2022 Corporate Responsibility Report

2022 AT-A-GLANCE

Corporate Responsibility Report

Yes, and . . . it’s the golden rule of improv, and of problem-solving as well. It’s a powerful mindset that will help us all create enduring solutions to today’s challenges together.

“Companies like ours must look beyond meeting financial objectives – we have the power to make a difference, and with that, have a social responsibility to improve the world. This is more than simply saying if we understand our customers and improve the community, we will be more successful. Our actions are based on our vision, which is to make a significant

Check out our Annual Review 2022/202 3.

All illustrations (except where noted): Brian Stauffer

positive contribution to the world."

— Pete DiMaggio, Co-CEO

OVERVIEW

We’re ensuring our firm’s sustainable development and contributing to more sustainable industries.

91% employees who feel our workplace is inclusive

47% increase in volunteer hours over previous year

51% employees working in green offices

Message from the Co-CEOs

Corporate Responsibility Approach

Corporate Responsibility Goals & Materiality

Corporate Responsibility Targets

Progress Report: Financials

Background image: Thornton Tomasetti's World by Elisabeth Malsch. Thornton Tomasetti

OVERVIEW Message From the Co-CEOs

One of our seven corporate responsibility goals is to demonstrate positive environmental and social impact across all our practices, because designing for a better world is the future of our industry. In the past year, we envisioned how our diverse expertise can translate into effective climate action.

Climate change is one of the most significant challenges our world faces. But the magnitude of the problem, along with the complexity of potential solutions, has given Thornton Tomasetti an unprecedented opportunity to have a positive impact on the world. We owe it to both current and future generations to reduce the effects of climate change and leave our planet in a better condition than when we found it.

We’re committed to addressing this challenge and working with our clients and partners to make lasting contributions. We’ve already begun applying our creativity and ingenuity – in science, engineering, technology and our entire skill set – to expand climate action across all our offices and practices.

Our goal is twofold:

• Decarbonization Reduce greenhouse-gas emissions to keep global temperatures from rising more than 1.5 to 2 o C above preindustrial levels.

• Resilience : Ensure that the world can respond to, withstand and recover quickly from the impacts of global warming.

At Thornton Tomasetti, we look beyond the obvious to identify and solve real problems. We’ve been solving challenging engineering problems since our inception, and our wide-ranging expertise in decarbonization and resilience is already helping address climate challenges. We’ve designed structures and systems that minimize embodied carbon and are designed to last generations. We’ve adapted centuries-old buildings and bridges to serve beyond their originally anticipated life spans. We’re helping develop next-generation transportation systems, like HyperloopTT that will enable transportation electrification and ensure safe deployment of alternative fuels in the rail industry. Our experience in disaster response – investigating, analyzing, repairing, protecting and rebuilding – has built our understanding of both multihazard mitigation and the road to recovery.

In the energy sector, we’ve made significant strides in helping clients transition to renewable energy, improving battery and nuclear safety , and safely capturing and storing carbon In the area of high-performance façades and whole-building energy modeling we’re designing and helping fabricate innovative systems that sustainably harness and use energy.

In the past five years, more clients have started thinking about how their goals and actions impact what’s happening around them. Their vision is widening. They want to understand the environmental and social impacts of their decisions. In the past, we’ve looked to government to drive change at this scale. Now, industry leaders have realized that, at minimum, we must partner with government. And when change isn’t moving in the right direction, we have to lead.

We believe that every stakeholder in our industry has the responsibility – as individuals, companies, government agencies, clients, developers and builders – to address the big issues of our time. With all of us aligned, our industry will continue to make a positive difference. Addressing climate change requires collective courage and ingenuity. Together we look forward to building a better future.

DiMaggio Co-Chief Executive Officer New York

Michael Squarzini Co-Chief Executive Officer New York

Peter

OVERVIEW Corporate Responsibility Approach

Thornton Tomasetti’s approach to business management focuses on the three P s of the triple bottom line, reflecting what we have long recognized: that responsible firms operate and grow in ways that are socially accountable (“people”), environmentally friendly (“planet”) and financially sustainable (“profit”).

We aspire to be one of the most sustainable firms in the AEC world, both in the way we design our projects and in how we operate as a responsible business. Thornton Tomasetti’s big goal is to be the global driver of change and innovation in our industry. Our purpose is that we exist to embrace challenges to make lasting contributions. These values define our corporate responsibility approach.

Strategy

In 2012, we founded a Corporate Responsibility department, led by a corporate responsibility officer who reports to a co-CEO and is guided by a steering committee that is representative of our diverse practices and office locations. And although the department was originally established to meet the reporting requirements of the American Institute of Architects’ 2030 Commitment for carbon-neutral buildings, corporate responsibility now spans all our departments and disciplines. To manage the firm’s positive and negative impacts on the economy, the environment and people, every five years the Corporate Responsibility department works with our Corporate Responsibility Steering Committee to update our short-, medium- and long-term strategies and reexamine our goals (above) and measurable targets for achieving this vision ( see Corporate Responsibility Targets ). By driving innovation and embracing challenges – seeing opportunity where others may focus on risk – we’ll ensure our firm’s own sustainable development and contribute to more sustainable industries. And in accordance with our core ideology, we’ll bolster our long-term growth

ENVIRONMENTAL & SOCIAL IMPACT PROJECTS

CORPORATE RESPONSIBILITY

Five-Year Goals

2020-2025

CARBON-NEUTRAL OPERATIONS

EMBODIED-CARBON REDUCTION

EQUITY, DIVERSITY & INCLUSION

LIFESTYLE-FRIENDLY WORKPLACE

and reduce business risks by making meaningful investments in people and the planet, recognizing that these investments drive innovation and lead to greater long-term value. Our approach will influence our clients and suppliers as we continue to build relationships with trusted partners who share our commitment.

What Was New in 2022?

To achieve our goal of being the global driver of change and innovation in our industry, we seek out opportunities for our design professionals to apply their technical expertise to challenging social and environmental problems. And to ensure that Thornton Tomasetti will continue as an enduring organization, we focus on areas in which our technical skills and multidisciplinary collaboration can have the greatest impacts.

In late 2022, we launched our climate action initiative, which unites our engineers, scientists, architects and sustainability professionals – and leverages our understanding of decarbonization and resilience practices – in our efforts to mitigate and adapt to the effects of climate change.

COMMUNITY SERVICE

PROFESSIONAL DEVELOPMENT

Thornton Tomasetti

OVERVIEW Corporate Responsibility Goals & Materiality

(Page 1 of 3)

Our goals help illuminate the environmental, social and governance (ESG) topics that are most material to our business and of interest to our stakeholders.

Demonstrate Positive Environmental & Social Impact Across All Practices

Designing for a better world is the future of our industry. To be the global driver of change and innovation in our industry, we must demonstrate that design professionals can solve the most challenging social and environmental problems through our work. We have the expertise and cross-practice opportunities to be a leader in this area. This path will result in an enduring organization.

Lead the Industry in the Reduction of Embodied Carbon in Structures

Our best opportunity to demonstrate positive environmental and social impact lies in areas where we can have the greatest contribution, based on our knowledge and talent, and where we can apply our ingenuity. Embodied carbon is a rapidly emerging area in which we, as a multipractice firm with a strong grounding in structural engineering and expertise in sustainability, can be a driver and hold a unique position in the AEC industry.

Achieve Carbon-Neutral Business Operations by 2030

15+ communities increase resilience

40% reduction in CO 2 e in sustainability projects

20% of R&D supports environmental & social outcomes

63% reduction in absolute CO 2 e emissions from baseline year (2018)

50% increase in sustainability projects with carbon-neutral goal

25% reduction in embodied carbon in structural frames

2.0 MT

CO 2 e or below per-person carbon footprint

Support Our Employees’ Passion for Community Service

Through our Sustainability practice and our adoption of the Architecture 2030 Challenge, Thornton Tomasetti is an active participant in reducing emissions from climate change. We engage our employees in the global effort to mitigate and adapt to climate change by practicing what we preach through our internal policies and behaviors.

Promote an Inclusive & Diverse Community

Everyone at Thornton Tomasetti is empowered to change our industry. We know diversity drives innovation, so we will set and achieve targeted data-driven goals to increase inclusion and diversity among our staff, leaders, owners and board of directors. We will cultivate a welcoming and rewarding environment where everyone can achieve their full potential throughout their career journey here. We will increase our investment in continuous learning to expand and nurture our staff and future leaders. And we will support opportunities for everyone at our firm to give back to their communities.

Support

a Healthy & Lifestyle-Friendly Workplace

Caring about our employees is part of our culture of respect. We want a healthy and lifestyle-friendly workplace because we care about our people, but also because we want to attract and retain the best talent and reduce healthcare costs.

Our employees have unique capabilities that can add value to their communities, and they want to share their skills with others in need. Community service allows us to challenge people to grow and build relationships in the communities where we live and work.

0 carbon emissions, first from reductions, then offsets 2030 Thornton Tomasetti 2022 Corporate Responsibility Report

Accelerate Leadership Development & Professional Growth Opportunities

Our firm encourages professional development at all levels. We are committed to creating a pipeline of world-class and diverse leaders. Our growth opportunities increase employee retention and lead to better work outcomes, innovation and leadership in the industry.

6

Progress toward our goal (the bull's-eye) is indicated in red. Thornton Tomasetti

OVERVIEW Corporate Responsibility Goals & Materiality

(Page 2 of 3)

Early in 2022, we conducted a materiality assessment that identified topics for measurement and reporting. This assessment built on our prior years of sustainability reporting and our corporate responsibility strategic planning.

100% of employees feel they have service opportunities

We examined these questions: What is the impact to our business, and what is important to our stakeholders? Our stakeholders include our employees and potential hires; owners, clients and partners; potential clients and partners; our suppliers; and our communities.

We approached our materiality assessment with the following assumptions:

• After almost a decade of corporate responsibility reporting, we had identified social and environmental topics important to our business. A materiality assessment could help uncover impact areas we had not explored.

• We could learn about what was important to our stakeholders by researching the material topics that rose to the top for clients and partners within our sector.

• Thornton Tomasetti is a private service company in a nonmanufacturing and nonextractive industry. Therefore, topics that are significant to large public companies may not be immediately significant to our firm.

We started the process by outlining the Global Reporting Initiative (GRI) material topics and the legacy topics we had been measuring and chronicling through our annual sustainability reports. Since no GRI sector standard exists for engineering, we didn’t include any sector standard topics. Then we reviewed the GRI reports of client and partner firms in our industry and identified the material topics they value. After acquiring this information, we held dialogue sessions with our department leaders, executive committee and corporate responsibility steering committee. Co-CEO Peter DiMaggio approved the final list of significant topics for reporting.

Three tiers of material topics emerged from these sessions:

• Tier 1 topics are of highest materiality to Thornton Tomasetti and are recounted in this 2022 corporate responsibility report.

• Tier 2 topics are of importance to our stakeholders and to the engineering sector (for example, occupational health and safety) but currently are not outstanding risk factors or major impact areas for our firm. We may consider including some or all of these topics in future reporting.

• Tier 3 topics do not apply to our business model or sector (for example, freedom of association).

Our Tier 1 topics include economic performance, energy, emissions, employment, training and education, diversity and equal opportunity, and nondiscrimination. In addition to these topics listed by GRI, we include our company-specific legacy topics of community service and employee wellness.

When evaluating the impacts of these material areas, we considered both short- and long-term impacts and any areas of grievances. We recognize that our Tier 2 topics may not be immediately important, yet they could become more material to our business and sector in the long term. In selecting material topics, we considered that Thornton Tomasetti often provides a service to a multidisciplinary design team as a subcontractor to another firm and therefore may not have direct influence on suppliers to our projects.

