Buildings with windows filled with water rather than gas could save energy in most of the world, according to researchers backing the new technology.
Matyas Gutai at Loughborough University, UK, believes the traditional approach to windows has gone as far as it can to aid increasingly ambitious climate goals. Triple-glazed windows typically use a layer of argon gas between panes to limit heat transfer in or out, helping keep homes warm in colder conditions or cool in hotter weather.
Instead of this gas, Gutai and Abolfazl Kheybari at the University of Kaiserslautern, Germany, turned to water for its ability to absorb the heat from the sun. They made two small prototype buildings, one in Hungary and one in Taiwan, which sandwich slowly pumped water between glass panes. Once warmed by the sun 鈥� a process called solar gain 鈥� the water is then used to produce hot water or for heating, saving energy.
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鈥淲hat if the glass actually gives you the opportunity to link building components together, to achieve an even higher energy efficiency? That gives a completely different paradigm in the built environment,鈥� says Gutai. He claims the water flows slowly enough to make it effectively transparent and invisible, which photos appear to back up.
Better than triple-glazing
With data from the prototypes, the researchers used two computer programs to simulate how much energy the windows would save in 13 towns and cities, including Beijing and New York, chosen to represent the world鈥檚 main climatic regions. They outperformed conventional glazing in all but the chilly climate of the Falkland Islands in the south Atlantic.
Looking at the building鈥檚 total electricity and space-heating demand, the simulation showed energy use in buildings with the water windows was 54 to 72 per cent below that of buildings with double-glazing, and 34 to 61 per cent below that of those with triple-glazing. The comparisons were with conventional windows meeting high German standards.
One reason for the energy savings is that the water-filled windows not only capture heat, but give you the opportunity to use that heat later. 鈥淭hat鈥檚 what makes a massive difference in the energy bill,鈥� says Gutai.
The architect envisages the water circulating in a closed system, requiring relatively little to initially fill it. He hopes to launch a spin-off company selling water windows for conservatories next year. Researchers in and are also exploring the idea.
There are still question marks over the technology. 鈥淚t is not easy to build such structures,鈥� he says. Whether water windows can compete on cost remains to be seen, though Gutai argues they will be competitive. The energy comparisons were also made for a full glass fa莽ade, so may not be borne out in buildings in the real world. Consumers may also worry about leaks.
Alastair Mant at the UK Green Building Council welcomes the approach and says society needs to embrace buildings that look and operate differently. 鈥淲ater-filled glass may well have a role鈥� in helping meet future net-zero carbon building standards, he says.
Energy and Buildings
