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Propane Refrigerants | Earth Wise

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About 10% of the world’s total electricity supply is used for air conditioning.  If current temperature trends continue, the energy demands for space cooling will more than triple by the year 2050.  Air conditioning is a double threat to the environment.  Apart from using lots of energy, ACs also make use of halogenated refrigerants that are extremely powerful greenhouse gases.

The most common space cooling appliances are split-air conditioners, which use an indoor unit and an outdoor unit connected by pipes.  These split ACS mostly utilize HCFC-22 and HFC-410 as refrigerants, which have global warming potential scores as high as 2,256 – meaning they trap 2,256 times more heat than carbon dioxide. 

A study by the International Institute of Applied Systems Analysis in Austria has shown that propane is a far better choice as an air conditioning refrigerant.  Its global warming potential is actually less than 1 meaning it traps less heat than carbon dioxide.  According to the study, if air conditioners switched to propane refrigerants, the world would avoid about a tenth of a degree Celsius of additional warming, which is a significant contribution to meeting the goals of the Paris climate agreement.

Propane-based split-ACs are already available commercially in China and India.  Elsewhere, many national regulations prohibit their use, primarily due to codes restricting the use of refrigerants with higher flammability.  Given the increasingly urgent need for climate action, it seems to be time to reconsider regulations on refrigerants.

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Propane — a solution for more sustainable air conditioning

Photo, posted March 24, 2021, courtesy of Phyxter Home Services via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Saving Lives With Air Conditioning | Earth Wise

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This summer, extreme heatwaves struck the United States, Europe, and Africa.  Thousands of people died as a result.  In July, the impact of extreme heat in places ill-prepared for it was evident.  In the U.K., where air conditioning is uncommon, public transportation shut down, schools and offices closed, and hospitals cancelled non-emergency procedures.

Air conditioning, which we mostly take for granted in this country, is a life-saving tool during extreme heat waves.  However, only about 8% of the 2.8 billion people living in the hottest – and often poorest – parts of the world have AC in their homes.

A new study at Harvard modeled the future demand for air conditioning as the number of days with extreme heat continues to increase across the globe.  The researchers identified a massive gap between current AC capacity and what will be needed by 2050 to save lives, particularly in low-income and developing countries.

If the rate of greenhouse gas emissions continues on its present course, the study concluded that that at least 70% of the population in several countries will require air conditioning by 2050.  The number will be even higher in equatorial countries like India and Indonesia.  At this point, even if the goals of the Paris Climate Accords are met, an average of 40-50% of the population in many of the world’s warmest countries will still require AC.

The research looked at various scenarios.  One in which emissions continue to increase leads to widespread need for air conditioning even in temperate countries.  In Germany, 92% of the population would need it, and here in the U.S., 96% would need it.

Planning for future power systems must take into account the essential needs of a warming world.

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In a hotter world, air conditioning isn’t a luxury, it’s a lifesaver

Photo, posted July 24, 2021, courtesy of Phyxter Home Services via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Solar-Powered Target Store | Earth Wise

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Many companies have made sustainability commitments of various types. Environmental organizations have urged big-box and grocery stores to install solar panels on their rooftops and parking lots thereby reducing their energy usage and expanding the country’s supply of renewable energy.  These places occupy large areas and therefore are capable of supporting large solar arrays.

According to a report by two environmental advocacy groups, rooftop solar panels on retail stores could generate enough electricity to power the equivalent of nearly 8 million U.S. homes.

Target Stores are one of the retailers that has been making an effort to be a greener company.  Target has installed solar panels on about 25% of its approximately 1,900 stores.  The Target store in Vista, California, about 40 miles north of San Diego, is the company’s most sustainable store.  It already had solar panels on its rooftop, powering a portion of the store.

But now it has installed massive carports topped with solar panels high above its parking lot.  With these panels, this Target can now produce enough renewable energy to power the entire store, from its refrigeration to its heating and air conditioning. Adding in some of the other energy-saving features of the store, Target expects to produce 10% more energy than the store needs, which it will return to the local power grid.  This is Target’s first net-zero energy store.

