The world’s first 3D-printed school is taking shape in Madagascar

Thinking Huts and its partners are building the world’s first 3D-printed school on the campus of a university in Fianarantsoa, Madagascar.

3D printing builds solid objects layer by layer, creating less waste than traditional manufacturing methods.

The solution addresses the lack of sufficient investment in physical infrastructure, which is one of the biggest barriers to education.

A new project in Madagascar is rethinking the building blocks of education – using 3D printing to create new schools.

Non-profit organization Thinking Huts has partnered with architectural design agency Studio Mortazavi to create the world’s first 3D-printed school on the campus of a university in Fianarantsoa, Madagascar.  It is aiming to tackle the shortage of educational infrastructure which in many countries contributes to fewer children getting a good education.

Using technology developed by Finnish company Hyperion Robotics, the school will be built using 3D-printed walls and locally sourced materials for the doors, roof and windows.  Members of the local community will then be taught how to replicate the process to build schools for the future.

In this way, a new school can be built in under a week, and with less of an environmental cost than traditional concrete-based construction.  The 3D-printed buildings use less concrete than other methods and the 3D cement mixture also emits less carbon dioxide compared to traditional concrete.

An artist’s rendering of how part of the school will look once completed.

Image: Thinking Huts

The design allows for individual pods to be joined together in a beehive-like structure and means schools can be easily expanded.  The Madagascan pilot project also features vertical farms in the walls, and solar panels.

Widening access to education

An absence of buildings to deliver education from is a significant hurdle in many countries, particularly in areas lacking skilled labor and resources for building.  By using the technology to build schools, Thinking Huts is seeking to widen access to education – something which will become particularly important post-pandemic.

UNICEF and other organizations have warned of a learning crisis exacerbated by the virus, with 1.6 billion children across the world at danger of falling behind because of school closures aimed at containing the spread of COVID-19.

So, getting children back in the classroom as soon as is safely possible will be vital to continuing their education, particularly for those with limited access to the internet and personal learning devices.

Printing the future?

The process of 3D printing, which is also known as additive manufacturing, uses a digital file to build solid objects layer by layer – meaning there is less waste compared to traditional methods, which often use molds or hollowed out materials.

3D printing has revolutionized manufacturing processes, enabling mass customization, creating novel visual forms not previously possible and creating new opportunities to increase the circularity of products.

The machines are increasingly used in the production of everything from consumer goods such as sunglasses to industrial items such as car parts.  In education, 3D modelling can be used to bring educational concepts to life and help build practical skills, such as coding.

In Mexico, it has been used to build a neighborhood of 46-square-metre homes in Tabasco.  The houses – consisting of a kitchen, living room, bathroom and two bedrooms – will be made available to some of the state’s poorest families, many of who earn just $3 a day.

The technology’s relatively easy portability and low cost has also proved vital in disaster relief.  When Nepal was hit by an earthquake in 2015, a 3D printer perched on a Land Rover was used to help fix water pipes flown in as part of a relief effort, the Guardian reported.


Written By: Natalie Marchant, World Economic Forum

IBM sets new climate goal for 2030

IBM plans to get rid of its planet-heating carbon dioxide emissions from its operations by 2030, the company announced today.  And unlike some other tech companies that have made splashy environmental commitments lately, IBM’s pledge emphasized the need to prevent emissions rather than developing ways to capture carbon dioxide after it’s released.


The company committed to reaching net zero greenhouse gas emissions by the end of this decade, pledging to do “all it can across its operations” to stop polluting before it turns to emerging technologies that might be able to capture carbon dioxide after it’s emitted.  It plans to rely on renewable energy for 90 percent of its electricity use by 2030. By 2025, it wants to slash its greenhouse gas emissions by 65 percent compared to 2010 levels.

“I am proud that IBM is leading the way by taking actions to significantly reduce emissions,” said IBM chairman and CEO Arvind Krishna.

IBM is putting more emphasis on its cloud computing and AI after announcing in October that it would split into two public companies and house its legacy IT services under a new name.  That pivot puts IBM in more direct competition with giants like Amazon and Microsoft in the cloud market, which is notorious for guzzling up energy.  Data centers accounted for about 1 percent of global electricity use in 2018, according to the International Energy Agency, and can strain local power grids.  All three companies have now made big pledges to rein in pollution that drives climate change.