Progress toward our goal (the bull's-eye) is indicated in red. Thornton Tomasetti

Corporate Responsibility Goals & Materiality

(Page 3 of 3)

We

Material Topic Impacts

Economic Performance

1. Enduring organization

2. Business vitality

3. Viable employment

4. Risk from climate-change impacts

Policies or Commitments

1. Core ideology, purpose and values

Goals, Actions, Measurement & Engagement

1. Financial Vitality Progress Report

2. Annual Financial Report

Energy

1. Operating costs

2. Climate change impacts, such as adverse weather events; Pollution impacts, such as poor air quality

3. Occupant comfort

4. Positive reductions of energy use from buildings through sustainable design

1. Environmental policy and statement

2. Carbon-neutral operations by 2030 commitment

3. U.S. Environmental Protection Agency Green Power program commitment

1. Our Good Work: Progress Report

2. Sustainable Operations: Emissions Report

Emissions

1. Impacts from climate change

1. Environmental policy and statement

1. Sustainable Operations: Emissions Report

2. Resilience of communities

3. Risk to business endurance

4. Positive impact on business vitality and innovation

5. Positive reductions of emissions from our projects through sustainable design

6. Positive reductions of emissions from our business operations

1. Employee satisfaction and retention

2. Employee turnover costs

3. Diversity losses and gains

4. Insurance costs

5. Economic development in local communities

2. Carbon-neutral operations by 2030 commitment

3. AIA 2030 Commitment and other industry climate commitments

2. Our Good Work: Progress Report Employment

1. Employee handbook and associated policies

2. Recruitment privacy policy

3. Modern slavery and human trafficking statement

1.

1. Building Great Workplaces: Lifestyle-Friendly Workplace

2. Legal Policies & Compliance

1. Building Great Workplaces: Equity, Diversity & Inclusion

2.

1.

1.

1.

OVERVIEW Corporate Responsibility Targets

(Page 1 of 2)

In addition to our seven corporate responsibility goals, we created annual short- and longer-term targets to inspire growth and tangible action across our organization. We shared our targets for 2022 in last year’s corporate responsibility report, and meeting them has brought us closer to achieving our goals in three areas:

Achieve a Carbon Footprint Below 3.48 MT CO 2 e per Person

In alignment with our goal of reaching carbon neutrality by 2030, we’ve reduced our operational emissions and surpassed our target, arriving at a carbon footprint of 2.00 MT CO 2 e per person in 2022. By working in high-performance offices, making office energy-efficiency improvements, using renewable energy, flying less and enabling flexible work, Thornton Tomasetti is committed to leading efforts in corporate climate action.

During the COVID-19 pandemic, our employees adopted new work-from-home practices. In 2022, we implemented a flexible return-to-work policy of having “most people in the office, most of the time.” This allows employees to choose a hybrid schedule while promoting collaboration and community. But while we’ve seen an uptick in in-office attendance, our commute-to-work numbers remain lower than prepandemic levels, which has led to a decrease in commuting emissions from our 2018 baseline. Our business-travel emissions are also low, compared to our baseline.

Goal: Achieve carbon-neutral business operations by 2030.

2022 Target: Achieve a carbon footprint below 3.48 MT CO 2 e per person.

Achieved! Our carbon footprint is 2.0 MT CO 2 e per person.

2022

2022 2022 2022

Goal: Accelerate leadership development & professional growth.

Target: Offer mentoring to all employees. Achieved! All employees receive mentoring.

Goal: Promote an inclusive & diverse community.

Target: Ensure employees are familiar with our equity, diversity & inclusion initiative. Achieved! 98% report familiarity with ED&I.

We’re reducing electricity use in our offices by implementing efficiency measures like replacing incandescent lights with LED bulbs and by using more efficient computer equipment. We’ve also improved our ability to adapt to new places. When we move into a new office, we adhere to our office fit-out best practices policy — seeking a green-building certification or the equivalent for each and ensuring that each location is more energy-efficient than the previous one.

We continue to follow our strategy for achieving carbon-neutral business operations –reducing as much energy use as we can rather than simply declaring carbon neutrality through the purchase of carbon offsets (except in the case of business travel, a business-critical activity that we offset each year).

ThorntonTomasetti

OVERVIEW Corporate Responsibility Targets

(Page 2 of 2)

Offer Mentoring to All Employees

Thornton Tomasetti’s mentorship program was originated by our Women@TT employee network group and initially offered only to women, due to the known challenges they face in STEM professions. A year ago, we expanded the program to include all interested staff. Now, 88% of both female and male employees report feeling that someone at the firm encourages their development.

By subscribing to an online mentorship platform, we were able to automate processes that allow us to administer the program at a high level. In 2022, we reached all employees through the platform, except in special cases where groups asked to make their own mentorship matches. We offer one-on-one mentoring during two six-month cohorts each year. The mentoring platform matches mentees with internal mentors who have relevant experience. Mentorship opportunities include formal long-term mentoring, informal peer groups and coffee breaks. This expansion of services has made mentorship and community support more accessible across our organization and promoted a culture of sharing knowledge and experience.

Goal: social & environmental impacts.

2023 Target: 20% of R&D focused on environmental or social outcomes.

2023 2023 2023

2023

Goal: Support a lifestyle-friendly & healthy workplace.

2023 Target: Maintain over 80% satisfaction with flexibility.

Goal: Support our employees’ passion for community service.

2023 Target: Increase service hours by 10% over 2022.

Looking to the year ahead, we’re working to achieve measurable short-term progress toward our corporate responsibility goals in these three target areas (and more!).

Thornton Tomasetti

Ensure Our Employees Are Familiar With Our Equity, Diversity & Inclusion Initiative

Ninety-eight percent of our employees report being familiar with our equity, diversity and inclusion (ED&I) initiative Supported by our top leadership, our employee network groups (ENGs) organized dozens of local and global activities in 2022 to promote ED&I initiatives. Awareness across the organization was fueled by these very visible events and by office leaders who encouraged involvement. Ninety-seven percent of our employees say that their managers promote equity, diversity and inclusion.

This year, our ED&I program featured an allyship learning series in which employees learned to recognize unconscious bias and advocate for others in the workplace. And in 2022, we added three paid holidays – Juneteenth, Veteran’s Day and Indigenous Peoples’ Day – to provide our employees expanded opportunities to celebrate their heritages and learn about the backgrounds of others.

Our ED&I initiative, started in 2016, has become a primary driver and exemplar of our workplace culture, and we continue to explore new ways to build an inclusive environment and improve our firm’s gender, ethnic and racial diversity.

OVERVIEW Progress Report: Financials

Each year, we report on several indicators (in U.S. dollars) that show progress toward achieving our financial-vitality goals. The trends this reveals can illustrate how our corporate responsibility programs contribute to our vitality over time.

Gross revenue is our total income for services. We continue to see strong financial returns from our work.

Net revenue is billings from our services, excluding our expenses and bad-debt allowances. In line with our gross revenue, we continue to see growth.

Net project starts indicates the total revenue expected from projects that started in the reported year.

Employee retention while not a direct financial indicator, is associated with financial vitality. Our overall retention rate is high but experienced a dip in the years following the pandemic, when the Great Resignation began affecting the economy. Thornton Tomasetti is focused on equity, diversity and inclusion and career-development initiatives to keep our retention strong.

OUR PROJECTS SHOWCASE

Progress Report: Our Good Work

Decarbonization

Embodied Carbon

Life Sciences

Mass Timber

New Technology

Resilience

Restoration & Renewal

Sustainability

Structural Engineering

We're helping decarbonize the environment by supporting clean-energy technologies like wind, solar, hydrogen, geothermal and nuclear power.

Designing for a better world is the future of our industry.

Thornton Tomasetti

OUR PROJECTS SHOWCASE

Progress Report: Our Good Work

Each year, we track several indicators that show progress toward our goals for socially responsible and sustainable projects.

The carbon dioxide equivalent (CO 2 e) reduction metric tracks the impact of energy-efficiency improvements from our sustainability consulting services. Each value is the sum of savings derived from energy modeling projects completed that year. We’ve increased our emissions savings significantly, due to a rise in the number and size of projects, along with increasingly stringent energy-reduction goals.

Engineering News-Record ’s annual Top 100 Green Buildings Design Firms ranking is based on the year’s design or construction revenue from projects that are green-building registered or certified by an independent rating organization (such as GBCI/LEED). For the past five years, we’ve ranked among the top 20 firms.

We ascertain the quantity of embodied carbon from our structural designs by calculating the global warming potential of the structural framing materials used in our major projects. Until 2019, we measured embodied carbon as part of an R&D project, the Thornton Tomasetti Embodied Carbon Lab. In 2020, we joined the Structural Engineers 2050 Commitment (SE 2050) and paused our annual embodied-carbon count to adjust to SE 2050’s reporting methodology. We reported on 30 projects in 2022 and are among the signatories with the most reported projects.

Our number of sustainability consulting projects represents the quantity of projects for which we provided sustainability services like energy modeling, developing net-zero strategies, and consulting related to green building certifications. Each year’s value is cumulative and represents all completed projects up to that date since we began reporting this indicator in 2018. Thornton Tomasetti launched our Sustainability practice in 2012.

Average per-project cost savings are derived from the average energy cost savings from our sustainability consulting projects each year. Completion of many larger-scale projects has contributed to a growth in total savings.

Our R&D spending includes staffing and other support for CORE studio, our virtual idea incubator, as well as to semiannual innovation tournaments that identify ideas from employees across the firm. We continue to prioritize research and development in pursuit of our big goal: to be the global driver of change and innovation in our industry.

Decarbonizing Transportation: Driving Electric Vehicle Production

As demand for electric vehicles (EVs) grows, we’re partnering with steel fabricators and erectors to optimize constructability for several U.S. manufacturing facilities.

Darren Hartman P.E., LEED AP Managing Principal & Construction Engineering Practice Leader Kansas City

Our construction engineering services streamline fabrication and simplify erection to speed construction:

• At Ford’s Blue Oval City a sustainable EV and battery manufacturing campus in Tennessee, we provided erection engineering for an assembly building and connection design for a stamping facility

• In Arizona , we’re helping EV start-up Lucid Motors expand its production facility by two million square feet.

• In Indiana , we’re providing erection engineering to Samsung and Stellantis – parent company of Chrysler, Dodge, Jeep, Ram and more – for a plant that will produce lithium-ion EV batteries.

• At Envision AESC in Kentucky , we’re working on a plant that will produce the next generation of ultraefficient lithium-ion battery cells, helping make EVs more accessible and affordable.

These new manufacturing facilities won’t just deliver products – they’ll also energize local economies, jump-start resilient supply chains and power a more sustainable tomorrow.

FIRE SAFETY FOR LITHIUM-ION BATTERIES

Electrification is a vital component of decarbonization – and that makes energy storage critical to efforts to limit climate change. But lithium-ion batteries in energy storage systems and electric vehicles pose unique fire and explosion risks.

We manage these risks through holistic analysis of the ways people, products and building systems interact. Using science and engineering, we can help incorporate this important technology safely .

Erection engineering keeps partially erected steel structures stable during construction. Thornton Tomasetti

OUR PROJECTS SHOWCASE

Embodied Carbon: Confidential Research Lab Headquarters

We collaborated with clients, contractors and other disciplines to push the boundaries of sustainability and embodied-carbon reduction.

Lisa A. Davey P.E. Senior Principal & Boston Co-Office Director Boston

Engineering a six-story, 462,000-square-foot research facility to meet ambitious sustainability goals posed a welcome challenge for our team. Our sustainability experts , façade designers structural and construction engineers, acoustics and vibration specialists and protective design engineers worked together to provide the building’s owner and the tenant with an efficient, coordinated design for the compositesteel structure and its fit-out.

Since vibration control is paramount for laboratories housing ultrasensitive equipment, we performed vibration analyses for the whole building – and for the fit-out – and installed five tuned mass dampers.

To counteract the high energy demands that are typical of laboratories, the owner and tenant were committed to extreme sustainability. Features like high-performance tripleglazed façades, exhaust-air heat pumps, rooftop solar panels, stormwater capture and geothermal systems will offset energy consumption and help the facility earn LEED Platinum Core & Shell certification.

Throughout the design process, our team continually fine-tuned the structural system to reduce embodied carbon (EC) in the composite floor decks, steel framing and concrete foundations. During procurement, we used our EC specifications – completed in 2022 – to set bold reduction goals for the concrete used in the building and worked with local suppliers to meet these requirements, with no significant increase in cost.

A whole-building life-cycle analysis performed for the project showed a 17% reduction in CO 2 e relative to a baseline created in One Click LCA life-cycle assessment software. This significant reduction – in both the structural and whole-building EC, per LEED v4.1 guidelines – is one example of the innovative features contributing to the success of this project, which will be one of the most sustainable laboratory buildings in Greater Boston.