Target is not the only big retailer going solar.   Home Depot, Lowe’s, and Walmart all have been installing solar panels on some of their rooftops.  Even some restaurants are trying to reach sustainability goals with solar panels.  This is a trend that hopefully will continue to grow.

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Target looks to massive solar panels in a California parking lot as a green model to power its stores

Photo, posted June 30, 2014, courtesy of Mike Mozart via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Smart Window | Earth Wise

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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.

Poverty And Climate Change

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According to the World Health Organization, climate change is expected to cause approximately 250,000 extra deaths per year between 2030 and 2050.  But climate change does not affect everyone the same.  In fact, the poorest people on the planet, who are often the least to blame for climate change, typically bear the worst of the impact.

Wealthier people and countries have more resources to shield themselves from the impacts of climate change.  For example, higher incomes allow people to purchase air conditioning as temperatures rise,  food as food prices soar, and homes in safer places.  Wealthy nations can also compensate citizens when climate change harms livelihoods. 

According to new research, people with lower incomes are exposed to heat waves for longer periods of time compared to those with higher incomes due to a combination of factors including location and access to heat adaptations like air conditioning.  This inequality is expected to increase as temperatures rise. 

The study, which was published in the AGU journal Earth’s Future, found that lower income populations face a 40% higher exposure to heat waves than people with higher incomes.  By the end of the century, the poorest 25% of the global population will be exposed to heat waves at a rate equivalent to the rest of the population combined.

On the other hand, the highest-income quarter of the population will experience comparatively little change in exposure to heat waves as their ability to keep up with climate change is generally greater.

The research team hopes its findings will prompt innovations into affordable cooling solutions for the world’s most vulnerable population. 

Climate change and poverty are, and will remain, inextricably linked. 

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Poorest people bear growing burden of heat waves as temperatures rise

Photo, posted October 27, 2019, courtesy of Jack via Flickr.

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Strategies To Cool Off Cities | Earth Wise

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Heatwaves in cities are becoming increasingly common and increasingly intense.  The warming climate is a big factor, but it is the nature of our cities that really drives up temperatures.  Solar radiation stored throughout the day on asphalt and buildings is released slowly during the night, which generates significant heat stress.

A study carried out by a major Barcelona university and published in the journal Urban Climate looked at the effectiveness of various ways to mitigate the heating effects in cities.  In particular, the study examined the effects of the use of white roofs on buildings and the expansion of urban green areas with daily irrigation in the Barcelona metropolitan area.  It simulated various scenarios incorporating combinations of these two mitigation strategies.

The strategy with the greatest impact was a combination of the use of both white roofs and the addition of six urban parks, which is a target set by the Barcelona Urban Master Plan.  This scenario resulted in an average temperature reduction of 2.25 degrees Fahrenheit.  The maximum reduction occurs during the mid-afternoon with a reduction of 7 degrees and the combination still provides more than 3 degrees of reduction at 9 pm.  Reducing temperatures this way also results in a reduction in energy consumption, with 26% less spending on air conditioning.

The 2-pronged strategy combines the benefits of reducing the temperature at night due to more urban green areas with the reduction of daytime heat due to both the increased reflectivity of white roofs as well as the irrigation of the green areas.

The study demonstrates how modeling efforts can help urban planners to counteract the impacts of heatwaves, which are likely to increase with climate change and intensification of urbanization.

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White roofs and more green areas would mitigate the effects of heat waves in cities

Photo, posted January 16, 2011, courtesy of Sean MacEntee via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Better Paint For Cooler Buildings | Earth Wise

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A research team led by scientists at UCLA have developed a super-white paint that reflects as much as 98% of incoming heat from the sun.  Such paint, if used on rooftops and other parts of buildings, could have a major impact on reducing the costs of keeping buildings cool.

Passive daytime radiative cooling is a well-known method to keep buildings cooler.  By having building surfaces reflect sunlight and radiate heat into space, building temperatures can be significantly lowered.  This in turn cuts down on air conditioner use and associated carbon emissions.

A roof painted white will result in lower indoor temperatures than a darker roof.  But a white roof will do even more:  it can reject heat at infrared wavelengths that are invisible to our eyes.  This results in even more radiative cooling.

