The Neutral Project is focused on developing carbon-neutral mixed-use and multifamily buildings that reduce embodied carbon emissions and minimize operational carbon emissions, an approach it roots in building with mass timber, designing using passive building principles, and verifying the approach through third-party life cycle analysis. 

Designed by Chicago-based HPA Architecture, The Edison will be built using a hybrid engineered wood system, with a CLT floor system, glulam columns, and concrete beams, stairs, and cores. Instead of drywall, the timber beams, columns, and ceiling will be left mostly exposed to achieve biophilic benefits for building occupants. Floor-to-ceiling glass will highlight views of Lake Michigan, allow for natural light, and expose the beauty of the wood assembly. 

“Wood is the best principal material available for building structures when considering total energy use, carbon emissions, and water usage,” the developer said in a press release. The Neutral Project is also developing
Baker’s Place, a Michael Green Architecture–designed 14-story mass timber mixed-use development with 206 homes that has begun construction in Madison, Wisconsin.

Think Wood spoke with The Neutral Project’s managing partner Nate Helbach about The Edison and why Milwaukee is such fertile ground for tall timber today.

The Edison
Render Credit: HPA Architecture
Building-Use Diagram

Think Wood: How did you get involved with building development? And how did you launch the Neutral Project?

Nate Helbach: I am a Wisconsin native, originally from Middleton, a suburb of Madison. I was at Harvard Extension School working on a sustainability degree and I was working full-time for a developer doing developments throughout Wisconsin—mostly in the low-rise multifamily market. The Neutral Project was a thesis I developed in school: to build carbon-neutral developments that reduce both embodied and operational carbon in the built environment. 

It was one of those things you develop in class and then you put on the shelf. But I had this unique opportunity to start the firm with two German investors who seeded me. They came in and said, “Hey, we really think that this idea of creating a company around sustainability is something that is unique in America, but prevalent in Europe.” There’s a lot of investment dollars in Europe that are now coming to the United States that are investing in projects that have ESG-focused initiatives.

When we started the Neutral Project, we thought we were going to conquer the world. Then when you get into the details, you get slapped in the face with all the challenges. People aren’t doing this because it’s very challenging. 

What spurred you to consider mass timber for your projects?

One of the things we look at is: What components of the building have the largest contribution to embodied carbon? The number one component is structure. Really the two structural components you can use are steel or concrete, but there’s this new mass timber that we can use, as well.

How has your most recent multifamily project, The Edison, evolved?

We acquired the site in late 2021. The original design was 15 stories. We decided to increase the scale because of financial feasibility. At 15 stories, the site wasn’t feasible. The land basis was too high, the construction costs were too high, and the returns were too low. So, what did we do? We said, let’s go larger. And if you, if you go larger, you get unique economies of scale that come from increasing the size of the building.

How tall might it be?

We’re at 32 stories right now, and our architect just said: “That’s it, we’re done. You have to stop designing more stories because we’ve added five or six floors during design.” 

That’s where we’re going to stay and move forward with our design concept throughout the summer, fall, and hopefully get in the ground by January of next year.

It seems Milwaukee is a hotbed of tall timber today. Why?

I think the main reason is because the authorities having jurisdiction are proponents of mass timber. That is hard to find right now because within the current Wisconsin building code there is actually no provision for heavy timber. We’re about to be in the 2018 [International Building Code], but Wisconsin still falls under the 2015 IBC. And within 2015, all you have is the old, antiquated Type IV, which is only for six stories.

As a developer, one of the biggest risks using mass timber is you have to go through a pretty intensive design process, pay your designers and structural engineers, and then you might get approval. You might get your permits from the city, but there’s a huge risk that if they’re against it, to just flat out deny it and say, no, you have to build with concrete. So the reason I think Milwaukee is a huge city for mass timber is because the authorities having jurisdiction are behind the actual material, including fire, building, city services—all those different state and city agencies that have to approve your building plans.

So, they’re all in alignment in Milwaukee at the moment?

Yes. We had a meeting at the fire department four or five weeks ago. Usually, the fire department in any city is kind of pessimistic. But the City of Milwaukee fire department was cheering us on about how much they enjoyed mass timber, which is good.

What’s next for mass timber in Wisconsin?

Wisconsin formed a mass timber task force within the Department of Safety and Professional Services. That task force’s main job is to engage with government, city, and the private sector with the goal of having more mass timber in Wisconsin. They’re talking about adopting 2024 IBC. That would allow Type IV that allows for more exposed timber framing, which is one of the big benefits from the development standpoint. If you build this beautiful mass timber building, you want the tenants or residents or anyone going to the building seeing these beautiful glulam columns, beams, and CLT decks.

This conversation has been edited for length and clarity.

Think Wood: Can you tell us a little bit about yourself and the mission of the Capital Area Development Authority (CADA)?

Renee Funston: I’m a development manager with Sacramento’s CADA—it’s a joint powers authority between the state of California and the city of Sacramento and is specifically here to implement the housing and support the retail goals of the Capitol Area Plan. We were founded in 1978 to essentially be the state property manager for residential and commercial properties around the capitol. CADA is a pretty unique public agency—we still get tax increment financing, and so that’s a portion of the tax dollars within our actual redevelopment area. We then reinvest that back into the surrounding neighborhoods. 

A big part of our mission is to help create a neighborhood for all, including all household types and incomes. CADA is mandated to preserve a quarter of its housing stock (units that CADA manages or builds) as affordable units. 


We understand a recent CADA-supported affordable housing project used mass timber. Can you tell us about that project?

Yes, one of our most recent projects, Sonrisa (1322 O Street), is a five-story mass timber building using cross-laminated timber (CLT). It consists of 58 micro-unit apartments with 1,300 square feet of ground-floor community space. All of the units are affordable at low- and very low-income levels. It is the first to be completed under Governor Newsom’s Executive Order N-06-19 for Affordable Housing Development. That order specifically calls for increased use of renewable sustainable construction methods such as modular mass timber construction. 

