windows

Saving birds from buildings

July 1, 2025 By EarthWise Leave a Comment

Researchers estimate that hundreds of millions of birds die hitting buildings every year in the United States. Striking buildings is believed to be one of the major factors behind the nearly 30% decline in North American bird populations since 1970.

Chicago is one of the most dangerous cities for migrating birds based on its location and its numerous tall, glassy buildings. Migrating birds that make their homes in forests and grasslands don’t perceive glass as solid and are confused by reflections.

While many Chicago skyscrapers are dangerous for birds, the Lakeside Center at McCormick Place is infamous for the fact that it claimed the lives of nearly a thousand birds on a single day in October 2023.

There are various strategies for reducing bird strikes. Over decades, McCormick Place management has tried erecting strips of netting, broadcasting calls of birds of prey, and putting up silhouettes of them. They commissioned a nine-acre park of native prairie and woodlands on the roof of a parking deck. None of these things made a major difference.

Last summer, the building installed a pattern of dots over the surface of the building’s windows. The dots are only a couple of inches apart, so even tiny hummingbirds don’t try to dart through. The window treatment cost $1.2 million paid for by the state of Illinois. People in the building scarcely notice the dots. Their views of the city and lake are unimpaired.

The results are nothing short of remarkable. During last fall’s migration, bird deaths were down by about 95% compared with the two previous autumns. This spring’s migration has been with implications for glassy structures far beyond Chicago.

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An Illinois Building Was a Bird Killer. A Simple Change Made a World of Difference.

Photo, posted May 19, 2023, courtesy of Warren LeMay via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Ecofriendly Glass

October 2, 2024 By EarthWise Leave a Comment

Glass has been used for thousands of years to make everything from windows to bottles to microscope slides. For all that time, most glass has been in the form of soda lime silicate glass, which is made by melting quartz sand with carbon-based ingredients – soda ash and limestone – at high melting temperatures of about 2600 degrees Fahrenheit.

The process results in substantial carbon emissions. Worldwide, glass manufacturing produces over 86 million tons of carbon dioxide per year. Most of that comes from burning fuel to reach the high temperatures needed to make the glass, but about a quarter of it comes from the decomposition of the carbon-based materials used.

Researchers at Penn State University have developed an entirely new type of glass that represents an alternative to soda lime glass. The glass – that they call LionGlass – eliminates the use of carbonate batch materials and has a melting temperature 700 degrees lower than traditional glass. The new material has the potential to cut the carbon footprint of glass manufacturing in half. It is also 10 times more crack-resistant than ordinary glass, which would enable light weighting of glass products, lowering the emissions associated with transporting glass and glass products.

Recently, Penn state has entered into a partnership with the Italian company Bormioli, one of the world’s leading glass manufacturers that specializes in high-end packaging for fragrances, cosmetics, and tableware. By focusing on a smaller, high-end market, the focus can be on fine-tuning the glass and determining the feasibility of scaling it up further for other uses.

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Ecofriendly glass invented at Penn State secures partner for product development

Photo, posted December 26, 2005, courtesy of Lachlan Hardy via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Making wind turbines safer for birds

September 18, 2024 By EarthWise Leave a Comment

There are people who oppose the installation of wind turbines for a variety of reasons. It is true that wind turbines can be dangerous to birds. Estimates are that about 250,000 birds are killed flying into wind turbines each year in the U.S.

However, this data needs to be looked at in comparison to bird deaths from flying into electrical lines (25 million), vehicles (214 million), and building glass (at least 600 million). And even these figures pale in comparison to the more than 2 billion birds killed by domestic cats each year.

Despite these facts, it would still be great if fewer birds died from flying into wind turbines. Researchers at Oregon State University are part of a team looking at reducing bird collision risks from wind turbines by painting a single blade of the turbine black.

Recent research in Norway found that painting a single turbine blade black reduced the number of bird collisions by nearly 72%. Why should this work? The hypothesis is that the black-painted blades disrupt the visual uniformity of the airspace around the turbines and makes them more noticeable to birds, which prompts avoidance behavior.

The Norwegian data is based on a relatively small sample size and the Oregon State researchers as well as others in Spain, Sweden, and South Africa are working on more rigorous and comprehensive studies.

The hope is that this rather simple strategy could make windfarms safer for birds. Unfortunately, this approach is not likely to be very effective with bats, which rely more on auditory cues rather than visual cues.

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Scientists studying impact of painting wind turbine blade black to reduce bird collisions

Photo, posted May 21, 2024, courtesy of Roy Harryman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Buildings and birds

November 29, 2023 By EarthWise Leave a Comment

Birds face a wide range of dangers. Billions of them each year face violent deaths. Concerned individuals point at such things as wind turbines, which in fact do kill hundreds of thousands of birds. But the great majority of bird deaths are caused by cats. And that’s a danger that isn’t going to go away.

