Looking for a way to lower the energy demands of a house or building is of significant importance, especially now with the climate crisis going on. Using less electricity reduces carbon emissions, and it also lowers the cost of power bills. A new approach Dr. Matyas Guai from Loughborough University, focused on making windows more energy-efficient since they are one of the least energy-efficient features of a building.
The British scientist created a ‘water-filled glass’ (WFG) system where all the windows of a house are filled with water. The water is used to heat and cool structures passively. Simulations show that it saves up to 61% more energy than buildings fitted with heating systems and triple glass and up to 72% more than ones equipped with heating systems and double glass. Furthermore, it can save energy in all climate types.
The problem with windows is that they allow heat to escape during cold weather and heat to enter when the sun is blazing hot. Meaning a building’s furnace has to run more during the winter while air conditioning has to kick in more frequently during the summer. This constant heating and cooling result in carbon emissions, and it’s expensive. The less it has to happen, the better and improving windows are critical.
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).
WFG involves two sheets of glass with water trapped in between. The water is nearly invisible. When the sunlight hits the glass, it heats the water. Therefore, the water absorbs the heat, and the room stays cool. When the sun-warmed water gets to a specific temperature, the system kicks in and pumps the water out of the window through a pipe to a storage tank. Colder water then takes its place. The amount of electricity needed to pump the water in and out is minimal compared to how much energy would have been required to keep the room cool with air conditioning. Then, when its cold outside, the heated water can be pumped out of the tank to fill the pipes and radiate heat through the walls.
Some additional benefits include no need for external shades (louvers) or tinting of the windows. Also, the water is a fantastic sound blocker. Windows aren’t very good at blocking sound out typically.
Dr. Gutai has built two prototype buildings already – one in Taiwan and the other in Hungary. Along with simulations, these buildings highlight that it’s better to focus on improving solar absorption of glass technologies rather than insulation.
