Water-filled glazing promises huge energy savings

A heating system using water-filled glazing could offer huge energy savings over more traditional approaches, according to the academic who devised the concept.

Loughborough University’s Dr Matyas Gutai says the system offers energy savings of up to 72% when compared to buildings with conventional heating and double glazing.

Gutai, who has been studying water-filled glass for a decade and has created two ‘water houses’ in Hungary and Tokyo, has developed the system using water to heat and cool structures.

The water-filled glass (WFG) system works by 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– which can either be in the foundations or placed somewhere in the
building. The heat is stored in the tank and, if the temperature drops, it can
be brought back to the walls to reheat the building using a monitoring system
similar to central heating. Alternatively, the stored heat can be used for hot
water supply.

Dr Gutai’s latest study, published in Elsevier’s Energy and Buildings Journal in collaboration with Dr Abolfazl Kheybari, of the University of Kaiserslautern, demonstrates how WFG can “revolutionise” building design and performance when used as part of a wider heating system.

Dr Gutai’s inspiration came from the fact that the insulation
capacity of windows is considerably worse than a normal wall surface and small
changes can lead to up to 25% energy savings for the whole building. He 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 people warm.

His latest research claimed that water-filled glass 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.

He is now looking to develop the product commercially.

Other claimed benefits include improved acoustics, less need
of ‘shading’, and no need to colour the glass to improve energy efficiency.

Dr Gutai said: “Glass is currently a liability in buildings
as it compromises energy consumption, thermal comfort, acoustics and other
aspects.

“WFG changes this paradigm and turns glass into an
opportunity for sustainable construction.

“It shows us that thinking holistically about buildings and
building components leads to a more efficient and sustainable built
environment.

“In case of a window for example, if we see it as an
isolated system, solar overheating is a challenge that needs to be remedied
with cooling.

“If we approach this holistically, the heat surplus is an
opportunity because the same heat is missing from somewhere else (i.e. colder
part of the building or hot water supply).”