- Project plans
- Project activities
- Legislation and standards
- Industry context
- Specialist wikis
Last edited 17 Feb 2022
Smart window coating
The new glass has a spectrally tuneable low-emissivity coating that uses a phase change material to control the amount of heat that comes into the room from the window, without affecting the quality of the light.
The thermal energy from the sun's infrared rays is absorbed by the glass and re-emitted as heat – either used to warm the room using transparent electrical heaters in the glass, substrate or reflected away to cool the room.
Dr Nathan Youngblood, formerly at Oxford and now at the University of Pittsburgh, said: "These windows can change according to seasonal needs. They absorb near infrared-light from the sun in the winter and turn it into heat for the inside of a building. In the summer months, the sun can be reflected instead of absorbed."
Working as part of the Wearable and Flexible Technologies Collaboration (WAFT), the project team proposed the heat-activated coating that could 'switch' in line with heating, cooling, and lighting demands.
The team built a prototype with an active chalcogenide-based phase change material so the new glass can adapt to the temperature, to save energy. When it is cold, the infrared rays from the sunlight are harvested and transformed into building heat to cut heating costs. If it is warm, the new glass can switch state to reflect the heat and reduce the need for air conditioning.
"Importantly, visible light is transmitted almost identically in both states, so you wouldn't notice the change in the window," Dr Youngblood said. "That aesthetic consideration is critical for the adoption of green technologies."
In comparison, the low-emissivity glass or low-E glass used in today's double-glazed homes and offices is inert. A nano-thin metallic reflective coating reflects the UV and infrared waves in sunlight to reduce heat transfer through the glass. Although the principle of reflecting heat when temperatures are warmer and retaining room heat when it is colder outside is the same as the new technology, low-E glass is not as responsive, the University of Oxford claims.
The thermal and optical properties of current windows are ‘set’ into glass coating as part of the manufacturing process – so the only real adjustment for local climate conditions is the choice of coating. Glass with a higher reflectivity property or a solar control coating lets in noticeably less natural light and vice versa, the university asserts.
The researchers estimate that using windows fitted with the new prototype glass – including the energy required to control the film – would save 20 to 34% in energy usage annually compared to double-glazed windows typically found in homes.
Harish Bhaskaran, professor at Oxford's Department of Materials, who led the research and the WAFT consortium, said: "Although significant future research is necessary before this technology can be commercialised, the results show that the concept is very promising and with further research can achieve very good efficiencies."
Featured articles and news
BG 50 & VDI 2035 – your questions answered.
Will the way we heat homes change when winter comes ?
Can XR technology be leveraged in design & construction?
Or are you capping.
Digital gaming competition for UK students aged 16 to 18.
Heritage protection in England vs Australia.
Three-quarters of fire doors fail inspections
The role of geoparks, biospheres and world heritage sites.
Just one month to go ! Find out more here.
A new gallery for the University of Huddersfield.
What will it take to stop it ?
To celebrate world bee day 2022 !
Not forgetting part F and the new part overheating part O.
As energy prices jump up in cost.
With people in the UK from Ukraine.
Industry leader Steve Murray takes on role.
An abundant and versatile building material.
600,000 heat pump installations targeted per year by 2028.
Helping prevent those unwanted outcomes.
How has transport changed due to Covid-19 ?
Will you need it ? after June 15 and the new Part O ?