Scientists develop energy efficient ‘liquid window’

Scientists at the Nanyang Technological University, one of Singapore’s leading engineering research institutes, have developed a unique liquid window panel. It can block sunlight to regulate solar transmission into a room while simultaneously trapping thermal heat. This can be released through the day and night, helping to reduce energy consumption in buildings. 

Large parts of the world set to undergo rapid urbanisation over the next 20-30 years and the United Nations released a report in 2009 that stated that buildings are responsible for 40% of global energy consumption, and windows account for up to 50% of that energy being lost. 

Countries today face the challenge of reviving the construction sector to strengthen public infrastructure. At the same time, they also have to keep in mind their global commitments to reduce carbon footprints. Experts suggest that adopting energy-efficient technologies to construct and utilise buildings is one of best ways forward to achieve this twin goal. 


The researchers developed this ‘smart window’ by placing hydrogel-based liquid within glass panels. They found that it can reduce up to 45 per cent of energy consumption in buildings in simulations, compared to traditional glass windows. It is also around 30 per cent more energy efficient than commercially available low-emissivity (energy-efficient) glass, while being cheaper to make. 

A composite photo showing the window in the before (cool) and after (hot) state. Image Credit: Nanyang Technological University.

Moreover, thanks to the high heat capacity of water, a huge amount of thermal energy can be preserved instead of being transmitted into the building through the glass during the hot daytime. This heat will then be slowly cooled and discharged at night-time. 

Impact on energy usage 

The team who tested the window also determined when the highest value of preserved thermal energy of the day took place. In the regular glass window, this “temperature peak” was 12 pm, but was shifted to 2 pm in the smart liquid window.  

If this shift in temperature peak is translated to a shift in the time that a building needs to consume electricity to warm or cool the building, it should lead to lower energy tariff charges for users. Soundproof tests also showed that the Smart Window decreased noise by 15% more effectively than double glazed windows when compared.  

The research team is now looking to collaborate with industry partners to commercialise the smart window.