Microsoft’s climate pledge focuses on driving the development of technologies that suck carbon dioxide out of the atmosphere; it reached net zero emissions in 2012 but still relies heavily on investing in forests to offset its carbon pollution.  Amazon committed to reaching net zero emissions by 2040.  Amazon’s emissions, however, continue to grow as its business expands.


There is still room for more ambition in IBM’s new climate commitment since the company so far is not setting targets for reducing emissions coming from its supply chain or the use of its products by consumers.  These kinds of indirect emissions often make up a majority of a company’s carbon footprint.  IBM does not track all of the pollution from its supply chain, but other indirect emissions (like those from the products it sells) made up the biggest chunk of its carbon footprint in 2019.  Microsoft and Amazon, on the other hand, consider all of these sources of emissions in their climate pledges.


By Justine Calma

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EIA projects renewables share of U.S. electricity generation mix will double by 2050

In its Annual Energy Outlook 2021 (AEO2021), the U.S. Energy Information Administration (EIA) projects that the share of renewables in the U.S. electricity generation mix will increase from 21% in 2020 to 42% in 2050.  Wind and solar generation are responsible for most of that growth. The renewable share is projected to increase as nuclear and coal-fired generation decrease and the natural gas-fired generation share remains relatively constant.  By 2030, renewables will collectively surpass natural gas to be the predominant source of generation in the United States.  Solar electric generation (which includes photovoltaic (PV) and thermal technologies and both small-scale and utility-scale installations) will surpass wind energy by 2040 as the largest source of renewable generation in the United States.

The AEO2021 Reference case projects that the natural gas share of the U.S. electricity generation mix will remain at about one-third of total generation from 2020 to 2050.  The natural gas share of generation will remain stable even though natural gas prices will remain low (at or lower than $3.50 per million British thermal units, in real dollars) for most of the projection period.  This stability occurs despite significant coal and nuclear generating unit retirements resulting from market competition as regulatory and market factors induce more renewable electricity generation.

The share of natural gas-fired generation in the United States will remain relatively constant through 2050, as projected in the AEO2021 Reference Case, and the contribution from the coal and nuclear fleets will drop by half.  Through 2050, the share of electricity generation from renewables will double.  Wind will be responsible for most of the growth in renewable generation from 2020 through 2024, accounting for two-thirds of the increase in that period.

After the production tax credit (PTC) for wind phases out at the end of 2024, solar generation will account for almost 80% of the increase in renewable generation through 2050.  EIA assumes that utility-scale (and commercial) solar PV facilities will receive a 30% investment tax credit (ITC) through 2023, which will then be reduced to 10% beginning in 2024 and lasts through 2050.  Residential solar PV will also receive a 30% ITC through 2023, which will expire in 2024.

Because renewable energy technology costs and natural gas prices are key determinants of these projections, EIA explores sensitivity cases with varying levels of both renewable costs and natural gas price trajectories.  Accordingly, the renewable technology share of generation will be higher in the Low Renewables Cost and High Oil and Gas Resource cases, relative to the Reference case, and the share of generation from renewables will be lower in the High Renewables Cost and Low Oil and Gas Resource cases.


Principal contributor: Kenneth Dubin

Source: U.S. Energy Information Administration, Annual Energy Outlook 2021 (AEO2021)

NYC’s roofs are getting a sustainable makeover

While buzz around the passage of New York City’s Climate Mobilization Act in April 2019 has fizzled, the city’s public officials, property owners, architects, real estate moguls and financiers are revving up to put new policies into practice.

As of Nov. 15, 2019, Local Laws 92 and 94 are in effect to target a vast, often overlooked and underutilized resource in New York: roofs.

The laws, known informally as the Sustainable Roof Laws, require most new buildings and buildings undergoing major roof reconstruction to include a sustainable roofing zone on 100% of the available roof space.

Sustainable roofing zones are defined as “areas of a roof assembly where a solar photovoltaic electricity generating system, a green roof system, or a combination thereof, is installed.” In other words, the roofs must have a solar panel array, green roof or both.

“When you fly into New York City, you see an amazing amount of unproductive roof space,” Jonce Walker, senior associate at Thornton Tomasetti, told Smart Cities Dive. Walker and others in the sustainable design community hope Local Laws 92 and 94 are going to change that.

