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Posts tagged ‘green’

March for the Climate – Meeting the Paris Agreement Climate Goals

Cate Leger, Principal, Leger Wanaselja Architecture

Environmental organizations around the country are organizing a massive march in San Francisco September 8.

Meeting the Paris climate goals requires a lot of changes—including many changes to buildings.  Even as the ink dried on the Paris Agreement, analysts were telling us that the international commitments were nowhere near enough to keep global warming to under 1.5 or even 2 degrees Celsius.  But it was a start.  And even as Trump and his cohort walk us back nationally from these commitments, we in California and many others around the world are leaning in.

In September,  leaders pushing forward on meeting the Paris climate goals will be gathering in California for the Global Climate Action Summit  to share new commitments and challenge each other to go farther.  The Summit includes many excellent and ambitious challenges, several quite relevant to architects:

  • Net Zero Carbon Building Challenge,
  • The 30X30 Forests, Food and Land Challenge,
  • Green & Healthy Streets (“Fossil Fuel Free Streets”) Declaration, and
  • Advancing Towards Zero Waste Challenge

To support this agenda and to encourage our leaders to go further still, environmental organizations around the country are organizing a massive march in San Francisco September 8.

As architects, we have good reason to join this march.  Our everyday work is critical to solving the climate crisis.  But even as we understand what we must do–i.e. design all electric, low carbon footprint buildings, powered by renewables, and supporting zero emission vehicles–we find our efforts hampered by state level regulations.  The new 2019 Title 24 Building Standards, while improved, still include assumptions favoring gas.  In addition, energy efficiency rebates are still not available when switching fuels. See AIAEB 2-18 Newsletter for details.

At a larger scale, all of this work at designing the best Zero Carbon Buildings is inconsequential if it is not met at the same time with a comprehensive climate strategy that includes reducing fossil fuel production.  In an LA Times Op Ed, Bill McKibben argues that managing the supply side of fossil fuels works to lower greenhouse gas emissions and it is necessary to accelerate reductions enough to meet the Paris climate goals.  As a start, Governor Brown to could say no to new fossil fuel permits and take the state level equivalent stance to President Obama’s denial of the Keystone XL Pipeline.   He could go a step further and create a plan to phase out all oil and gas production in the state.

The national AIA has taken a public position in support of the Paris Climate Agreement.  Let’s ask our leaders to make our Zero Carbon Buildings more meaningful and march on September 8.

Help Your Consultants Help You: Green

Steve Gross is a Senior Energy Analyst and Mechanical Engineer with Interface Engineering, a Bay Area progressive mechanical and electrical consultancy, focusing on innovative engineering solutions for high-performance projects.

Delivering a truly high-performance building is an immense challenge that requires a concerted, impassioned effort from all the project’s stake holders. But there are a few habits that the architect can employ to help the team of consultants to achieve success. The most important is COMMUNICATION. Projects rarely, if ever, achieve high performance by accident. It takes a vocal leader to continually remind the team of what we are all striving for. Push your consultants to think along the lines of sustainability at every stage of the project. Over time, you’ll notice that your team will start to operate this way without being asked to. I truly love those moments when someone from the structural team or the civil team comes up with a great sustainability idea that would have never come to light under a “typical” team structure.

Be an ADVOCATE for analysis. You can set the tone for the project by talking to the owner about the benefits of early-stage analysis and analytical decision-making whenever possible.  Help the owner and other members of the design team understand the value of energy analysis and how it can be used to inform the design of the building. We all know it’s much easier (and less costly) to modify the design at early stages rather than during the Design Development and Construction Documents phases.

Increase your LITERACY of energy and financial analyses so that you can participate directly in the analysis process. Depending on the project’s goals, you may seek to reduce first cost, annual energy cost, carbon footprint, or lifecycle cost. Each goal requires a different analytical approach and likely requires different design strategies. It will be your direction, as the leader of the consultant team, that will ultimately steer the team towards accomplishing one of these goals.