LEADING ON EMBODIED CARBON

Thornton Tomasetti recently updated our Division 1 Specification – Embodied Carbon Design Requirements –to address EC in steel and timber, in addition to concrete. This specification is one of the first of its kind in the AEC industry. We also provided data from 30 projects to the SE 2050 Commitment database, more than most contributing firms. See our SE 2050 Environmental Action Plan .

OUR PROJECTS SHOWCASE Life Sciences: Biomedical Digital Twins

Design and review of new medical technology, accelerated with digital twin modeling.

The biomedical industry is looking to innovative methods, such as in silico trials, to save time and resources and reduce clinical-trial risks. Combining machine learning with our engineering simulation expertise, we’re creating virtual models of living systems that can serve as a substitute for physical testing. In the U.S. market, this approach can aid both designers of new technology and the Food and Drug Administration (FDA) in evaluating those technologies.

Our team produced an in silico simulation, or digital twin, of a surgical implant of a generic stent graft for a virtual patient with a thoracic aortic aneurysm. They used machine learning to analyze how the patient’s anatomy and the structure of the stent graft affected therapeutic outcomes. The simulation identified the inputs that will have the most influence on the likelihood of the stent migrating or leaking.

Kristian Debus Ph.D. Vice President & Silicon Valley Office Director Silicon Valley

Stent grafts are often used to treat aneurysms by reinforcing a weakened vessel wall. Here, we used computational fluid dynamics modeling to simulate blood flow through and around a stent graft (top), in which red denotes the highest velocity and blue denotes the lowest. The bulge above the stent shows leakage. The bottom image shows a successful stent placement without leakage, in which the aneurysm is depicted as the tan, shaded bulge.

Thornton Tomasetti

“Efficacy and safety analyses like this are critical for the efficient development of lifesaving therapies,” says Kristian Debus, head of our life sciences team. “Through rapid iterations, developers can quickly zero in on optimal design strategies.”

Our next challenge? Based on this demonstrator case, we’re now developing a graphical framework that will facilitate discussions between a medical device maker and the FDA. The framework will be the first to combine real-world clinical outcomes and simulation data in this format to maximize the benefits of digital twins in device design.

OUR PROJECTS SHOWCASE

Mass Timber: Factory of the Future

An innovative mass-timber research facility at the University of Maine will embody the goals of its Green Energy & Materials (GEM) initiative.

UMaine’s GEM initiative is dedicated to developing and demonstrating bio-based and recyclable materials in support of a sustainable future. Its Advanced Structures and Composites Center is building the GEM Factory of the Future, a research facility that will expand the frontiers of large-format and AI-enabled arrays of additive manufacturing systems to create new markets for sustainable building materials. The 60,000-squarefoot facility in Orono will include office and academic spaces.

Planners at UMaine wanted to use mass-timber construction for the new building to display – and celebrate – forward-thinking uses of renewable building materials. Their architect, Grimshaw brought Thornton Tomasetti on board because of our experience with nonstandard mass-timber applications. “The factory area is a grand high-bay space with long spans and a unique roof form. The complex structure of the facility is proposed to be constructed entirely from mass timber,” says Vice President Chris Williams, based in our Portland, Maine, office “The factory structure will also support cranes and other equipment, so there are a lot of unique intricacies to it.”

That complexity calls for more than ingenuity – teamwork is essential. Our team worked closely with architects from Grimshaw and SMRT. “The level of collaboration, creativity and expertise the crew at Thornton Tomasetti brings is unmatched,” says SMRT Principal and Senior Architect Nicole Rogers. “We’re excited to be working with such a talented group of people on such an inspiring project.”

At Thornton Tomasetti, we are committed to driving global change and innovation. With the Factory of the Future, we’re applying innovative design to support the invention of technology that will change the way building and manufacturing shape our world.

The GEM Factory of the Future mass-timber structure is redefining what factories can be made of. Courtesy Grimshaw

Paul Becker P.E., SECB Senior Principal Portland, ME

OUR PROJECTS SHOWCASE

New Technology: HyperloopTT

Saying yes to hyper-fast, hyper-clean transportation.

Moving at twice the speed of the world’s fastest train, Hyperloop Transportation Technologies’ HyperloopTT system bridges the gap between train travel’s comfort and convenience and air travel’s speed. Passengers on HyperloopTT will ride in a capsule that is magnetically levitated within a low-pressure tube. And since it’s all electric, the system could yield enormous reductions in carbon emissions related to intercity travel.

Thornton Tomasetti has a significant stake in this clean-energy technology – as an investor and an engineering partner on the project. We recently concluded a two-and-a-half-year study with the submission of our final report on the system’s operational safety. The report included an analysis of external threats, such as terrorist attacks, and a mitigation plan to address those risks. We’re also supporting an application by HyperloopTT, with ENSCO and Colorado State University Pueblo, for a Federal Railroad Administration CRISI (Consolidated Rail Infrastructure and Safety Improvements) grant, to fund the development of a test track in Pueblo for further research.

Pawel Woelke Ph.D., P.E. Senior Principal & Applied Science Practice Co-Leader New York

U.S. Department of Transportation representatives visit HyperloopTT's full-scale test system in Toulouse, France. Courtesy HyperloopTT

OUR PROJECTS SHOWCASE Resilience: Paysandú Master Plan

Our resilience assessment will help the Uruguayan city adapt to future climate change, protect the ecosystem and minimize damage and loss of property value.

With its humid, subtropical climate and its proximity to the Uruguay River, Paysandú, the capital of western Uruguay's Paysandú Department, is exposed to natural hazards like heavy rainfall and riverine flooding. According to a recent Intergovernmental Panel on Climate Change (IPCC) report , the impacts of climate change in this region are already evident and will continue to intensify as global temperatures rise. Without resilience planning, these hazards could lead to power outages, flood damage, service interruptions, and a host of other problems.

Our team, led by architect OMA , with landscape architect West 8 and mobility specialist MIC-HUB prepared a resilience-focused master plan for developing and revitalizing the city’s waterfront. The plan, for a 3.5-square-kilometer area along the river, sets out ambitious guidelines for culture, sports, leisure and real-estate development. It also calls for the creation of a lagoon and construction of a university campus. For many in the city, the vision effectively transforms the threat of flooding into a promise of rebirth.

We performed a comprehensive resilience assessment that considers future climate risks and proposes strategies to limit their impact. Our goals? To adapt to future climate change; protect the ecosystem; minimize damage and loss of property value; and prevent interruptions to business, school and critical services. The plan also promotes public safety and enhances quality of life by offering new amenities; mitigating the effects of extreme heat, droughts and floods; and ensuring equitable access to the waterfront.

Riverine flooding is the most significant climate risk in Paysandú, having caused widespread damage to the city in recent years. Our resilience plan will improve the city’s storm drainage system and connect the community to one of its greatest resources: its ample waterfront. Raising land elevations, introducing protective berms and flood walls, and directing river overflow into absorbent wetlands are complementary strategies for protecting the natural landscape and the unshielded urban areas along the river.

Streets will be designed to enable safe access for pedestrians, cyclists, motorists and transit riders while supporting green infrastructure for stormwater management. And buildings will be protected by flood walls and barriers, berms, elevated critical equipment and utility access points, watertight sealing systems, and watertight building envelopes.

Land-use planning will consider not only the likelihood of future hazardous events, but also the goals and aspirations of the community. For each neighborhood and building, a flood emergency action plan will empower residents to respond to flooding events and deploy resilience measures – long after we’ve left the premises.

– Paysandú Mayor Nicolás Olivera, commenting on the master plan’s principles of “resisting, protecting and adapting to water.”

In December 2022, Thornton Tomasetti staff, along with other team members, presented the Paysandú master plan to Uruguay President Luis Lacalle Pou (front left).

Thornton Tomasetti

Julie Pietrzak P.E., ENV SP, WEDG, CFM Associate Principal & Resilience Practice Leader New York

What we saw as a threat, we are going to see as an opportunity.

OUR PROJECTS SHOWCASE

Restoration & Renewal: Terminal Warehouse

This landmarked structure, built in 1891, will have a new life as a Class A office and retail destination.

Charu Chaudhry P.E., ENV SP, WEDG, CFM Associate Principal & Resilience Practice Leader New York

A Historic Warehouse – Reimagined

In New York's West Chelsea Historic District, the massive terminal where freight trains once unloaded goods ferried across the Hudson River is undergoing a large-scale renewal. Building owners L&L Holding Company and Columbia Property Trust initially selected Thornton Tomasetti for historic building-envelope restoration and façadeengineering services. But within a few months, we were invited to take on sustainability and resilience services as well.

Our teams collaborated to develop creative ways to preserve the historic building’s features, including the two enormous arched doorways through which freight trains once rumbled. The tracks are still visible inside the building, along the main archway. Our preservation strategies often coincided with sustainability and economy, as when our plan for salvaging and reusing many of the original brick walls, as well as in situ upgrades, both saved money and reduced embodied carbon.

Over the years, several of Terminal Warehouse’s 600 classic arched windows and entryways had become damaged or deformed by age or fire. We preserved and stabilized those that were salvageable and replaced any that weren’t, closely mimicking the look of the originals.

But while major emphasis was placed on preservation, the warehouse also underwent massive alterations, including construction of a two-story glass-and-steel overbuild and installation of an open-air courtyard, which required cutting a large hole in the center of the building and removing a sizable portion of its structure. Our analyses of leakage, loads and stresses helped determine which modifications would be feasible without affecting the historic character of the building and helped stabilize it during installation of the courtyard and overbuild.

The renovated Terminal Warehouse will feature an elegant central courtyard with cascading terraces. Courtesy Tomorrow AB & Gensler

Sustainability: Mercy Hospital Campus

Two of Maine's first all-electric affordable housing projects, and among the first projects to meet Portland’s Green New Deal energy-efficiency standards.

Michael Pulaski Ph.D., LEED AP BD+C Vice President & Portland Office Director Portland, ME

A massive redevelopment of the 1940s-vintage Mercy Hospital campus in Portland, Maine, will feature two of the state’s first all-electric affordable housing projects, including 95 units designed to Passive House performance criteria. They will be among the first projects to meet Portland’s Green New Deal energy efficiency standards.

Winter Landing’s energy footprint will be 34% more efficient than that specified by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Collaboration between our structural and sustainability teams, in coordination with CWS Architecture + Interior Design, accelerated accurate energy modeling for thermal bridging and insulation details.

Next door, we’re providing sustainability consulting to Ryan Senatore Architecture for the equally energy-efficient Equinox development, which will include 43 of the 95 units. The annual operational energy cost savings projected for both developments is $57,000, compared to the widely used ASHRAE baseline.

The rental units, developed by Community Housing of Maine and Portland Housing Development Corporation, will provide homes for residents earning less than 60% of the area’s median income, help alleviate a rental housing shortage, and provide walkable access to the city’s West End neighborhood.

Redevelopment of the three-acre Mercy Hospital campus will make way for Winter Landing (left foreground) and the Equinox (left background) affordable housing developments.

Courtesy CWS Architecture + Interior Design

OUR PROJECTS SHOWCASE

Structural Engineering: JFK Airport, Terminal One

JFK's Terminal One will be replaced with a sustainable, future-focused facility designed to set the standard as a global gateway.

John Barry Principal New York

When it opened in 1998, John F. Kennedy International Airport’s Terminal One served fewer than three million passengers a year. By 2019, that number had jumped to more than four million and was expected to quickly exceed the terminal’s design capacity. Now it’s being replaced by the New Terminal One (NTO), a sustainable, future-focused facility designed to set the standard as a global gateway.

We’re providing several services for the NTO’s first phase, which broke ground in August 2022. The 14-gate, 1.85-million-square-foot project is being delivered by a design-build team headed by AECOM Tishman and Gensler.

Integrated Services Streamline Design

We initially came on board for connection design and peer review services – another firm was designing the NTO structure. Later, our scope expanded to include value engineering.

After a pandemic-related pause, Gensler was named lead architect. They selected our firm as the structural engineer of record and engaged us to perform façade engineering, protective design and construction engineering as well. We worked with the design team, including several minority partners, to adjust the structure in support of the revised architectural vision.

