Shot of a room inside the 24 story HoHo Tower complex in Vienna.

The twenty-four-story high HoHo Tower complex in Vienna, Austria, is currently the world’s tallest timber building. It houses a hotel, apartments, a restaurant, a wellness center, and offices. Most of the building was prefabricated and assembled on-site. The construction system was kept deliberately simple, consisting of stacks of four prefabricated building elements: supports, joists, ceiling panels, and facade elements. About eight hundred wooden columns made of Austrian spruce carry the floors. It is designed to achieve “passive- house” energy efficiency.

Credit: DPA Picture Alliance / Alamy Stock Photo

Carbon Architecture

Call to action:

Transform buildings into carbon sinks by designing and constructing them with materials that sequester and store carbon.

The mining, manufacture, transport, installation, and maintenance of materials used in building construction generate significant amounts of greenhouse gases, called upfront or embodied carbon. This situation is changing. Traditional bio-based building materials such as wood, bamboo, straw, and hemp are being reformulated to be carbon negative. New architectural designs aim to be net zero. Innovations in carbon-storing products, including engineered living materials such as biocements, bioplastics, and mycelium-based composites and insulation, are emerging. Combining carbon-storing construction materials with cutting-edge technologies and design techniques can transform buildings from sources of emissions into global carbon sinks. Through research, investment, and collaboration across construction industries, we can move quickly to decarbonize the built environment while creating inspiring structures that promote health and well-being.

Nexus Rating System^Beta

Solutions to the climate emergency have unique social and environmental effects, positive and negative. To develop a broader understanding of the solutions in Nexus, we rate each solution on five criteria.

Sources for each Nexus are graded numerically (-3 through 10), and the average is displayed as a letter grade. You can explore each source in depth by clicking “view sources” below. For more information, see our Nexus Ratings page.

Carbon Architecture

0.00

6.67

Social Justice
Culture
Women
Biodiversity
Carbon

Reference	Social Justice	Culture	Women	Biodiversity	Carbon
The Role of Green Building Materials in Reducing Environmental and Human Health Impacts	7.0
Embodied Carbon and Climate Justice: Confluence or Conflict?	5.0
Integrating Social Equity into Green Building	6.0
The Health Economic and Community Benefits of Zero-carbon Buildings	9.0
Why transitioning to zero-carbon buildings is a vital urgent and rewarding investment for cities	7.0
The Materials Movement: Advancing Low-Carbon Healthy Materials for Sustainable Communities	8.0
The Economic and Social Benefits of Low-Carbon Cities: A Systematic Review of the Evidence	9.0
Decarbonization and Social Equity	8.0
Architectures Carbon Problem	8.0
Building Decarbonization & Equity	7.0
Alternative Cement - Project Drawdown					7.0
3 Advances in Sequestering Carbon in the Built Environment					7.0
Hempcrete Australia					6.0
	7.4	0.0	0.0	0.0	6.7

The Anandaloy Building, in Rudrapur Bangladesh, is made out of wood, ceramic, and bamboo,

the Anandaloy Building, Rudrapur Bangladesh, shown here under construction and is made out of wood, ceramics, and bamboo.

Action Items

Individuals

Learn about the importance of carbon architecture. Nearly 40 percent of global carbon dioxide (CO₂) emissions originate from the building sector, of which 70 percent are produced by building operations, and the remaining 30 percent come from construction. Conventional cement production alone accounts for 7 percent of CO₂ emissions worldwide, three times those produced by aviation. Steel and aluminum production also generate significant amounts of greenhouse gases. To meet global climate targets, all building emissions must be eliminated by 2040, especially since population growth is expected to fuel a doubling of the global building stock. A study showed that emissions from the new infrastructure could claim 30–60 percent of a remaining carbon budget based on limiting a global temperature increase to 2°C.

Promote and utilize materials that can transform the built environment into carbon sinks. Carbon architecture replaces high-emissions products with carbon-sequestering ones whose footprint and emissions can be measured using calculators, such as this Embodied Carbon in Construction Calculator (EC3). These materials are engineered to compete with and replace conventional counterparts in terms of durability, fire resistance, and structural strength. Common materials, whose embodied carbon coefficients can vary depending on harvesting, processing, and transport, include:

