Researchers at the US Department of Energy used the rise in extreme heat events as an opportunity to find unique solutions to help people beat the scorching heat and keep their homes cool. Three different types of roofing material – solar panels, green roofs, and cool roofs – were put up to the test to determine which ones lowered temperatures and air conditioning consumption during heatwaves. The results are explored in this article.

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Summer is a time to relax, spend time with friends, travelling and making memories. For many, it is also a time to stay indoors because it is too hot outside. At least the latter has become more commonplace over the past decade. In the US alone, heatwaves have increased 200% from an average of two per year in the 1960s to six per year in recent years, lasting an average of four days. The heatwave season now lasts over 70 days, meaning that, on any given summer day, there is a 34% chance the thermometer will be reading higher than normal. 

As temperatures rise, air conditioning (AC) gets cranked up as well. A rush of cold air is a welcome reprieve from sweaty and sticky conditions outside. 

And yet, the very same technology that is helping the world cool off is also heating it up. Air conditioning alone is responsible for 10% of total energy consumption worldwide and this number is predicted to grow dramatically into the future. The higher the temperature, the more the AC runs. The more the AC runs, the more energy is used. The more energy used, the greater the emissions. The greater the emissions, the higher the temperature. And repeat. 

Unfortunately, vacuuming carbon dioxide (CO2) out of the sky will not become feasible on a large-scale for several decades, and 100% clean, renewable energy has its own list of hurdles to clear before it can completely replace fossil fuels. So, how can this cycle be broken? 

Researchers at the US Department of Energy’s (DOE) Argonne National Laboratory may have found an answer while studying the potential for green roofs, solar panels, and cool roofs to reduce the temperature and AC consumption in a building. PV solar panels and green roofs may get all of the publicity, but a cool roof proved to be most effective during a heat event, lowering temperatures by 1.5C and AC consumption by 16.6%.

Researchers at the Argonne National Laboratory’s Center for Climate Resilience and Decision Science (CCRDS), which was responsible for the study, led by its director Rao Kotamarthi, focused on the Chicago Metropolitan Area (CMA), which endured a devastating heatwave in 1995, and saw the heat index reach 120F (48.8C) just this past summer. They created data models to represent the three-dimensional heat transfer properties of the diverse cityscape, including shading from trees, building height, and urbanisation density. These models measured how a mass deployment of each of the roof types impacted a building’s temperature and need for air conditioning using weather data collected between 21 August and 27 August 2021, during which a one-day heat event occurred.

Why Focus on Roofs?

A building can gain heat from a few different sources: the activity inside, the temperature outside, and the radiation that arrives via the rays of the sun. While TVs, ovens, warm bodies, and whether or not it is a hot day certainly create a need for AC, the sun’s radiation turns up the temperature more than anything else. 

Cooling down a space can be accomplished in many ways, including larger and more efficient air conditioners. However, as previously mentioned, the energy demand from AC units is projected to keep growing at a fast rate in the coming years as the climate crisis intensifies. So, instead of pumping hot air out, it makes more sense to never let a building heat up in the first place.

This goes to show that the ability for a roof to reflect solar radiation back into the environment and away from the building’s residents is integral in making sure it does not get too hot indoors.

A cool roof is designed to reflect more sunlight than a conventional roof, absorbing less solar energy. The reflective characteristics are increased from a mixture of colour choice, like white, and material choice, like ceramic tile, metal, or specialty shingles. The end result is a roof that can reflect up to 80% (an albedo of 0.8) of the solar radiation it is bombarded with. 

In the study, researchers measured roofs covered by solar panels (0.2 albedo), green roofs (0.25 albedo), and cool roofs (0.8 albedo) as well as a control scenario for a standard roof (0.2 albedo).

The Results

Throughout the course of a day, each roof showed an ability to reduce its surface temperature relative to the control scenario, peaking in the late afternoon when outside temperatures began to reach their highest point. The cool roof was the most effective in this measure, lowering temperatures by 1.5C compared to 1.2C for green roofs, and 0.6C for solar panels. 

As day shifts to night, some of the radiative energy absorbed by a roof can begin to flow into the building, raising the indoor temperature. Cool roofs were the only solution that did not exhibit nighttime warming because they reflect rather than absorb solar energy.

