Earth Wise

A look at our changing environment.

You are here: Home / Archives for roofs

roofs

Community Solar On The Rise | Earth Wise

By Leave a Comment

Community solar is a way for people who can’t put solar on their own roofs to still take advantage of its benefits.  Whether they can’t afford to install their own panels, have too much shade on their roof, or don’t even own a home, community solar is another way to participate in green energy.

Community solar – also called “shared solar” or “solar gardens” – is a kind of development in which consumers can subscribe to a large solar installation in their area and receive credits on their monthly utility bills for their share of the solar electricity produced.

The large majority of community solar installations are in six states:  Colorado, Illinois, Massachusetts, Minnesota, New Jersey, and New York.  After substantial growth in community solar in 2022, New York now is the national leader, thanks to initiatives by the state government and the nonprofit sector.  Some programs focus on giving low-income households access to solar.  As of last fall, New York had over 728 community solar projects online.

One should understand that electrons are indistinguishable.  The power generated by a community solar installation is not piped directly to subscribers’ homes.  It just goes into the grid.  Subscribers get credit for their share of the power, but that is essentially a matter of bookkeeping, not physics.

The federal government now has $7 billion that can be used for community solar as part of the Greenhouse Gas Reduction Fund within the Inflation Reduction Act enacted last August.  The EPA plans to award up to 60 grants to assist projects deploying residential and community solar.  Research firm Wood Mackenzie forecasts the community solar market will double by 2027.

**********

Web Links

Community Solar Is About to Get a Surge in Federal Funding. So What Is Community Solar?

Photo, posted November 18, 2008, courtesy of the Oregon Department of Transportation via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Are Companies Really Reducing Emissions? | Earth Wise

By Leave a Comment

Many companies around the world are declaring tremendous progress in reducing their greenhouse gas emissions.  Sometimes these claims are the result of actions that really do  reduce emissions but other times they are the result of something called “market-based accounting”. Businesses buy credits from clean energy providers that allows them to say they are running on green power when they actually are not.

The market analysis firm Bloomberg Green analyzed almost 6,000 climate reports filed by corporations last year and found that over 1,300 of them employed market-based accounting to erase over 120 million tons of emissions from their records.

Some clean energy contracts do have major climate benefits.  For example, companies like Amazon, Nestle, and Target have signed long-term power purchase agreements that ultimately help renewable developers finance new energy projects.

On the other hand, renewable energy credits are often short-term transactions with existing facilities and do little to stimulate investment or otherwise lead to greater use of green power.  They simply shift around ownership of existing renewable energy without doing anything new for the climate.

Some companies have made meaningful cuts to their pollution by putting solar panels on their roofs, upgrading their lighting and air conditioning equipment, and so on.  But many are reluctant to spend their capital in this way, even if it eventually saves money through lower electric bills.

Customers and shareholders want to see corporations do their part in reducing emissions.  But too many are making grandiose claims enabled by market-based accounting while doing far too little to help the environment.  Dubious claims of climate progress are not harmless; it is essential for the world’s companies to really do their share.

**********

Web Links

What Really Happens When Emissions Vanish

Photo, posted July 16, 2014, courtesy of Mike Mozart via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Recycling Shingles | Earth Wise

By Leave a Comment

Every year in the US, about 13 million tons of asphalt material is removed from old roofs to be replaced with new shingles.  Only about 10% of that is recycled for use in paving and various roadway projects.  The other 12 million tons of asphalt ends up in landfills where it takes a very long time to break down.

GAF, the largest roofing manufacturer in North America, has developed a shingle recycling process for which it has received three patents.  The process involves grinding torn-off shingles into a refined material which can then be introduced into the shingle manufacturing process.  The material – referred to as RAS for recycled asphalt shingles – has the potential to significantly reduce the amount of virgin asphalt needed to make new shingles.