Wood: If the wood is properly sourced, mass timber—engineered wood products like glue-laminated timber (glulam) and cross-laminated timber (CLT)—can offer many advantages. In addition to having 70 percent lower carbon emissions than concrete, mass timber is also lighter and stronger, and more fire-resistant than steel and concrete. A research library of information can be found at ThinkWood. The Nature Conservancy initiated a global mass timber assessment, reported here.
Bamboo: A woody-stemmed grass that is known as the fastest-growing plant on earth, bamboo can be engineered into lumber to serve as a structural alternative to steel, concrete, and wood. It competes with these materials in strength, pliability, and fire resistance. Bamboo stores more carbon per ton than timber, and can be harvested sustainably for decades (see Bamboo Nexus).
Hemp: In use by humanity for centuries, hemp is fast-growing and versatile. Hempcrete, a lightweight concrete made out of hemp shiv, lime, and water, can be fabricated into blocks and panels and used as an alternative to concrete in non-load-bearing structures. Hempcrete is nontoxic, fireproof, mold resistant, and good at regulating moisture and heat (see Hemp Nexus).
Straw: A renewable agricultural by-product that stores carbon, straw can replace conventional insulation in exterior walls, offering good thermal and humidity control as well as structural integrity. Straw bale wall systems can withstand fire twice as long as those made with standard materials. A study in China showed the embodied carbon emissions of rural houses can be reduced by close to 40 percent when straw bale is used.
Clay: Clay has been used in building construction since the earliest human settlements. When mixed with water or reinforced with straw or bamboo (called adobe in parts of the world), it can help create durable products that substitute for concrete in countertops, flooring, and bricks, with very low embodied carbon.
Green cement: Humans have been perfecting concrete since the construction of ancient cities, and it remains our most widely used and most polluting building material, making it a top priority. Yet fixing concrete’s carbon footprint is complex, as emissions are embedded in the chemistry of conventional manufacturing. Global industry leaders have released a road map to fully decarbonize by 2050, involving renewable energy to heat the kilns needed for the process, recycling waste into components of concrete, and capturing CO₂ on an industrial scale (see Green Cement Nexus).
Biocement: Cement binds together the aggregates that makeup concrete and is responsible for a large part of associated carbon emissions. Biocement uses living microorganisms that can be raised using photosynthesis, a process that removes CO₂from the atmosphere. It can also reduce maintenance and extend the life of concrete buildings through the biogenic self-healing of cracks, currently the subject of research and development.

Visit carbon architecture buildings and see the materials in use.

This article describes three award-winning green cement buildings in North America.
Wood buildings include the 24-story HoHo building in Vienna, Austria; the 8-story mixed-use building Carbon12 in Portland, Oregon; and the 18-story student residence Brock Commons at the University of British Columbia, among many others.
You can check out these beautiful bamboo structures around the world.
Here are some wonderful straw bale homes that you can visit, along with a school built from straw in Denmark.

Raise awareness about the benefits of carbon-negative materials. Lack of awareness about carbon architecture is among the top reasons for its slow uptake. Educating leaders in the building sector is key.

Speak up. Write an op-ed for a newspaper advocating for carbon architecture by highlighting the many benefits it can offer. See examples here and here. If you work or live in a carbon architecture building, share your perspective and describe your experience.
Join a forum. Engage with other natural building advocates in Facebook groups to discuss materials, methods, and architecture, or start a local chapter with the Carbon Leadership Network.

Attend training to learn how to build with carbon-negative materials. Regardless of your skill level, you can increase your familiarity and get hands-on experience building with a variety of these materials.

Here are courses specific to straw bale, cob and earth, and hemp.
Search upcoming workshops to find ones local to your area.
Enroll in specialized degree programs, certifications, or functional training for natural materials use and installation.
Green Roofs for Healthy Cities offers a Living Architecture Academy and Green Roof Professional training and accreditation.
Attend carbon architecture industry events and conferences that feature pioneering new products, companies, and research. Popular events include the International Mass Timber Conference, the US Hemp Building Summit, and the International Conference of Green Concrete.

Volunteer to build community carbon architecture projects. Consider an eco-building service opportunity, or an organization like Red Feather that partners with Indigenous nations in the United States on sustainable housing, to help improve and build straw bale homes. Search for volunteer opportunities around the world on various natural building organizations’ social media groups, volunteer websites, and volunteer calendars.

Support innovative building materials companies on crowdfunding platforms. You can fund start-up companies via platforms like WeFunder, StartEngine, or Raise Green, which focuses on climate investment. These industry leaders might need extra support to purchase a first-of-a-kind hemp manufacturing facility, plant regenerative bamboo crops, or develop plant-derived cement alternatives.

Groups

Architects

Select carbon-negative materials for buildings. Firms across the world are pioneering carbon architecture across their project portfolios and can play an essential role in encouraging clients to shift towards regenerative materials. (See Key Players).

