here, or visit this page to read Gutai’s paper.

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