Committee on the Environment

 View Only

Community HTML

ALBION DISTRICT LIBRARY BY PERKINS + WILL IS A 2018 COTE TOP TEN RECIPIENT. IMAGE: DOUBLESPACE PHOTOGRAPHY

Quick Links

Who we are

The Committee on the Environment (COTE®) is an AIA Knowledge Community working for architects, allied professionals, and the public to achieve climate action and climate justice through design. We believe that design excellence is the foundation of a healthy, sustainable, and equitable future. Our work promotes design strategies that empower all AIA members to realize the best social and environmental outcomes with the clients and the communities they serve.

Enjoy our latest on COTE news (and follow us on X and LinkedIn). 

To learn about the Framework for Design Excellence (formerly the COTE Top Ten Measures), click here.

Check out COTE's history and timeline. 

Starting a local COTE or sustainability group and need some guidance? Check out the AIA COTE Network Resources here.

A big thank you to our 2024 sponsors: 
Founding sponsors: Building Green
Premier sponsors: Sherwin-Williams
Sustaining sponsors: GAF Roofing, Milliken, Andersen Windows,
BlueScope Buildings
Green sponsors: EPIC Metals
Allied sponsors: TLC Engineering, Sierra Pacific Windows

Expand all | Collapse all

How Small Building designs impact Embodied Emissions.

  • 1.  How Small Building designs impact Embodied Emissions.

    Posted 03-30-2022 01:03 PM

         The sheer number of small buildings worldwide illuminates an opportunity to control the carbon destiny of this sector through the practice of informed design, a rather striking opportunity. Not only do residential dwellings com­prise the largest share of small buildings, residences constitute the largest number of all buildings. The annual construction of new dwellings in the United States and the upgrade of inadequate shelters worldwide elucidate this reality, the two ends of the spectrum. At one end, approximately one million single-family homes are built in the United States annually with an average floor area in the vicinity of 2,500 square feet. At the other end, one and a half billion people live in temporary, minimal, or inadequate housing worldwide which will be replaced by more substantial structures through the alleviation of poverty and forced displacement. The produc­tion of construction materials for each scenario will release carbon emissions annually that far outweigh years of potential operating emissions reductions in the future. Both scenarios offer opportunities to decrease this buildup of embodied carbon over the next 10 to 15 years through conscientious build­ing design and material choice.

         Although a small building pales in carbon footprint relative to its urban high-rise counterpart, their relative numbers provide a different dynamic. This holds especially true when considering shelter for the billion-plus people who are impoverished or displaced. Initial upgrades in housing are typically from bamboo, wood, thatch, cardboard, fabric, and corrugated metal to cinder block and concrete, the worst mate­rial emitters on the list. To make matters worse, these upgraded replace­ments will be discarded and replaced as well, by multi-story structures on the march toward urbanization over the decades to come-more than doubling the emissions from this group, the largest of all. This first upgrade alone, though providing a minimally sized dwelling, will be responsible for releas­ing sizeable emissions.

         For example, more than a million and a half dwell­ings in Vietnam's 2009 housing census were classified as "simple" structures, constructed with supporting columns, roof, and walls that were all classified "flimsy"-constructed with materials such as mud, leaves, bamboo, thatch, or tar paper. Replacing them all with minimal 320-square-foot dwellings-a mere four cinder-block walls and a corrugated-metal roof-would emit nearly 40 million metric tons of CO2 to produce the building materials alone. Building with brick would not fare much better, and clad­ding with brick over cinder block would be far worse. This 40-million metric tons covers just the upgrade of four walls and a roof. To provide minimally adequate shelter for the 1.6 bil­lion people with such need, multiply that by 1,000. This hurdle for curbing emissions is created in good part by defaulting to cinder block and concrete, rather than low-carbon or carbon-sequestering building materials such as wood.

         On the other end of the spectrum, single-and multi-family housing provides a different type of design challenge. In the United States, new buildings construction every year is equivalent to adding the entire building stock of New York City annually. Only 5% of the single-family homes built in 2018 were clad primarily in wood. Nearly 800,000 were clad with other materials, 26% vinyl sid­ing, 25% stucco, 21% brick, 20% fiber cement, and 3% using other products. Unfortunately, most materials manufactured for cladding either contain cement or use a cementitious material such as mortar for mounting. This includes stucco, fiber cement, thin clay-brick, and cut stone cladding products. Cement production is responsible for 7% of all energy related emissions worldwide. Vinyl is the exception neither containing nor adhered with cement, but it too has a high-carbon footprint resulting from its carbon content. These cladding materials have average manufacturing emissions in the vicinity of 7 kgCO2/m2, which varies widely as a function of the cladding's thickness, finish, and the volume of mortar used for mount­ing, if any. Vinyl siding seems to be the lowest, at less than half the average in its simplest composition and minimum thickness. Facing with full-size clay bricks on the other hand, which is not included in the above average, in the vicinity of 30 kgCO2/m2 can be four times worse than the mean and 10 times vinyl.