  • Photo Credit: Kurtis Ostrom Photography
  • Photo Credit: John Swain Photography
  • Photo Credit: John Swain Photography
  • Photo Credit: John Swain Photography

What are some of the benefits you found from using mass timber?

It will provide beautiful, warm environments and will help boost the ceiling height to over nine feet in the units and 12 feet on the ground floor. That is a real plus, especially when building micro suites, as it gives more light and a greater sense of openness, contributing to a sense of well-being. We will also be able to take advantage of modular prefab construction, so we can frame and get the structure up a lot quicker. It’s well-suited to smaller urban infills. And then of course the sustainable properties associated with mass timber make it a no-brainer.


Why is it important to consider sustainability, biophilic design and using materials like exposed wood, in an affordable housing project?

I think with any project, not just affordable housing, it is important to consider these things. At the same time, our organization is long-term mission-driven, maybe more than a traditional developer. So we go above and beyond for a lot of these types of things, knowing that we are building affordable housing as part of a long-term sustainable development strategy. With mass timber, we can sequester carbon into this solid form and as a building material it’s going to have a lot more longevity—you could potentially even use those CLT panels for another project in the future if we think in terms of design for disassembly and re-use. That’s something that we should all be striving for. Beyond this, we are doing things like not including parking but instead making sure there’s excellent walkability and access to transit. 


As a public agency, do you see CADA as needing to take a leadership role to showcase innovations to the wider industry, such as the case of using mass timber?

Absolutely. And I think that’s certainly already happening in Sacramento. The Sonrisa is a great example and so we’re happy to share our findings and knowledge. We’re sharing everything from design details and pro forma to acoustical studies. These projects can help everyone in the industry as we learn together and fine-tune our best practices.


What are some of the learnings you can share when it comes to mass timber and affordable housing?

I think generally working together really closely early on a mass timber project is important. There are many things that are happening at once and you don’t always identify what pieces are missing from the drawings until you are actually working with your sub-consultants. As much as possible, you want to have that really close upfront coordination, checking everything out, that everyone is on the same page and has thought through what things potentially could go wrong. Giving close attention to delivery schedules of mass timber panels is also key. For the Sonrisa project, it took three days for the truckload deliveries to arrive and we had to figure things out between the delivery schedule and when people are working, factoring in weekends and holidays. 


Any last words or advice to other industry professionals or public agencies looking to take on a mass timber project? 

Innovation can be overwhelming and a little scary. It’s understandable that developers are looking for certainty. I definitely recommend reaching out to the growing community of mass timber experts in the field. Developing a close collaborative, trusting, working relationship between the owner, architect, and contractor can really make a difference when it comes to mass timber projects. You can never go wrong reaching out to other successful design teams. I would certainly recommend connecting with others in your region who have successfully completed mass timber projects.

This interview has been edited for length and clarity.

Aureus Earth’s Leadership Team

Wil Srubar, PhD Founder and Managing Director | Salmeron Barnes Founder and Managing Director | Adam Orens Founder and Managing Director | Michele Grieshaber, PhD Strategic Advisor


Think Wood: As an organization, what is Aureus Earth? How do you answer that question for those who are new to carbon accounting and financial solutions?

Aureus Earth Leadership Team: Aureus Earth monetizes the built environment’s ability to combat climate change. Our central focus and mission are to decarbonize the construction industry by providing financial incentives to builders and developers, encouraging them to use carbon-storing materials, like mass timber, in non-residential and multifamily buildings. Aureus Earth quantifies and values the carbon stored in the building project, then issues carbon offsets on the basis of the amount of biogenic carbon stored in the building. The carbon offsets can be monetized and sold to help reduce the cost of building with mass timber. 

What kind of team did you need to develop this new way of quantifying carbon storage?

We certainly have a unique team with a robust set of expertise spanning alternative construction materials, finance, and strategy. Together, we’ve worked on a model that we think is a win-win for those who want to build with greener materials and for those who wish to purchase carbon offsets that are demonstrably transparent, high quality, and durable. 

So, are you creating a new carbon market?

We are not a carbon market, but we do work with carbon marketplaces and exchanges to essentially sell offsets that are generated from the projects we support. We do that by financially incentivizing the choice of climate-positive materials and verifying and monetizing the carbon stored in the mass timber elements.  

Who would buy these carbon offsets?

They can include individuals, corporations, or other organizations that wish to offset their current or past carbon emissions through voluntary action—and in some instances, companies are legally mandated to offset their emissions.

How will this work for architects, developers and other building professionals? What are the steps to issue the carbon offsets for a mass timber building?

Aureus Earth issues carbon offsets on the basis of biogenic carbon stored in a mass timber building. The first step is carbon storage calculations. We quantify how much carbon will be stored through the use of mass timber used in structural elements—which are unlikely to be altered for the duration of the building’s lifetime—as we want to avoid leakage. The stored carbon is then converted into carbon offset equivalents based on our Mass Timber Building Protocol (MTBP). Aureus Earth matches these carbon offsets with potential buyers of carbon offsets and provides the proceeds to the building owner. 

So can a developer or owner get a cash rebate for choosing a carbon-storing material like wood?

Aureus Earth helps builders and developers offset the green premium associated with sustainable building materials, such as mass timber. The offsets we issue can be retained by the building owner or sold on a carbon market. In the latter case, the builder essentially gets a “cash rebate” for choosing to use a carbon-storing material like wood. 

You completed a pilot of the program with the University of Washington’s Foster School of Business—providing carbon offsets for the newly completed Founders Hall mass timber building as a proof of concept. Can you elaborate on that project?

In the UW Foster School project, Aureus Earth demonstrated how to use a sound and vetted scientific method to figure out the amount of carbon stored in a building and do what we call an end-to-end transaction. We demonstrated a few novel concepts with this pilot. First, we demonstrated that science-based methods can be used to calculate the amount of biogenic carbon stored in mass timber for a specified—and guaranteed—period of time. Offsets were issued on this basis, taking that amount of carbon stored and then subtracting emissions from harvesting, manufacturing and transporting the timber. Second, the carbon in the building can be considered as physical property, like a mineral or wind right. So, we worked with a premier title company to create title and access rights to the carbon that were recorded with county authorities and could serve as the basis for transferring the asset to another party. And third, the process was audited by a well-recognized audit firm to verify the whole process.