Our protective design and applied science teams worked together to quickly tackle several challenges. One example? Developing advanced models of how the tree columns – which support the terminal’s expansive roof – would behave under blast loading. This approach helped us optimize their design.

Creative use of hidden braced frames allowed us to trim the number and size of the columns, reducing construction materials and costs while also opening up the interior space. This change was especially beneficial for busy areas like the security checkpoint and circulation zones.

Collaboration between Gensler and our façade and structural engineers was critical for the updated façade design. We opted for slender perimeter columns set 30 feet on center, an approach that opened up the façade without altering the terminal’s form. This also eliminated more than 10,000 tons of steel and 1,000 piles from the project, significantly reducing material costs – and embodied carbon.

The Need for Speed

To compensate for time lost during the pandemic, design had to move fast. We used several automation tools to speed our work. Another big plus came from effective collaboration – our team is concentrated in New York but spread across 13 offices, so we could leverage our capacity and draw on expertise from across the firm.

Our construction engineering specialists used our Advanced Project Delivery™ process to integrate the design and construction teams, producing complete connection design much earlier than usual and delivering a detailed Tekla model. These expedited deliverables are helping speed the overall schedule.

As a response to rising sea levels, the entire NTO will be built above the design flood elevation. Image by TMRW, Courtesy of the New Terminal One at JFK

SUSTAINABLE OPERATIONS

We aim to achieve carbon-neutral business operations by 2030.

Progress Report: Sustainable Operations

Emissions Update

Green Offices Update

Responsible Purchasing Update

Employees in our San Francisco office celebrate Daylight Hour 2022.

SUSTAINABLE OPERATIONS Progress Report: Sustainable Operations

Each year, we track several indicators that show progress toward achieving our sustainable-operations goals. The trends revealed by this data show us where we need to stay the course and where we need to make changes.

Total fuel consumption is the sum of each office’s heating fuel use, which is the whole building’s fuel consumption divided by the amount of space our office occupies. Fuel consumption has decreased over the years due to increased energy efficiency and, in some cases, building electrification.

We estimate Air-travel emissions via a regression model formula that uses the dollar amount of business air travel claimed on employee expense reports. We saw a dramatic decrease in business travel in 2020 and 2021 due to COVID-19. While the number spiked in 2022 due to a return to normal business operations, we’re committed to reducing emissions from air travel by minimizing the number of flights we take.

We calculate total annual electricity consumption by summing the electricity use of each of our leased offices. For offices that are not individually metered, we estimate use by dividing the whole building’s consumption by the proportion of the building we occupy. We have reduced electricity use since 2018 by designing more energy-efficient spaces when moving to new offices and by implementing energyefficiency measures in existing offices.

Our per capita electricity use emissions with the purchase of RECs is a measure of the emissions intensity of electricity use per person. It takes into account the renewable energy certificates we purchased each year. In addition to reducing overall electricity consumption by implementing improved energy-efficiency measures, more offices than ever before opted to purchase RECs this year, replacing 59% of our U.S. energy use with renewable power.

Note for energy and emissions charts:

Data does not include estimates for post-2018 acquisitions in baseline year (2018) totals.

Our total carbon footprint captures the carbon emissions of our offices in five categories: electricity consumption, heating fuel use, airplane travel, employee commuting and office waste. The pandemic led most employees to work from home, considerably decreasing our employee-commuting and businesstravel emissions. But from 2020 to 2022, as employees transitioned into a hybrid work schedule, these types of emissions rose. Despite this increase, we still surpassed our overall emission-reductions targets and have seen a 44% decrease in absolute emissions from 2018 through 2022. Our purchase of offsets and renewable energy certificates (RECs) brings our total emissions reduction to 58% over that same time frame.

Average carbon footprint per employee is calculated by dividing our total carbon emissions by our number of employees. Visualizing emissions per capita showcases the emissions intensity of the firm, irrespective of overall growth.

This graph indicates the amount of carbon dioxide equivalent reduced from the purchase of offsets and Renewable Energy Certificates (RECs) Airplane business travel was at its highest in 2018, leading us to purchase the most offsets that year. The year 2020 saw a low of offsets purchased due to minimal air travel. Air travel in 2022 is still lower than 2018 numbers and more offices opted to purchase Renewable Energy Certificates in 2022 than in previous years.

SUSTAINABLE OPERATIONS

Emissions Update

(Page 1 of 2)

Since 2012, we’ve been steadily moving toward our goal of carbon-neutral business operations by 2030 – by limiting activities that produce greenhouse gases and offsetting any emissions that remain. This initiative complements our project work, where we’re reducing emissions from buildings and developing innovative decarbonization solutions.

We make progress toward these targets by:

Designing high-performance offices. We apply our sustainable fit-out policy to all major office moves and renovations and encourage green-building certification, so our energy-performance goals exceed minimum standards. In our offices, green champions work to reduce energy use according to our sustainable-office guidelines.

Using renewable energy. We’ve met our green-energy purchasing percentage targets every year since 2015 as a member of the U.S. Environmental Protection Agency’s Green Power Partnership. And for 2022, we purchased green power through renewable energy certificates (RECs) for 59% of our U.S. electricity use.

Flying less, offsetting the rest. The pandemic required us to become better at building relationships without traveling. With robust tools to enable remote meetings, we’re actively seeking ways to minimize travel. And we’re encouraging reductions by sharing our data. Since 2014, we’ve offset all our air travel as a business-critical activity.

Enabling flexible work. In 2017, we established a global flexibility policy, offering work options that reduce commuting emissions while maintaining our collaborative culture. A recent survey shows 92% of our people are satisfied with workplace flexibility.

SUSTAINABLE OPERATIONS

Emissions Update

(Page 2 of 2)

Our 2022 carbon footprint reduction surpassed our targets.

We calculated the carbon footprint of 29 large offices and found that 19 had reduced greenhouse-gas emissions since 2018, our baseline year. Absolute emissions from electricity use, heating fuel, waste, commuting and business travel totaled 2,733 metric tons of CO 2 e, lower than in 2018.

The shift to remote work caused by COVID-19 curtailed commuting and business travel, leading to a 61% decrease in absolute emissions from 2018 to 2020. As the pandemic eased, commuting and air travel rebounded. Combined with the firm’s growth, this led to a 47% increase from 2020 to 2022. Our total reduction for 2018 to 2022, however, was 44%. We attribute that overall decrease to efforts to reduce air travel, moves to more energy-efficient office spaces, and less commuting. When purchased offsets and RECs are accounted for, we have achieved a 58% reduction in emissions.

SUSTAINABLE OPERATIONS Green Offices Update

With our recently updated Office Fit-Out Best Practices Policy firmly in place, by 2022 we were more prepared than ever to pursue carbon neutrality in the design of new offices and major office renovations.

Our Washington, D.C ., and London offices were the first to implement the updated policy, which prescribes LEED-equivalent standards for creating sustainable offices that are conducive to good health and are energy-efficient. Our Boston and San Francisco offices are seeking LEED certification for their new locations.

Nine of our offices now boast some type of green-building certification (or equivalent rating). In total, 12 – including three former offices – have been designed to “green” standards and that number will grow as offices relocate.

Our team of more than 60 volunteer green champions, in 33 offices worldwide, continues to move us closer to accomplishing our corporate sustainability goals, including carbon-neutral operations by 2030, by helping their offices reduce energy consumption and waste and meet carbon-footprint targets.

They also work to improve employee wellness and workplace comfort, organize community-service activities, and implement local sustainability initiatives.

In 2022, we awarded 22 grants, totaling $45,000, to support their work in 20 locations, funding such healthy and environmentally friendly activities and purchases as reusable water bottles, wellness workshops, transit cards, fitness supplies and tree-planting events.

EDINBURGH OFFICE REFURBISHMENT MINIMIZES WASTE

Refurbishment of our Edinburgh office began in August 2022, but before the eight-week project could start, the facility had to be completely emptied. Throwing away the entire contents of the office would create a large amount of unnecessary waste, so we found a more sustainable solution: instead of disposing of unwanted furniture, we invited staff to take it home. Usable items that weren’t claimed by employees were donated to local charities, including the High Valleyfield Community Centre; Dunfermline mental health support services; and Eats Rosyth, which provides food to people in need. Everything, from chairs and bookshelves to desks and dishes, went on to a second – greener – life.

51%

Employees in our Houston, Texas, office spell "light" with their bodies, in celebration of Daylight Hour, a social media campaign aimed at increasing awareness of energy conservation. Thornton Tomasetti

Employees Working in Green Offices

SUSTAINABLE OPERATIONS

2022 Responsible Purchasing Update

We seek trusted partners who share our value of responsible procurement and educate clients and collaborators about sustainable options for their projects.

As designers and consultants in the AEC industry, we typically aren’t involved in buying building materials or other project-related resources. So our direct procurement activities tend to be limited to the purchase of office supplies. In cases where we can influence the selection of sustainable project materials, we apply our in-house specifications, policies and sustainability expertise.

Construction Materials

When we hire subconsultants or specify materials for projects, our Ethical Sourcing Policy helps ensure that products are sustainably and responsibly sourced and that individuals involved in their manufacture are working in a safe and fair environment. This policy promotes social equity by encouraging the hiring of small businesses owned by socially and economically disadvantaged people or employing firms that have demonstrated a clear mission of promoting social equity.

In line with our environmental statement – to apply creative means of reducing carbon in our projects – we’ve developed embodied-carbon specifications for concrete, steel and timber for use when sourcing building materials. Such materials typically constitute the largest portion of the embodied carbon in a building, and these specifications guide our structural engineers and clients to consider materials or adjustments to materials that are less carbon-intensive than standard options. We also aim to avoid the use of toxic materials identified in the Living Building Challenge Red List in our sustainability consulting projects.

Office Supplies

Following our sustainable office guidelines, we give preference to office supplies with high recycled content and low toxicity. Our operations staff meets regularly to discuss options for responsible purchasing throughout our offices. In 2019, we instituted a policy that limits our use of beverages in plastic bottles, discontinuing their purchase for meetings and their sale through in-office vending machines. Many of our offices provide reusable tableware for employee meals. For our printed material, we always source paper with recycled content and work only with providers following guidelines such as the Forest Stewardship Council and PrintRelief Certified™ Reforested.

In the United States, we purchase about half our office supplies through Staples, which categorizes eco-products as either “basic” or “advanced.” “Basic” products share ecofeatures that are common among products in the industry, such as containing postconsumer content. “Advanced” products boast industry-leading environmental features such as certification by third-party programs like Energy Star, Green Seal or Cradle to Cradle. In 2022, 22% of the office supplies and 54% of the paper we purchased from Staples met the criteria for “eco-products.”

In recent years, the total amount we purchase from Staples – and hence, the number of eco-products ordered from this vendor – has fallen. We also purchase from Amazon, with guided buying for diversity certifications and climate pledge friendly products, and from the Paradigm Group’s Emerald brand, which designs, manufactures and distributes sustainable products. Our offices also purchase supplies from local businesses.

Implementation of our sustainable office guidelines, which suggest options for reducing spending on office supplies, has resulted in a decline in our purchase of office products. The guidelines include practical recommendations like two-sided printing, distributing documents electronically, purchasing used furniture and buying in bulk to reduce packaging.

Our Tampa, Florida, office embraces our “no plastic bottles” policy by providing employees with refillable water bottles that track how much they drink.

Thornton Tomasetti

HELPING COMMUNITIES

We support our employees’ passion for community service.

Progress Report: Helping Communities

Community Service Update

Charitable Giving Update

Disaster Response & Relief

Thornton Tomasetti Foundation

Our Washington, D.C., Cycle for Survival team helped raise over $13,400 for cancer research at the Memorial Sloan Kettering Cancer Center.

Thornton Tomasetti

HELPING COMMUNITIES

Progress Report: Helping Communities

Each year, we track several indicators that show progress toward achieving our community-service and philanthropy goals.

Company-paid community service hours metric tracks the on-the-clock hours our employees spent in community service activities, including hours for local volunteerism through our Volunteer Days benefit and half the hours they spend participating in the ACE Mentor Program. The pandemic years of 2020 and 2021 saw reduced hours due to limited opportunities for in-person service. However, we’re committed to increasing employee service hours by 10% each year, and in 2022 we met this target, with a 47% increase.