    Unlike any of these materials, wood provides a benefit. Wood shingles, shakes, or clapboards continue to sequester the carbon they have already removed from the atmosphere. If 20% of the houses in each non-wood clad­ding category were clad with wood, the net CO2 emissions saved annually would near 1 million metric tons in the United States alone, solely from the cladding materials, solely from U.S. single-family homes. This does not include the backboard materials that support the cladding nor waterproofing membranes, mounting systems, or insulation, all of which can be selected to minimize a wall's composite carbon. The same can be said for window-frame, door, flooring, and roofing materials; choices among wood, plastics, metals, and ceramic, petroleum, or cement-based products. Such gains may seem small for each individual residence, especially in regard to a minimal shelter, but the quantities built and renovated multiply the impact. Additionally, each material purchase activates a re-supply chain, initiating a release of carbon emissions in the "now" time frame. Those emissions not only negate many years of potential operating savings, the massive carbon they release immediately exacerbates the warming rate. 

         Single-family and small-multifamily dwellings are not the only structures comprising the Small Buildings category, let us not forget low-rise and mid-rise apartments, commercial and industrial buildings. Although significantly fewer than their one- to four-story residential counterparts, they are framed predominately with a combination of concrete and steel; often clad with fiber cement composites, concrete blocks, brick, clay tiles, aluminum, or steel-some claddings layered with a decorative or protective plastic-laminate fin­ish. They too provide an opportunity to reduce embodied carbon through material selection and their structural methodology.

    Yes, the design of small buildings and their material choices can significantly reduce carbon emission-now.


    Adapted from "Thwart Climate Change Now: Reducing Embodied Carbon Brick by Brick", published by the Environmental Law Institute, Nov. 2021.



    ------------------------------
    Bill Caplan, Associate. AIA
    Author of "Thwart Climate Change Now: Reducing Embodied Carbon Brick by Brick"
    Environmental Law Institute ELI Press, November 2021
    ------------------------------


  • 2.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-04-2022 08:12 AM
    Thank you for that informative discourse on material choices. These are the considerations that matter.

    ------------------------------
    Brian Pape AIA Member Emeritus
    Brian J. Pape Architect and Consultant
    New York NY
    ------------------------------



  • 3.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-06-2022 11:04 AM
    The article brings up the matter of scale and that is the most important one in combatting climate change. Its good to understand that a huge amount of small structures will make a big difference. Its a bit hard to derive the appropriate conclusions, though. Not providing the marginally housed with sturdier structures? Use wood siding instead of brick?

    The juxtaposition of embodied carbon with operational one, while formally correct, may lead people a bit astray. For example with the comparison of vinyl and wood siding. Wood siding loses its carbon retentive advantage if it has to be replaced more often than other sidings.(can it be reycled for anything better than wood pellets or paper?)  Vinyl siding loses its "low" embodied carbon advantage when it is not resilient against to be expected frequent high winds (and flies off) or when it gets removed, replaced or a structure gets demolished and the stuff winds up in a land-fill. Again, can it be recycled?.

    ------------------------------
    [Klaus] Philipsen FAIA
    Archplan Inc. Philipsen Architects
    Baltimore MD
    ------------------------------



  • 4.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-13-2022 09:03 AM

    Mr. Philipsen, thank you for questions regarding the efficacy of wood and vinyl siding for reducing emissions over time. This is an important question. To reduce embodied carbon emissions over the most critical timeframe, the next 10 to 15 years, there is nothing comparable to wood.