Why are you starting with mass timber buildings and why are they a good choice for this incentive program?

Aureus Earth prioritizes new construction methods and practices that can turn buildings into a positive force to reverse climate change. Mass timber has the potential to do just that by cutting emissions from cement and steel production. And buildings constructed with mass timber can be thought of as carbon sinks that hold onto carbon for the lifetime of the building and beyond. When it’s time to take the building down, the reuse of mass timber elements is likely to be attractive in the future, creating a secondary market for the mass timber and keeping it out of landfills.

Are there minimum standards a mass timber building must meet to be part of the program?

To qualify, a project must use mass timber such as CLT or glulam and be a commercial nonresidential or multifamily residential building of over 20,000 square feet. 

How much does this service or process cost? Can it offer savings in the long run?

Building owners do not pay to work with Aureus Earth, instead, they receive revenue for the carbon offsets that represent the amount of carbon stored in their building project. One great benefit of this program is it can reduce the green premium sometimes associated with using more materials that store carbon. As the market for high-quality carbon removal offsets grows, the amount of the green premium that the offsetting revenue can address will improve even more. Today, we’ve found that even a small percentage of the cost is enough to provide building owners with a reason to consider climate-positive materials, like mass timber.

How does this program compare to other green building programs? Will it be something a building owner or company can promote as part of its commitment to fighting climate change?

We believe there is a market for buildings that store carbon and we’re looking at developing programmatic recognition as we scale. In the meantime, buildings that work with Aureus Earth can get the dual benefit—the offsetting revenue from working with Aureus Earth and the ability to apply for LEED or BREEAM certification as well. The difference is in the Aureus Earth case they will get paid. For the other certifications, they must pay a fee.

Most folks in the building industry agree we need to tackle climate change—but why are carbon-storing incentives just as critical as energy and operational efficiency?

Think of it this way—there are estimates indicating that the equivalent of a New York City will be added to the planet every 35 days for the next 40 years. That equates to at least 600 billion square feet of new buildings every decade or more. Without intervention, without these types of incentives and carbon-storing materials, conventional construction will eat up nearly two-thirds of the remaining global carbon budget alone—if we are to meet the 1.5 degrees Celsius target limit. 

Tackling climate change can be overwhelming, especially for the upcoming generation of professionals. Any words of advice?

AE Team Member Michele Grieshaber: As a researcher and university lecturer, I’ve been asked this exact question. It can be overwhelming hearing bad news about the climate, especially as a young person—and it might sometimes be hard to feel hopeful. First of all, I will say this, and I cannot remember where I read this, so it’s not my original idea: to address climate change we are looking for a silver buckshot, not a silver bullet. In the case of Aureus Earth, we are tackling one important component and that’s improving the amount of carbon stored in our buildings. Others are looking at major boosts to energy efficiency or alternative fuel sources. And outside the building industry, efforts are being made as well. I believe we can find some solace in the cumulative effect of many different solutions.

What is the future outlook for Aureus Earth?

Aureus Earth wants to move beyond the carbon offset to the carbon asset. We are currently exploring how we can transform biogenic carbon stored in mass timber construction into a real, transferable, and depreciable asset. In the next decade, we believe real-estate-backed, climate-positive financial instruments will become the next “mineral rights.”

Interested in sustainable building solutions for your next project?

Founders Hall
Photo Credit: Tim Griffth
View project
To address climate change we are looking for a silver buckshot, not a silver bullet. We are tackling one important component—improving the amount of carbon stored in our buildings…I believe we can find some solace in the cumulative effect of many different solutions.
Michele Grieshaber, PHD
Strategic Advisor | Aureus Earth

Founders Hall

A Model of Climate-Smart Design

With the climate crisis weighing heavy on the minds of college students, post-secondary institutions are increasingly looking for ways to lower the carbon emissions of their campuses while also supporting student and faculty well-being.

Founders Hall
Photo Credit: Tim Griffth
View project

Think Wood: What is Gensler’s Lab of the Future concept?

Chad Yoshinobu: The need for better-designed lab spaces and science workplaces is growing rapidly. As you can imagine, designing labs comes with lots of competing demands and challenges. And the design of many conventional labs just doesn’t cut it anymore. The Lab of the Future concept is thinking about the design of these buildings very differently. We really put ourselves in the place of the occupants and consider what they will need in a next-generation lab facility. We wanted to open up the space and make it more than just a container; we wanted to give developers a building concept that would differentiate them. Along with this, we made cutting carbon central to its design.


TW: What differentiates this concept from conventional lab designs?

CY: It started with a very simple question: what would compel a science tenant to want to come to this building? We wanted to alter the trajectory of how a science building could be designed from the inside out—and we really rethought the entire lab layout,starting with the grid. We created a grid of 33’ by 33’ because it’s based on a lab module for a science tenant. We also relocated the building core from the center to the side of the building. Putting a core in the middle of a building is like putting a fireplace in the middle of your living room. Together, the grid and the shifted core gives the client maximum flexibility.


TW: Why did you choose mass timber as the primary structure for the concept lab and what role did it play in cutting carbon?

CY: We discovered that timber is particularly suited to offsite modular construction, which would allow us to produce the project in a nearby factory and deliver it to the site as a kit of parts. This approach would be 30% faster and 10% cheaper to construct than a conventional concrete building. With 85% fewer deliveries to the site and a 75% reduction in construction waste, NEXT uses 80% less carbon to build than a conventional concrete lab building. This amounts to a savings of approximately 5200 total metric tons of CO2. The material also has an emotional appeal because it lends warmth to a building’s interior; steel and concrete must be covered with extra material to achieve the same result.


TW: What other advantages and challenges did mass timber pose for this conceptual design?