Our Volunteer Days benefit allows employees to receive compensation for up to two days per year for community service activities. This metric tracks the hours logged under the “volunteer day” code on employees’ time sheets. It does not account for volunteerism by employees on their personal time. This number dropped during the pandemic, but we’ve more than doubled the number of hours logged in 2022 compared to 2021. We hope to increase the number of employee volunteer hours by linking U.S. holidays like Martin Luther King Jr. Day and Juneteenth to days of service.

We track company-paid ACE Mentor Program participation, which is the amount of time U.S. employees spend as mentors or board members with the ACE Mentor Program of America. ACE volunteers are paid for 50% of their participation hours – an average of 15 per year – with the remainder a donation of their personal time. The development of remote programming during the pandemic enabled employees to continue to serve as mentors virtually. The program is back in person, and our number of volunteer hours continues to grow.

Charitable contributions include all payments in each year coded as “donations” in our accounting system. This includes annual contributions – such as those to the Thornton Tomasetti Foundation – and donations by our offices to local charities. It doesn’t account for contributions like pro bono work for nonprofits, lecturing at universities and colleges, or labor hours spent performing community service. Spending fell during the pandemic, but the overall trend is toward increased philanthropy.

HELPING COMMUNITIES 2022 Community Service Update

Our Thornton Tomasetti Gives Back program supports our employees’ passion for community service, encouraging them to build relationships and challenging them to grow.

This three-pronged initiative encompasses local volunteerism through our Volunteer Days benefit, mentoring the next generation of professionals through the ACE Mentor Program, and helping disadvantaged communities through our partnership with Bridges to Prosperity.

Volunteer Days allows 16 paid hours per year for each employee to perform community service. In 2022, among other activities, many employees took advantage of this benefit to help clean and beautify parks in under-resourced areas of their cities. The program has proven popular, with 240 employees participating and 976 volunteer hours recorded in 31 offices.

Since the 1994 creation of the ACE Mentor Program by Thornton Tomasetti Founding Principal Charles Thornton the firm has been a major sponsoring partner at both the local and national levels. Our employees are dedicated mentors and board members, helping achieve ACE's mission to engage, excite and enlighten high school students, and empower them to pursue AEC careers. One hundred employees logged 979 hours as ACE volunteers. This represents approximately 2,000 hours of actual service, as the firm permits 50% of mentoring hours to be recorded as paid time.

The third prong of the Thornton Tomasetti Gives Back program takes our people across the globe to apply their skills and resources in aid of disadvantaged people in remote regions. We partner with Bridges to Prosperity to construct pedestrian bridges in isolated communities, as lifelines to schools, healthcare, markets and vital services. Construction of a third bridge in Rwanda was temporarily delayed by the COVID-19 pandemic, but we now have plans to resume our work in July 2023.

Staff from our Philadelphia office volunteer at Corinthian Gardens, a community garden in Fairmount, Pennsylvania. Thornton Tomasetti

ACE’s Engineering Inc. magazine profiles how we're helping make a difference through Thornton Tomasetti Gives Back.

HELPING COMMUNITIES 2022 Charitable Giving Update

Charitable giving is one of many ways we strive to fulfill our commitment to serving local communities. Our charitable contributions align with many of the initiatives and organizations our employees support and for which they volunteer.

In 2022, we donated $369,859 to humanitarian causes and organizations, including the ACE Mentor Program, the Salvadori Center, Direct Relief for Ukraine and the American Red Cross.

We’re a major sponsor of the Thornton Tomasetti Foundation, a 501(c)(3) organization that funds scholarships and assists organizations that engage in philanthropic activities related to structural engineering, design and technology.

Regional offices were responsible for 13% of our 2022 contributions. They supported a variety of local causes that speak to the culture of each Thornton Tomasetti community, including the Alzheimer’s Association (Chicago), the City Parks Foundation (New York), St. Francis Food Pantry (New York) and Race for Every Child (Washington, D.C.).

In 2022, we continued to put our service work with, and associated sponsorship of, Bridges to Prosperity on hold due to ongoing safety concerns related to the COVID-19 pandemic. But in summer 2023, 10 employees will once again travel to Rwanda with the organization to construct a footbridge in an isolated rural community, facilitating access to economic and educational opportunities.

Total charitable donations grew by 21% over the previous year, and our full scope of charitable giving is estimated at more than 1% of our net profits. This accounts for donations of over 1,955 hours of staff time toward community volunteerism, the ACE Mentor Program, and lecturing at colleges and universities. We also regularly provide pro bono professional services to nonprofit clients.

Charitable Giving 2022

Industry Charity Events

Local Giving

Renewable Energy (Offsets)

Chicago-area ACE mentors and students tour our project at 110 North Wacker. Thornton Tomasetti $370K

Thornton Tomasetti Foundation

Education & Scholarships

Disaster Relief

HELPING COMMUNITIES 2022 Disaster Response & Relief

As part of our mission to support the communities where our employees and partners live and work, we’re committed to providing technical and financial aid to those affected by human-made and natural disasters.

Immediately after Hurricanes Ian and Nicole, we mobilized engineers, architects and other specialists from our offices across the United States to help communities in Florida and up the Eastern Seaboard evaluate the damage and begin to recover.

We conducted rapid-response assessments of the safety of more than 50 single-family homes and over 200 commercial, residential and municipal properties. Our involvement in these communities, educating property owners on how federal and local laws affect their plans for rebuilding, is ongoing.

In addition to our forensics work, we provide financial support for on-the-ground disaster-relief efforts. Hurricane Ian devastated neighborhoods, impacting our Florida colleagues and communities. The firm matched staff donations to Hurricane Ian relief, supporting the American Red Cross relief fund. In the aftermath of Hurricanes Ian and Nicole, we launched an ongoing corporate-giving program with the Red Cross, which matches employee donations to general disaster relief up to a preset maximum.

In 2022, we also matched employee donations to Direct Relief, a nonprofit humanitarian organization, giving $17,000 (for a combined firm/employee donation of $34,000) to support aid to Ukrainian refugees.

Beachfront properties across 16 counties in Florida were hit especially hard by Hurricanes Ian and Nicole. Thornton Tomasetti

HELPING COMMUNITIES Thornton Tomasetti Foundation

The Thornton Tomasetti Foundation is an independent nonprofit organization that helps more young people say yes, and to careers in building engineering, design and technology by funding scholarships and fellowships for undergraduate and graduate students.

The foundation also supports philanthropic organizations and individuals working in building engineering, design and technology.

Support in 2022 went to Archive Global , The Cooper Union , Community Impact Nepal Build Change , Engineers in Action , Engineers Without Borders , Engineers for a Sustainable World and the Urban Assembly . Since its inception in 2008, the foundation has distributed $1.6 million in grants and scholarships.

Raymond Daddazio Eng.Sc.D., P.E., F.EMI Senior Consultant New York

Pedestrian bridges funded in Eswatini (formerly Swaziland) in southern Africa allow safe year-round passage to markets and schools for over 7,000 people. Courtesy Engineers in Action

BUILDING GREAT WORKPLACES

We strive to cultivate a welcoming & rewarding environment.

Progress Report: Building Great Workplaces

Equity, Diversity & Inclusion Update

Lifestyle-Friendly Culture

Training & Education Update

Our New York structural engineering team enjoys a boat ride during a firm-sponsored outing. Thornton Tomasetti

BUILDING GREAT WORKPLACES Progress Report: Building Great Workplaces

Each year, we report on several indicators that show progress toward achieving our goals for inclusion and diversity, professional growth and a lifestyle-friendly workplace.

The percentage of employees who are women is based on self-reported employee records. While this breakdown is in line with numbers typical of our sector, we’ve enhanced recruitment efforts aimed at increasing the number of women in our firm, and solidified our support for employee network groups like Women@TT.

The percentage of employees of nonwhite ethnicity or race in our U.S. offices is based on self-reported employee records. Thornton Tomasetti is hiring a diverse workforce through enhanced recruitment efforts and by supporting Mosaic, an employee network group focused on multicultural issues.

The percent of employees in our U.S. offices who are women or are of nonwhite ethnicity or race is based on self-reported employee records. Over half our U.S. employees are women or of nonwhite ethnicity or race, and we’re working to improve this percentage over time.

We’re working to expand opportunities for women in leadership positions by supporting women at pivotal stages in their careers and to encourage promotions into leadership positions.

Thornton Tomasetti prioritizes recruitment of a more diverse workforce by hiring women and employees of nonwhite ethnicity and race

During the COVID-19 pandemic, the overall number of new hires fell, but since 2020, we’ve substantially increased the number of diverse hires each year in the U.S.

Employees receive promotions for exemplary performance. The surge in promotions in 2021 is due to a moratorium during the pandemic in 2020 and an adjustment was made the following year to account for delayed promotions.

Employees with company ownership tallies the share of employees who are stockholders. Ownership opportunities are offered based on merit at the level of vice president and above. This number is dependent on the number of shares available for sale in a given year.

Employees Who Are Women Employees of Nonwhite Ethnicity/Race U.S. Employees Who Are Women or of Nonwhite Ethnicity/Race

Employees Receiving Promotions Employees With Company Ownership

Senior Leaders Who Are Women U.S. Hires of Women and Employees of Nonwhite Ethnicity/Race

GREAT WORKPLACES

Equity, Diversity & Inclusion Update

Since 2016, our ED&I initiative has contributed to building an inclusive environment and increasing the firm’s gender, ethnic and racial diversity.

This initiative is supported at the top levels of leadership, with senior executives partnering with emerging leaders to engage all our employees. In 2022, our employee network groups (ENGs) organized dozens of local and global activities supporting ED&I goals.

The flagship of our 2022 ED&I program was an Allyship Learning Series, which focused on some of the ways allies can uncover unconscious bias and advocate for others. Our ENGs produced several skits to illustrate the concept, and these engaging videos sparked discussions among employees and raised awareness of the ways allyship can support people facing discrimination or inequity.

Our 2022 annual Wellness Challenge – in which employees competed to earn points and win prizes – evolved to intersect with our ED&I program. Activities that celebrated diversity, such as cooking healthy Hispanic/Latinx meals or getting to know co-workers over conversations about allyship, served both goals.

For 2023, we’ve adopted additional work holidays – Juneteenth, Veterans Day and Indigenous People’s Day – to provide more opportunities for the celebration of diversity.

ED&I COMMITTEE Employee Network Groups

WOMEN’S Employee Network Group

MULTICULTURAL Employee Network Group

LGBTQIA+ Employee Network Group

Employees from our New York office and members of Build Out Alliance attend the 2022 Pride parade in Manhattan. Thornton Tomasetti

BUILDING GREAT WORKPLACES

Lifestyle-Friendly Culture Update

In late 2021 and early 2022, the rapid spread of the omicron variant drove an enormous worldwide surge in COVID-19 cases. Despite the ongoing public health crisis, our workforce continued to expand, with a net growth of over 15%.

In 2022, we onboarded more than 400 full-time staff and 140 interns, the most diverse group in the firm’s history (38% women and 49% nonwhite employees across the United States), with substantial increases in diverse hires in non-U.S. offices as well. We also improved our already industry-leading employee retention rate, lowering attrition for the second consecutive year.

To reinforce our commitment to diversity and employee well-being, we added four paid holidays to our permanent U.S. roster: Martin Luther King Jr. Day, added in 2022, and Juneteenth, Veterans Day and Indigenous Peoples’ Day, added in 2023.

Our existing flexible workplace policy remained in effect, along with health and safety measures initiated in 2020 and 2021, while we continued to develop strategies to support employees wishing to return to offices either full- or part-time as the pandemic began to abate.

In observation of World Menopause Week, 2022 also saw the introduction of our U.K. menopause policy, which established training to raise awareness of the physical, emotional and psychological challenges that can occur at this phase in women’s lives. The policy aims to foster an atmosphere in which employees can freely discuss issues associated with menopause and to provide options – such as work-schedule adjustments and access to counseling services – for staff coping with its effects on themselves or family members.

To add flexibility and reduce costs for single parents and couples without children, we introduced a new coverage tier to our U.S. medical-dental-vision coverage, separating them from our family coverage. The medical coverage now includes travel reimbursement for when a specialist is not locally available. And three new voluntary insurance programs – critical illness, accidental injury and hospital indemnity – now offer employees group rates and the convenience of benefit administration through our payroll department.