Tests by GAF reclaimed upwards of 90% of the waste shingle material and produced new shingles containing up to 15% recycled content.  Underwriters Laboratories certified the shingles containing RAS material with regard to their safety and effectiveness.  The GAF process opens to door to creating a circular, sustainable economy for asphalt used for roofing shingles.

Roofs play an important role in the transition to a green economy.  Apart from recycling asphalt shingles, there are increasing options for solar shingles, which take the place of both traditional asphalt shingles and ordinary solar panels by integrating them into a single roofing product.  There are also so-called green roofs, which replace conventional roofing materials with a contained green space atop a building. Such roofs provide stormwater management, cooling, and an interesting aesthetic.

All aspects of buildings play important roles in our environment – even their roofs.

**********

Web Links

5 Ways Roofers Can Celebrate Earth Day, Everyday

Photo, posted April 15, 2012, courtesy of Robert Taylor via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Solar-Powered Target Store | Earth Wise

By Leave a Comment

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.

**********

Web Links

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.

Living Walls | Earth Wise

By 1 Comment

Green roofs are popular in many European countries.  A green roof is a layer of vegetation planted over a waterproofing system installed on a flat or slightly sloped roof.  Such roofs provide shade, remove heat from the air, and reduce temperatures of the roof surface, reducing energy use in the building and diminishing the urban heat-island effect.

A recent study by the University of Plymouth in the UK looked at the effectiveness of living walls – essentially the equivalent of a green roof located on the wall of a building.

The study looked at the effect of retrofitting an existing masonry wall with an exterior living wall façade consisting of a flexible felt fabric sheet system with pockets holding soil in which plants could grow.

Five weeks of measurements demonstrated that the amount of heat lost through the retrofitted wall was 31.4% lower than that of the original structure.  They also found that daytime temperatures within the newly covered section remained more stable than the area with exposed masonry, so that less energy was required to heat that area.

The concept of living walls is fairly new but could be valuable in temperate climates such as Great Britain.  Buildings in the UK account for 17% of greenhouse gas emissions and space heating accounts for 60% of all the energy used in buildings.  So, improving the thermal performance of buildings would have a significant effect on reducing energy use and therefore emissions.

So-called green infrastructure, including green roofs and living walls, provides a nature-based solution that can help tackle climate change, air pollution, and other modern urban problems.

**********

Web Links

Living walls can reduce heat lost from buildings by over 30%, study shows

Photo, posted June 19, 2011, courtesy of Linda Hartley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar On Commercial Buildings | Earth Wise

By Leave a Comment

The United States installed 3.6 gigawatts of photovoltaic solar capacity in the first quarter of this year to reach a total installed capacity of 81.4 GW.  That is enough to power about 16 million American homes.  More than 2/3 of that capacity has been installed during the past five years.  

There has been a boom in solar installations in recent years and, until the Covid-19 pandemic stuck, 2020 was expected to be the biggest year yet.  Now the unprecedented health, social, and economic conditions in our country creates great uncertainty in such forecasts.

Nevertheless, the opportunities for growth in solar power continue to be substantial.  A new report from the energy research firm Wood Mackenzie looked at the prospects for using the roof space of commercial buildings for solar power.

Currently, just 3.5% of commercial buildings in the U.S. have solar panels on their roofs.  Another 1% of those buildings are attached to solar projects located off-site.  The report looked at how many buildings are potential targets for solar projects.

After accounting for buildings that are too small or that use too little electricity to make solar power a worthwhile investment, the report estimated that 70% of commercial buildings in the U.S. – amounting to some 600,000 sites – are candidates for solar installations.  Doing this would provide 145 GW of new solar capacity, which is nearly twice as much as currently exists in this country. 

Commercial solar installations have their own unique logistical and financial challenges.  While utility solar can scale to lower costs and residential solar has financing opportunities, commercial solar has neither.  But ultimately, it represents an important opportunity for our future energy system.

**********

Web Links

U.S. Commercial Rooftops Hold 145 Gigawatts of Untapped Solar Potential

Photo, posted June 25, 2014, courtesy of Rob Baxter via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Roofs Going Green

By Leave a Comment

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.

