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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.
The reason why this process saves energy is because water
absorption and pumping take much less energy than traditional
heating, ventilation, and air conditioning (HVAC) systems.
The technology also has other benefits, including acoustics,
less need of ‘shading’ (methods used to avoid overheating and
the greenhouse effect), and there is no need to colour the glass to
improve energy efficiency, so it has aesthetic benefits too.
Dr Gutai has developed a more sophisticated version of the
system by adding a heat pump, which can heat and cool the water
depending on the season – and this is the system he examines in
the latest research paper.
KEY FINDINGS
Dr Gutai joined Loughborough University in 2017 and has
used data gathered on the two Water Houses to develop a
simulation system that can evaluate the energy performance of
such structures.
“The WFG system he has
developed uses water to heat and
cool structures in a bid to reduce
energy use and carbon emissions.”
His latest paper uses simulations to compare the performance
of the WFG system (with heat pump) against a typical building
heating system (windows paired with gas heating and air
conditioning).
For the study, Dr Gutai focused on the annual energy
consumption for a typical office space (17.5m 2 ) with one
glazed façade of equilateral orientation (south in the northern
hemisphere). He used the simulation to explore how this office with
a WFG system would fair in 13 cities from all major climate regions
– tropical, dry, temperate, continental and polar. The study reveals
that WFG systems can save energy in all inhabited climates.
For the traditional systems, Dr Gutai looked at the
performance of double glass window with low-e (a type of
radiation coating), and triple glass - which are filled with gas,
specifically argon gas, as opposed to a liquid.
The main findings of the study are:
• The WFG system is able to use the absorption of the water
effectively to improve the energy performance of glass.
• The water layer lowers the load for heating and cooling
effectively, minimising daily and seasonal peaks.
• The WFG system saves energy in all major inhabited regions
(every climate region except polar) with savings of:
º 47%-72% compared to double glass (with low-E) and
º 34%-61% compared to triple glass
The simulations also highlighted that current glass technologies
could lead to bigger energy savings if more focus was put on
improving solar absorption as opposed to insulation.
Of the research’s importance, 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)”.
Dr Gutai is now looking to develop this technology into
a product and is working with colleagues in academia and
enterprise to achieve this goal. He is also to build on the research
by comparing WFG with dynamic glazing, evaluating life-cycle
impact and simulating thermal comfort.
The entre research of Dr Gutai’s latest study, is titled ‘Energy
consumption of water-filled glass (WFG) hybrid building envelope’,
for more information. RACA
The waterfilled
glass
panel
prototypes.
Humid Equatorial Climate – No Dry Season
Humid Equatorial Climate – Short Dry Season
Humid Equatorial Climate – Long Dry Season
Dry Climate – Semi-Arid
Dry Climate – Arid
Humid Temperature Climate – No Dry Season
Dry Winter
Dry Summer
Humid Cold Climate – No Dry Season
Humid Cold Climate – Dry Winter
Cold Polar Climate – Tundra and Ice
Unclassified Highlands
www.hvacronline.co.za RACA Journal I September 2020 9