Facing change

The Sustainable Roofs Laws have mobilized several sectors in New York City, from government to investment, each one grappling with how to manage new regulations designed to drive drastic changes in the city.

“The goal [of Local Laws 92 & 94] is to make sustainable roofs just one of the parts of how you put a good building together,” Mark Chambers, director of the Mayor’s Office of Sustainability, told Smart Cities Dive.

Currently, sustainable roofs are far from the norm in New York. According to a mapping project from The Nature Conservancy, there were only about 730 green roofs out of over 1 million rooftops in New York City in 2016.

Solar is much more prevalent, with a total of about 22,000 completed solar projects throughout the city as of 2019, according to the team at Sustainable CUNY. They indicate the number of new solar projects implemented each year in the city has increased dramatically since 2016, due in part to the establishment of Professional Certification (Pro-Cert), which shortened the review period of new solar projects to just 24 hours.

Not all property owners will be immediately faced with required adjustments. Buildings dedicated to affordable housing have an alternative compliance timeline of five years during which the New York City Department of Housing Preservation and Development (HPD) will conduct studies on the impact of the law on affordability.

But Jennifer Leone, sustainability officer at HPD, pointed out that the department has “already been leading the charge” when it comes to sustainable roof practices with programs like the Green Housing Preservation Program.

The case for green roofs

As the sustainable roof market has grown over the past decade, helped partly by the passage of new roof laws around the world, sustainable roofing systems have become the ideal solutions for eco-minded contractors and architects. But is one system better than another?

“To be honest, our very strong opinion…is that green roofs have more benefits,” said Walker. “If it’s either-or [green roofs or solar panels], we typically try to steer the design team toward green roofs.”

Water management

Walker and other green building advocates praise the wide range of social benefits that green roofs can offer. Beyond protecting roof membranes, they serve as a water management solution, soaking up stormwater that might otherwise contribute to the city’s already-overburdened stormwater management system.

During heavy storms, New York’s Combined Sewer Overflow (CSO) system is unable to handle excess stormwater, so untreated wastewater gets pumped into the city’s waterways. With additional green roofs to soak up that stormwater, New York may soon see cleaner waterways.

Stormwater and energy savings also contribute to a positive return on investment (ROI) in green roofs. While installation, replacement and maintenance of a green roof over a 50-year period​ can present a cost of $18 per square foot of roof, the stormwater and energy savings make up for the cost by providing a benefit of approximately $19 per square foot of roof over that same period, according to the General Services Administration (GSA).

Overall, GSA estimates that a 3-inch to 6-inch green roof covering 10,000 feet has a net present value of $2.70 per square foot per year.

Heat reduction

A city plagued annually by the urban heat island effect, New York might cool down with added green roofs. “Through the daily dew and evaporation cycle, plants…are able to cool cities during hot summer months,” according to Green Roofs for Healthy Cities.

Councilmember Rafael Espinal, a sponsor of the Sustainable Roofs bill, said green roofs have already been proven to cool cities. “These bills show that New York will not be idle in the face of an existential threat like climate change,” he said in a press release.


Green roofs can restore biodiversity to urban areas by attracting pollinators like butterflies, bees, birds and bats that have been pushed out of the city as their natural habitats get bulldozed.

“This island was once a lush, green habitat that we have made impermeable,” said Walker.

The Javits Center, New York’s largest convention center, installed a 7-acre green roof in 2014 that now boasts 29 species of birds, five species of bats and three honeybee hives.

The pollinators are not the only ones benefiting from the Center’s green roof. The Javits Center itself harvests honey from the rooftop beehives, for sale at the convention center’s market.

For New York as a whole, focusing on increasing biodiversity can help improve the health of the entire city, as biodiversity is an indicator of clean air and waterways.


Finally, green roofs might just make New Yorkers feel good. Marni Majorelle, founder and owner of Brooklyn-based green roof construction company Alive Structures, emphasizes the psychological benefits of having more green space in urban areas.

“I think it’s really important to have that connection with plants and with nature,” she said at a green roofs educational and networking event in June 2019. “I know there’s a lot of emphasis on reducing energy consumption…which is also extremely important, but we have to understand that we have to have nature in our cities.”

The case for solar

Although solar panels do not provide the same lushness to the cityscape that green roofs do, solar roofs have a number of attractive features.