Use green concrete and responsibly sourced timber and wood products for structural building elements. Companies can ensure a higher standard of sustainable sourcing by supply chain due diligence through certification, third-party auditing, or other assessment tools. Builders must ensure that the mass timber they use does not come at the expense of mature and primary forests.
Alternatives can be used to replace petroleum-based foam and fiberglass insulation. Replacing conventional insulation with a natural material can have a 16 percent reduction in embodied carbon at no cost premium. Hempcrete and cellulose insulation are good natural insulator options that are fire and mold resistant. Cork, straw, wood fiberboard, and mycelium can also be used for building envelopes and cavity insulation.
Performing life-cycle assessments for each new building early in the design phase. Whole building life-cycle assessments look at multiple impacts of materials from extraction and manufacturing all the way to disposal. See a simple example of a building life-cycle assessment and read guidance on how to conduct one.
Compare building materials and systems and identify “hot spots” for embodied carbon reductions.
Publicly share the life-cycle assessment data to help build the overall knowledge base and benchmarking for the carbon architecture field. Canadian architect Kelly Alvarez Doran published an open letter on the need for embodied carbon benchmarks and targets in building standards and policies and what it would take to cut the embodied carbon of Toronto's multi-unit residential building stock in half.

Learn from traditional and Indigenous examples of carbon architecture. Cultures around the world have a rich heritage of vernacular architecture that incorporates available natural materials and reflects local climate, geography, needs, and culture:

Lo-TEK, a design movement inspired by Indigenous ingenuity and building philosophy, highlights how these traditional methods can be adopted to serve as solutions to the climate crisis.
Check out examples of Indigenous low-carbon architecture from Ghana, Thailand, and Canada.

Investors

Invest in businesses that are developing innovative carbon-negative products for the construction industry. Research suggests that financing is one of the key obstacles in the sector’s tremendous potential for growth. Invest in help to scale up manufacturing and production or support research and development.

RePlant Hemp Impact Fund promotes hemp as an alternative building material by investing $500 million by 2030 in the supply chain.
Built by Nature is an accelerator fund to scale the use of sustainably harvested timber as a building material across Europe.
Impact Finance Center launched a Sustainable Forestry Investor Club to drive investment capital to mass timber technologies.
Market opportunities are expanding in the low-emissions concrete industry, in companies such as Low Carbon Materials.

Home and Building Owners

Use carbon-negative materials in your home or building. Carbon architecture can be incorporated at scale by building the entire structure out of materials like engineered timber, adobe, or straw bale, or on a smaller scale by using natural materials like hemp for insulation or bamboo and cork for flooring. Here’s an article on finding a reliable and qualified green building professional.

To start, check out the most common carbon-negative building materials for homes, and get a quick orientation for the process and what to expect.
Read guidelines on how to construct an entire house from straw bale, or how to use it for insulation. Straw bales are relatively affordable and can be sourced from local farms or purchased as prefabricated straw panels from leading companies like EcoCocon.
Follow step-by-step guidelines on how to procure and use hempcrete as insulation for walls, roofs, and floors.

Industry Associations and Networks

Address gaps in data and materials benchmarking to increase the adoption of carbon architecture. Since the field is still developing, collaborating and sharing information is critical to accelerating the efforts within the sector. Data standardization and knowledge sharing help quantify the life-cycle assessments (LCAs) of buildings more efficiently, supporting a rapid transition to net-zero buildings.

Publicly share resources and best practice strategies. Conduct and publish studies that explore the safety, durability, strength, cost, health, and environmental aspects and impacts of engineered natural building materials. See examples here and here.
Promote the wide use of standardized tools and databases that compare the carbon emissions of building materials. Available tools like Tally, Athena Impact Estimator, or OneClickLCA can help industry professionals evaluate building design choices and identify materials with the most regenerative potential, and include training on their use. The Canada Green Building Council offers a primer on embodied carbon along with other relevant reports and training.

Advocate for the use of natural materials in construction. Industry and nonprofit groups play a key role in raising awareness and inspiring collaboration across the sector.

Join an initiative, like Built Environment Declares, and commit to a set of actions that challenge conventional building approaches and adopt regenerative design principles.
Ecological Building Network (EBNet) connects green construction innovators with designers, builders, engineers, and government officials, providing technical support and taking part in international conferences. Its BuildWell Source is an online library of low-carbon building information.
Architects! Climate Action Network is working to accelerate an industry-wide transition by hosting free educational events open to practitioners, owners, contractors, and policymakers.

Suppliers

Use regenerative farming and forestry practices when sourcing natural materials. To realize the full climate benefits of carbon architecture, the building materials themselves must be grown, managed, and harvested responsibly. Otherwise, an increased demand for products like wood or bamboo can contribute to global forest and land degradation through deforestation and clear-cutting, application of agricultural chemicals, and monocropped tree plantations.