A final habit is to employ PASSIVE design strategies wherever possible, and push your consultants to do the same. This can be challenging, especially if there is a perception that passive strategies do not perform as well. For example, do corridors and other transitional space really need to be heated and cooled to the same setpoints as the other regularly occupied spaces? Most mechanical engineers will simply assume that these spaces should be conditioned in the same way, unless they are told otherwise. The team will take comfort in knowing that you believe in this design approach and have helped the owner understand the implications of passive strategies.

Greening Your Buildings, Greening Your Practice

Cate Leger, Principal, Leger Wanaselja Architecture

Whether you are looking for small changes or radical rethinking, there are plenty of steps to take to green your buildings and better align your architectural practice with climate and environmental goals.

 

 

 

 

  • Electrify your buildings. Electric appliances are increasingly the best choice for reducing greenhouse gas emissions.  Switch to electric when appliances or systems need replacing.  Avoid gas infrastructure in new buildings.[1]
  • Make your buildings net zero greenhouse gas emissions. Add solar photovoltaic (PV) panels or sign up for 100% renewable electricity from your electricity provider.[2]
  • Air seal and insulate using low global warming potential, non-organohalogen flame retardant insulation like blown-in cellulose and cork.[3]
  • Avoid carcinogenic, endocrine disrupting, persistent pollutants. With so many products on the market and little information on their safety, Healthy Building Network’s “Homefree“ General Spec Guidance” provides straightforward guidance to help architects and builders avoid some of the worst health concerning chemicals.  For chemical content, check out HNB’s new Chemical Hazards Data Commons. The Living Building Challenge, a third party green building rating system similar to LEED, has a red list of chemicals.
  • Incorporate water conserving appliances and infrastructure. Low flow fixtures are required by the Calgreen building code. Take a step further and install greywater infrastructure and rainwater collection.  Even making projects greywater or rainwater collection ready–with pipe and gutter layout—will make it easier for future owners to install systems.
  • Specify low carbon and carbon sequestering material. Low-carbon materials provide greenhouse gas emissions reductions now, when they are needed most.[4] Ask for low-carbon concrete mixes. Specify Forest Stewardship Council (FSC) certified wood and other renewable materials such as cork, straw, hemp, and bamboo over plastics and metals. For hardscape and finish surfaces, choose stone over concrete and tile.[5]
  • RECLAIM AND REUSE. Specify FSC certified and reclaimed wood. Not only do FSC certified woods sequester more carbon than their counterparts, but they are better at preserving habitat and right livelihood . Using reclaimed and recycled materials reduces
  • Remodel rather than building new. A renovation and reuse project typically saves between 50 and 75 percent of the embodied carbon emissions compared to constructing a new building.[6] This is especially true if the foundations and structure are preserved, since most embodied carbon resides there.
  • Minimize the size of new buildings. All of the impacts of buildings are reduced when buildings are smaller—fewer materials, less energy to operate, less space to furnish and maintain.
  • Support alternatives to fossil fuel cars. Prioritize transit oriented locations. Provide EV charging and bicycle infrastructure.
  • Sign the AIA 2030 Commitment. The AIA 2030 Commitment program offers architects a way to publicly show their dedication and track progress toward a carbon-neutral future.
  • Join the AIAEB Committee on the Environment. The committee hosts monthly lectures and members shares information on green architecture events and strategies. Participation is open to all.

More ideas for going green at:
https://www.aia.org/resources/77561-sustainability
https://www.buildinggreen.com/feature/20-ways-advance-sustainability-next-four-years

 

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[1] Methane leakage from well to appliance infrastructure is worse than thought and combustion appliances are one of the main sources of indoor air pollution. In addition, the dramatic increase of renewables generating electricity on the grid and the development of heat pump technologies for space and water heating make electricity the cleaner source of energy.  http://aiaeb.org/2017/08/cote817/

https://sfenvironment.org/download/methane-math-how-cities-can-rethink-emissions-from-natural-gas

[2] Check with your utility provider.  In areas with Community Choice Energy, signing up for 100% renewably generated electricity comes with only a  small premium.  Watch for this option as Alameda County rolls out its East Bay Community Energy in 2018.