Clean energy

From a sustainability standpoint, the primary benefit of solar panels is their ability to generate renewable energy. In a city with notoriously ambitious emissions goals — 100% clean electricity by 2040 and carbon neutrality by 2050 — increased solar supply can advance New York to reach those targets.

The solar market is also well-established in New York, leading to easier deployment of new solar projects. “There’s more infrastructure built up in the solar community [than in the green roof community],” said Majorelle. “It’s streamlined.”


Designers don’t always have a choice on how to construct a sustainable roof zone. Contractors conduct analyses prior to construction to determine which roof system will work best, based on the property’s available roof space and access to sunlight.

Roofs that get abundant sunlight and are unblocked by neighboring buildings, and especially those with sloped roofs, are prime for solar. Green roofs, on the other hand, cannot exist on a slope.


Solar incentives for property owners have been around in New York since at least 2005. New York’s solar market benefits from multiple tax incentives at city, state and federal levels. It is likely that some property owners will choose solar panels over green roofs, regardless of their benefits, to comply with laws at a lower cost.

While solar incentives are bountiful in New York, financial incentive plans for green roofs are limited to a property tax abatement of $5.23 per square foot of green roof, although alternate options like Property Assessed Clean Energy (PACE) financing also exist.

In addition to lower upfront costs, solar arrays are “revenue-generating machines,” in Majorelle’s words.

Affordable housing building owners and HPD have taken advantage of the earning possibilities of solar power. “Solar is the go-to option [for affordable housing],” Leone said. “There’s a visible payback.”

Paybacks are both direct and indirect, allowing building owners to save money on energy bills and even sell energy credits, earning them money that can then be allocated towards building maintenance costs.

Benefits beyond sustainability

While both green roofs and solar panels help reduce energy consumption and costs, combining the two systems may be the most cost-effective option. Solar panels work most efficiently when they are at a low temperature, while a green roof (which has a cooler microclimate) can reduce heat. However, there are currently very few combined solar-green roof projects in New York City.


Author: Cailley LaPara

Image by Alex Potemkin vis Getty Images


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Top U.S. cities for women in construction

Men outnumber women in construction, substantially, but more women continue to join the field and often at higher wages than they would in other careers.

Women make up 10% of the construction workforce — 1.1 million women, compared to 9.9 million men — according to data from the Bureau of Labor Statistics.  Despite the gap in the number of workers, women in construction make nearly $47,000 a year, more than their non-construction counterparts, who make about $43,400.

The opposite is true for men, who often make less in construction than they do in other careers. The pay gap for men and women is also smaller in construction, at 3.7% compared to 19% across all fields.


In a new analysis of data from the U.S. Census Bureau, Construction Coverage magazine broke down the cities in the U.S. with the highest share of women construction workers.  Here are the top 20 large U.S. cities (population of 350,000 or more) by their share of female construction workers:

Rank City Female employment share Median annual earning
1 Minneapolis 19.1% $54,521
2 Seattle 17.6% $70,966
3 San Francisco 17% $70,711
4 Washington, D.C. 16.1% $52,035
5 Virginia Beach, Virginia 15.5% $52,325
6 Colorado Springs, Colorado 15.4% $55,363
7 Atlanta 14.6% $44,346
8 El Paso, Texas 14.1% $35,710
9 Charlotte, North Carolina 13.6% $36,988
10 Wichita, Kansas 13.4% $40,067
11 San Diego 13.3% $53,990
12 Tampa, Florida 13.3% $53,990
13 Kansas City, Missouri 13.1% $41,742
14 Portland, Oregon 13% $63,892
15 Baltimore 12.3% $50,740
16 Louisville, Kentucky 12.1% $46,560
17 New Orleans 11.9% $37,300
18 Austin, Texas 11.8% $40,595
19 Denver 11.7% $49,437
20 Columbus, Ohio 11.7% $40,913

SOURCE: Analysis of U.S. Census Bureau Data by Construction Coverage


The number of women with the title construction manager increased by 101%, from 49,400 to 99,4000, between 2015 and 2019, according to a recent study by Smart Asset.  That made it the third highest grossing position for women in that time period.

More women also began working as construction and maintenance painters (a 64% increase to 53,300) and construction laborers (a 50% increase to 71,800).  The number of women who chose careers as civil engineers also grew by 46%, from 45,400 to 66,000.