Source mass timber products only from softwood that is certified by the strict standards of the Forest Stewardship Council (FSC).
Use small trees collected from forest thinning and salvaged timber from previous forest fires. This has the added benefit of helping reduce the odds and the intensity of wildfires (see Fire Ecology Nexus).

Companies

Develop company-level carbon reduction goals that account for embodied emissions in buildings. Companies around the world have signed agreements such as the Net Zero Carbon Buildings Commitment or put in place science-based targets, taking a first step toward identifying carbon footprints across all emissions scopes. Consider setting mandatory embodied carbon reduction targets for all new construction projects.

Consider using carbon architecture for your next new building. A variety of companies are already commissioning carbon architecture:

Toyota is building an entire city out of mass timber, where some buildings will use traditional Japanese wood joinery techniques. The "Woven City" will include a Toyota car factory and will house about two thousand company researchers, their families, retailers, and retirees.
A brewery in England built its distribution center from hempcrete blocks and used glulam timber for framing. Hemp's strong insulation properties enable the building to forgo any artificial refrigeration or heating to keep the beer at the desired storage temperature.

Governance

Incentivize the private sector to use low-impact materials in the built environment. Public actors can provide various forms of financial support for early adopters of carbon-negative materials. Also, because data and benchmarking information are still being standardized for carbon architecture, government programs can be structured to reward projects that incorporate knowledge sharing. Putting a price on carbon can be an effective way for governments to alter behavior in favor of greener materials.

This study examines the ways that a carbon taxation policy such as the one introduced in Canada, Sweden, Norway, or New Zealand can encourage the construction industry to reduce emissions.
Australia’s Timber Building Program will invest $300 million to encourage mass timber construction in the country.
British Columbia’s Mass Timber Demonstration Program is investing $5.4 million to accelerate the use of mass timber in the province.
The U.S. Department of Energy has awarded $45 million in funding for carbon architecture research and development, including the design of carbon-negative materials and building life-cycle analysis tools to measure carbon drawdown and storage in the construction sector, creating a project called Harnessing Emissions into Structures Taking Inputs from the Atmosphere.

Update regulations around building codes and standards. One of the big barriers to carbon architecture is that some local code officials still consider low-carbon building materials as a hazard despite the fact that some of these materials have been incorporated into the International Building Code since 2015.

Jurisdictions that have adopted codes that include natural materials include Washington and Oregon for tall mass timber and California for straw bale.
In the European Union, Denmark, Finland, France, the Netherlands, and Sweden are leading the way toward carbon neutrality in the construction sector with regulations and initiatives, including the Green Deal that aims to promote circular buildings and low-carbon design.

Create procurement policies that mandate the use of carbon architecture in public construction projects. Develop policies that give clear goals to the market, such as:

France’s mandate requires all new public buildings to be built from at least 50 percent timber or other bio-based materials, such as hemp and straw.
Starting in 2025, 20 percent of new buildings in Amsterdam will need to be constructed from wood or other natural materials. Amsterdam is also planning to build an entire neighborhood out of mass timber.
In Canada, Vancouver approved a plan to reduce embodied emissions from new buildings by 40 percent by 2030, including increased use of mass timber, green concrete, and low-carbon insulation.

Key Players

Architects

IBUKU (Indonesia) is a team of young designers, architects, and engineers exploring groundbreaking ways of using bamboo to build homes, hotels, schools, and event spaces.

Kéré Architecture (Germany) has a dual focus on design and social commitment, encompassing building, design and knowledge sharing.

The Miller Hull Partnership (U.S.) creates impactful, beautiful, and planet-positive designs. EMission Zero is an initiative targeting the elimination of GHGs incurred by the buildings they design.

LEVER Architecture (U.S.) is a leading architectural practice recognized for design excellence and material innovation.

Lake|Flato Architects (U.S.) strives to create restorative environments that reduce carbon emissions and enhance our understanding and relationship to the natural world.

Shigeru Ban Architects (Japan) was founded by award winning Japanese Architect Shigeru Ban in 1985 and renowned for its innovative work with timber, paper, and bamboo structures, provides full architectural design services globally from early concept through construction administration.

de Rijke Marsh Morgan (UK) generates architecture that utilizes construction with a lower environmental impact, reduced waste, modular components, and recycled materials.

Bensley (Thailand and Indonesia) is a small atelier of youthful, energetic architects, interior designers, artists, and landscape architects who know no limits.

Vo Trong Nghia Architects (Vietnam) is a leading architectural practice in Vietnam with offices in Ho Chi Minh City and Hanoi. International architects, engineers, and staff work closely on cultural, residential, and commercial projects worldwide.