[3] Make sure there is adequate ventilation and fresh air as the building envelop gets tighter.

[4] The embodied energy of the building materials can be as much as 50% or more of a new building’s total carbon footprint in the first 20 years of a building’s life.  As it approaches zero net operating energy, these numbers increase, eventually reaching 100%. Greenhouse gas (GHG) emissions reductions are needed now because of the self-reinforcing loops that GHGs trigger.  Low-carbon construction can reduce the embodied energy by 30 to 50%, with 20% achieved through simple substitutions. http://www.siegelstrain.com/site/pdf/201105_ClockisTicking-LStrain.pdf

[5] For more on low carbon and carbon sequestering construction see The New Carbon Architecture.

[6]https://www.aia.org/articles/70446-10-steps-to-reducing-embodied-carbon:2976

 

Natural Building for Remodels and The New Carbon Architecture

Imagine that the act of building actually helped heal the environment.  What would that look like?  Massey Burke takes on this question both in her work as a local natural builder and in a chapter in the inspiring new book The New Carbon Architecture, by Bruce King.

Massey answers questions below in conversation with AIAEB COTE’s Cate Leger. 

Cate:  Natural building is generally associated with expensive or do-it-yourself new, custom houses  in the countryside, but I have seen firsthand that natural building is appropriate and cost effective for remodels and city building.  We met when you installed natural earth finishes for an apartment building renovation I was working on.  The prices were competitive with the alternative:  wood floors and plastered sheetrock walls  and 3 years later the earth finishes are holding up well.

Why do you like working with natural finishes and materials?

Massey:  I like working with natural materials because they help me maintain a direct relationship to the landscapes that they come from, both aesthetically and practically.  Working with natural materials usually involves a much shorter and more accessible supply chain, and often means that I am sourcing and refining the materials as well as building with them.  I love this process:  it allows me to make choices about how I affect the environment through building.

Cate:  We’ve heard a lot about zero net energy buildings as a key step to reducing use of fossil fuel consumption and greenhouse gas emissions.  In The New Carbon Architecture, you argue that buildings can go a lot farther in solving the climate crisis.  Tell us more about that.

Massey:  Shifting to natural building materials can sequester carbon, and, done right, can make our buildings carbon sinks rather than carbon emitters.

Wood and other plant-based natural materials  are now understood to sequester carbon within a building–because plants absorb carbon dioxide from the atmosphere and turn it into stable non-atmospheric carbon.  As long as they do not break down, the carbon within the plants remains locked up and does not return to the atmosphere.  

While it is less common in modern construction than wood, straw has been used worldwide in building for many thousands of years.  Straw bale construction is typically the most familiar to people, but there are actually many different ways to use straw in construction.   Straw is also used in a most earth or clay building systems, like adobe, cob, earth plasters, and earth floors. 

Cate: Where will you be taking this research in the future?

Massey:   This year is a mix of building work and carbon sequestration research, which is moving me toward creating high-performance buildings that are explicitly designed to remove carbon dioxide from the atmosphere.  I’m also developing more avenues for using natural materials for remodels.  In particular I am interested in expanding the applications of clay plasters in remodels to improve humidity control and energy efficiency. 

Removing Barriers to Electrification

Cate Leger, Principal, Leger Wanaselja Architecture and Commissioner, Berkeley Energy Commission

The new round of updates for Title 24 2019 Building Efficiency Standards are in the final stages of creation.  They will go into effect in 2020. While incredibly arcane and mind-numbingly complex, these standards have been the cornerstone of California’s leadership in energy efficient construction.  It is through standards like these and regulations that implement them that high level state policies, such as reducing greenhouse gas emissions to 80% below 1990 levels by 2050, are achieved.

