From low-carbon concrete to carbon-smart decision making, Mattamy Homes is rewriting the rules of residential construction.
At a time when the building industry is still coming to terms with its carbon footprint, Mattamy Homes is leaning in hard. One of the largest privately owned homebuilders in North America is now focused on a huge elephant in the room: embodied carbon.
Low-carbon concrete, geothermal heat pumps and various structural designs at the mixed-use Carding House have reduced operational carbon emissions by about 29 percent annually. Credit: Mattamy
Embodied carbon is the amount that is emitted during construction, maintenance and tear-down of a building. This includes the carbon emitted from extracting raw materials, processing and manufacturing building materials, transport, construction, maintenance, repair, replacement and, at end of life, taking down a building and disposal of the materials.
Mississauga, Ontario-based Mattamy likes to be an example of how things should be done. “We want our carbon footprint to be as small as possible,” says Philip Squires, Mattamy’s corporate vice president of sustainability and procurement. “All carbon production has an impact on climate change, whether it’s operational or embodied emissions.”
In situations where carbon emissions are already low, solar panels can initially be an environmental negative because of fossil fuel-based production methods. But the panels quickly become carbon neutral after installation. Credit: istock/pk24
Rock Solid Relationships
The first step toward embodied carbon cleanup: Partnering with concrete manufacturers across North America to guarantee that the mixes used on their sites are verified low-carbon blends. That’s a big deal, considering that concrete alone is responsible for more than 8 percent of global CO2 emissions, Squires notes.
“Concrete can be a major contributor to carbon emissions,” he says. “We work diligently to lower the impact concrete can have on our environment.”
A grand example is Carding House, a five-story mixed-use development in Oakville, Ontario that includes 157 condominium units. According to the company, the project represents a significant step forward in reducing operational carbon emissions—in this case, cutting it by as much as 29 percent annually when compared to Ontario Building Code requirements. It achieves this by using a geothermal system and ground source heat pumps for the building’s heating and cooling, “a testament to the development’s commitment to sustainability.”
Carding House also achieved an embodied carbon intensity that is 16 percent less than Mattamy’s historical average embodied carbon. Measures taken to reduce embodied carbon in the project included use of low-carbon concrete, and rebar that was manufactured using electric-arc furnace technology. The upper floors of the development were constructed using a combination of hollow-core slabs, prefinished exterior insulation and finish systems, cold-formed steel walls and cast-in-place concrete.
As part of its partnership, Mattamy uses several brands of low-carbon concrete, including Holcim ECOPact and CEMEX Vertua. Brands are selected based on the housing project’s location. “The building sector accounts for nearly 40 percent of our world’s CO2 emissions,” notes Holcim. “Decarbonizing the built environment is therefore essential for a net-zero future.”
Keeping up to date with the latest products, technology, and training ensures that builders are able to remain relevant in an ever-changing construction world. Credit: Mattamy
Determining True Value
Mattamy is also redefining how decisions about solar energy installations are made. Their decisions are not just based on marketing or incentives, or what Squires calls ROCI, or “Return on Carbon Invested.”
A typical example: In certain Canadian markets where the grid is already clean, adding rooftop solar can sometimes increase a home’s total carbon footprint due to the embodied carbon in the panels themselves. “We use third-party building science professionals to evaluate the embodied and operational carbon impacts of products,” Squires explains. “If the ROCI doesn’t meet our threshold, we look for better options.”
This analytical approach reflects a deeper commitment to carbon literacy within the company. But translating that into a value proposition for consumers—especially in a market fixated on price-per-square-foot—is no small feat. The breakthrough moment came when the company started looking beyond the upfront price to the total cost of home ownership.
One-fifth of the overall carbon generated during a building's life cycle comes at the beginning stage during creation and transportation of products, and the subsequent construction. Credit: Mattamy
“The cost of home ownership includes taxes, insurance, and utilities,” Squires says. “If we can reduce utility costs through better performance, the total cost of the home might not change—even if it’s a higher-performance house.”
Still, challenges remain. Low-carbon materials often come at a premium price. Or worse, they aren’t available in every market. “Why are we still being charged more for green products that would clearly make the industry better?” Squires asks. “If we can provide homes with lower operational costs and greater resilience at the same sale price, what are we waiting for?”
Low-carbon concrete blends, such as ECOPact by Holcim, help offset the traditional product that is responsible for more than 8 percent of global CO2 emissions.
Cooperation and Communication are Key
When it comes to progress in embodied carbon reduction across the industry, Squires points to innovations in concrete and drywall, where lower-carbon versions are already in use. But he also notes that too often, greener versions of standard materials are treated as premium options. “Anything that’s available in a lower-carbon version should be the standard for everyone,” he notes. “That’s how we get economies of scale.”