The best performing white paints currently available reflect about 85% of incoming solar radiation.  The rest is absorbed by materials in the paint.  The new research has identified simple modifications in paint ingredients that lead to a major increase in reflectivity.

Current reflective white paints use titanium dioxide, which absorbs UV radiation and therefore heats up under sunlight.  The researchers studied replacing it with other substances such as barite – an artist’s pigment – or with powdered Teflon, both of which allow the paint to reflect more of the sun’s radiation. 

Many cities are encouraging the use of cool-roof technologies on new buildings.  Using the most reflective coatings possible on rooftops, if applied on a sufficiently large scale, could have a real impact on climate change as well as saving significant amounts of energy used for running air conditioners in buildings.

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UCLA-led Team Develops Ways to Keep Buildings Cool with Improved Super White Paints

Photo, posted August 15, 2012, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Roofs Going Green

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Green roofs are roofs on buildings that are partially or completely covered with vegetation and a growing medium, generally planted over a waterproofing membrane.  The modern version of these roofs began in Germany in the 1960s and spread to many other European countries over time.  With concerns about climate change and shrinking natural resources rising, green roofs are becoming increasingly popular across North America.  The Toronto-based organization Green Roofs for Healthy Cities estimates that the number in North America has increased by about 15% since 2013.

Replacing black asphalt and shingles with plants can lower the surrounding air temperature, filter dirty storm water, and reduce building energy use.  The National Research Council of Canada estimates that a green roof can reduce air conditioning use in a building by as much as 75%.  The roofs also help to reduce air pollution and greenhouse gas emissions according to the EPA.

As the benefits of green roofs become more widely known, cities around the world are passing green roof legislation.  Copenhagen passed a law in 2010 requiring all new commercial buildings to have green roofs if their roofs are not sloped too much.  Toronto was the first city in North America to pass a green roof law in 2009.  Over 640 green roofs covering more than five million square feet have since been constructed in Toronto.

Apart from the environmental benefits, green roofs are providing pleasant spaces in the urban environment that may include flower beds, trees, herb gardens, gazebos and picnic tables.  As for the economics, studies show that over the course of a roof’s lifetime, green roofs are actually considerably cheaper than conventional roofs taking into account energy savings.

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The Green Revolution Spreading Across Our Rooftops

Photo, posted July 15, 2014, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A See-Through Heat Shield

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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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See-through film rejects 70 percent of incoming solar heat

Photo courtesy of MIT researchers/MIT. 

Earth Wise is a production of WAMC Northeast Public Radio.

City Geometry And Urban Heat Islands

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More than half of the world’s people now live in cities so understanding climate issues in cities is crucial.  One of the most important city climate effects which has a profound impact on both human health and energy consumption is the Urban Heat Island Effect.

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Breathe Better With Air Conditioning

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For many people, commuting to and from work is a time-consuming, stressful part of their lives.  In fact, the average American spends nearly an hour a day facing traffic jams and congested highways.   There are direct health hazards in commuting as well.  Drivers are exposed to increased amounts of air pollutants that have been linked to a wide range of medical problems including cardiovascular disease, respiratory issues and even lung cancer.

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Solar Power In Las Vegas

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The Las Vegas Strip has been referred to as an energy consumption nightmare.  Just one look at the place provides evidence for the claim:  an endless sea of lights, glitz and glamour and cavernous casinos running huge banks of air conditioning equipment in the desert heat.  Even with Boulder Dam a hop, skip and jump away, Vegas is struggling to meet its electricity needs.

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Green Steam

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Many of the world’s biggest cities have miles of underground pipes built decades ago that provide district energy.   District energy systems use a central plant to produce steam, hot water or chilled water that is then piped underground to individual buildings for space heating, domestic hot water heating and air conditioning. As a result, individual buildings served by a district energy system don’t need their own boilers or furnaces, chillers or air conditioners.

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Female Thermal Demand

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office-temp

If you work in an office, you know the following scenes are not unusual: a coworker wearing a woolly sweater at her desk on a 90-degree day; a woman vigorously rubbing her hands together for warmth in the conference room; or two colleagues engaged in a passive aggressive battle over the thermostat.

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