In 2022, 229 U.S. employees took advantage of our fitness-reimbursement program for gym memberships, aerobics, and other fitness classes. Our Walkingspree step challenges also continued, motivating employees to improve their health by digitally tracking their fitness activities.

Our corporate responsibility grants program funded wellness improvements for 18 offices, including blenders and fruit for making healthy breakfasts, golf lessons, ergonomic chairs, air purifiers, office vegetable gardens, well-being workshops, bike racks and bike repair supplies.

Employees from our Ho Chi Minh City, Vietnam, office celebrate International Women’s Day, March 8, 2023. Thornton Tomasetti

BUILDING GREAT WORKPLACES Training & Education Update

Our training and educational programs continue to expand. In 2022, we began offering all-staff mentoring, online continuingeducation courses and a webinar series on notable projects and best practices. Employees at designated stages in their careers participated in group coaching, cultural onboarding and project management training. Our knowledge-sharing program keeps employees connected, engaged and informed in a wide range of technical subject areas.

Group Coaching

Our group coaching model prepares people who have reached career transition points to meet future role expectations. This popular program, with a 75% adoption rate among those invited, brought together 77 senior engineers and senior project engineers to meet in small groups with two lead coaches who guided them toward relevant goals. The outcomes of this learning model include improved performance, accelerated career advancement and new relationships across offices and disciplines. According to Director of Learning Linda Warren, “Our people are very enthusiastic about this program. The coaches are phenomenal – the experiences and stories they share give it tremendous value.” And Principal Mark Andrews, a former coach, says, “Our people get a lot out of meeting with others from across the firm and being exposed to different perspectives. I’ve seen our coaching guide people to success in their next career steps, improve their networking skills and help them with their client relationships.”

Cultural Onboarding

Two hundred sixty-five employees in the very early stages of their careers participated in a cultural onboarding program initiated in 2022. Cultural onboarding is based on the premise that employees who feel included and are better acquainted with the company are likely to stay longer. In our U.S. offices, new employees participate in a year of leadership insight conversations and peer-to-peer discussion groups. Cultural onboarding begins with a “Meet the CEOs” dialogue. Monthly discussions introduce new employees to influencers in the firm and to subjects like career development, innovation and what it means to be a professional-services firm. Peer groups give new employees a forum for navigating the firm together, in a group-directed experience.

Mentoring

Thornton Tomasetti

A pillar of our training and education program is mentorship throughout an employee’s tenure. In 2021, we expanded our formal mentoring program, which initially targeted women. We now offer mentoring to most employees at least once a year. Each mentee is introduced to a suitable match through our mentorship platform matrix.

Technical & Management Training

We continue to offer project management training, and our technical training now includes courses at the Roux Institute at Northeastern University . Our partnership with the institute focuses on developing a workforce that has the skills necessary for future success. We collaborate with the institute to design courses that meet our technical training requirements, offer guidance on the types of courses the workforce needs and provide a pool of students from among our employees and trusted partners. In partnership with Roux, we developed and participated in three courses taught virtually in 2022: Introduction to Machine Learning, Data Warehousing, and Data Analysis. Using multiple delivery strategies, our 2022 training program included more than 600 online courses and 24 Thornton Tomasetti University seminars taught by firm experts. Our employee-driven communities of practice (CoPs) promote learning activities, networking and organizational development. They cover a plethora of topics, from building science to drones. In 2022, 865 people (53% of our staff) participated in our 30 CoPs.

Embodied-carbon (EC) community of practice leaders meet in Portland, Maine, to train structural engineers in EC assessment and reduction methods.

U.N. Sustainable Development Goals

Global Reporting Initiative Content Index

Environmental Policy (external link only)

Ethical Sourcing Policy (external link only)

Compliance Policies (external link only)

U.N. Sustainable Development Goals

(Page 1 of 4)

Thornton Tomasetti contributes in a significant way to many of the United Nations’ Sustainable Development Goals. As a multipractice firm with more than 100 capabilities , we apply scientific and engineering principles across disciplines to solve the world’s challenges. Our impact stretches across many of the U.N.’s global goals.

End poverty in all its forms, everywhere

By contributing to the development of affordable housing projects through research, 3D printing and design of projects – such as our work on Winter Landing in Portland, Maine – Thornton Tomasetti is working toward ending poverty (Target 1.4). Additionally, our Thornton Tomasetti Gives Back program and the Thornton Tomasetti Foundation support non-profit organizations like Bridges to Prosperity and invest in impoverished communities in underresourced regions of the world (Target 1.a). Thornton Tomasetti has a resilience practice that helps clients prepare, endure, adapt and thrive in a disruptive and changing world (Target 1.5).

Ensure healthy lives & promote well-being for all, at all ages

We promote healthy living and well-being for our employees and the communities we serve through our work. Our employees receive excellent, affordable health insurance, annual fitness reimbursement, generous family leave for new parents, and free access to fitness, mindfulness and other wellness programs (Target 3.8). Our largest office, our New York headquarters is certified through the WELL Health-Safety standard to ensure a safe work environment during the COVID-19 pandemic and beyond. Our team of sustainability experts has worked on more than 450 green building certification projects and helped clients realize their project certification goals toward standards like WELL, WELL Health-Safety, LEED, BREEAM and the Living Building Challenge, as well as others that seek to improve the health and well-being of building occupants – in projects as diverse as schools and airports. Our recent work on PlaNYC: Getting Sustainability Done includes 32 citywide initiatives with implementable actions that promote a healthier, more climate-resilient New York City for all.

Ensure inclusive & equitable quality education & promote lifelong learning opportunities for

all

This goal is woven into the fabric of Thornton Tomasetti. Founding Principal Charles Thornton launched the ACE Mentor Program of America (ACE) – a free after-school program designed to attract high school students into AEC careers –28 years ago. Around 70% of ACE mentees are minority students, and over 83% of our offices in cities where ACE chapters exist participate (Target 4.4). Thornton Tomasetti, Inc., funds several scholarships for engineering students and offers regular internships, and the Thornton Tomasetti Foundation offers fellowships and scholarships for undergraduate students planning to pursue graduate studies in building engineering, design or technology (Target 4.b). Many of our professionals are educators at colleges and universities worldwide. Within our firm, we offer our employees discretionary tuition reimbursement toward a degree program or for relevant courses.

U.N. Sustainable Development Goals

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Achieve gender equality & empower all women & girls

Thornton Tomasetti aspires to be an industry leader in fostering the professional advancement, success and visibility of women, not just at all levels of our firm, but also in the engineering field. A passion for gender equality and innovation through diversity drives our efforts to increase our number of female shareholders and employees, encourage women to become involved in company management, empower women through our Women@TT employee network group and encourage girls to enter STEM professions (Target 5.5). Our Equity, Diversity and Inclusion and Women@TT initiatives promote education of all employees regarding challenges faced by women as a gender underrepresented in our industry. These initiatives create opportunities to improve inclusion for women, foster a supportive community for women in our firm at all stages of their professional development, and help create a culture in which women are treated equitably and inclusively (Target 5.1). We support shared responsibility within the family by offering generous parental leave for both mothers and fathers (Target 5.4).

Ensure availability & sustainable management of water & sanitation for all

Our sustainable design projects – to which we apply our expertise to meet a broad range of sustainability objectives – contribute to the goals of clean water and sanitation. We assist our clients in meeting green building certification water efficiency and net-zero water credits by helping them establish a water budget for their projects and employing programs like LEED and the Living Building Challenge (Target 6.4). Our projects reduce water use and take a holistic water budget approach, especially in places like California, where drought is common. We provide services in green infrastructure and master planning natural habitat regeneration through our resilience practice (Target 6.6). These services support water solutions based on climatic analysis at a building and site level and provide for stormwater management (Target 6.5).

Ensure access to affordable, reliable, sustainable & modern energy for all

Thornton Tomasetti's work in decarbonization supports the goal of achieving affordable and clean energy globally. We are helping decarbonize the power sector and heavy industry by minimizing the risks associated with carbon capture and storage technologies and onshore and offshore energy facilities. We are also advancing technologies for more efficient energy storage and electrifying transportation systems (Target 7.a). Our engineers apply their expertise to solving the structural and functional challenges of alternative energy systems. Our sustainability experts guide clients to pursue embodied-carbon reduction energy efficiency and net-zero-energy buildings (Target 7.3). We fund renewable energy by purchasing renewable energy certificates to reduce the greenhouse gas emissions generated by our offices’ electricity consumption, as well as by buying carbon offsets for our business travel (Target 7.2).

U.N. Sustainable Development Goals

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Promote sustained, inclusive & sustainable economic growth, full and productive employment & decent work for all

Attention to diverse and nondiscriminatory recruitment and company policy means that Thornton Tomasetti contributes to the goal of decent work and economic growth opportunities for all. Our company standard practices and healthy work environment support our employees. Our work on a variety of projects, across a range of sectors, contributes to economic growth (Target 8.1). Many of them, such as the Order of Saint Francis Healthcare headquarters in Peoria, Illinois, and Capital One Center in Washington, D.C., contribute to community development, offering new avenues for economic growth. Through our R&D and innovation accelerators, we contribute new technologies to the building sector and beyond, and we support entrepreneurship through AEC Angels which funds technology start-ups (Target 8.2). We provide mentorship and scholarships to high school students, building a pipeline to the engineering and architecture professions (Target 8.6).

Build Resilient Infrastructure, Promote Inclusive & Sustainable Industrialization & Foster Innovation

Thornton Tomasetti’s innovation engine, CORE studio, develops innovative and dynamic tools that improve efficiency and enable us to provide optimized client solutions. This positively impacts the quality of the infrastructure in the cities where we work. Every year, R&D funding is made available to employees in an open call for innovation developments. Our services contribute directly to the industry, innovation and infrastructure goal. Our resilience consulting helps clients prepare, endure, adapt and thrive in a disruptive and changing world. In addition, we’re working with hospitals and subways to develop resilient infrastructure designs, and we have numerous Institute for Sustainable Infrastructurecertified Envision Sustainability Professionals (Target 9.1). Our Applied Science practice engages in research, development and design to engineer practical solutions that manage risks across a range of military and civilian applications. One project is HyperloopTT with the goal of creating the world's fastest, most efficient and most affordable end-to-end transportation solution (Target 9.4).

Reduce inequality within & among countries

Thornton Tomasetti applies fair employment policies and equitable wages across our 40-plus offices and in our work in more than 50 countries. The company assesses pay parity to ensure income equity (Target 10.4). Our Equity, Diversity and Inclusion initiative and antidiscrimination policies help ensure equal opportunities for all employees (Target 10.2). We promote involvement in our ED&I employee resource groups across locations as far-flung as Mumbai, India, and Washington, D.C. By sharing our technology and expertise across locations, we contribute to greater equality among countries. Our designs of buildings and communities can have a secondary effect of increased social equity. Our service work in Rwanda with Bridges to Prosperity helps reduce inequality for underresourced and isolated communities (Target 10.3).

U.N. Sustainable Development Goals

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Ensure sustainable consumption & production patterns

We adopt sustainable practices and integrate sustainability information into our reporting and help others in our industry do the same. Per our environmental policy we aim to apply our embodied-carbon specifications so that our projects use materials or adjustments to materials that are less carbon intensive than typical choices are (Target 12.6). Since buildings produce 40% of global CO 2 emissions, and about 11% of those are from building materials, our embodied-carbon action plan commits us to advocate for the use of low-embodied-carbon or carbon-storing materials within our sector and adjacent industries. Another area of impact is the selection of healthy materials. We avoid the use of toxic materials on the Living Building Challenge Red List and endeavor to influence clients and partners to choose responsible material consumption and production (Target 12.7). We contribute to a circular economy through our master-planning projects, into which we incorporate circular economy principles (Targets 12.2, 12.5). Our work in carbon capture and storage reduces the release of greenhouse gases into the atmosphere (Target 12.4).