    The energy spent to dress 1 lb of wood for construction, milling etcetera and preparation, emits approx. 1/2 lb of CO2. The remaining wood continues to sequester the 1.5 lbs it removed from the atmosphere during growth. Therefore, wood building products have an effective negative 'net' carbon footprint, they store a net 1 lb of CO2 for each pound of dressed wood. Wood siding is considered to have a service life of 15 to 40 years, depending upon its environment and maintenance. Sequestration for even a 15-year period during this critical time is reason enough to use it. In regard to recycling wood pellets for fuel, which returns the sequestered CO2 to the atmosphere, that would be a bad idea. Reuse for paper would continue sequestration. However, there is also an active market for reclaimed wood, which would be ideal. From the prospective of climate change, at the rate we have emitted CO2 for the last 10 years, we will exhaust the opportunity to cap warming to 1.5°C as early as 2027, and diminish our shot at 2°C in the future. That's why the use of wood to diminish embodied emissions is so important.

    In regard to sturdy structures for the marginally housed – forgoing concrete and brick – given that multistory wood structures are constructed around the world, sturdiness is not an issue. 

    Vinyl does have a carbon footprint, though lower the many other products. I am not familiar with its advisability in severe wind regions. I imagine that would rely on the grade of siding and method of mounting. Regarding recycling, it appears that re-ground vinyl is used by the vinyl industry.

    The Pratt School of Architecture Housing Research Consortium is presenting an Earth Day 2022 Housing Decarbonization Symposium, Friday, April 22, 2022, on Zoom. The emerging market for carbon-sequestering materials, like mass timber and other bio-based materials, will be one of the topics. Free Registration is available at: https://pratt.zoom.us/meeting/register/tJIuc-2rrT0sHdzQATVkPbBubrdq3hPc53_4



    ------------------------------
    Bill Caplan, Associate. AIA
    Author of "Thwart Climate Change Now: Reducing Embodied Carbon Brick by Brick"
    Environmental Law Institute ELI Press, November 2021
    ------------------------------



  • 5.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-15-2022 11:50 AM
    Just a few comments. My understanding, from many wood industry experts, is that lumber (not trees) is 50% carbon by mass, not  1 lb per 1lb equivalent.. the value of lumber as carbon mitigating or lower intensity material is also relative to the use of the land before and after logging and of course the method of harvest. For good or ill, part of reclaimed (perhaps more correctly, simply extended life) lumber's value for GHG benefit is just avoiding its "premature" release of CO2 or CH4 from decomposition, not so much its low production energy. Reuse or extended life of any material avoids production energy and so generally one would certainly want to prioritize reuse of materials with the highest embodied energy like metals, plastics, concrete. Unfortunately, the reuse of these materials is very low. All to say, lumber certainly is the preferred material given it currently has  multiple options for good end-of-life management.

    ------------------------------
    George Guy AIA
    Material Reuse
    Gainesville FL
    ------------------------------



  • 6.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-13-2022 09:04 AM

    Interesting discussion on cladding and environmental impact. Of course, every material has its pluses and minuses.

    Much of the discussion around reducing carbon footprint tends to lean towards either renewable products like wood or resource efficient products like vinyl siding.

     Today's vinyl siding has a sophisticated formulation which has dramatically increased the life expectancy of the product to at least 50 years or more. Further, product testing standards for wind and other performance measures have improved the resiliency of the product in high wind events including hurricanes.

     The science to determine environmental impact of course is life cycle assessment (LCA) and plugs in scientific measures to understand products impact on the environment which gives specifiers a transparent understanding and helps the makers of the product understand different areas they can focus on to reduce these impacts.

    Part of LCA includes the use phase of the products, less maintenance means less impact, so with lower maintenance products like vinyl siding or brick, you have very little that is needed for it to be maintained. This is good. Unfortunately, with wood products they require significant materials for them to remain durable and resilient. Much of the information is typically contained in an Environmental Product Declaration (EPD), we have an industry-wide EPD currently available.

    Finally, vinyl siding can and is recycled, it can be quite simple if the right infrastructure is in place.

    The Vinyl Siding Institute offers a program currently on Hanley Wood University (including CEUs) on these topics and is available to put on online or in-person presentation on this topic as well. Here is the link to Hanley Wood University on the topic.

    https://www.hanleywooduniversity.com/search/vinyl_siding/#

     We look forward to continued engagement on this topic and for more in-depth information on these topics goto www.vinylsiding.org.



    ------------------------------
    Matthew Dobson
    Vinyl Siding Institute, Inc
    Burlington NC
    ------------------------------



  • 7.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-13-2022 09:04 AM

    Interesting discussion on cladding and environmental impact. Of course, every material has its plusses and minuses.

     

    Much of the discussion around reducing carbon footprint tends to lean towards either renewable products like wood or resource efficient products like vinyl siding.