CY: Designed with an offset core, NEXT’s mass timber grid provides maximum tenant flexibility for the lab/workplace at 33 x 33 feet. By optimizing the column grid to this unique layout, the lab bench can be oriented in either an east/west or north/south planning layout. 

As for challenges, vibration is a key concern for buildings of this type. In a lab setting, you need to minimize this as it can directly impact the accuracy and quality of lab results. Because mass timber can be prone to a little more vibration, we partnered with KPFF to find a solution that resolved any negative impact. We achieved a vibration of 6,000 micro inches per second (MIPS), a go-to standard for most lab buildings.


TW: Did you find out anything surprising or unexpected in your research to reinvent lab and science buildings?

CY: This is perhaps not entirely surprising, but something conventional lab buildings often don’t provide is outdoor space. Our research showed that access to the outdoors topped the wishlist of our tenants and building occupants. Traditionally, adding operable windows and outdoor balconies to labs hasn’t been considered possible since air flow direction and pressure tiers would be disrupted. But by using conference rooms or other spaces as a vestibule, it is possible to allow labs to have access to fresh air for meeting spaces and to provide space to hold meetings outdoors. Fresh air and views help make meetings more enjoyable and encourage more creative collaboration and discussion, while also potentially mitigating airborne pathogens.


TW: Unique to a science laboratory, your team focused on connection to the wider community—what design features helped you achieve this?

CY: Gensler wanted to demonstrate how a science building could be a community catalyst to benefit the local area by creating opportunities to activate public programs at the ground floor. 

And by shifting the stair access to the building and making it accessible and transparent, the design sends the message that it is outward-looking to the community. The most underutilized aspect of a building now has daylight, it has views, and it creates community because it’s an inner connecting stair for the entire building.

NEXT was designed to host a multipurpose arts and entertainment venue as well as a shared incubation restaurant and shared kitchen space to celebrate the diverse culinary arts in the city. It looks beyond the perimeter of its walls to stitch together an approach that benefits its community, creating a synergy between community and building.


TW: What are the biggest lessons learned by undertaking this conceptual design process?

CY: Beginning with the tenant in mind and what they want the building to feel like as a holistic experience was critical to our approach, and, I believe, to its success. The idea is to look at the areas that our science and lab tenants really need us to advise on and how their needs are evolving with changes in their industry. Ultimately, NEXT is a platform that allows tenants and developers to reimagine what a science building can be. In addition to delivering top-of-line functionality within the lab and workspace, NEXT offers opportunities for a variety of connections—to the outdoors, the community, and to the surrounding cultural context—without sacrificing tenant flexibility. This is our call to action to shift from the past to a more resilient and inclusive future for lab buildings.

Think Wood: Hi Ruth, Bobby. To get us started can you explain a bit about Passive House, for those who might be less familiar?

Ruth Mandl: Passivhaus is a building standard that was developed in Germany in the early 1990’s. It focuses on high-performance construction through the use of extensive insulation, energy-efficient windows, and the use of an air-tight membrane that wraps the entire structure, reducing the impacts of hot and cold weather. Passive House design can offer huge energy savings and ultimately cut harmful greenhouse gas emissions. When done right, all of these factors can reduce the operational energy consumption of a building by 80 to 90%. 


TW: How did you get started with Passive House design?

RM: Our own house was actually our first Passive House project and now serves as a great test case. Working with an existing building from 1889, it was important to us to keep and reuse as much of the original moldings and millwork as possible, while updating the building to the Passive House standard. We removed all of the wood finishings and stored them in a tent in our backyard. Once the high-performance thermal envelope was completed, we reinstalled most of these materials; what we couldn’t reuse, we donated for reuse. The project demonstrated to us that it is possible to achieve a high-performance Passive House renovation while retaining salvaged materials.


TW: How does CO Adaptive approach Passive House design in renovation and adaptive reuse projects?

Bobby Johnston: Depending on the context and condition of the building, our approach is to carefully consider what we can retain from the original construction while updating the thermal envelope to meet high efficiency standards. The goal is always to update the building for airtightness without demolishing the interiors. We are starting to focus much more on how we can approach adaptive reuse and renovations with minimal waste, opting to focus on deconstruction rather than demolition.  It’s a trade-off between minimizing a building’s embodied carbon by retaining as much of the existing structure as possible and the operational benefits that you achieve through Passive House design.


TW: How do Passive House structures perform in different climates?

RM: Given the ever-hotter weather due to climate change, buildings in the U.S. need to mitigate heat as much as cold temperatures, particularly in southern climates and during summer months. Passive House was originally developed for Germany—a relatively cold climate—but it also works really well in a hot climate, as long as you’re preventing the sun in the summer from penetrating the interior. The key is in getting your building envelope to work harder than your active systems—in turn reducing your reliance on HVAC systems.


TW: What role can prefabricated timber systems play in Passive House design?

RM: Along with minimizing demolition in renovations, we are starting to look more rigorously at prefabrication and modularity in our adaptive reuse and renovation projects—and how we can make use of demountable timber panels, ultimately prefabricating portions of a Passive House envelope for retrofit applications. Thermally, wood is superior to steel and concrete and offers added thermal mass. All of our Passive House projects use wood as the primary material. Wood provides more versatility and given its natural renewability, it lends itself to our goals of regenerative, circular design. There’s more modularity and prefabrication in new builds but we haven’t seen a lot in the retrofit market, especially in an urban context. I think that’s really what is needed. So we’re working on a prototype here at the office, doing just that.


TW: Is Passive House part of a broader vision for your architectural practice?

RM: Very much so—we’re constantly evolving what sustainability means to our practice, but we know at the core we want to think as systemically and regeneratively as we possibly can. Cutting embodied and operational energy is definitely a part of that. In urban environments, these principles are best applied in adapting historic building stock, reducing demolition when it can be avoided, and respecting and optimizing the materials that we’re using and reusing. To do this, it makes sense to use low carbon building materials—like timber—and design for disassembly with adaptability in mind, so that things can be taken apart, reused, and become part of a circular design loop.