The effectiveness of a cool roof also demonstrated an inverse relationship with the urbanisation of the city, meaning that, as the city became more dense with skyscrapers, roads, and traffic (all factors that increase the Urban Heat Island effect), the cooler a building was kept. Currently around 55% of the world population lives in urban areas, and by 2050 that number is projected to reach 6.6 billion people, equivalent to 66% of the world’s population. 

All of this avoided temperature gain is going to alleviate some of the burden on an AC unit because it will be staving off less heat. And the less cooling an air conditioner needs to do, the less energy it will consume. 

The cool roof also made the largest difference by reducing overall AC energy consumption by 16.6% across the Chicago Metropolitan Area, followed by green roofs at 14.0%, and solar panels at 7.6% (excluding any energy created by the solar panel itself). While 16.6% may not seem like a jaw-dropping number, every kilowatt-hour of energy saved will help protect electrical grids from a dramatic rise in demand due to both increased human consumption, and mass adoption of technologies like EVs.

Are Cool Roofs the Future?

Cool roofs are a simple solution that has proven its effectiveness time and time again across the globe, so why are they not more popular? 

A silver bullet, save-the-day technological breakthrough is exciting to dream of, instilling hope, and drawing the attention (and dollars) of many. Changing the material on a roof? Much less so. But in situations where a small reduction in emissions here and a better use of electricity there begin to add up, the simple answer is often the best answer. Because the reality of it is that the vast majority of progress towards net-zero will be made by limiting the emissions currently being produced rather than pushing this problem off into the future. 

The research team plans to continue their work, conducting more experiments across wider ranges of cityscapes, and including seasonal data. As more evidence mounts in its favour, one can look to pioneers like the state of Telangana in India which recently announced a Cool Roof Policy that aims to bring 300 square kilometres of heat-reflecting roofs to the state by 2028 saving 600Gwh per year of electricity.

Will it be enough for cool roofs hit the mainstream?

The post Cool Roofs Are a Sustainable Solution to Beat the Heat, but Will They Ever Hit the Mainstream? appeared first on Earth.Org.

The Alaska Longline Fishermen’s Association (ALFA) has been on a multi-year journey that saw the group partnering with the US Department of Energy’s (DOE) Energy Transitions Initiative Partnership Project and researchers from the National Renewable Energy Laboratory (NREL) and Sandia National Laboratories. The goal? Reducing the environmental impact of commercial fishing. The answer? Hybrid fishing boats.

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Hidden in the pristine rainforests between Alaska’s Glacier Bay National Park and Tongass National Forest is Sitka, an island community proud of its culture and relationship with nature. Brown bears and eagles roam the forest floors and mountain peaks while salmon patrol the seas. Sitka, in fact, is home to all five species of Pacific salmon, so it is no surprise that fishing is embedded in the culture. This spring, a much-maligned commercial fishing industry will take some pivotal steps toward working with the delicate ecosystem it relies upon. 

A typical fishing trip requires boats to power through miles of ocean, troll a wide area while looking for their catch, and, of course, return home safely. Diesel engines would drive a vessel for years on end to make this trip a possibility, at least until now. ​

Hybrid Fishing Boats

I Gotta, a 46-foot salmon troller and subject of the experiment, will be one of the first of its kind when its low-emission system goes into operation next spring. Researchers specialising in commercial vehicle decarbonisation were able to strike the right balance between cutting fuel costs and emissions and maintaining the boat’s speed and range. Using historical data of the entire ALFA fleet, solutions ranging from future fuels like hydrogen and ammonia to fully electric propulsion systems were considered for retrofitting the salmon troller. 

“Once we looked at the data, built the models, and ran the analysis it became clear that a plug-in hybrid model was the right path forward for this boat,” said Michael Lammert, a researcher at NREL.

I Gotta, one of the first low-emissions fishing vessels in Alaska. Photo: Eric Jordan.

Using a hybrid battery-diesel design, I Gotta will be able to travel at full speed, then cut the diesel engine and switch to a battery-electric motor while fishing, resulting in a reduction in fuel use of about 80%. 

“Our fishermen are really eager to reduce their greenhouse gas emissions and their fuel costs” said Linda Behnken, Executive Director of ALFA. Not only will the new troller have a hybrid system powering it but that system will also be charged with electricity from Sitka’s hydroelectric dams. A 100% renewable energy source, further decreasing greenhouse gas emissions.

