International News
WATER-FILLED WINDOW
SOLUTIONS
FOR HEATING AND COOLING
By Loughborough University, UK
new study reveals water-filled windows could make a
A significant difference in both energy savings and reducing
global carbon emissions.
It is now common knowledge that heating and cooling
buildings is not only expensive, but a massive contributor in the
resulting carbon emissions.
According to the UK Green Building Council and various
studies, the built environment contributes approximately 40% of
the UK’s total carbon footprint – with heating alone contributing
to 10% of the total.
To address this issue, Dr Matyas Gutai of the School of
Architecture, Building and Civil Engineering, notes that we need
to turn our attention to improving windows. Though the area
they occupy may be small on a building, their insulation capacity
is much worse than a normal wall surface, and small changes can
lead to up to 25% energy savings for the whole building.
The academic says he has found a material that can save
more energy than current technologies on the market – including
double and triple glazing: Water.
Dr Gutai has been researching the concept for over a decade
and his latest study, published in Elsevier's Energy and Buildings
Journal in collaboration with Dr Abolfazl Kheybari, of the
University of Kaiserslautern, demonstrates how ‘water-filled glass’
(WFG) can revolutionise building design and performance when
used as part of a wider heating system.
The research reveals that WFG systems perform well in any
inhabited climate – keeping buildings in hot climates cool, and
buildings in cool settings warm – without requiring an additional
energy supply, highlighting the technology’s potential to make a
real splash when it comes to reducing carbon emissions.
WHAT IS WATER-FILLED GLASS?
WFG involves a sheet of water being trapped between a panel of
glass, and the water is practically invisible.
Dr Gutai developed the concept while studying for a PhD at
the University of Tokyo after being inspired by Japanese outdoor
baths – known as ‘rotenburo’ – which are used also during the
winter as the water’s thermal properties keep us warm.
All images by Dr Matyas Gutai
One of the original two prototype buildings – this one in Hungary.
The Water House prototype building that was constructed in Taiwan.
Dr Gutai developed the idea into a working design and then
created two prototype buildings in different climates – in Hungary
and Taiwan – that use WFG as part of a larger mechanical system.
The WFG 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. This system allows the ‘Water
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; this warm water is then circulated to the storage tank–
Continued on page 9
www.hvacronline.co.za RACA Journal I September 2020 7