BJ: Our passion is for retrofitting historic and aging buildings but we found that there can be a significant cost to doing that. We’d like to find ways to curb those costs and make Passive House design more affordable and accessible. Prefabricated timber systems, modularity, and systemized assemblies are part of that vision. I think our cities—in particular those with larger, older building stock—need solutions that can be easily implemented. We want to retrofit existing buildings to higher performance while doing it in a way that is affordable and not completely disruptive. At present, there’s a gap in the market and our goal, as a practice, is to fill that gap. 



Ruth and Bobby live in Brooklyn, New York, where they completed a self-commissioned renovation of their own brownstone, transforming a beautiful, century-old building into a highly resilient home to take their family into the future, while respecting and celebrating the past. Their firm’s name CO Adaptive takes inspiration from the same biological term used to describe the process by which a bee adapts to a flower, just as the flower adapts to the bee.


Learn about
CO Adaptive's approach to low-carbon construction.

To stay within 1.5°C warming, greenhouse gas emissions need to decline 45% below 2010 levels by 2030 and reach net zero emissions by 2050. The built environment accounts for 40% of GHG emissions, so buildings—and the climate impact of their construction and operation—are an essential part of reducing carbon emissions. Meanwhile, our need for buildings is not going away. About 60% of buildings that will exist by 2050 haven’t been built yet. This means constructing a city the size of Stockholm or Milan every week until 2050, or a city the size of Singapore or New York every month.

The good news is that cutting carbon in cities could mean a U.S. $20 trillion boost to global gross domestic product (GDP). In addition, design firms with green building expertise stand to gain from a market set to grow nearly 15% by the end of 2027.

Our sector has a critical role to play. Discover how cities are leading the way and forging new approaches with the help of the AEC sector and how your design team can play a role in cutting your city’s carbon footprint.

What does net-zero carbon mean? Is it different from carbon neutral?


Net zero refers to a state in which the greenhouse gases going into the atmosphere are balanced by removal out of the atmosphere. The term net zero is important because—for CO2 at least—this is the state at which global warming stops.


Carbon neutral means that any CO2 released into the atmosphere from an activity or project is balanced by an equivalent amount being removed.


Climate positive (also known as net negative) means that an activity’s GHG removals exceed its emissions.


High Impact Climate Solutions in Cities

Cities are major contributors to climate change—which means they can also be a key solution to it.

Over half of the world’s population lives in cities. According to UN Habitat, cities consume 78%  of the world’s energy and produce more than 60% of greenhouse gas emissions, yet they cover less than 2% of the Earth’s surface. 

We can greatly reduce our per capita carbon footprint by changing how we plan, build, manage, and power cities and towns. The ideal low carbon and resilient city is well-designed, compact, walkable, and has good public transportation.

Photo credit: Adam Blank

A number of organizations are dedicated to this premise. A partnership between the Cities Alliance, the World Bank, UN-HABITAT and the United Nations Environment Programme (UNEP) works globally to help cities address climate challenges through sustainable urban development. Another organization, called C40, is a network of mayors of nearly 100 cities around the world whose mission is to halve the emissions of its member cities within a decade while improving equity and building resilience. C40 cities earn their place through action—with membership based on performance requirements, not member fees.

Led by the city of Oslo, C40’s Clean Construction Forum helps cities working to achieve zero embodied emissions from buildings and infrastructure by 2050. They focus on reducing emissions from construction materials and machinery by:

  • Understanding the methods and data needed to establish city wide targets; 
  • Collaborating on available standards and tools to assess the environmental impact of materials and construction sites, and;
  • Using cities’ collective power to develop a market for low emission construction materials and construction equipment.

Cutting emissions will require a change in business as usual. According to UN News, “The extraction and manufacturing of materials for buildings such as steel and concrete and construction processes produce carbon dioxide[,] so using low carbon infrastructure will also slash emissions.” 

In addition to reduced emissions, cities built from bio-based materials such as timber that store carbon during their service lives can serve as constructed carbon sinks. They could increase the existing carbon pool of urban areas (1–12 GtC) by 25 to 170%.”


Climate Ready Boston

C40 member Boston is an example of one city cutting carbon and making progress on a number of fronts. New England’s largest city stands to be impacted disproportionately by rising seas due to global warming and launched Climate Ready Boston more than seven years ago to help the region plan for the impacts of climate change with an update in 2019 to boost its focus on curbing carbon.

A cornerstone of the plan is adopting a zero net carbon standard for new construction by 2030 and pursuing strategies to reduce building emissions over the next five years such as a zero net carbon standard for new municipal buildings and a carbon emissions performance standard to decarbonize existing large buildings. Along with these measures, Boston is also promoting policies that support walkable neighborhoods and enable residents to live car-free.

And so far, the city is seeing results: citywide GHG emissions are 17% lower than they were in 2005, and emissions from city government operations have been reduced by almost 25% in the same period. An embodied carbon technical advisory group formed in 2021 is exploring the use of more carbon sequestering materials and the city is setting stricter standards for city-funded low carbon affordable housing, inspiring solutions like six new mass timber affordable housing projects. 

To incentivize low-carbon construction, Boston launched the Boston Mass Timber Accelerator through grants from USDA Forest Service, Softwood Lumber Board, and ClimateWorks Foundation. The initiative provides design teams with technical assistance and funding grants to expand the use of low carbon mass timber products. This March, seven projects received funding ranging from a seven-story commercial office building to an eight-story, 215-unit affordable senior, and assisted living facility—along with other housing projects that provide equitable access to affordable accommodations while reducing their carbon footprint.

Photo credit: Jacob Licht
The project will focus on the lightweight structural benefits of mass timber for building additions—commercial office building addition and seven stories of new construction.

Boston is also home to a number of mass timber projects under construction including 11 E Lenox St, a 7-story, 34-unit multifamily project in the city’s Roxbury neighborhood.

Designed by Monte French Design Studio, it combines the thermal benefits of mass timber construction and Passive House design, reducing operational energy use by more than 80%. 