**********

Web Links

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.

Capital Region Community Solar

By Leave a Comment

New York’s Capital Region is getting a major new community solar farm.  A community solar farm is a solar power installation whose output is shared by multiple community subscribers who receive credit on their electricity bills for their share of the power produced.  The primary purpose of community solar is to allow members of a community to have the benefits of solar power even if they cannot or prefer not to install solar panels on their own property.

US Light Energy has broken ground on the Sugar Hill Solar Farm, to be located on 40 acres of land on the Sugar-Hill/Sugar-View Farm in Clifton Park.  The 7-megawatt, ground-mounted solar project will include nearly 20,000 solar modules.  When fully operational later this year, the facility is expected to produce more than 8.6 million kilowatt-hours of energy a year.

The farm will be part of New York state’s Community Solar Program, and the electricity it generates can be supplied to customers anywhere in National Grid’s existing distribution system.  Residential and commercial properties in Clifton Park will have 30 days to subscribe before the solar energy generated by the farm is opened to the general public.  Subscribers of community solar farms typically save 10% on their electricity bills.

There are already community solar programs in operation in several Capital Region communities, but this is the first one in the Clifton Park Area.  Apart from providing savings on utility bills, community solar allows consumers to support clean, locally generated power with little or no upfront costs.  Not everyone is in a position to put solar panels on their roof, but community solar is increasingly an option for New York residents.

**********

Web Links

Construction begins on 7-MW community solar farm in New York

Photo, posted March 19, 2012, courtesy of Kate Ausburn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Schools And Solar Power

By Leave a Comment

A new study from Stanford University looked at the benefits of installing solar panels on the rooftops of schools.  According to the study, taking advantage of all the viable space for solar panels could allow schools to meet up to 75% of their electricity needs and reduce the education sector’s carbon footprint by as much as 28%.

Given the long list of spending priorities for schools, solar power seems like a luxury item.  But the Department of Energy estimates that K-12 schools spend more than $6 billion a year on energy and, in many districts, energy costs are second only to salaries.  In the higher education sector, yearly energy costs add up to more than $14 billion.  In total, educational institutions account for approximately 11% of energy consumption by U.S. buildings and 4% of the nation’s carbon emissions.

The Stanford study suggests that investments in the right solar projects combined with the right incentives from states could free up much-needed money in school budgets.

To no surprise, the study finds that three large, sunny states – Texas, California, and Florida – have the greatest potential for generating electricity from solar panels on school rooftops.

Apart from measurable effects on air pollution and electricity bills, solar installations at schools can also provide new learning opportunities for students.  In fact, some schools are already using data from their on-site solar energy systems to teach students basic ideas about fractions, as an example, as well as more sophisticated concepts such how shifting solar panel angles can affect power production.

According to the study, nearly all states could reap value from school solar projects.

**********

Web Links

What happens when schools go solar?

Photo, posted February 28, 2011, courtesy of Black Rock Solar via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar Equity for Low-Income Communities

By Leave a Comment

A couple of years ago, the number of American roofs covered with solar panels passed the one million mark and the numbers keep growing.  But nearly half of U.S. households – accounting for more than 154 million people – aren’t able to host their own solar arrays because they lack suitable rooftop space, or they rent their homes.  But millions more simply can’t afford to spend tens of thousands of dollars to buy or lease solar panels.

In recent years, community solar has become popular.  These are projects where multiple participants own or lease shares in a mid-sized solar facility and receive credits that lower their monthly utility bills.  Community solar in the U.S. has more than quadrupled just since 2016.

However, the majority of community solar subscribers to date have been businesses, universities, government agencies, and higher-earning households.  These users can generally pay steep project enrollment fees or meet various financial requirements.  Meanwhile, those who could benefit most from access to renewable energy and lower utility bills – low-income residents – have largely been left out.

Low-income households on average spend over 8% of their income on utility bills, about three times more than moderate- to high-income households.  So, reducing electricity bills with community solar power is a big deal for them.