Leers Weinzapfel Associates (U.S.) pioneered the first large-scale academic Mass Timber building in the United States at UMass Amherst Design Building, evaluating the applicability of Mass Timber through Schematic Design and Design Development phases before an official switch was made from a Steel structure to a Mass Timber structure.

Anna Heringer Architecture (Germany) uses architecture to strengthen cultural and individual confidence, support local economies, and foster ecological balance.

KAISER+PATH (U.S.) is comprised of real estate developers, architects, and builders who believe sustainable, responsible development is not only the right thing to do—it’s the smart thing to do.

Made in Earth Collective (India) is a community of artisans, architects, engineers, artists, and makers who believe in forging lasting relationships within our ecosystem.

Organizations

The Institution of Structural Engineers (UK) has showcased structural engineering excellence for 50 years and believes the industry has a responsibility to help mitigate the climate emergency by changing the way buildings and infrastructure are designed, commissioned, and constructed.

The MIT Concrete Sustainability Hub (U.S.) is a dedicated interdisciplinary team of researchers from several departments across MIT working on concrete and infrastructure science, engineering, and economics since 2009.

Cob Research Institute (U.S.) aims to make cob legally accessible to all who wish to build.

Ontario Natural Building Coalition (Canada) is an advocacy group of designers, builders & homeowners working to promote healthy, high-performance natural building strategies in the construction industry.

California Straw Building Association (U.S.) is an all-volunteer non-profit organization committed to building with straw.

Strawbale Association (France) promotes and recognizes the use of straw in building.

Adobe in Action (U.S.) is a non-profit organization that supports owner-builders, practitioners, and communities with the planning, construction, and preservation of adobe homes.

Earth Building Association of New Zealand (New Zealand) provides information on natural building methods and techniques, especially for New Zealand conditions, and as a network for those interested in natural building.

Oregon Mass Timber Coalition (U.S.) creates equitable economic development and family-wage rural and urban jobs from sustainable wood products grown and manufactured in Oregon.

WoodWorks (U.S.) is a resource for commercial and multi-family wood building design, engineering, and construction.

ThinkWood (U.S.) is a communications campaign that provides commercial, multifamily, and single-family home design and build resources to architects, developers, and contractors.

US Hemp Building Association (U.S.) supports and advocates for hemp-building professionals, projects, and materials.

Materials Companies

Plantd (U.S.) makes carbon-negative materials for every new home and building on earth.

Basilisk Self-Healing Concrete (Netherlands) offers a range of bio-based products that make concrete more sustainable, durable, and waterproof.

Green Cement (U.S.) transforms byproducts and natural minerals into sustainable products that eliminate the greenhouse gas emissions from cement while making it stronger and more economical.

CarbiCrete (Canada) has innovative manufacturing technology that substitutes cement with steel slag, eliminating a highly polluting substance from the concrete mix and replacing it with repurposed industrial waste.

InventWood (U.S.) develops high-performance, cost-effective, and carbon-sequestering wood and cellulose materials to replace unsustainable alternatives that are widely used today.

Hempitecture (U.S.) produces healthier, more sustainable alternatives to conventional, toxic thermal insulation.

ISOHemp (Belgium) creates hemp blocks that are a non-load-bearing glued masonry product designed for the production of healthy and natural insulating envelopes, partition walls, and counter-partitions.

UK Hempcrete (UK) is a market-leading company specializing in the use of Hempcrete (or ‘hemp-lime’) and other bio-based materials in construction.

StructureCraft (Canada) engineers and builds efficient and beautiful timber and hybrid structures.

Stora Enso (Finland) is a leading provider of renewable products in packaging, biomaterials, and wooden construction and one of the largest private forest owners in the world.

Mayr Melnhof Holz Holding AG (Austria) is one of the leading timber-processing companies in Europe, a major producer of glued laminated timber, and a driving force in the advance of cross-laminated timber, the building material of the future.

RIZOME (U.S.) believes a more beautiful world is created through the natural beauty, strength, and planet-healing properties of bamboo.

WiDuz (Singapore) aims to advance the transition from a petroleum-based industry into a circular bio-economy for a sustainable future,

Moso International (Netherlands) creates outdoor bamboo products for residential and commercial use.

Plyboo (U.S. creates decorative and acoustic wall/ceiling panels, bamboo plywood and veneer, and bamboo flooring.

BamCore (U.S.) is a pioneer in developing building solutions with a beyond-zero carbon footprint.

ReNüTeq (U.S.) is a world leader in architectural / structural engineered bamboo and is committed to delivering renewable structural technologies & innovative building solutions.