Slated for completion later this year, 11 E Lenox’s wood structural system will store 844 tons of CO2 throughout the building lifecycle and offset 327 tons of CO2 when compared to conventional steel or concrete alternatives.

Photo credit: Monte French Design Studio
The project team will assess cost effective implementation of mass timber at Mary Ellen McCormack Redevelopment in a high-rise multi-family residential building—302 units of mixed-income affordable housing in a nine-story building.

Portland’s Climate Action Plan

Over 3,000 miles west of Boston, the city of Portland and Multnomah County, OR is also making headway in the fight against climate change. The city’s Climate Action Plan authored in 2015, aims to reduce carbon emissions 80% below 1990 levels by 2050 with an interim goal of a 40% reduction by 2030.

In 2017, city leaders specified 2030 energy efficiency goals for the built environment, which include achieving zero net carbon emissions in all new buildings and homes.

The City’s June 2020 Climate Emergency Declaration committed to a “climate justice and equity-focused approach that centers Black, Indigenous, other communities of color and youth from those communities in the next chapter of climate action planning and implementation.” In addition to multiple initiatives in support of this approach, the City also amended carbon reduction targets to at least 50% by 2030 and net-zero carbon emissions before 2050. 

Portland has both a Sustainable Procurement Policy and Green Building Policy for City-owned facilities. The Sustainable Procurement Policy outlines best practices for purchasing activities including developing and applying a shadow price for carbon to inform decision-making on capital projects and purchases of goods and services, utilizing sustainably sourced wood for City-owned building and landscape projects, and specifying low-carbon services. Shadow pricing is a method of investment or decision analysis that adds a hypothetical surcharge to market prices for goods or services that involve significant carbon emissions in their supply chain.

Portland’s plan identified over 247 actions to be completed or significantly underway by the end of 2020. Nearly all the actions in the 2015 Climate Action Plan are underway, with 77% of actions complete. The region cut total local carbon emissions to 19% below 1990 levels, and per person, emissions were cut by 42% as of 2018.

Photo credit: Unsplash

Portland is also home to a rapidly growing stock of timber buildings. The state’s rich supply of local, sustainably harvested timber helped make it home to the first certified U.S. producer of mass timber, which opened in Riddle, OR in 2015.

Oregon was also the first state to adopt the 2021 International Building Code to allow tall mass timber buildings. Two mass timber projects in Portland’s Burnside Bridgehead neighborhood standout: Sideyard, a 20,000 square-foot commercial office and infill project that makes the most of a narrow site, and Fair-Haired Dumbbell, a mixed-use office and retail complex designed by FFA Architecture and Interiors that includes two canted six-story towers wrapped in hand-painted artwork. Adjacent to one another, each with their own distinct design, these projects reveal just how versatile mass timber can be while also boosting density and helping to revitalize urban areas with climate-conscious ingenuity. 

Portland is also seeing a rise in the design of nearly all-wood buildings, boosting carbon-capture by combining light-frame wood and mass timber construction—a recent example being the Cascada, a mixed-use project to be built in the city’s lively Alberta Arts District. This project includes hotel, coworking, restaurant, and wellness program space as well as leasable retail spaces.

Photo credit: KUDA Photography

Taking Action In Your City

The actions taken by cities like Boston and Portland can only happen through collaboration with forward-thinking architects, developers, and other building professionals looking to innovate in the fight against climate change.

Design teams can help their city through an increased focus on reducing embodied and operational carbon emissions and by building with bio-based materials, turning urban centers into carbon sinks—and literally converting the built environment from a carbon emitter to a long-term carbon storage solution.

As C40’s executive director emphasized in a past global competition for solutions, “[We need] inventive collaboration to combat the climate crisis—from the skills and creativity of architects, artists, environmentalists and entrepreneurs. The creation of new and exciting developments in cities not only reduces carbon emissions from construction, but also builds the resilient urban environments we need to cope with rising temperatures and more extreme climate events.”

Photo credit: Zixi Zhou

Most homebuilders are familiar with operational carbon, which refers to the greenhouse gas emissions from a home’s energy use after it’s built, but embodied carbon looks at all the energy it took to build the home in the first place. That includes the energy that went into manufacturing and transporting its materials, as well as during the act of its physical construction. Right now, that number is higher than most green-focused homebuilders probably realize.

For example, the average U.S. home produces 45 kg of CO2 per square meter annually from an operational perspective according to a 2020 University of Michigan study. But a recent Canadian report found embodied carbon accounted for 250 kg of CO2 per square meter in residential buildings, or more than five times as much.

That means even the most energy-efficient new homes built today have already contributed five years’ worth of greenhouse gas emissions to the environment before their new owners move in. Put another way, the embodied carbon of constructing the 1.6 million homes built in the United States last year put the same amount of greenhouse gases into the atmosphere as operating 22 million cars for an entire year.

Think Wood spoke to Aaron Smith to learn more about net zero carbon houses. As CEO of the Energy & Environmental Building Alliance (EEBA) as well as his own firm, GreenSmith Builders, Aaron is passionate about sustainable and low carbon construction.

Think Wood: Tell us about EEBA. What is your mission?

Aaron Smith: In 1982, a group of builders from the US, Canada, and Scandinavia came together and said, “Let’s try to build more energy efficient homes.” We’ve seen that transition to energy efficiency through building science and education, but today I would say the focus for EEBA’s builders is healthy, electric, resilient, decarbonized, and net zero.

We’ve heard a lot about net zero energy homes but EEBA also has a focus on embodied carbon?

AS: We’re talking about both embodied and operational carbon now. The primary thing we’re trying to do is get people educated about what decarbonization is, what an environmental product declaration is, what a lifecycle assessment is. When I look at two different materials, what does it mean to think about the embodied carbon in that material?

Why does lowering carbon emissions matter to builders?

AS: It matters for a few reasons. First, builders have a pride of craftsmanship and they extend that same care to thinking about the environmental impact of the materials they use because they’re thinking about the future. My grandfather was a builder and he always asked, “Are you happy with what you did? Because it’s going to be there for 100 years. 