Take urgent action to combat climate change & its impacts

With our new initiative, Climate Action at Thornton Tomasetti, we're structuring many of our practices around providing decarbonization and resilience solutions (Target 13.1). We’re combating climate change through our internal policies, projects and services, and advocacy and partnerships. We participate in committees focused on reducing emissions in our industry and sponsor organizations like the Carbon Leadership Forum. We promote and apply creative means to reduce carbon in our projects and are committed to achieving carbon-neutral business operations and influencing policies and practices for sustainability and resilience in our industry and communities. We’re a recognized leader in moving consideration of embodied carbon to the forefront of our industry. We co-initiated the Structural Engineers 2050 Challenge, urging all structural engineers to understand, reduce and eliminate embodied carbon in their projects by 2050, and are an inaugural member of the Structural Engineers 2050 Commitment (Target 13.3). Our sustainable design , decarbonization and resilience services help clients combat climate change and its impacts (Targets 13.1, 13.3).

Make cities & human settlements inclusive, safe, resilient & sustainable

Thornton Tomasetti provides consulting services in resilience and sustainability, which positively impact the goal of sustainable cities and communities. Our work in all our practice areas requires that we honor our oath as engineers to protect public safety in the communities we serve. We’re committed to constructing a cleaner, healthier built environment by measuring, tracking and eliminating embodied and operational carbon in buildings and neighborhoods. We collaborate with other firms to create high-performance, low-energy facilities and communities that are efficient, comfortable and healthful at every stage of their life cycles. Our broad range of sustainability services – from water balancing, green building certification, circular economy guidance and healthy materials research to parametric energy analysis – contributes every day to creating sustainable cities and communities (Target 11.6). Our firm contributes widely to this goal through our work on affordable housing development (Target 11.1), transportation (Target 11.2), master planning and resilience (Target 11.3), building renewal (Target 11.4), community resilience and building forensics for natural disasters (Target 11.5).

Protect, restore & promote sustainable use of terrestrial ecosystems

Master planning is an opportunity to maximize long-term sustainability and resilience. We help communities develop sustainable master plans, encouraging biodiversity and habitat regeneration. We also recommend green spaces to co-benefit stormwater management and heat mitigation. This enhances wildlife corridors and creates habitats that may not have existed in urban settings (Target 15.9). We recognize that mass-timber construction has great potential to reduce embodied carbon and that reducing carbon means sustainably managing forests. We are structural engineer for the world’s tallest mass-timber tower As a leader in mass-timber design, we have an opportunity to impel wood suppliers toward more sustainable practices. Our structural engineering work includes green roof design. Green, vegetative roofs can provide unique habitats for biodiversity in urban settings (Targets 15.1, 15.2, 15.b).

GRI Content Index 2022 Using GRI 1: Foundation 2021

Thornton Tomasetti has reported the information cited in this GRI content index for the period January 1, 2022, through December 31, 2022, with reference to the GRI Standards.

ESG DISCLOSURES

GRI 2: General Disclosures

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2-1 Organizational details

2-2 Entities included in the organization’s sustainability reporting

2-3 Reporting period, frequency and contact point

Thornton Tomasetti

Nature of ownership: Private, employee-owned corporation Headquarters: New York City 11 countries of operation: ThorntonTomasetti.com/Contact-Us

All subsidiaries and joint ventures associated with Thornton Tomasetti, Inc., are covered in the report.

Year 2022 annual reporting: January 1, 2022, through December 31, 2022

Publication date: June 22, 2023

Financial reporting: May 2023

Contact: Amy Hattan, Corporate Responsibility Officer, AHattan@ThorntonTomasetti.com

2-4 Restatements of information

2-5 Restatements of information

2-6 Activities, value chain and other business relationships

2020 GHG emissions are 43% lower compared to the level of emissions previously reported. The reason for this restatement is a calculation error in the 2020 emissions inventory. 2018 GHG emissions are 1.7% higher compared to the level of emissions previously reported. The reason for this is an adjustment to our baseline to reflect new office locations.

No external assurance.

Activities: T horntonTomasetti.com/Capabilities

Sectors: Private; architecture, engineering and construction (AEC); building sector; consulting Markets: www.ThorntonTomasetti.com (Client Solutions)

Value chain:

• Upstream (construction materials, computing supplies, office products, contracted labor and project subcontractors to supplement workforce)

• Downstream (buildings and other structures, infrastructure, clients – contractual relationships)

• Operational supply chain: Leased buildings and vendors (IT, office supplies)

ESG DISCLOSURES

GRI 2: General Disclosures

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2-7 Employees

Our data includes continuous staff. We did not include seasonal workers, interns, temporary staff or retirees in the data set unless specified. Full-time/part-time is defined by the respective country of work. Gender of employees is self-designated.

Number of Permanent Employees by Gender and r egion

Number of Temporary Employees by Gender and Region

ESG DISCLOSURES

GRI 2: General Disclosures

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2-7 Employees (cont.)

ESG DISCLOSURES

GRI 2: General Disclosures

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DISCLOSURE RESPONSE

2-8 Workers who are not employees

2-9 Governance structure and composition

We use consultants who work independently. All workers whose work is controlled by the firm are our employees.

Our highest governance body responsible for decision-making and overseeing the management of impacts is our board of directors. The board comprises 12 employees and one external member. All employees on the board hold executive positions in the firm. See our leadership page for roles and competencies of board members. For diversity of leadership, see disclosure 405-1.

Our governance structure is organized as a matrix, with regions, practices and departments reporting to the coCEOs, who report to the board. The co-CEOs manage the company, and the board assures that the company is effectively managed. Board members serve two-year terms, with no term limits. Every two years, membership is reviewed and put to shareholder vote at the annual meeting.

The corporate responsibility steering committee and the equity, diversity and inclusion committee are management committees responsible for working with the CEOs on decision-making for ESG impacts. The corporate responsibility department helps develop firm-wide goals and drive policy implementation.

2-10 Nomination and selection of the highest governance body

Nomination and selection of board members are done at the election of the board and coordinated by the board chair. Both existing and new board members are evaluated on past performance. Ownership is one criterion for board membership but is not compulsory, as we allow for external members, who cannot hold stock.

2-11 Chair of the highest governance body

The board chair is Thomas Scarangello, former CEO. Conflicts of interest are prevented by the chair not being the same person as the CEO. The chair is a senior executive but is not the highest governing individual in the firm.

The firm’s leadership structure provides checks and balances. The CEOs report to the board, and the chair reports to the CEOs. This arrangement provides the firm with the best level of governance and an appropriate number of checks and balances.

ESG DISCLOSURES

GRI 2: General Disclosures

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DISCLOSURE RESPONSE

2-12

Role of the highest governance body in overseeing the management of impacts

Members of our highest governance body are directly involved in both the development and oversight of the organization's impacts on the economy, the environment and people. The CEOs manage the company and set the direction for the management of impacts, in collaboration with senior leadership. The board challenges and supports, assuring that policies are effective in building an enduring organization and in representing shareholder interests. The CEOs meet with the board quarterly. The management approach is driven down to the matrix leaders. Wherever viable, hard metrics are set and we execute our programs to meet those metrics, which the board reviews quarterly to ensure the direction meets the stakeholders' vision.

One of the CEOs is a member of the corporate responsibility steering committee and the direct supervisor of the corporate responsibility officer. The corporate responsibility steering committee is composed of leaders representing a diversity of our locations, practices and departments. This committee updates our goals for management of the organization's impacts on the economy, environment and people every five years. The president and a board member are executive advocates of the equity, diversity and inclusion committee They work with our employee network group leaders to weave ED&I into our company and culture. These processes are inclusive of employee stakeholders, and they are influenced by our clients' interests.

2-13 Delegation of responsibility for managing impacts

See disclosure

2-12.

The corporate responsibility officer, reporting to one of the co-CEOs, is a senior member of the staff, responsible for managing some of the impacts. Corporate responsibility is woven into our culture at Thornton Tomasetti. Therefore, management responsibility is delegated to leaders in the areas most relevant to specific impacts. In addition to the corporate responsibility department, this includes our equity, diversity and inclusion committee; our human resources department; our legal department; our sustainability practice, etc. A regular weekly call between our department leaders and executive team enables regular reporting, as do lines of supervision between managers and the CEOs.

2-14 Role of the highest governance body in sustainability reporting

The highest governance body is responsible for reviewing and approving the reporting information. Reviews take place via regular weekly department leader/executive leader meetings and regular meetings between the coCEO and the corporate responsibility officer. The co-CEO approves a final review before the sustainability report is released.

2-15 Conflicts of interest

The interests of all senior and executive leadership, the board and stakeholders are aligned around our purpose and values. This mitigates conflicts of interest, as the board is in agreement with the direction of our purpose and values. Our five-year plan is clear about the company’s direction during any five-year period, and the board ensures that we are aligned with the five-year plan and our purpose and values.

ESG DISCLOSURES

GRI 2: General Disclosures

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DISCLOSURE RESPONSE

2-16 Communication of critical concerns

The co-CEOs bring any critical operational concerns to the executive committee, and these concerns are discussed in this forum. Weekly meetings of the department leaders and executive committee also cover areas of critical concern. At the quarterly board meetings, concerns are discussed under the umbrella of strategy and vision. Then, messages about critical concerns are communicated to department leaders, practice leaders, regional leaders and employees via direct CEO town halls for their office locations.

2-17 Collective knowledge of the highest governance body

The collective knowledge of the highest governance body on sustainable development is advanced through shared articles, invited speakers, internal seminars, conference attendance and involvement of individuals in industry associations.

2-18 Evaluation of the performance of the highest governance body

Evaluation of our performance in sustainable development starts at the CEO level. The board evaluates how the co-CEOs are performing in the areas of the economy, the environment and people. This evaluation happens over time. Ultimately, the shareholders will inform the board if the evaluation is effective. Shareholders and other employees learn about our performance, as does the board, through several communication channels. Shareholders can voice disagreement or agreement with the company performance in sustainable development semiannually when selecting and reappointing board members.

2-19 Remuneration Policies

2-20 Process to determine remuneration

Compensation decisions are conveyed through the matrix, from the top down. The board oversees CEO compensation, and the co-CEOs make compensation decisions for the firm.

Thornton Tomasetti adheres to a holistic compensation process consisting of elements of salaries, bonuses and equity. Our process is informed by firm performance, performance evaluations, project data and market conditions.

ESG DISCLOSURES

GRI 2: General Disclosures

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DISCLOSURE

2-21

The ratios for annual total compensation and for the percentage increase for our highest-paid employee to the median in each country of significant operations follow.

2-22 Statement on sustainable development strategy

Ratio of Annual Total Compensation for Highest-Paid Employee to Median for All Employees Except Highest-Paid

Ratio of Percent Increase in Annual Total Compensation for Highest-Paid to Median Increase for All Employees Except Highest-Paid

Total compensation is calculated based on salary, hourly pay, allowances and all bonuses except relocation and referral.

In corporate responsibility report (CRR): CEO letter, corporate responsibility approach, goals and targets.

• A Message from Our Leadership

• Our Approach

• Goals & Targets

Annual total compensation ratio

ESG DISCLOSURES

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DISCLOSURE RESPONSE

2-23 Policy commitments

See:

• Environmental Policy

• Ethical Sourcing

• Legal & Privacy Policies

These policy commitments are approved by the executive committee and communicated via our website and employee handbook, and in our responses to requests for information.

2-24 Embedding policy commitments

Policy commitments are overseen by the department and practice leaders whose jurisdictions can have the greatest influence on the policy, with guidance and oversight from the executive committee. Staff in our departments and practices are rewarded in performance reviews, awards and bonuses and evaluated on how they embody the values outlined in our policies. Communication of our policies to our clients ensures compliance, as the results are seen in how we design our projects and how we deliver our services.

2-25 Processes to remediate negative impacts

Thornton Tomasetti uses NAVEX Global, a confidential ethics-reporting hotline, to enable employees to report workplace grievances. This hotline can be accessed by all employees through our intranet on either a smartphone or computer. Employees also have the option to call the hotline directly to file a complaint. Our human resources business partners (HRBPs) are the only individuals with access to the account, and they monitor it regularly. Aside from the hotline, employees are encouraged to reach out to their local HRBP or the CHRO with any employee-relations issues. As with the hotline, once an issue is reported, the local HRBP or CHRO follows up with the employee to understand the issue in more detail and decide what next steps are needed. Once the issue has been resolved, the HRBP requests feedback on the process, which enables stakeholders to help improve the firm’s processes. Each employee-relations issue is logged into a spreadsheet, and the outcome is recorded (e.g., involuntary/voluntary termination, retained employee).