The second largest cause of bird deaths is collisions with building windows. Building collisions kill hundreds of millions of birds each year in the U.S. alone. As other places have seen glass skyscrapers proliferate, such as in Chinese cites, these collisions have become a major global factor in bird mortality.

There are growing efforts across the U.S. and Canada to reduce bird collisions. Many businesses are taking part in “lights out” programs in which their buildings dim lights during spring and fall migrations. Some buildings now use special glass that birds can see and avoid. Some communities even have adopted ordinances that require bird-friendly glass in new construction. Keeping bird attractants away from windows is another important way to reduce bird strikes. All these measures have been proven to be effective in reducing the number of bird collisions.

Companies sell vinyl film with tiny dots that can be affixed to windows. Both businesses and homeowners have seen substantial reduction in bird collisions with such films installed.

Bird collisions are not a new problem but is one that wasn’t really taken seriously until at least the 1970s. There isn’t much to be done about the greatest threat to birds – namely cats – but how buildings are constructed and operated is something we can control.

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As Bird Kills from Buildings Mount, Cities Look for Solutions

Photo, posted December 24, 2017, courtesy of Nicolas Vollmer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Windows To Cool Buildings | Earth Wise

December 15, 2022 By EarthWise Leave a Comment

About 15% of global energy consumption is for cooling buildings. Because of this, there is an ever- growing need for technologies that can more efficiently cool buildings. Researchers at Notre Dame University have used advanced computing technology and artificial intelligence to design a transparent window coating that is able to lower the temperature inside buildings without using any energy.

The idea is to create a coating that blocks the sun’s ultraviolet and near-infrared light, which are parts of the solar spectrum that otherwise pass through glass and help to heat an enclosed room. Cooling needs can be reduced further if the coating can radiate heat from the surface of the window so it can pass through the atmosphere into space. Designing a coating that does both of those things simultaneously while transmitting visible light is difficult. Coatings should not interfere with the view out the window.

The Notre Dame researchers used advanced computer modeling to create a so-called transparent radiative cooler that meets these goals. The coating consists of alternating layers of common materials like silicon dioxide, silicon nitride, and aluminum oxide or titanium dioxide on top of a glass base and topped with a film of polydimethylsiloxane. The computing method was able to optimize this structure far faster and better than conventional design techniques.

The researchers say that in hot, dry cities, the coating could potentially reduce cooling energy consumption by 31% compared with conventional windows. The same materials could be used in other applications, such as car and truck windows. In addition, the quantum computing-enabled optimization method used for this work could be used to design other composite materials.

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Clear window coating could cool buildings without using energy

Photo, posted September 6, 2015, courtesy of Robert Otmn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Solar Windows | Earth Wise

September 1, 2022 By EarthWise Leave a Comment

Solar windows are an attractive idea. It is very appealing to have the vertical surfaces on the outside of almost any building generate electricity. The challenge is to have a transparent window be able to function as an efficient-enough solar panel.

Most conventional solar panels use silicon solar cell technology, which is not based on a transparent material. Transparent solar cells use dye-sensitized technology, which has been the subject of research for decades but has yet to achieve widespread use.

Researchers at the University of Michigan have recently published work on a new process to manufacture solar windows that can be large (over six feet in each dimension) and efficient at electricity production.

The windows make use of dye-sensitized cells which are connected to lines of metal so small that they are invisible to the naked eye. The individual cells are fairly small but the connection technology allows the construction of large windows.

The solar window has an efficiency of 7%, meaning 7% of incoming sunlight energy is converted to electricity. The researchers believe that 10% efficiency should be attainable with their technology. Conventional solar panels have efficiencies of 15% or more.

However, the goal is not necessarily to compete with silicon solar panels. The real opportunity is to be able to generate electricity when rooftop solar is not practical or to produce additional electricity even when there is already a solar roof.

Going forward, the goals of solar window development are to increase efficiency and to reduce costs to where installing the windows is economically attractive. Estimates are that the windows currently would cost about twice as much as a conventional window but would pay for the difference in two to six years depending on such things as the level of sun exposure.

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Inside Clean Energy: What’s Hotter than Solar Panels? Solar Windows.

Photo, posted April 17, 2017, courtesy of Shelby Bell via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Smart Window | Earth Wise

March 31, 2022 By EarthWise Leave a Comment

Researchers at Oxford University have developed a new adaptable smart window technology that has the potential of reducing the energy usage of the average home by a third.

The technology uses a spectrally tunable low-emissivity coating that can control the amount of heat that comes into a room without affecting the quality of the light that enters.

The thermal energy from the sun’s infrared rays is absorbed by the glass and then is re-emitted as heat. That heat can either be used to warm the room using transparent electrical heaters embedded in the glass or can be reflected away to cool the room. The windows can change according to seasonal needs.