And, we’re starting to see carbon codified across North America. California, Oregon, Washington, they’re headed in that direction. I’ve got a buddy in Texas who builds 1,000 homes a year. This year, his investment firm called him and said 20% of the product that you build for us now needs to be net zero. That’s not quite to decarbonization yet, but when finance starts telling production builders you need to do this, that’ll be a game changer.

What steps can builders take in the design phase to achieve low carbon homes?

AS: EEBA members asked us to research the best tools accessible to builders for calculating operational and embodied carbon. We counsel them to put their houses into a building information modeling (BIM) system like AutoCAD or Revit. You can import that into some whole-building life cycle analysis (WBLCA) tools and start to generate a carbon footprint for the home design. We’ve added kilograms per ton of CO2 for your home to EEBA’s intake form because we want to start benchmarking it, too. In the future, we’ll start to compare those benchmarks across the industry.

Can you tell us about your Gateway to Zero program?

AS: There is a path to zero for everyone, but with so many programs, guidelines, and standards, finding the one that’s right for you can be overwhelming. Though we know that “getting to zero” is not always a linear process, we’ve organized resources in categories from “base energy code” to “zero embodied carbon.” EEBA can help you become a more sustainable builder from wherever you’re starting. You may be at code today; you may then want to look at the Energy Star program. It’s free, and it’ll make you a better builder. And then you might want to move to one of the zero energy programs out there. We provide support throughout this entire journey.

Does building with wood provide any advantages when low carbon construction is the goal?

AS: Once you’re educated on how material selection impacts a home’s carbon footprint, I think it’s a little bit ‘back to the future’. You start to say, “Well, instead of putting the steel beam in, I could put a cross laminated timber beam in and have a carbon sink instead of a huge carbon cost to my home.” To reduce carbon, I think it’s going to be a return to wood in a lot of cases. Homes can literally be a carbon sink instead of emitting carbon.

A Trent University graduate student’s study compared the net carbon emissions of the same building using different materials in each modeled scenario.

The results were drastically different depending on the products used:

  • The highest emission scenario used clay tiles, steel joists, high-VOC carpets, steel framing, cement brick for cladding, and high embodied carbon concrete for the slab.
  • For the same structure built to the same level of performance (to local code), the net carbon emissions were lowered by 144 tonnes by using trusses and asphalt shingles, drywall and mineral wool, wood framing and drywall, fiber cement for the cladding, and an average concrete with mineral wool for the slab.

Keep reading to learn more about two U.S. homebuilders making affordable energy-efficient low-carbon home construction a reality.

Thrive Home Builders

Thrive Home Builders have made energy efficient and eco-friendly features central to the design and construction of their clients’ homes. This includes achieving environmental certifications like LEED®, Indoor airPLUS, Zero Energy Ready Homes, and Energy Star®. The Denver based homebuilder has a successful track record delivering zero operational energy homes and is now turning its attention to their homes’ embodied carbon impact.

Thrive is pioneering a new design process that evaluates the use of  carbon measurement tools and technologies like BIM to better understand the embodied carbon impact of materials and how it can curb emissions through design and offset measures. The firm has been recognized by the U.S. Department of Energy’s Housing Innovation Awards since 2017 for its commitment to the department’s Zero Energy Ready Home program (DOE ZERH).

“Thrive Home Builders delivers energy-efficient homes with a mission focused on healthy and local solutions. We’ve been making conscious choices in the design of our homes for 30 years to make them healthy for families, the environment, and the planet. We think the carbon conversation is a great tie-in to what we are doing already—and we believe it’s becoming clear for our buyers: you can’t be healthy yourself without a healthy home and a healthy planet.”

Bill Rectanus, Chief Operating Officer

Bettr Homes

With a mantra of “people, planet, purpose!” Bettr Homes is focused on the triple bottom line, while delivering sustainable build-to-rent homes designed to be high performance, healthy, and resilient. The firm exclusively builds net-zero energy homes that meet certification standards like Zero Energy Ready Home, EPA Indoor Air Plus, Energy Star, LEED and Resnet HERS Index.

Bettr Homes’ vertically integrated business model positions the company to work well with real estate investment trusts (REITs) to deliver affordable net-zero rental homes, expanding access to much needed entry-level environmentally-sustainable housing. By attracting ESG-focused investors that perceive long-term benefits of healthy, affordable, low carbon homes, Bettr is demonstrating that sustainable home construction is not only good for the environment, but for the bottom line as well.

“What we’ve created with Bettr Homes is a triple-bottom line enterprise and we’re working with investors to add affordable net-zero homes to their rental portfolio—in doing so we’re creating healthy communities with a focus on decarbonizing the rental housing business. Its success is showing us, when you manage to an ESG standard, you create real value.”

Corey Donahue, Co-Founder


Think Wood: What inspired you to take on such an ambitious project—the tallest timber tower in the world to date?

Tim Gokhman: Innovation has always been a focus for New Land. We have a pioneering history and a higher tolerance for risk because that’s something we’ve always done—whether it be taking a risk geographically, such as building in a less desirable, up-and-coming neighborhood, or being one of the first firms to use radiant hydronic floors in some of our multifamily projects. 

When I saw the renderings for River Beech Tower—a conceptual tall timber design by Perkins&Will and Thornton Tomasetti—it was a revelation that not only was it possible to build a highrise with wood, you could also expose that structure inside, making the visual experience for the occupant incomparable. Our strong experience in multifamily development and ability to put together a team of proven mass timber experts gave us the confidence to move forward with the project.


TW: How did you know the project would pencil out?

TG: When it came to penciling it out, we treated Ascent more or less like any conventional development project. If we were able to realize additional benefits through mass timber, we saw that as a bonus. In fact, the primary driver for this project wasn’t speed of construction, environmental benefits, or carbon savings—although we will realize all of those advantages. The initial motivation was the feeling you get when you walk into a mass timber building. A few years ago I didn’t know the term biophilia, and now it’s become a central tenet of this project. While we don’t yet have enough data on tall wood, and I can’t yet quantify that benefit entirely—whether through leasing rates or ROI—intuitively you can see the added value and differentiator is there for this project. We expect it to continue to pay off. 