By tracking the outcomes and retention, the firm is able to assess whether the processes are effective.

ESG DISCLOSURES

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DISCLOSURE RESPONSE

2-26 Mechanisms for seeking advice and raising concerns

Employees who seek advice and raise concerns start with their supervisors or other matrix leaders. These concerns roll up to department leaders, the executive committee or the board. If employees are not comfortable speaking with their supervisors or other leaders, they can express their concerns through our confidential hotline, NAVEX Global. See disclosure 2-25.

2-27 Compliance with laws and regulations

No instances of noncompliance in reporting period.

2-28 Membership associations

The membership associations in which we have significant (highest spend and most engagement on committees) involvement include the American Institute of Architects, the ACE Mentor Program of America, Beverly Willis Architecture Foundation, Urban Green Council, Structural Engineers Association of New York, Chicago Architecture Center, Council on Tall Buildings and Urban Habitat, American Council of Engineering Companies and the New York Building Congress.

2-29 Approach to stakeholder engagement

Our significant stakeholders are clients, business partners, employees, governments, industry associations, shareholders, suppliers, and underrepresented groups. We engage with stakeholders to identify materiality areas for our sector, to identify areas of concern and reduce negative impacts, and to involve our stakeholders in the solutions. We work as a team with our stakeholders and seek inclusion for our employees in decision-making.

2-30 Collective bargaining agreements

N/A - no collective bargaining entities.

ESG DISCLOSURES

GRI 3: Material Topics

GRI 201: Economic Performance

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DISCLOSURE RESPONSE

201-1 Direct economic value generated and distributed

See Financial Vitality .

We do not engage in profit distribution to shareholders. We are a private company and do not publish profit or operational costs.

201-2 Financial implications and other risks and opportunities due to climate change

The risks and opportunities posed by climate change that have the potential to generate substantive changes in our operations, revenue or expenditure include physical risks such as extreme weather, shortages of materials and health pandemics that impact our employees; new competition from a change in demand for particular services and new technologies; and civil unrest that can result in uncertain markets in our locations.

After our New York headquarters weathered Superstorm Sandy, we developed a business-continuity plan to reduce risk from extreme weather.

As an engineering-services firm that provides sustainable-design services, we have an opportunity to be competitive and to quickly respond to changes in demand for sustainability services as more climate-change policies and codes demand sustainable design and as more clients seek to achieve net-zero carbon in their projects.

We have an excellent opportunity to apply our expertise and capacities to solve climate-change problems. We are expanding our climate-action service areas in decarbonization and resilience and applying to these services our expertise in sustainable design, mass-timber structures, embodied carbon, carbon capture and storage, renewables and batteries, manufacturing, transportation systems and resilience. We're also developing new technologies that can be used toward reducing greenhouse-gas emissions and improving resilience against climate-change impacts.

Government policies and programs that seek to regulate emissions from businesses are less likely to impact Thornton Tomasetti, a private company, than large public companies. We set our goal of reaching carbon-neutral business operations by 2030 – informed by the Greenhouse Gas Protocol – before many private companies did, and we're on target to achieve it.

ESG DISCLOSURES

GRI 201: Economic Performance

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DISCLOSURE RESPONSE

201-3 Defined benefit plan obligations and other retirement plans

Thornton Tomasetti offers a defined contribution plan. U.S. employees may select a pretax contribution percentage, subject to the annual limit set by the U.S. IRS. The firm makes a matching contribution of 50% to the first 7% of employee contributions, not to exceed the maximum current-year tax-deferred limit.

201-4 Financial assistance received from government

N/A. Thornton Tomasetti did not receive financial assistance from government in the reporting period.

ESG DISCLOSURES

GRI 302: Energy

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DISCLOSURE RESPONSE

302-1 Energy consumption within the organization

See Sustainable Operations Progress Report .

Electricity consumption: 10,416,897 megajoules

Heating consumption: 5,017,494 megajoules

Total energy consumption (purchased) within the organization: 15,434,391 megajoules

Total renewable energy purchased: 4,952,581 megajoules

Total nonrenewable energy consumption (purchased) within the organization: 10,481,810 megajoules

302-2 Energy consumption outside of the organization

See Our Good Work Progress Report

302-3 Energy intensity Energy intensity ratio:

15,434,391/1367 = 11,291 megajoules (8.066 GJ) per employee

Organization-specific metric: 1,367 employees counted in 2022 emissions analysis

Energy included: Fuel and electricity consumed within the organization

302-4 Reduction of energy consumption

Reduction of energy consumption in our operations is measurable where we have direct control in our leased office spaces. We can measure gains in energy efficiency resulting from designing our new offices to a green building standard by comparisons with the average energy use intensity. We can also measure gains in efficiency from changes in equipment or technology.

Twelve of our offices have been certified or are registered with a green-building certification program such as LEED, Living Building Challenge or equivalent, as outlined in our office fit-out best-practices policy. The energyuse reduction in lighting power intensity from a LEED Commercial Interiors project is an average of 20%. In 2022, our Denver and London offices moved into energy-efficient spaces.

Our corporate responsibility grant program provides support to offices implementing energy-reduction measures. In 2022, out of 23 grants awarded to offices for corporate responsibility initiatives, two were slated specifically for office energy-use reduction.

Thornton Tomasetti has made a concerted effort over the last 10 years to switch from desktop computers to laptops. Considering the rated power of the standard-issue workstation (950 watts), compared with the rated power of the standard-issue mobile workstation (90 watts), we've realized a 91% reduction in possible energy use per switch. Between 2021 and 2022, we reduced our total number of computers by 122 and desktop computers by 309.

ESG DISCLOSURES

GRI 302: Energy

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DISCLOSURE RESPONSE

302-5 Reductions in energy requirements of products and services

See Our Projects Progress Charts.

Our sustainable design services contribute significantly to reductions in the operational and embodied energy requirements of buildings. Our consulting and design services assist clients in meeting project goals for energy efficiency; net zero energy design; passive house; life-cycle assessment and embodied-carbon reduction; and LEED and other green building certifications.

Our growing services in decarbonization are further reducing the energy requirements of the building projects on which we consult, and we're helping our clients in the energy sector develop non-fossil fuel energy supplies. In addition, we're working on reducing the energy requirements for transportation.

ESG DISCLOSURES

GRI 305: Emissions

Minimal Scope 1 emissions: We do not own facilities or vehicles in the United States, where we have the majority of our operations. Our only owned facilities and vehicles are in the United Kingdom. We will account for these emissions in our 2023 emissions inventory.

N/A. We do not track, as we are a service company.

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ESG DISCLOSURES

GRI 401: Employment

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401-1 New employee hires and employee turnover (cont.)

Total Employee Turnover* During the Reporting Period, by Age Group, Gender and Region

*Employee turnover: employees who leave the organization voluntarily or due to dismissal, retirement or death in service.

ESG DISCLOSURES

GRI 401: Employment

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401-2

Full- and part-time U.S. employees regularly working a minimum of 30 hours per week are eligible for the Thornton Tomasetti benefits plans below. Other countries have similar offerings and differ based on local law and benefit norms.

• Cigna medical plans (employer/employee paid)

• High medical OAP

• Low medical OAP

• High deductible health plan with health savings account

• Cigna dental plan (employer/employee paid)

• Dental PPO

• EyeMed vision insurance (employer paid)

• Provides eye exams and offers discounts on lenses, frames and contacts

• Life insurance (employer paid)

• Basic life and AD&D insurance for $100,000

• Voluntary life (employee paid)

• Employees may purchase life insurance for employee or spouse/domestic partner

• Short-term disability (employer paid)

• Provides partial replacement income due to disability, up to a maximum of 26 weeks

• Long-term disability (employer paid)

• Provides partial replacement income in case of disability from 90 days to age 65 years.

• Employee assistance program (employer paid)

• This confidential program assists employees and their dependents with personal problems and/or workrelated problems that may impact their job performance, health, or mental and emotional well-being.

• Offers other services and information on elder care, pet care, financial, emotional health, physical health, job/career, relationship, family life, legal, and substance use.

• Flexible savings pretax accounts (employee paid)

• FSA healthcare

• FSA dependent care

• Limited purchase FSA

• Fitness program (employer paid)

• Fitness reimbursement up to $400 paid in a 12-month period

• Bicycle program (employer paid)

• Bicycle reimbursement up to $240 per year

• Commuter pretax benefits (employee paid)

• Parking

• Transit

Benefits provided to full-time employees that are not provided to temporary or part-time employees

ESG DISCLOSURES

GRI 401: Employment

(Page 4 of 4)

DISCLOSURE RESPONSE

401-2 Benefits provided to full-time employees that are not provided to temporary or part-time employees (cont.)

• Health savings account (employer/employee contribution)

• HSA available for employee enrolled in the high deductible health plan

• Receives employer new hire and annual contributions

• Employee may contribute to HSA

• Contributions are based on annual IRS limits

• Raymond James (employer paid)

• Offers one-on-one financial advice to improve employees’ financial health and provides a monthly series of webinars covering financial planning topics.

• 401(k) profit sharing plan (employer match/employee contribution)

• Retirement savings plan that allows employees to save and invest a portion of their earnings on a pretax basis.

• 50% match, up to 7% employee contribution

• 401(k) student loan matching program (employer match)

• Enables employees who are repaying a student loan to save for retirement while continuing to pay down their student loan(s).

• Cigna programs, wellness tools and applications (employer paid)

• Voluntary programs (employee paid)

• Critical care insurance

• Hospital care insurance

• Accidental injury insurance

• Wellness apps (employer paid)

• Walkingspree

• Headspace

401-3 Parental leave

Continuing full- or part-time employees with a minimum of one year of service at Thornton Tomasetti who have become disabled due to pregnancy are eligible to receive full salary under the Parental Family Caregiver Leave benefit, based on years of service. Part-time employees’ leave days are in proportion to the average number of hours worked in the year preceding the beginning of leave. Paid family leave begins with the birth of the baby and is paid based on years of service.

Maternity leave: At least one year of service, 40 days

At least three years of service, 45 days

At least four years of service, 50 days

Number who took parental leave: 15 women and 46 men

Number who returned to work after leave and were still employed 12 months after return: 13 women and 44 men

Return-to-work rates of employees who took parental leave: 86% women and 95% men

Retention rates of employees who took parental leave: 93% women and 96% men

ESG DISCLOSURES

GRI 404: Training & Education

DISCLOSURE RESPONSE

404-1 Average hours of training per year per employee

8,003 total hours

5.3 hours average per employee

14,289 courses taken:

4,624 by females

9,627 by males

38 by nonbinary/not listed

404-2 Programs for upgrading employee skills and transition assistance programs See Training and Education.

404-3 Percentage of employees receiving regular performance and career development reviews

Performance alignments are optional for part-time staff (less than 30 hours). 99% completion of performance alignments (both male and female).

GRI 405: Diversity & Equal Opportunity

405-1 Diversity of governance bodies and employees

See Inclusion & Diversity.

Percentage of Individuals Within Executive Committee and Board Governance Bodies by Gender

Number of Individuals Within Executive Committee and Board Governance Bodies by Age Group

405-2 Ratio of basic salary and remuneration of women to men

We're not including a ratio of basic salary and remuneration of women to men in this report. We have a pay parity report that we publish internally every year, based on specific technical job categories, but our categories do not currently match those of GRI.

GRI 406: Nondiscrimination

406-1 Incidents of discrimination and corrective actions taken

Our policies dictate that we respect the privacy and confidentiality of these sensitive matters, so numbers and details are omitted.

Company-Specific Materiality Topic: Community Engagement

DISCLOSURE RESPONSE

TTCE-1 Employee participation in community service

See H elping Communities Progress Report. See Community Service.

TTCE-2 Charitable contributions

See H elping Communities Progress Report. See Charitable Giving.

Company-Specific Materiality Topic: Employee Health & Wellness

DISCLOSURE RESPONSE

TTEHW-1 Employee engagement in wellness program See Lifestyle-Friendly Workplace.

TTEHW-2 Employee satisfaction with benefits 78% of employees satisfied with benefits. 92% of employees satisfied with workplace flexibility.