Historically, energy efficiency standards and incentive programs have been based on the assumption that natural gas appliances have lower environmental impacts than electric appliances.  However, this is no longer the case.  The dramatic increase of renewables in supplying electricity and the development of heat pump technologies for space and water heating have turned this balance around.  If the significant fugitive emissions from gas infrastructure were added to the equation, the scale definitely tips in favor of electric heating.

Building efficiency standards and other programs need to stay current with the science in order to be effective tools in achieving high level state goals.

The good news in the Title 24 updates is that heat pump hot water heaters will be given equal standing with gas.  They will have their own baseline for calculating compliance.  No longer will designs be penalized for using high efficiency electric water heaters.

The bad news is that the metric used to calculate building performance, TDV, will not be updated to adequately reflect the costs of natural gas.   The TDV metric is a bit of a black box created by the regulators in 2006 to give value to the time energy is used.  While greenhouse gas emissions and energy use are part of the TDV algorithm, the problem with TDV is that it generally over values natural gas, giving the false impression that natural gas heat is better for the environment than electric.  This was born out in one of the regulators own studies prepared by E3 which showed that in almost every climate zone gas outperformed electric based on TDV but had higher greenhouse gas emissions.

The continued use of TDV is one area where California’s energy regulations are not keeping pace with science.  Another is energy rebates and incentive programs.

For example, the ratepayer-funded Energy Upgrade California program supports tens of millions of dollars of rebates for energy efficiency upgrades including insulation and appliance upgrades. However, these rebates are not available when switching fuels.

To address these inconsistencies, the AIAEB Committee on the Environment members are supporting a coalition effort advocating for climate leadership in Sacramento and across the state agencies to decarbonize buildings (see attached).  Cities, environmental groups, architecture and energy consulting firms across the state are asking for regulations and programs to be aligned with state climate goals.  This realignment is absolutely consistent with the AIA’s support of the Paris Agreement and zero net energy in new construction by 2030.

There is no time to lose.  Energy efficiency programs must be realigned quickly to support accelerated reductions in greenhouse gas emissions.

Does Your Building Pass the Lick Test?

Cate Leger

Energy codes have done a good job of moving California architecture to more energy efficient buildings.  However, green building needs to also include green building materials.

Back in the 1990s a great deal of attention in the green architecture community was placed on materials.  Materials were researched and compared for their toxicity, life cycle impacts on the environment and human health, carbon footprint, sustainable yield, cultural impacts of extraction and more.  However, as concern about the climate has grown and disagreements sprang up on the ‘greenness’ of various building systems and materials, the focus has generally shifted to energy efficiency and more recently shifting to 100% renewables.

While CALGreen has incorporated standards to limit off gassing of some toxic chemicals, there are many human and environmental health issues of materials these standards don’t address.  Here are some excellent resources to fill the gaps:

  • Healthy Building Network’s HomeFree offers a short, easy to use specification focused on indoor air quality and health. Healthy Building Network also has extensive database on chemical content and environmental impacts for thousands of products and great articles explaining their research. https://homefree.healthybuilding.net/reports
  • The Living Building Challenge, a third party green building rating system similar to LEED, has a comprehensive Red List of chemicals to avoid and a database with materials meeting those standards. https://living-future.org/declare/declare-about/#the-red-list
  • The Green Science Policy Institute provides guidance on avoiding toxics in the home. They also have a series of short videos breaking down the toxic chemical landscape into 6 classes, allowing the layperson to understand the general problems.  http://greensciencepolicy.org/
  • The Forest Stewardship Council provides the most comprehensive third party certification for sustainably harvested wood.

What we build with also has a significant impact on the climate.  The embodied energy or the carbon footprint of building materials varies widely.  Using low carbon materials for construction is critical in addressing climate change because the greenhouse gas emissions savings are accrued earlier, at the time of construction, when they have the biggest impact.  Prioritizing low carbon materials can significantly reduce the lifetime carbon footprint, and in some cases even reverse it!