TW: What was one of the biggest challenges in this project?

TG: While there was a lot to figure out in terms of the design and a fair bit of troubleshooting for some of the timber engineering solutions, by far our biggest challenge was insurance. Tall mass timber is a relatively new building type, so there just aren’t a lot of data points, which of course makes an insurance underwriter’s job very tough. There’s no precedent. When you’re pioneering a project like this, you’re working with a smaller pool of potential insurers, but in the end, we made it work. I think that over time, as more and more of these types of tall timber projects are completed, it will get easier and cheaper.


TW: What do you see as some of the most significant benefits of using mass timber?

TG: We were able to erect the building faster with mass timber and through the use of BIM and just-in-time deliveries than we would have been able to do using other materials. The amazing thing about mass timber is that you’re not really giving anything up. I often compare it to Tesla—as a car company, they didn’t have to convince you to give something up in order to do something that’s right for the environment because it wasn’t at the expense of aesthetics or performance. Similarly, mass timber checks all the boxes: it’s faster and more precise; it’s light-weight and easy to work with; it’s beautiful; it’s sustainable; and it delivers a superior experience across all categories. When you are looking to shift the paradigm like mass timber is, whether it’s fair or not, that’s the bar you have to set. You have to be as good, or better, than conventional construction.


TW: Do you see more tall timber projects in the future for New Land Enterprises?

TG: Absolutely—that’s the goal. We have just a few months left of work on Ascent, but already the team is taking in the lessons learned and contemplating where we might build the next one. We’ve invested a lot of time and R&D into this project, and we definitely see this as a model and case study to repeat. With our experience on Ascent, we will be able to streamline the process and realize even more of the benefits of tall mass timber construction on future projects.

Learn more about
Ascent in this project profile.

The good news is that industry expertise and resources are evolving to help design teams make the best decisions for their projects.

In this video, Kristina Miele, senior engineer at Fast + Epp, answers specifiers’ most pressing questions about mass timber connections.

Want to dive deeper into mass timber connection design? Check out WoodWorks’ Mass Timber Connections Index: Optimal Connection Considerations, a resource covering a wide range of topics including structural basics and aesthetics, tolerances and connection classes, performance and fire protection, and moisture and shrinkage concerns. Complete with tables and schematic diagrams, this paper is a helpful resource for anyone evaluating connection options for their next mass timber project.

Andy Quattlebaum Outdoor Education Center
Photo Credit: Jonathan Hillyer
View project

1) Is mass timber fire resistant?

Heavy timber and mass timber building elements char at a slow and predictable rate, providing for inherent fire resistance. During fire exposure, mass timber chars on the outside, which forms an insulating layer protecting interior wood from damage. During a fire resistance test of a 5-ply cross-laminated timber (CLT) panel wall, the panel was subjected to temperatures exceeding 1,800 degrees Fahrenheit. The assembly sustained loads for three hours and six minutes, far more than the two-hour fire resistance rating that building codes require. Additionally, when the code requires mass timber to be protected with gypsum wall board, it can achieve nearly damage-free performance during a contents-fire burnout event.


2) How is a structural member’s fire resistance measured?

Fire resistance ratings for mass timber building elements are commonly developed from empirical models contained in the National Design Specification® for Wood Construction and TR10 – Calculating the Fire Resistance of Wood Members and Assemblies. The models use char rate data collected during ASTM E119 fire resistance test of exposed mass timber. Since char rates are predictable, it has been possible to develop structural models that account for the loss of cross section due to charring and the ability of the member to support the applied load. Like all materials, structural failure eventually occurs. For steel, failure is due to weakening of the metal. For mass timber, failure occurs when the cross section is no longer adequate.


3) What’s important to know about fire resistance rated assemblies?

Fire resistance rating is performance criteria used in the building code to ensure the structure will not collapse when exposed to fire. The fire resistance rating time assigned to a building is based on the perceived risk due to building area, height, and occupancy. Buildings that represent a greater risk are required to have a greater fire resistance rating. Any material that can achieve the required fire resistance is permitted, but there are often limits to the allowable height and area of combustible construction.


4) Does a building’s construction type determine how mass timber systems can be used?

Buildings are classified according to height and area limitations so the construction type does have an effect on how mass timber systems can be used. In the 2021 International Building Code (IBC), mass timber construction is classified as Type IV and has four subcategories, A, B, C, and Heavy Timber (HT). The code currently allows:

  • Type IV-A – Maximum 18 stories, with gypsum wallboard on all mass timber elements.
  • Type IV-B – Maximum 12 stories, limited-area of exposed mass timber walls and ceilings allowed.
  • Type IV-C – Maximum 9 stories, all exposed mass timber designed for a two-hour fire resistance.
  • Type IV-HT – Maximum 6 stories, previously the Heavy Timber construction type under the 2018 IBC.

Types III and V permit the use of light wood framing throughout much of the structure. However, it is possible to classify a building as Type III or Type V when constructed primarily of mass timber building elements due to the height and area of the building. For example, a mass timber building six stories in height could be classified as Type III-A or a four-story building as a Type IV.


5) How does mass timber’s fire performance compare to other structural materials?

Building codes require all building systems to perform to the same level of safety, regardless of material—and wood-frame construction is approved in the IBC and International Residential Code (IRC). 

For mass timber specifically, the result of the years-long ICC process to develop and approve safety requirements for each of the new types of construction (Type IV-A, Type IV-B, and Type IV-C), tall mass timber buildings have fire protection requirements more robust than those required for comparable noncombustible buildings.

Ken Bland is Vice President of Codes and Regulations for the American Wood Council. He is a former building official and has a BS in Architectural Engineering and an MS in Fire Protection Engineering. He is also a licensed engineer.

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