The researchers built a prototype using a material called an active chalcogenide-based phase change material. When it is cold, the infrared rays from the sunlight are harvested and used to heat the building. When it is warm, the new glass can switch state to reflect the heat and reduce the need for air conditioning. The active phase change material is adjustable so that the amount of heat absorbed or reflected can be tuned for precise temperature control. There is essentially no effect on visible light passing through the window. Current low-emissivity glass for windows can reduce heat transfer, but its properties cannot be altered according to seasonal needs.

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 found in many modern homes.

A spinout company from Oxford called Bodle Technologies is collaborating with two existing industrial partners to develop the technology further.

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New adaptable smart window coating could help heat or cool a home and save energy

Photo, posted April 26, 2008, courtesy of Lima Andruska via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Immersion In Nature Is Good for You | Earth Wise

February 20, 2020 By EarthWise Leave a Comment

There is a growing body of research that shows that getting outdoors in nature can be good for people’s health and well-being. There are so many studies supporting this idea that policymakers, employers, and healthcare providers are increasingly considering this need for nature in how they plan and operate.

A new study of 20,000 people by researchers at the University of Exeter in the UK actually looked at how much exposure to nature was enough to make people say they feel healthy and have a sense of well-being. The answer turned out to be 2 hours a week. And the correlation was strong. People who didn’t meet that threshold did not report the benefits.

Studies have shown that time in nature – as long as people feel safe where they are – is an antidote for stress. It can lower blood pressure and stress hormone levels, reduce nervous system arousal, enhance immune system function, increase self-esteem, reduce anxiety, and improve mood. Most of these studies are correlational rather than causal, but the results tend to be robust.

Given all this, cities are adding or enhancing parks, and schools and other institutions are being designed with large windows and access to trees and green space. The Scandinavian tradition of “forest schools” – where learning takes place in natural settings outdoors -.is finding a home in the US. Japanese researchers study the effects of “forest bathing”, a poetic term for walking in the woods.

With two-thirds of humanity projected to be living in cities by 2050, we are awakening to the idea that we need to be able to spend time in nature for our own wellbeing, even if it’s just a walk in a park.

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Ecopsychology: How Immersion in Nature Benefits Your Health

Photo, posted November 6, 2011, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Dangerous Cities For Migrating Birds

May 14, 2019 By EarthWise Leave a Comment

Billions of birds migrate north in the spring and south in the fall. The majority of them fly at night. But as they pass over large cities, the birds can become disoriented by bright artificial light – so-called light pollution, causing them to crash into buildings or windows.

Researchers estimate that 600 million birds die from building collisions in the United States every year. Now, a new paper from researchers at Cornell University reveals which metropolitan areas are most dangerous for birds and why.

The researchers ranked cities where, as a result of geography and exposure to light pollution, birds are at the greatest risk of becoming attracted to and disoriented by lights and crashing into buildings. They combined light pollution levels with bird density data in order to make their calculations. Their paper was recently published in the journal Frontiers in Ecology and the Environment.

Chicago, Houston, and Dallas finished as the three most dangerous cities for migrating birds. While migration routes vary depending on the season, these three cities still topped all others during both the spring and fall migrations due to their size and geographic positioning in the heart of North America’s most trafficked aerial corridors.

Audubon’s Lights Out program is one of several national efforts encouraging cities to reduce light pollution, particularly on heavy migration nights, in order to reduce bird mortality.

But homeowners need to do their part as well since an estimated quarter-million birds die from collisions with residential houses every year. The suggestion to cities and homeowners alike is the same: If you don’t need the lights, turn them off.

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Chicago tops list of most dangerous cities for migrating birds

Photo, posted May 18, 2017, courtesy of Pedro Szekely via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A See-Through Heat Shield

January 8, 2019 By EarthWise Leave a Comment

It is estimated that air conditioners use about 6% of all the electricity produced in the United States for an annual cost of $29 billion. With rising temperatures, this expense is only going to get larger.

A significant part of the heat load in buildings arises from heat coming through windows. It turns out that for every square meter of window, about 500 watts of heat energy can be brought in by sunlight, equivalent to 5 old-fashioned light bulbs.

Researchers at MIT and the University of Hong Kong have developed a heat-rejecting film that can applied to a building’s windows that will reflect 70% of the sun’s incoming heat. The film is similar to transparent plastic wrap. It remains highly transparent at temperatures below 89 degrees Fahrenheit. Above that temperature, tiny microparticles embedded in the film shrink and the film becomes more translucent or frosted, still letting in a good amount of light, but rejecting a lot of heat.

There are already so-called smart windows on the market, similar to the electrochromic mirrors in cars that darken to prevent trailing headlights from blinding drivers. But that technology is not very effective in rejecting heat and it requires power to operate, which means you would have to pay to turn windows opaque.

Tests of the new film demonstrated its ability to reject heat and lower temperatures. The researchers estimate that if every exterior-facing window in a building were covered in the heat-rejecting film, the building’s air conditioning and energy costs could drop by 10%. Saving ten percent of tens of billions of dollars is no minor matter.

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