Cooperation among builders and other industry supporters is key. In June 2024, the Climate Smart Buildings Alliance (CSBA), a joint effort between Mattamy, construction services company EllisDon and RBC (a.k.a., the Royal Bank of Canada) launched the Responsible Buildings Pact.
This is a voluntary agreement for any developers, consultants, contractors, and supporters interested in working together to reduce the embodied carbon of buildings they create. Participants agree to remain educated on lower-carbon materials, establish an internal process to consistently evaluate whether lower carbon materials or design strategies can be used, and report publicly on the results of evaluations and the use of lower carbon materials.
As one of North America's largest privately owned homebuilders in North America, Mattamy Homes focuses on creating homes that reflect how people live and breathe, emphasize architecture, and promote sustainability and wellness. Credit: Sagiper North America
Twenty-three signatories and supporters were on board with the pact when it was announced. One year later, the number has grown to 40, CSBA reports. “Most builders have their own sustainability targets, but for any of us to succeed, we need everyone to be moving in the same direction,” notes Brad Carr, CEO of Mattamy Homes Canada. “We can only get more low carbon materials and technologies in the market if others in the industry are also sending the same signal to suppliers. The Pact will help us coordinate and collaborate towards shared climate objectives.”
So can a business move beyond incremental gains to a true “moonshot” moment? For Squires, it starts with mandatory reporting. “There needs to be a standard way to track and report embodied carbon,” he says. “And manufacturers should be required to publish Environmental Product Declarations (EPDs) for everything they make.”
Mattamy Homes had a solid 2024 fiscal year, with ENERGY STAR and NetZeroReady home closures increasing by almost 65 percent, and EcoSelect-FGBC certifications tripling from fiscal 2023. Image: Mattamy
Squires doesn’t see regulation as the main hurdle—he sees culture and mindset as the real drivers of transformation. “The change will be brought about by accountability,” he says. “Our customers are starting to demand more from us, and we’re demanding more from our suppliers. That’s what will move the needle.” Another huge challenge: apathy.
“We know how to build more resilient homes with lower operational costs, but we still face resistance when it comes to adoption,” Squires says. “Let’s push manufacturers to make high-performance products the default. Lower SKU counts. Higher profits. Better results for the planet.”
Alan Naditz is managing editor of Green Builder Magazine. He has covered numerous industries in his extensive career, including residential and commercial construction, small and corporate business, real estate and sustainability.
Home Builder Rewrites Rules on Embodied Carbon
From low-carbon concrete to carbon-smart decision making, Mattamy Homes is rewriting the rules of residential construction.
At a time when the building industry is still coming to terms with its carbon footprint, Mattamy Homes is leaning in hard. One of the largest privately owned homebuilders in North America is now focused on a huge elephant in the room: embodied carbon.
Low-carbon concrete, geothermal heat pumps and various structural designs at the mixed-use Carding House have reduced operational carbon emissions by about 29 percent annually. Credit: Mattamy
Embodied carbon is the amount that is emitted during construction, maintenance and tear-down of a building. This includes the carbon emitted from extracting raw materials, processing and manufacturing building materials, transport, construction, maintenance, repair, replacement and, at end of life, taking down a building and disposal of the materials.
Mississauga, Ontario-based Mattamy likes to be an example of how things should be done. “We want our carbon footprint to be as small as possible,” says Philip Squires, Mattamy’s corporate vice president of sustainability and procurement. “All carbon production has an impact on climate change, whether it’s operational or embodied emissions.”
In situations where carbon emissions are already low, solar panels can initially be an environmental negative because of fossil fuel-based production methods. But the panels quickly become carbon neutral after installation. Credit: istock/pk24
Rock Solid Relationships
The first step toward embodied carbon cleanup: Partnering with concrete manufacturers across North America to guarantee that the mixes used on their sites are verified low-carbon blends. That’s a big deal, considering that concrete alone is responsible for more than 8 percent of global CO2 emissions, Squires notes.
“Concrete can be a major contributor to carbon emissions,” he says. “We work diligently to lower the impact concrete can have on our environment.”
A grand example is Carding House, a five-story mixed-use development in Oakville, Ontario that includes 157 condominium units. According to the company, the project represents a significant step forward in reducing operational carbon emissions—in this case, cutting it by as much as 29 percent annually when compared to Ontario Building Code requirements. It achieves this by using a geothermal system and ground source heat pumps for the building’s heating and cooling, “a testament to the development’s commitment to sustainability.”
Carding House also achieved an embodied carbon intensity that is
16 percent less than Mattamy’s historical average embodied carbon. Measures taken to reduce embodied carbon in the project included use of low-carbon concrete, and rebar that was manufactured using electric-arc furnace technology. The upper floors of the development were constructed using a combination of hollow-core slabs, prefinished exterior insulation and finish systems, cold-formed steel walls and cast-in-place concrete.