     

    Today's vinyl siding has a sophisticated formulation which has dramatically increased the life expectancy of the product to at least 50 years or more. Further, product testing standards for wind and other performance measures have improved the resiliency of the product in high wind events including hurricanes.

     

    The science to determine environmental impact of course is life cycle assessment (LCA) and plugs in scientific measures to understand products impact on the environment which gives specifiers a transparent understanding and helps the makers of the product understand different areas they can focus on to reduce these impacts.

     

    Part of LCA includes the use phase of the products, less maintenance means less impact, so with lower maintenance products like vinyl siding or brick, you have very little that is needed for it to be maintained. This is good. Unfortunately, with wood products they require significant materials for them to remain durable and resilient. Much of the information is typically contained in an Environmental Product Declaration (EPD), we have an industry-wide EPD currently available.

     

    Finally, vinyl siding can and is recycled, it can be quite simple if the right infrastructure is in place.

     

    The Vinyl Siding Institute offers a program currently on Hanley Wood University (including CEUs) on these topics and is available to put on online or in-person presentation on this topic as well. Here is the link to Hanley Wood University on the topic.

    https://www.hanleywooduniversity.com/search/vinyl_siding/#

     

    We look forward to continued engagement on this topic and for more in-depth information on these topics goto www.vinylsiding.org.



    ------------------------------
    Matthew Dobson
    Vinyl Siding Institute, Inc
    Burlington NC
    ------------------------------



  • 8.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-15-2022 11:50 AM

    Vinyl composite question: it seems to me that whether or not you buy into the anti-vinyl crowd's health issues or the vinyl industry's LCA argument, one question remains, which is what happens at the end of the life-cycle? By chemically and mechanically bonding wood fiber, cellulose, etc. to plastic, it seems to me we have taken a biodegradable material and made it non-biodegradable. Whereas with other non-composite materials we can either biodegrade them (wood, etc.) or recycle them (metal), or re-use them (stone, brick, concrete.)

    The same goes for composite materials that fuse cellulose and cementitious materials, I think.

    To me that is the stumper.



    ------------------------------
    James Carr AIA
    www.jamescarrarchitect.com
    James Carr, AIA architecture & design
    Brookline MA
    ------------------------------



  • 9.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-18-2022 02:12 PM

    In response to George Guy and James Carr:

    Mr. Guy, yes, whatever the material, reuse is the best means to reduce carbon emissions. Regarding lumber being "50% carbon by mass" and "not 1 lb per 1lb equivalent", these represent two different measures. Nominally, 50% of lumber's mass is carbon. But nominally, 1lb of wood absorbed 1.5lbs of CO2 from the atmosphere during growth. Likewise, it will emit 1.5lbs of CO2 when burned or during decomposition. Carbon dioxide has more mass the Carbon. In general, the nominal average emissions released dressing wood for lumber products is 0.5lbs of CO2. Therefore, while 1lb of wood sequesters 1.5lbs of CO2, after emitting 0.5lbs CO2 for dressing, its net benefit is -1lb CO2 per 1lb of lumber.

    Mr. Carr, absolutely, the end-of-life cycle is a component of "embodied carbon". First let me state that I am not promoting the use of vinyl or any particular material, other than the use of wood when possible. A particular product's value always comes down to the total mass of the material used in a particular application. A thin layer of aluminum could have lower emissions than a thick piece of vinyl, etc. Researching my book, I was surprised to learn that CO2 emissions for a kg of vinyl were far less than many other materials. As such, depending upon the material's total composition, it could be a better alternative than many other claddings. But that was not a universal endorsement.

    The real issue at hand concerns the dwindling time available to us to reduce carbon emissions, we cannot wait for the 2030s. In reality, using any product that is already in stock is better than manufacturing a new one. That product has already done its damage. It comes down to consumer demand, impacting resupply – which means reducing new manufacturing, which is usually in large lots. If architects reduce demand, it will have a significant impact on resupply over the next few years, and thereby reduce new emissions. After the economic downturn in 2007, on heels of the 2006 housing bubble, cumulative energy-related CO2 emissions from the U.S. alone decreased by 700 million metric tons for 2008 and 2009 relative to the average emissions from 2006 and 2007. The slowdown in U.S. cement and steel production for the construction sector was responsible for 32 million metric tons of that reduction, kicking off a real-time supply-chain response.  We need to kick off a real-time supply-chain response now, through material choice. Material choices from every architect, from projects big or small, add up.   



