Jay Arehart News

Architectural engineering receives DOE Zero Energy Design Designation

Anonymous — Tue, 04 Oct 2022 15:04:04 +0000

Architectural engineering receives DOE Zero Energy Design Designation Anonymous (not verified) Tue, 10/04/2022 - 09:04

Susan Glairon

CU Boulder’s architectural engineering Bachelor of Science degree program has earned a Zero Energy Design Designation from the U.S. Department of Energy.

The new DOE designation, awarded to 17 educational programs nationwide, recognizes the growing importance of zero-energy design, which means a building produces as much energy as it consumes in a year. The designation honors post-secondary academic programs that require students to apply the best practices of zero energy design in their projects.

Jennifer Scheib, an assistant teaching professor who led CU Boulder’s 2021 Solar Decathlon team to a first-place win, said the new designation recognizes the program’s longtime sustainability focus.

“It’s not just us saying we care about sustainability,” Scheib said. “A third party reviewed our curriculum and said, ‘Yes, this program is focused on sustainability.’ Not only are we an accredited engineering program, but sustainability is part of our course goals.”

The Zero Energy Design Designation Program supports the Biden-Harris Administration’s goal of a net-zero emissions economy by 2050. With buildings being one of the main contributors to carbon emissions, building professionals must be trained to design and construct high-efficiency, low-carbon buildings powered by renewables to achieve this goal, the DOE said. Today, 35 percent of the nation’s energy-related carbon dioxide emissions are attributed to buildings.

The program’s senior design capstone class, taught by Assistant Teaching Professor Jay Arehart, is at the core of the DOE designation, Scheib said. The senior capstone class gives all students — not just those able to participate in the Solar Decathlon build activity — the opportunity to learn about sustainability goals and design and modeling practices for buildings and to put those skills to use on a large design project. During the year-long course, fourth-year students design a zero-energy commercial building.

CU Boulder has participated five times in the DOE’s Solar Decathlon competition’s build program, winning first place in 2002, 2005, and 2021, and their involvement in the decathlon led to Scheib sending in the curriculum and meeting with DOE staff for consideration for the Zero Energy designation. During the collegiate competition, students design and build high-performance, low-carbon buildings that mitigate climate change and are affordable, resilient and energy efficient.

“Our students are our future,” Scheib said. “If they want a sustainable world for themselves and their children, they need to be aware of the amount of energy used in the built environment. We want to make sure they have those skills.”

Scheib added that zero-energy building is not only important for society, but also for the students’ pathway after graduation.

“It’s important for us to also let employers know that our students have those skills,” she said. “Employers want young people who know how to energy model.”

The new DOE designation, awarded to 17 educational programs nationwide, honors post-secondary academic programs that require students to apply the best practices of zero energy design in their projects.

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Bloomberg: The Best Cities for Low Carbon Emissions Aren’t the Tallest

Anonymous — Mon, 30 Aug 2021 15:58:01 +0000

Bloomberg: The Best Cities for Low Carbon Emissions Aren’t the Tallest Anonymous (not verified) Mon, 08/30/2021 - 09:58

As the world continues to urbanize, cities are reaching new heights every year. The southern Chinese city of Shenzhen, for example, built 14 new skyscrapers in 2018 alone. The pursuit of such lofty living spaces follows the conventional thinking that it’s more sustainable for growing cities to build up than build out.

Compact, high-rise cities are the antithesis to urban sprawl, and in theory, they limit the carbon footprint of the built environment in part because they can house more people in fewer structures. That’s significant considering that buildings currently account for more than half of a city’s emissions on average. Living in a dense city is also notably less energy-intensive, on a per-person basis, than spread-out suburban or rural life.

But a new study suggests that while density is indeed necessary to limit the greenhouse gas emissions of a growing population, height is not. In fact, a densely packed city of low-rises — think central Paris, where buildings typically stay below 10 stories — may be the best kind of urban environment for curbing carbon, even if they use more land than a high-rise-filled one that accommodates the same number of people, according to the researchers.

“The architectural futurism in which the way buildings have been depicted over the last five years has really focused on skyscrapers that have trees hanging off of them, and that appear to be very green,” says Jay Arehart, an architectural engineer at University of Colorado Boulder and a coauthor of the report, published last week in the journal npj Urban Sustainability. “But in reality they’re not.”

At least not always.

He says the calculation begins to change when you consider the emissions generated over the entire lifecycle of a city’s built environment, including the manufacturing of construction materials and the deconstruction of old buildings — not just what’s produced to keep the lights on. “As soon as you start building taller, you need more materials,” he says, pointing to the need for bigger foundations and larger steel columns, for example, which in turn involve more embodied, or hidden, carbon.