“We care about our legacy to the next generation of fishermen and people who live in these coastal communities. This isn’t just a way to earn a living – it’s a way of life. And this is our way to honour our deep commitment to the ocean” said Behnken. 

The ocean they have such respect for has changed quite a bit since the Industrial Revolution. One of the most impactful changes is the pH level falling from 8.2 to 8.1. That small change in number represents a 30% increase in acidity. This is in large part because oceans act as the world’s largest carbon sink absorbing about 30% of all carbon dioxide (CO2) released into the atmosphere. A more acidic ocean can cause integral species of marine ecosystems, like oysters and corals, to suffer. When CO2 is absorbed by seawater, it creates an environment that consumes the very ingredients needed to form shells and skeletons, even leading to some beginning to dissolve. 

A pteropod shell shown dissolving overtime in seawater with a lower pH. Image: NOAA.

More about the topic: What is Ocean Acidification?

It has taken a long time for the fishing industry to deploy low-emissions vehicles, even when high fuel costs can eat up to 30% of a boat’s revenue, according to Behken.

Small commercial boats have been deterred from testing new technologies by the risk of a less-than-stellar fishing season due to a compromised vessel. That’s why ALFA sought the DOE programme along with the additional grants. Removing this barrier was all it took to get these fishing boats on board with being early adopters of cutting-edge propulsion systems. 

ALFA is also planning significant outreach and training to ensure Sitka community members have the opportunity to benefit from the project’s efforts. Starting with the retrofitting of I Gotta, local boat builders will handle all installation for new hybrid or electric systems. Renewed funding will also allow research to continue by testing three different propulsion systems based on various ways fishing boats travel. I Gotta may be the pioneering boat, but the group has aims to enlist its entire fleet of over 160 small-boat commercial fishers committed to sustaining salmon fishing for future generations.

“Our goal is to inspire decarbonisation across more fleets…we hope to set an example by walking the walk and showing how it can be done.”

Featured image: Forest Service Alaska Region, USDA/Flickr

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For the first time in two decades, American homes may face updated water heating standards. A move that aims to lower utility bills and cut down emissions.
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On 21 July, 2023, the US Department of Energy (DOE) proposed long overdue changes to the efficiency standards of residential water heaters. If finalised and implemented, these new water heating standards would avoid 501 million metric tonnes of greenhouse gas (GHG) emissions and save Americans nearly $200 billion over the next 30 years, according to DOE. 

Water heating is responsible for roughly 13% of both annual residential energy usage and consumer utility costs, and this number can be even higher for renters and low-income households who spend a greater percentage of their income on utility bills. By increasing the efficiency of electric and gas-fired water heaters, homeowners and renters alike would save $11.4 billion annually on their energy and water bills. This would be done by requiring the most common-sized electric water heaters to achieve efficiency gains with heat pump technology and gas-fired instantaneous water heaters to adopt condensing technology. 

“Today’s actions – together with our industry partners and stakeholders – improve outdated efficiency standards for common household appliances, which is essential to slashing utility bills for American families and cutting harmful carbon emissions,” says US Secretary of Energy Jennifer M. Granholm.

According to DOE, consumers could expect to see an average savings of almost $2,000 over the lifetime of the appliances, which is about 10-15 years.

“This has been a long time coming, but it’s a strong proposal that will cut household bills, reduce strain on the electric grid, and help protect the climate. The department should look to finalize it promptly next year,” said Steven Nadel, executive director of the American Council for an Energy-Efficient Economy (ACEE). This came as part of a joint statement issued by various industry stakeholders and advisors. 

Heat pumps have gained popularity because of their ability to provide heated air and water two to three times more efficiently than traditional electric solutions. However, despite the energy and emissions benefits, this technology is sparsely used in American homes. A problem the Biden-Harris administration hoped to address with the Inflation Reduction Act, and the many incentives and tax rebates designed to “expand the accessibility and [increase] the affordability of water heaters […], making it easier for families across the nation to switch to a more efficient model when deciding to replace a water heater.”

These changes must still be accepted, and, even if implemented, they would come into effect for six more years. If the lofty goals of net-zero by 2050 are to be reached, technology like heat pump water heaters will need to be widely adopted, and at a much quicker rate than they are now. The proposal is just one of the many advanced by the Biden-Harris administration as they continue to update efficiency standards of different product categories. All in the name of energy efficiency and savings.

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