Metal and plastics in general have a very high carbon footprint.  Concrete, while lower in embodied energy per pound, is used in such great quantities that its global warming impact tends to dwarf that of other materials used in construction.  Blowing agents used in some of the foam plastic insulations have such high carbon footprints that their addition to a building can negate the operating energy savings for decades.  For more information, The New Carbon Architecture by Bruce King offers inspiring examples and details of low carbon construction.  https://ecobuildnetwork.org/projects/new-carbon-architecture

If the health of workers, occupants and our planet are not reason enough to use healthy building materials, fire is yet another one. The toxicity of building materials and furnishings can be amplified when they are burned. Smoke that engulfed the North Bay – and blanketed the entire Bay Area – was laced with dangerous chemicals: dioxins, furans, hydrogen cyanide and heavy metals, threatening the health of all.  Sadly, firefighters are known to have some of the highest rates of cancer.  Frequent exposure to these kinds of chemicals may be a contributing factor.   Many of these dangerous chemicals are also left behind in the ash.

Energy Return on Energy Invested (EROEI)

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Judhajit Chakraborty, Assoc. AIA, LEED® AP, WSP Built Ecology

In February 2016 I attended the Net Positives Conference organized by the International Living Futures Initiative (Living Building Challenge) in San Diego, CA and I was very impressed with the quality of both the presenters and the presentations. Unlike the Greenbuild it was more of a closed group conference with about 350 attendees, digging deep into the water and energy problems of the world and providing far-fetched but definitely achievable solutions.

In this article I would like to mention one presentation that I really liked. On a conceptual level it talked about a term which is not generally used while talking about energy efficiency in the built environment. This is Energy Return on Energy Invested (EROEI) and this term has been in use in the world of Energy Economics and Carbon Economics for a long time now. But now as high performance design is looking more towards embodied energy (total energy from source – production + transportation), having a basic understanding of EROEI is important.

So, what actually is this Energy Return on Energy Invested (EROEI)? Mathematically it is a simple ratio: ratio of the amount of usable energy acquired from a particular resource to the energy expended to acquire that energy.green1

The higher the EROEI, the more “profitable” the energy resource (from an energy standpoint). If the EROEI drops below 1, it means that it takes more energy to produce the usable energy than is contained in the finished product. In other words, EROEI is a measure of the amount of energy society gets, as a ratio of the amount of energy we put in to get that energy. Net energy available is thus the amount of energy left for a modern society to function (Food production + support and education of people + healthcare for people + arts, entertainment, sports and other amenities) after spending the initial energy to get that energy. The more it costs to extract the energy, the less net energy is left for use. This leads to the energy cliff exponential graph to the left.

green2The dark gray area is the net energy available for a society to run smoothly and the light gray area is the energy used to procure that energy. According to this graph, a minimum EROEI of 14 is required for a smooth functioning of society. The graph also shows EROEI’s of major fuel sources. The conventional fossil fuels have the highest EROEI’s and that is why they are continuing to sustain our society. Even a reduction of 50 to 25 EROEI (which means gradual depletion of natural resources and hence more energy required to extract) have an inconsequential effect on the percent energy out. However that percentage changes sharply when unsustainable means of fuel is being brought into practice (corn ethanol, shale oil, bitumens etc). This also means that going forward, as our natural resources gets depleted, we as a society need to make smarter choices and invest in the right form of energy. Alternative clean fuel sources such as PV, nuclear and wind play a huge part in this. They have low EROEI’s but they don’t consume natural resources. However, currently these fuel sources are nowhere close to replacing the conventional fossil fuels. It can make good economic sense for an individual — or a society — to invest in a renewable energy producing system as long as the system can be maintained and operated for a long time.

As we debate our future energy choices and policies, energy return on investment should be an important part of such discussion. This gives us a “reality check” as we figure out where to put our energy investments.