There are also limitations to how densely developers can realistically pack high-rises, and how many people those buildings can house — which affect both land use and efficiency. Skyscrapers require large footprints and gaps between like-sized buildings, and as they grow taller, the usable space on each floor diminishes. “When you look at New York, for instance, the spaces between buildings are actually quite significant in comparison to more low-rise environments, like in any late 19th century European city,” Arehart says.

To compare the full lifecycle emissions of various urban environments, Arehart and his colleagues at Edinburgh Napier University started by simulating 5,000 built environments of varying population sizes and land area availability. They then classified each into one of four different urban typologies: high-density and low-density environments with either high-rise or low-rise buildings. To simulate how those environments might realistically form, the models were based on real-world data from different cities across the U.K. and Europe, including London, Berlin, Oslo and Vienna.

The authors use real-world data to simulate four types of urban environment of varying densities and building height.

npj Urban Sustainability

Comparing these simulated cities, researchers found that for all population sizes (which range from 20,000 to 50,000), the lifetime carbon emissions increase along with building height, independent of the amount of land needed. High-density, high-rise cities also resulted in the largest carbon emissions compared to the other three models — and that includes low-density, low-rise scenarios that resemble suburban-styled cities. The lowest carbon emitters were high-density, low-rise configurations.

For a city supporting 20,000 people, moving from low rises to high rises without changing the density results in 140% more carbon emissions. For a city of 50,000 people, the increase is slightly lower, at 132%.

In scenarios in which researchers observed the number of people each typology can house in a given amount of land, they found that high-density, low-rise cities on average can support more than twice as many people as high-density, high-rise cities without increasing carbon emissions.

Arehart is careful to say that the study focuses solely on building emissions, and doesn’t account for other factors like transportation, design or the type of land cities build on, which affect their carbon output. More study is also needed to confirm if their conclusions still hold true for increasingly larger populations.

“The takeaway here shouldn’t be that skyscrapers are bad,” he says. But reconsider them as the solution to our current climate crisis.

The debate itself isn’t new. While experts generally agree unchecked urban sprawl is detrimental to the environment, the negative impacts of supertall buildings — which rack up massive amounts of embodied energy and typically demand yet more power to heat, cool, and run elevators, compared to shorter structures — are a focus of growing attention. The recent report from the United Nations Intergovernmental Panel on Climate Change points to cities’ urban geometry as one of three main factors contributing to the urban heat island effect: Tall buildings placed in close proximity tend to trap heat and reduce natural ventilation.

“We're showing you an example of how you can use greenhouse gas emission to evaluate urban density,” says Arehard. “That's just one piece of the puzzle.” Ultimately, how tall a city should build depends on multiple environmental and socioeconomic factors, including affordable housing needs and greening efforts.

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Cities like Paris may be optimal urban form for reducing greenhouse gas emissions

Anonymous — Tue, 10 Aug 2021 21:20:33 +0000

Cities like Paris may be optimal urban form for reducing greenhouse gas emissions Anonymous (not verified) Tue, 08/10/2021 - 15:20

Researchers at CU Boulder are part of a newly published study that finds that low-rise, high-density environments like those found in Paris are the optimal urban form when looking to reduce greenhouse gas emissions over their whole life cycle.

The work, recently published in npj Urban Sustainability, builds on a growing debate around the design of future urban environments and was done in partnership with Edinburgh Napier University. The built environment is a big contributor to carbon emissions, global energy demand, resource consumption and waste generation. In the U.S., it accounts for 39% of all greenhouse gases emissions, while in the European Union, it accounts for 50% of all extracted materials and 42% of the final energy consumption – making it a rich area for understanding and improvement related to climate change.

Jay Arehart, an author on the paper and instructor in the Department of Civil, Environmental and Architectural Engineering, said the work challenges current conventional understanding that tomorrow’s cities must be densely packed and stretch upwards to address and curb greenhouse gas emissions. The idea being that tall buildings make optimal use of space, reduce operational energy use for heating and cooling and enable more people to be accommodated per square meter of land.

“Both the urban sprawl that we see in the suburbs of the United States and the high-rise that we see in places like New York City are not necessarily optimal,” Arehart said. “We showed that new development should focus on minimizing whole-life carbon of buildings, not just the emissions from their operations or their materials. That density is needed for a growing urban population, but height isn't.”

The team investigated four different urban typologies – from dense-and-tall to sparse-and-low – by simulating 5,000 environments based on real-world data to establish their lifecycle greenhouse gas emissions. This approach considered both premium for land (the extra land needed to build low-rise compared to high-rise) and premium for height (the extra materials to build high-rise compared to low-rise) to make comparisons fair said Francesco Pomponi, the lead author on the paper and professor at Edinburgh Napier University.

"We developed a novel urban density metric to measure things up as accurately as possible," Pomponi said. "Our results show that density is indeed needed for a growing urban population, but height isn't. So it seems the world needs more Parises and fewer Manhattans – as much as I love New York – in the next decades."

Urban Sustainability is the newest addition to the Nature Partner Journals series.

Full paper

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