Sustainable buildings start with sustainable materials

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Sara Neff

Buildings are more than the sum of their parts. However, as the construction sector is responsible for approximately 40% of global CO2 emissions, these individual parts can play a vital role in limiting the global temperature increase to 1.5°C in order to protect our planet from worst impacts of climate change.

Multi-family builders and developers can reduce the carbon footprint of a new building in particular by choosing more environmentally friendly building materials. Some options are new and others are proven, but all can help reduce embodied carbon, which is the carbon released during the manufacture, production and transport of building materials. By constructing a project with low carbon steel, green concrete or solid wood, for example, developers are creating a more sustainable building and setting an example of environmental stewardship.

Reduced carbon steel

Steel is the backbone of our modern cities. From the innovative steel frames that supported the first skyscrapers to the ultra-tall structures rising around the world today, the dense urban environments that many of us call home would not be possible without steel. .

Unfortunately, steel happens to be a major contributor to global greenhouse gas emissions. The iron and steel manufacturing process accounts for around 7% of global CO2 emissions, according to the International Energy Agency. And since buildings and infrastructure together consume half of the world’s annual steel production, any efficiency in the use of steel that the commercial real estate sector can implement will go a long way towards mitigating the contribution from steel to climate change.

Decarbonizing the steel sector will require several strategies, including electrification of manufacturing facilities, better scrap metal recycling, carbon capture and storage, and better access to renewable energy at competitive prices for steel producers. . These efforts could impact steel prices in the near term, although the cost will come down over time as more low-carbon steel becomes available. That’s why it’s important for commercial real estate companies to partner with organizations such as ResponsibleSteel and the Climate Group’s SteelZero initiative, to reduce emissions throughout the supply chain by driving market demand. for net zero carbon steel.

Lendlease has committed to using low carbon steel on a new transformative project. Claremont Hall is a mixed-use academic and residential building located on the historic campus of Union Theological Seminary in the Morningside Heights neighborhood of New York City. When complete, the building, which is aiming for LEED Gold certification, will provide approximately 165 condominiums offering a mix of one-, two-, three- and four-bedroom residences, as well as 54,000 square feet of classrooms, academic and faculty offices. . designated apartments. Claremont Hall’s environmental successes go beyond LEED: more than a quarter of steel-related emissions at Claremont Hall have been eliminated on this project through the use of low-carbon steel.

green concrete

Concrete is another ubiquitous yet carbon-intensive building material. Producing Portland cement, the key ingredient in concrete, requires intense heat and results in significant releases of carbon dioxide, which is why the concrete industry is responsible for approximately 8% of anthropogenic carbon emissions.

The easiest approach to making concrete more durable is to reduce the amount of cement in the concrete mix. For decades, manufacturers have been hard at work finding sustainable, low-carbon alternatives to include in their concrete mixes, and we’re only just beginning to see real solutions that can work at scale.

Green concrete is currently being used at The Reed, a 440-residence tower under construction in Chicago’s South Loop neighborhood. This is the first application of a proprietary concrete mix from Chicago-based McHugh Concrete. Created in partnership with Oremus Material, this concrete mix replaces up to 60% of traditional Portland cement with ash and slag, a glassy waste product formed in blast furnaces during the steel production process. Switching to green concrete at The Reed will reduce the building’s overall embodied carbon emissions by more than 10%.

Low-carbon concrete has proven to be stronger and more durable than regular concrete. However, it can also increase construction costs by 1-2% and impact project schedules. As with low carbon steel, the high costs of this material will come down as it becomes more common in new construction.

A side benefit of this particular concrete mix is ​​a smoother finish compared to traditional concrete. This will be important at The Reed, as the Perkins and Will-designed skyscraper will feature an industrial-chic aesthetic incorporating exposed concrete ceilings and columns for loft-like interiors.

Solid wood

Just as fashion trends can come back in style, so can construction techniques. The retro-cool material that many commercial real estate players are turning to to reduce their carbon footprint is perhaps the oldest building material there is: wood.

Wood is renewable, strong, easy to work with, provides biophilic benefits, and weighs less than concrete and steel, reducing both the size of foundations needed and the impact of transportation. Even better, wood sequesters carbon, further reducing the embodied carbon footprint of log buildings.

While a mass timber building typically has a higher initial cost than a traditional concrete structure, mass timber buildings often experience a decrease in total life cycle cost due to a longer estimated lifespan. and because the wood has a salvage value if the building is demolished. .

Lendlease has a long experience in solid wood construction. For example, First Community Housing recently engaged SERA Architects and Lendlease to design and build a transit-focused affordable housing project near San Jose’s Diridon Station. The 365-unit McEvoy Apartments residential development has an ambitious goal of achieving LEED Platinum. One of the main ways the two-building project will achieve this will be through the use of a solid timber frame in a traditional side system.

McEvoy Apartments will also implement new pre-engineered technologies during construction – an easy-to-execute technique with cross-laminated timber and other engineered wood products. Building modules in the factory and transporting them to the job site reduces the need for truck deliveries, lowers costs and speeds time to market.

McEvoy Apartments’ efforts complement this work with solid timber which Lendlease has already successfully delivered, including five solid timber hotels.

Look forward

Reversing the course of climate change will not be easy. However, innovations in building technology can help mitigate the effects of this crisis and any additional costs should be ignored as more developers choose to implement them in their projects. Time is a critical factor in dealing with this global threat, which is why multifamily developers must act now, take the lead, and implement the use of sustainable materials in their projects.

Sara Neff is Head of Sustainability at Lendlease.

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