Regulating indoor temperature with water-filled windows

Dr Matyas Gutai of Loughborough University in the UK developed water-filled glass, which can be used to heat and cool structures, reducing energy used and carbon emissions.

Heating and cooling building generates massive carbon emissions. Heating alone amounts for 10% of the UK’s total carbon footprint.

Though windows cover relatively little of a building’s surface, their insulation capacity is much worse than a normal wall surface. Small changes can lead up to 25% energy savings for the whole building.

The insulating properties of glass have already improved with double or triple glazing, but Gutai discovered that water-filled glass (WFG) can save even more energy. WFG consists of a sheet of water trapped between two panels of glass. The water is practically invisible. The system works in any environment, keeping buildings cool in hot climates and warm in cold ones, without an additional energy supply.

Gutai designed two prototypes of buildings in different climates, in Hungary and Taiwan, that use WFG as part of a larger mechanical system. The water-filled panels are attached to a storage tank through pipes hidden in the wall, so that the water can circulate between the two.

When it is warm, the building stays cool as the water absorbs external and internal heat. The warm water is then circulated to the storage tank. The water is stored there, and when the temperature drops, it can be brought back to the walls to reheat the building. Alternatively, the stored heat can be used for hot water supply.

The process saves energy because water absorption and pumping take much less energy than heating and cooling systems. Compared to double glass, the system saves 47-72% energy and compared to triple 34-61%.

In addition to the heating and cooling, the panels also improves acoustics and has aesthetic benefits. The system can also be combined with a heat pump.

Photos: Longborough University