    ------------------------------
    Bill Caplan, Associate. AIA
    Author of "Thwart Climate Change Now: Reducing Embodied Carbon Brick by Brick"
    Environmental Law Institute ELI Press, November 2021
    ------------------------------



  • 10.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-21-2022 02:04 PM
    Responding to these factoids:
    "After the economic downturn in 2007, on heels of the 2006 housing bubble, cumulative energy-related CO
    2 emissions from the U.S. alone decreased by 700 million metric tons for 2008 and 2009 relative to the average emissions from 2006 and 2007. The slowdown in U.S. cement and steel production for the construction sector was responsible for 32 million metric tons of that reduction, kicking off a real-time supply-chain response.  We need to kick off a real-time supply-chain response now, through material choice. Material choices from every architect, from projects big or small, add up."

    If these numbers are to be believed - not sure where they came from, but I have read similar numbers in other places (does that really mean anything, even though it is clearly how we reach consensus these days!) - (pause for breath) ANYWAY, if these numbers are to be believed, the takeaway for me is that in a carbon-based economy Dollars still = Carbon. Economic activity = carbon. Tinkering with the values of the carbon embodied by building materials is surely a good idea, and definitely that is something that we as architects CAN do, and SHOULD do, to make a contribution to reducing carbon while staying "in our lane." 

    However, it makes me reflect on other questions that we (as advisors to property owners) can and do tackle, such as how to grow the capacity of businesses, schools, hospitals, homes and so on to achieve their core purposes in ways that do not necessarily depend on the values of "more", "bigger", "newer", or "higher-value" that we as architects in service to a consumer economy have widely promoted over the century and a half of our formal existence as a profession -- with plenty of imaginative and innovative exceptions, of course.

    What are those alternative values?



     


    ------------------------------
    James Carr AIA
    www.jamescarrarchitect.com
    James Carr, AIA architecture & design
    Brookline MA
    ------------------------------



  • 11.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-25-2022 12:24 PM
    James Carr, you have hit the nail on it’s head! You’s is the essential question!
    Thank You
    Mike Mense

    Sent from my iPhone




  • 12.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-21-2022 02:04 PM

    Many of the composite materials are a good amount of vinyl and then a few other additives, for example many of the deck boards are still mostly vinyl, we are calling it cellular pvc but not because it has wood in it but because it using a blowing agent used to make it lighter (and less material) which then creates more space or "cells" - so most of the rigid vinyl products are easily recycled. One area that can't be mixed is the rigid vinyl products and flexible.... like siding vs. LVT. Both vinyl products but because one used plasticizes and one doesn't they can't be mixed.



    ------------------------------
    Matthew Dobson
    Vinyl Siding Institute, Inc
    Burlington NC
    ------------------------------



  • 13.  RE: How Small Building designs impact Embodied Emissions.

    Posted 04-25-2022 12:24 PM

    Mr. Carr, responding to your questions and thoughts:

    First the emissions vs construction downturn factoids. While researching my book "Thwart Climate Change Now: Reducing Embodied Carbon Brick by Brick", I wanted to get a sense of the magnitude of the relationship between construction activity and CO2 emissions. The data to compute the decrease in CO2 construction emissions after the 2007 downturn, was extracted from the following reports for the years involved:

    1. USGS Mineral Commodity Summaries.
    2. EIA Emissions of Greenhouse Gas Emissions in the United States.
    3. EPA Inventory of U.S. GHG Emissions and Sinks.
    4. EIA Monthly Energy Review: Carbon Emissions from Energy Consumption.
    5. EIA Commercial Buildings Energy Consumption Survey.
    6. gov/consumption/commercial/data.
    7. gov/programs-surveys/economic- census/data/tables

    Your point about "more", "bigger", "newer" is very salient in regard to the expenditure of excessive or unnecessary embodied carbon, but the need and desire for more buildings and economic activity will always grow. There will always be a demand, and yes, economic activity = carbon. But that's where architects, designers and engineers come in. There are always material choices and construction methodologies to choose from to design "more", "bigger" and "newer". They can be accomplished with a lot less embodied carbon than we use now. Yes, "less", "smaller", "renovation" or "retrofit" are the most desirable to reduce emissions on the timeline needed, but where that fails, careful choices can get us part of the way.



    ------------------------------
    Bill Caplan, Associate. AIA
    Author of "Thwart Climate Change Now: Reducing Embodied Carbon Brick by Brick"
    Environmental Law Institute ELI Press, November 2021
    ------------------------------