The Smart Asset study used data from the Bureau of Labor Statistics, which tracks information on jobs in all industries. Its most recent analysis shows that the construction jobs popular with women have a range of salaries, from about $156,000 for the high end of a construction manager salary to a high end of about $68,000 for laborers and painters.

The statistics show women increasingly are joining the construction workforce, though it’s unclear how that may have been impacted by COVID-19.  Nevertheless, industry insiders still say more work needs to be done to attract women to construction.

“We clearly have much more work to do as an industry to recruit, hire and retain a more diverse population of workers, particularly women,” Brian Turmail, Vice President of public affairs and strategic initiatives at the Associated General Contractors of America, told Construction Dive.  “The good news is we are heading in the right direction.  Moving forward, [the AGC is] committed to redoubling our efforts to attract an even more diverse construction workforce.”


Author:  Zachary Phillips, Construction Dive

AR, VR Find More Real-World Applications in Construction

Global Data:  “Technology can improve accuracy, efficiency and safety of construction projects”


The construction industry is slowly shifting from years of the wait-and-watch stance to adopting digital technologies to improve the overall project lifecycle from conceptual design to construction.  Considering such developments, alternative reality technologies such as augmented reality (AR) and virtual reality (VR) are increasingly finding their use cases to improve accuracy, efficiency and safety of construction projects, says GlobalData, a leading data and analytics company.

Venkata Naveen, Senior Disruptive Tech Analyst at GlobalData, comments: “While the alternative reality technologies have been used in the gaming and entertainment industries for years, they started to make waves in the construction by merging the digital and physical view of jobsites to address various bottlenecks.  The demand to complete projects within budget and on time has propelled construction companies to leverage AR and VR technologies to save time, reduce errors, prevent rework and create a long-term return on investment.”

The Digital Solutions Map in Construction of GlobalData’s Disruptor Intelligence Center uncovers the use cases of AR and VR across the construction industry value chain.  A few examples:

Virtual Collaboration

Boston-based Suffolk Construction has partnered with New York’s VR startup InsiteVR to help its engineering teams meet virtually to coordinate, plan and resolve issues, irrespective of their geographical locations.  Users can join the platform via their desktops wearing a VR headset to review project designs, spot issues and make changes, all inside the virtual environment.

Project Planning

London startup XYZ Reality developed a helmet-mounted device combining augmented reality with building information modeling (BIM) to let contractors visualize the structures, eliminating the need for physical floor plans.  It helps to make BIM more precise and allows engineers to identify if the ongoing construction project follows the original model and spot errors in real-time.

4D Modeling and Visualization

Pennsylvania-based infrastructure and engineering software provider Bentley Systems launched mixed reality solution SYNCHRO XR for 4D modeling and visualization of construction projects.  Using Microsoft HoloLens, contractors and engineers can walk around and interact with digital models through intuitive gestures.  The models can help contractors to flag potential errors in project designs and visualize the construction schedule.

Smart Glasses

British multinational infrastructure group Balfour Beatty implemented Vuzix Blade smart AR glasses at one of its construction sites in the US to help with a request for information (RFI) from project stakeholders, who can no longer visit the sites due to the COVID-19 pandemic. Site managers walk through the project site wearing the Vuzix smart glasses, wherein clients can view the project progress remotely.

Virtual Guidance

Aussie tech startup Fologram rolled out an app to merge digital construction models with the physical jobsites to ease laying bricks in complex patterns.  The app pulls data from computer-aided design (CAD) software such as Rhino, translates it into digital instructions and projects them onto Microsoft’s HoloLens heads-up display.  Wearing the headsets, masons can virtually see where to place each brick more precisely.

Naveen concludes: “Despite their immense potential, AR and VR technologies are still falling short of widespread use in the construction industry.  Key concerns such as wearing bulky AR headsets for long hours, susceptibility to harsh jobsite environments and the non-availability of low latency Internet connectivity are hindering the mass adoption of the technologies.  As AR and VR continue to mature, they can be coupled with 5G and artificial intelligence to become an invaluable asset to the construction industry.”

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GM will announced boosting investment for EVs

General Motors Co will roll out details of an expanded and accelerated electric vehicle strategy in an effort to convince investors it can be a serious competitor to Tesla Inc, people familiar with the plans said.