Green: Emerging Technologies and Resources for Photovoltaics

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Judhajit Chakraborty, Assoc. AIA, LEED AP WSP Built Ecology

1. ClearView Power™: PV’s are getting transparent. Yes that’s right, past MIT researchers and current entrepreneurs, Miles Barr, Ian Millard, Vladimir Bulovic and Richard Lunt are making transparent solar cells that could turn everyday products such as windows and electronic devices into power generators— without altering how they look or function. How? Their new breakthrough in solar cells absorb only infrared and ultraviolet light, thereby only letting visible light pass through the cells unobstructed, so our eyes don’t know they’re there. They estimate that this technology of using PV coated windows in a skyscraper could provide more than a quarter of the building’s energy needs without changing its look. They’re now beginning to integrate their solar cells into consumer products, including mobile device displays and have started a venture called Ubiquitous Energy (http://ubiquitous.energy/).5

Current versions of the ClearView transparent PV cells transmit more than 70% of the visible light, which is within the range of tinted glass now used in the windows of buildings. But their tested efficiency is very low—only about 2%, but they are working on it. In theory, their design should realistically be able to reach over 12% efficiency, comparable to that of existing commercial solar panels. This will be challenging, but they believe they can do it by carefully optimizing the composition and configuration of the PV materials. The other challenge is the longevity of PV. In commercial applications such as window coatings, the solar cells need to continue performing well for many decades. With many industries tackling the same issue, the team believes that this engineering problem should be solved in the coming years, and their solar cells should be guaranteed to have a commercially viable lifespan. And this may well be a game changer in the PV industry.

62. Project Sunroof by Google: Until now you had used Google for comparing air-fares, hotel fares and for umpteen searches, now Google lets you weigh the costs and benefits of installing solar panels on your rooftop through its new online tool ” Project Sunroof” (https://www.google.com/get/sunroof#). This new tool, now available for select cities in CA, AZ, NV, CO, CT, NY, NJ, NC and MA, requires a user to enter the home address and it computes how much sunlight hits your roof in a year. It takes into account:

• Google earth’s database of aerial imagery and maps
• 3D solar radiation modeling of your roof
• Shadows cast by nearby structures and trees
• All possible sun positions over the course of a year
• Historical cloud and temperature patterns that might affect solar energy production

Project Sunroof then computes the savings by using the current solar industry pricing data to run the numbers on leasing, taking a loan, or buying solar panels for your house to help you choose what’s best for you. Not only that, it also compiles the following incentives to calculate the final PV cost.

• Federal and state tax credits
• Utility rebates
• Renewable energy credits and net metering

Project Sunroof is a faster, simpler way of sizing up possible pros and cons of solar than calling someone for a site evaluation or using the more complex calculator offered by the U.S. Energy Department

Green: Red List Building Materials and Living Building Challenge

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Judhajit Chakraborty, Assoc. AIA, LEED AP WSP Built Ecology

First of all, I wish all the readers and members of AIA East Bay a very happy and prosperous 2016.

“Monumental Green,” the theme of Greenbuild 2015 held at Washington D.C. paid a lot of emphasis on the environmental impact of materials on buildings and building environmental standards like WELL, SITES, Living Building Challenge (LBC), PEER and I am going to write about Red List building materials and how LBC has been leading the way in material disclosure and transparency.

