Using cellulose nanofibers from wood pulp, a team have made a clear gel that can be sandwiched between existing window panes.
Glass windows have been around since ancient Rome. Modern windows, made of two glass panes of glass with air in between, have come a long way since those drafty windows of old. But they still let some heat and cold through, wasting energy.
Replacing the air in today’s double-pane windows with a new see-through gel made from wood could make them as insulating as walls, a new study shows. The insulating aerogel film, reported in the journal Nature Energy could be made for cheap on large scale, is more transparent than glass, and it could be used to retrofit existing windows, its developers say.
Buildings consume around 40 percent of the world’s energy. Most of that is used for heating, cooling and ventilation. Windows and skylights, by allowing heat to enter or escape out of a building, lead to much of this heating and cooling being wasted. Single-pane windows, which are still common, are especially energy-inefficient.
So Ivan Smalyukh, a physics professor at the University of Colorado, Boulder and his colleagues made flexible films of aerogels—sponge-like solids composed mostly of air—using cellulose nanofibers derived from wood pulp.
They make a network of these fibers in water to make a hydrogel. Then they swap the water with ethanol solvent, stick the gel film on a plastic layer and roll it, before drying the gel to remove the solvent, giving an aerogel film. Finally, the team coated the cellulose nanofibers in the aerogel with a silicon-based chemical that made the film water-repellant to prevent condensation.
The aerogels films are 97–99 percent transparent, more than glass, which has a transparency of 92 percent. Millimeter to centimeter-thick slabs of the aerogels could be bent and rolled without loss in transparency, cracks or any deterioration in performance.
To test the materials, the researchers placed a film on the inside of single-pane window glass, and put a 2.5 cm-thick slab in the gap between two panes of a modern window. They placed these test panels in the openings of hot and cold boxes with inside temperatures of 40°C and -20°C, mimicking summer and winter temperatures.
Aerogel-containing windows more efficiently blocked heat flow between the inside and outside of the boxes. And the 2.5-inch layer made the double-pane window as insulating as a wall. In addition to making the windows more insulating, the aerogels also increased their resistance to condensation.
the 2.5-inch layer made the double-pane window as insulating as a wall.
Cost and scale-up have been two critical challenges for widely deploying conventional aerogels made from silica, the researchers say. For this new aerogel, raw material cost should be minimal since the cellulose nanofibers can be derived from waste wood pulp, or from food and beverage waste with the help of bacteria, as the researchers have reported before. The team estimates the raw materials to cost about $1 a square foot.
The special rolling and drying process they use should reduce manufacturing costs, Smalyukh writes. “Nevertheless, further research is needed to reduce the haze of thick aerogel slabs and to lower manufacturing costs to drive widespread deployment.”
Source: Abraham, E., Cherpak, V., Senyuk, B. et al. Highly transparent silanized cellulose aerogels for boosting energy efficiency of glazing in buildings. Nat Energy, 2023.
“We MUST respect this earth - it is all we have
Claudio Dametto - South Australia
“I will always Vote to Preserve Our World.
Liam McGregor - Western Australia
“A simple message that even a politician can understand
Felicity Crombach - Victoria
“Please show you care about our future generations!!
Phil Harmer - New South Wales
“Save our world , Life & health before profits.
Kerry Lillian - New South Wales
“Close down all coal mines and Do not mine gas . Make these Companies
Daniel Johnson - New South Wales
“We want carbon free energy!
Edan Clarke - New South Wales
“Feels good to be taking a voter action step
Beaver Hudson - New South Wales
“Great Initiative. Let’s Hold elected officials Accountable to their bosses, us!
John Paul Posada - New South Wales
“We need actions not words we need honest democratic govt We need a pm
Bob Pearce - South Australia
“Thank you for this great resource. I was feeling helpless. Even this small step
Silvia Anderson - Victoria
“If political parties continue receiving political donations, we will rarely have politicians working for
Dan Chicos - New South Wales
“I only vote for people who will take urgent action to restore a safe
Susie Burke - Victoria
“Current government is not representing the opinion of the majority of Australian to meet
Neil Price - Tasmania
“We are fighting to rescue our kids' future from those who seek to steal
Vanessa Norimi - Queensland
“No time to waste Now or Never My vote is for NOW
Rosalie White - Victoria
“I am only 9 but I already care
Ava Bell - New South Wales
“From New Lambton Uniting Church - Caring for our world is a moral imperative.
Niall McKay - New South Wales
“Our federal govt is an International climate Embarrassment - its about time they stepped
Oriana Tolo - Victoria
“Vote earth this time!
Sue Cooke - Queensland
“We are in one on the wealthiest countries in the world. we have the
rowan huxtable - New South Wales
“The climate Emergency is the public health opportunity and urgent priority of the 21st
Mike Forrester - Victoria
“If they want my vote they better act now
Barbara McNiff - New South Wales
“We need to act locally now for the earth. Our only home. Vote Earth
Anne Miller - New South Wales
“I often look at the places I've known all my life and see how
Jim Baird - New South Wales
“Strike one For people power!!! Democracy might prevail outside the current cronyism that faces
Lorraine Bridger - New South Wales
“Our federal politicians Are Afraid to make action on climate change a major election
Jennifer Martin - New South Wales
“climate election, let's go!
Fahimah Badrulhisham - New South Wales
“Great to see this website that is a focus on action for climate change
Lynette Sinclair - New South Wales
“Let’s show politicians and the Murdoch media that climate change is by far the
Jane Aitken - Australian Capital Territory
“If you want to stay in power You need to take action to stop
Jane Bulter - New South Wales
“We are all that stands between terminal climate change and the vulnerable. We are
Carol Khan - Queensland
“We need a Government that Believes this is real and not taking money from
Ken Gray - New South Wales
“I'm voting for my childrens future
Anneliese Alexander - New South Wales