GM Chief Executive Mary Barra, who is scheduled to speak at a conference hosted by Barclays, is expected to say the automaker is ready to spend more on electric models by 2025 than the $20 billion previously outlined, the sources said.

Supplier sources said previous plans to make the Cadillac brand all electric by 2030 are being sped up, possibly to 2025, and other sources said that acceleration will be repeated in other brands and in segments such as commercial vans.

The Detroit automaker is also expected to discuss a new timeline for many of the EVs to follow those already identified, such as the GMC Hummer EV pick-up and Cadillac Lyriq crossover, people familiar with the plans said.


Authors: (Reuters) Ben Klayman, David Shepardson


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Bentley’s US$100 million fund for digital twins

Infrastructure engineering software company Bentley Systems has announced US$100 million of venture funding to accelerate the development of infrastructure digital twins.  A digital twin is a digital representation of a physical object or system. The technology behind digital twins has expanded to include large items such as buildings, factories and even cities, and some have said people and processes can have digital twins, expanding the concept even further.

Bentley iTwin Ventures will invest in promising technology companies addressing the emerging opportunity for infrastructure digital twin solutions for roadways, railways, waterways, bridges, utilities, industrial facilities, and other infrastructure assets.

Bentley iTwin Ventures is a US$100 million corporate venture capital fund which will co-invest in startups and emerging companies that are strategically relevant to Bentley Systems’ objective of advancing infrastructure through going digital.  The fund will target investments in transformational digital twin solutions supporting the design, simulation, construction, and/or operations of physical infrastructure.

The fund will invest in early and mid-stage companies that demonstrate ability to develop applications and solutions that leverage and extend infrastructure digital twin opportunities, particularly in the public works and utilities, and industrial and resources, infrastructure sectors.

“Taking advantage of the momentum from Bentley Systems’ initial public offering, we are excited to expand our Acceleration Initiatives by formally launching the Bentley iTwin Ventures fund to support the growth of entrepreneurial companies dedicated to infrastructure digital twin solutions,” said Greg Bentley, CEO of Bentley Systems.

“Our iTwin Platform provides a scalable open-source foundation for technical and commercial innovation that will empower a vibrant ecosystem to creatively combine and connect what digital twins now make possible for infrastructure constituents.  Proprietary analytics, data services, benchmarking, and infrastructure-as-a-service commercial models, for instance, are not in Bentley Systems’ direct scope, but we are glad to have a stake in bootstrapping these future successes.”


By Andy Brown, November 11, 2020

Liquid-filled window absorbs solar heat by day, releases it at night

While double-glazed windows do help save energy, Singaporean scientists have tweaked the concept to make it even more effective.  Instead of leaving an air gap between the two panes of glass, the researchers have inserted a heat-absorbing, light-blocking liquid.

Developed at Nanyang Technological University, the experimental new “smart window” consists of two panes of ordinary glass, the space between which is filled with a solution consisting of a proprietary hydrogel, water, and a stabilizing compound.

During the day, as sunlight passes through the window, the liquid absorbs and stores that light’s thermal energy.  This keeps the room from heating up, reducing the need to run the air conditioning.

Additionally, as the liquid warms up, the hydrogel within it changes from a transparent to an opaque state.  Although this ruins the view out of the window, it also reduces the amount of visible light that passes through from outside, further helping to keep the room cool.

Before and after photos of one of the smart windows, the bottom half of which incorporates the new technology. Nanyang Technological University

When the sun goes down at night, the gel cools and becomes clear again, releasing the stored thermal energy.  Some of that energy passes through the glass and into the room, reducing demands on the building’s heating system.

And as an added bonus, the smart window reportedly absorbs exterior noise 15 percent more effectively than traditional double-glazed windows.

Based on simulations and real-world testing, it has been determined that use of the windows could reduce energy consumption in office buildings by up to 45 percent.  The university is now looking for industry partners to help commercialize the technology, which is described in a paper that was recently published in the journal Joule.

Scientists at Britain’s Loughborough University have been working on a similar system, although theirs utilizes plain water.  Once that water has been heated by the sun, it’s pumped out of the window and stored in a tank.  At night, the warm water is then pumped out of the tank and into pipes in the walls, heating the interior of the building.