Given this situation, there are now a growing number of programs that make use of community solar to reduce living expenses for low-income households.  In a dozen states, new programs include a variety of mandates, financial incentives, and pilot programs targeting benefits for people with low incomes.  These programs will allow them to participate in both the environmental and economic benefits of renewable energy.

**********

Web Links

Energy Equity: Bringing Solar Power to Low-Income Communities

Photo, posted November 27, 2012, courtesy of Oregon State University via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Another Way To Make Solar Cells

By Leave a Comment

Millions of rooftops now contain solar panels and the majority of the solar cells that make up those panels today are made from silicon.  Silicon solar cells require expensive, multi-step processing conducted at very high temperatures in special clean room facilities.  Despite these complications, the price of solar panels has continued to drop dramatically over the years.

But even as the price of solar cells gets lower and lower, there are still widespread efforts to find even better ways to make them.   One of those ways is with perovskite solar cells.  Perovskites are materials with a characteristic crystal structure and are quite common in nature.  Perovskites can be formed with a wide range of elements and can exhibit a variety of properties.

They were first used to make solar cells about 10 years ago and those first cells were unimpressive in most respects.  However, there has been steady progress since that time.  The potential advantages of perovskite solar cells are that they can be made from low-cost materials and can be manufactured using liquid chemistry, a far cheaper process than what is used to make silicon cells.

Researchers at MIT and several other institutions have recently published the results of research on how to tailor the composition of perovskite solar cells to optimize their properties.   What used to be a trial-and-error process can now become much more engineered and should lead to perovskite solar cells with performance that could exceed that of silicon cells.

Silicon solar panels are a huge, worldwide industry and displacing them in favor of an alternative technology is a tall order.  But if perovskite cells can be optimized for large-scale manufacturability, efficiency and durability, they could definitely give silicon a run for its money.

**********

Web Links

Unleashing perovskites’ potential for solar cells

Photo courtesy of Ken Richardson/MIT.

Earth Wise is a production of WAMC Northeast Public Radio.

Making Cities Cooler

By Leave a Comment

Cities are particularly miserable during heatwaves.   With lots of concrete and asphalt surfaces, they soak up lots of heat and re-radiate it.  Lots of tall buildings block cooling breezes.  Factor in car exhaust and heat from air conditioners and it all adds up to the urban heat island effect.  Cities can be several degrees warmer during the day and as much as 20 degrees warmer at night.  All of this extra heat is not just a comfort issue, it is a serious health problem.

[Read more…] about Making Cities Cooler

Cooling Cities With White Roofs

By Leave a Comment

The phenomenon of urban heat islands has been well known since the 19th century.  The materials from which city buildings and roads are made reflect much less solar radiation and absorb more of it than the vegetation they have replaced.  The absorbed energy is then radiated in the form of heat into the surrounding air making cities warmer.

[Read more…] about Cooling Cities With White Roofs

Spray-On Solar Cells

By

One of the most exciting possibilities for future solar energy technology is that of solar cells that can be sprayed or printed on to surfaces like the windows of skyscrapers, the roofs of sports utility vehicles, or the walls of houses.  And the expectation is that such technology would be far cheaper than today’s silicon-based solar panels.

[Read more…] about Spray-On Solar Cells

One Million Roofs

By

Sometime early in May, the United States installed its one millionth solar energy system.  Achieving this milestone took the solar industry about 40 years to accomplish.  Because of the phenomenal growth of solar power in this country, industry experts predict that it will only take two more years to reach the second million and there are predictions that by the year 2025, there will be one million new installations in the U.S. each year.

[Read more…] about One Million Roofs

Mandatory Solar In San Francisco

By

California leads the nation in the use of solar energy with well over half the country’s solar electric capacity. The state is the home of several of the largest thermal solar generating plants in the world and between those and multiple utility-scale photovoltaic plants, California utilities get more than 5% of their power from the sun.

[Read more…] about Mandatory Solar In San Francisco

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)