Red List Materials, as the name suggests, are materials that contain chemicals that have been labeled as harmful and detrimental to living creatures, including humans and/or the environment. These lists have primarily been developed by green building rating system developers and some big architecture firms like Perkins and Will. These lists are typically developed from chemical hazard lists published by several government agencies, such as the Environmental Protection Agency (EPA), European Union Commission on Environment, and the California Department of Toxic Substances Control.pg. 5 green 1

Of all the environmental building standards that prohibit red list materials in any building project, the LBC has been more rigorous in implementing this and has developed their own Living Building Challenge Red List. Following is the LBC’s Red List materials which are banned from any project adhering to LBC certification:

■ Alkylphenols
■ Asbestos
■ Bisphenol A
■ Cadmium
■ Chlorinated polyethylene and chlorosulfonated polyethlene (CSPE); HDPE and LDPE are
Chlorofluorocarbons (CFCs)
■ Chlorobenzenes
■ Chloroprene
■ Chromium VI
■ Chlorinated polyvinyl chloride
■ Formaldehyde (added)
■ halogenated flame retardants (HFRs)
■ Hydrochlorofluorocarbons (HCFCs)
■ Lead (added)
■ Mercury
■ Polychlorinated biphenyls
■ Perfluorinated compound
■ Phthalates
■ Polyvinyl chloride (PVC)
■ Polyvinylidene chloride
■ Short Chain Chlorinated paraffin
■ Wood treatments containing creosote, arsenic or pentachlorophenol
■ Volatile organic compounds (VOCs) in wet applied products

Following the development of this list, LBC developed the DECLARE product labeling program and includes a database of materials which are LBC compliant. Here is the database.

Sound that Chills! – Thermoacoustics

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Juhajit Chakraborty Assoc, AIA, LEED AP WSP Built Ecology

Energy Efficient Building HVAC systems have been gaining grounds in the United States since the last decade. One of the areas that have achieved significant improvement is the refrigerant emissions. We all know that refrigerants contribute greatly to global warming. A project cannot be LEED certified if they use CFC based refrigerants. Almost all state and local building codes have banned CFC use and mandates use of only low ozone depleting potential (ODP) and global warming potential (GWP) refrigerants. But they still contribute to global warming. Refrigerants are an integral part of the HVAC process as they transport heat thru continuous compression and expansion cycles.

Xerox-owned Palo Alto Research Center (PARC) has developed a technique to enable sound or thermoacoustic cooling technology for air conditioning applications. In a nutshell, what they have been develop-ing is an air conditioner but it works like a loudspeaker. Interesting, isn’t it?

What is Thermoacoustics?
It is the interaction between temperature, density and pressure variations of acoustic waves. A thermoacoustic HVAC system compresses and expands gases with high intensity sound waves. When compressed, heat is generated because of the pressure applied and during expansion, cooling happens. More so like the chill we get when a carbon dioxide cartridge or canister is suddenly discharged and the gas is allowed to expand. The thermoacoustic system can potentially allow the compressor to complete 10,000 compression/expansion cycles, way more than a mechanical compressor system. Thermoacoustic compressors have been traditionally used mainly in labs and cryogenic cooling to turn on atmospheric gases like nitrogen into chilly liquids and therefore they usually perform best under extreme conditions and not efficient for commercial use for maintaining ambient temperatures (70°F -75°F) – this is what PARC has developed a prototype system, for ambient temperatures. With this technology hitting the com-mercial market, not only will result in zero emissions, but also it will save tremendously on energy. Cooling applications represent 25% of all electricity use in the United States, consuming over seven quadrillion BTUs of energy and generating nearly 600 million metric tons of CO2 emissions annually. If widely used, this prototype technology can save up to 13% reduction in energy consumption in US, double the efficiency of air conditioning and reduce CO2 emissions by 311 million metric tons annually.

How does it work?
Gases are first inserted into a tube filled with mesh membranes which are called regenerators. As the sound wave passes through the regenerators, a low-pressure, low-temperature/high-pressure, high-temperature gradient begins to form. One end gets hot while the other gets cool. Heat exchangers are then used to extract and exploit the cooling or the heating as required. The prototype’s increased efficiency comes from the electromechanical couplings generated in the “transducers” (device that converts variations – in this case pressure and temperature) through the interconnected thermoacoustic chambers in series such that unused energy is efficiently passed from one chamber to another. The image below shows a basic system (left) which is used in labs and the improvised prototype developed by PARC for ambient temperatures (below).

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