Author: Ben Coxworth, November 05, 2020, New Atlas

Understand the facts about UV-C LEDs and Germicidal Applications

With the COVID-19 pandemic raging, interest in germicidal technologies has surged as well. Ultraviolet radiation, specifically in the UV-C (100‒280 nm) band, is one technology that has gone from a very niche subject to the front pages of major newspapers because UV-C energy can deactivate the virus.  So let’s consider the facts about germicidal UV-C and the sources that can produce such energy, including LEDs.

This column was prompted in part by a document we posted on the Center for Lighting Enabled Systems & Applications (LESA) website at Rensselaer Polytechnic Institute.  We posted the top 10 questions that we have been asked relative to germicidal UV-C and a coronavirus such as SARS-CoV-2. Being that this column is in LEDs Magazine, we will revisit part of our top 10 list and add information that is specific to the use of UV-C LEDs in germicidal applications.

The first question we are generally asked is whether UV-C radiation can kill SARS-CoV-2.  The fact is that a virus is not technically alive, so killing it is not the goal.  Rather, we seek a technology that can deactivate or suppress the virus.  And yes, UV-C radiation applied correctly can deactivate the coronavirus.

“Applied correctly” is the key phrase.  The application depends on whether you seek to disinfect a surface, water, or air.  Moreover, the germicidal efficacy depends on UV-C dosage.  Dosage is determined by the radiometric power or watts delivered by a UV-C source, the distance from the target, and the duration of UV-C exposure.  Distance is easily understood if, for instance, you want to disinfect a surface.  In an air disinfection application, such as within an HVAC air duct, the distance would not be easy to estimate, as air disinfection can happen along the length of the duct through which UV-C radiation, along with the air, passes.  Distance becomes an even more complex issue were you to try and use a UV-C source to disinfect all of the air in a room.  Digging into the details, UV-C irradiance is measured in watts per unit area (typically W/cm2 in the US) and dose is calculated by multiplying the irradiance by the exposure time in seconds to get energy per unit area [typically joules (J)/cm2].

Moving to UV-C sources, LEDs are progressing as an alternative to mercury-discharge lamps in all types of UV-C applications.  But just as early visible-light LEDs struggled to usurp legacy sources, UV-C LEDs face similar challenges.  Generally speaking, UV-C LEDs have relatively higher cost, lower output power, and shorter lifetime. We’d expect the LED manufacturers to overcome those limitations over time.

However, LEDs are viable in some UV-C applications.  The technology is already used embedded inside various water-disinfection systems ranging from a home kitchen faucet to pumps for water processing to water supply for soda dispensers.  Indeed, mercury lamps would be tough to deploy in such applications due to size and potential contaminant concerns.

Most of the UV-C systems that have been in the news of late, however, are more focused on surface or air disinfection. And most of those systems use legacy lamps. For example, LEDs Magazine covered a United Airlines application for disinfecting surfaces in the jet cockpit and a Jet Blue application that uses robots to disinfect the passenger cabin of a jet.

The output power restrictions of UV-C LEDs would limit the effective use of the components in some such applications, or the number of LEDs required could be prohibitively expensive.  Other applications such as deployment in HVAC ducting might be a different story.

When you think about LEDs relative to a legacy source such as a mercury lamp, you have to think about how a system based on the source would operate.  Source lifetime is very important for a mercury lamp because lamp warmup time and lifetime reduction with repeated on/off switching will require continuous operation even if the utilization rate (e.g., airflow) isn’t continuous.

LEDs can be powered on and off and achieve virtually full power output instantaneously. Cycling power does not damage the components. In an HVAC system, the UV-C LEDs could be turned off when air is not circulating.  So the consideration of product lifetime changes.  There is also evidence that LEDs used in pulse mode can deliver greater germicidal efficacy in some applications.  Some research has shown such efficacy improvement in water disinfection and E.coli.  The reason is not fully understood at this point and more research is needed.

We are also asked about LEDs at the so-called far UV-C wavelengths in the 222-nm range.  For now, there are no LEDs available at such short wavelengths and the challenges of delivering such LED components appear stout.  Our message, however, remains that only a thorough analysis of the application and the model of system usage will determine whether LED or legacy sources are the best choice in a project.

Author: Robert Karlicek, PhD, Director of the Center for Lighting Enabled Systems & Applications (LESA) for LEDs Magazine