As part of its partnership, Mattamy uses several brands of low-carbon concrete, including Holcim ECOPact and CEMEX Vertua. Brands are selected based on the housing project’s location. “The building sector accounts for nearly 40 percent of our world’s CO2 emissions,” notes Holcim. “Decarbonizing the built environment is therefore essential for a net-zero future.”
Keeping up to date with the latest products, technology, and training ensures that builders are able to remain relevant in an ever-changing construction world. Credit: Mattamy
Determining True Value
Mattamy is also redefining how decisions about solar energy installations are made. Their decisions are not just based on marketing or incentives, or what Squires calls ROCI, or “Return on Carbon Invested.”
A typical example: In certain Canadian markets where the grid is already clean, adding rooftop solar can sometimes increase a home’s total carbon footprint due to the embodied carbon in the panels themselves. “We use third-party building science professionals to evaluate the embodied and operational carbon impacts of products,” Squires explains. “If the ROCI doesn’t meet our threshold, we look for better options.”
This analytical approach reflects a deeper commitment to carbon literacy within the company. But translating that into a value proposition for consumers—especially in a market fixated on price-per-square-foot—is no small feat.
The breakthrough moment came when the company started looking beyond the upfront price to the total cost of home ownership.
One-fifth of the overall carbon generated during a building's life cycle comes at the beginning stage during creation and transportation of products, and the subsequent construction. Credit: Mattamy
“The cost of home ownership includes taxes, insurance, and utilities,” Squires says. “If we can reduce utility costs through better performance, the total cost of the home might not change—even if it’s a higher-performance house.”
Still, challenges remain. Low-carbon materials often come at a premium price. Or worse, they aren’t available in every market. “Why are we still being charged more for green products that would clearly make the industry better?” Squires asks. “If we can provide homes with lower operational costs and greater resilience at the same sale price, what are we waiting for?”
Low-carbon concrete blends, such as ECOPact by Holcim, help offset the traditional product that is responsible for more than 8 percent of global CO2 emissions.
Cooperation and Communication are Key
When it comes to progress in embodied carbon reduction across the industry, Squires points to innovations in concrete and drywall, where lower-carbon versions are already in use. But he also notes that too often, greener versions of standard materials are treated as premium options. “Anything that’s available in a lower-carbon version should be the standard for everyone,” he notes. “That’s how we get economies of scale.”
Cooperation among builders and other industry supporters is key. In June 2024, the Climate Smart Buildings Alliance (CSBA), a joint effort between Mattamy, construction services company EllisDon and RBC (a.k.a., the Royal Bank of Canada) launched the Responsible Buildings Pact.
This is a voluntary agreement for any developers, consultants, contractors, and supporters interested in working together to reduce the embodied carbon of buildings they create. Participants agree to remain educated on lower-carbon materials, establish an internal process to consistently evaluate whether lower carbon materials or design strategies can be used, and report publicly on the results of evaluations and the use of lower carbon materials.
As one of North America's largest privately owned homebuilders in North America, Mattamy Homes focuses on creating homes that reflect how people live and breathe, emphasize architecture, and promote sustainability and wellness. Credit: Sagiper North America
Twenty-three signatories and supporters were on board with the pact when it was announced. One year later, the number has grown to 40, CSBA reports.
“Most builders have their own sustainability targets, but for any of us to succeed, we need everyone to be moving in the same direction,” notes Brad Carr, CEO of Mattamy Homes Canada. “We can only get more low carbon materials and technologies in the market if others in the industry are also sending the same signal to suppliers. The Pact will help us coordinate and collaborate towards shared climate objectives.”
So can a business move beyond incremental gains to a true “moonshot” moment? For Squires, it starts with mandatory reporting. “There needs to be a standard way to track and report embodied carbon,” he says. “And manufacturers should be required to publish Environmental Product Declarations (EPDs) for everything they make.”
Mattamy Homes had a solid 2024 fiscal year, with ENERGY STAR and NetZeroReady home closures increasing by almost 65 percent, and EcoSelect-FGBC certifications tripling from fiscal 2023. Image: Mattamy
Squires doesn’t see regulation as the main hurdle—he sees culture and mindset as the real drivers of transformation. “The change will be brought about by accountability,” he says. “Our customers are starting to demand more from us, and we’re demanding more from our suppliers. That’s what will move the needle.”
Another huge challenge: apathy.
“We know how to build more resilient homes with lower operational costs, but we still face resistance when it comes to adoption,” Squires says. “Let’s push manufacturers to make high-performance products the default. Lower SKU counts. Higher profits. Better results for the planet.”
By Alan Naditz
Alan Naditz is managing editor of Green Builder Magazine. He has covered numerous industries in his extensive career, including residential and commercial construction, small and corporate business, real estate and sustainability.Also Read