This time last year, we were on track to construct the most eco-friendly office campus LinkedIn had ever built– three brand-new buildings (almost 765,000 additional SF) in Mountain View, CA. All the buildings would be LEED Platinum and WELL certified, and constructed on top of low-carbon concrete foundations, (see our recent HQ build). City approvals were granted, construction was underway.
Then, we realized we still weren’t doing enough to help protect the environment.
Microsoft, our parent company, announced it would become carbon negative by 2030 and it would remove its historic carbon footprint by 2050. We decided to match their ambitious goals.
(Before I get much further, I want to acknowledge something very important. Typically, when we look to expand our office footprint, our first choice is to use existing buildings– the thinking has long been that most eco-friendly building is one that was designed with the environment in mind and that already exists. But in this case, we decided that building a new building is actually the best thing we can do, for our impact on the environment, for the experience we want to give our employees and for the story we want to tell, with the hope of inspiring others to follow suit… now, back to how we plan to go about doing it.)
Though it was very eco-friendly, our planned buildings would still use traditional materials like steel, concrete, glass and insulation that have a high carbon footprint associated with manufacturing them (known as embodied carbon).
Jennifer Mitchell, our Senior Manager of Design and Build at LinkedIn and in-house concrete expert asked, “What if we constructed the building from a combination of low embodied-carbon materials and carbon-sequestering concrete?” She imagined taking it a step further, “If we leveraged new technologies to increase the amount of carbon sequestering concrete in the building, we could sequester the building’s entire embodied carbon footprint!”
We loved the idea and challenged our zero carbon consultants Adrian Smith + Gordon Gill Architecture to help our team transform our architectural plans into our first-ever carbon-negative building.
While working from home, our team reviewed the edgy carbon-negative building proposal. Our conclusion? We became more committed than ever.
Peggy Brannigan, our Director of Global Environmental Sustainability at LinkedIn said, “It’s now or never. If we humans want to avoid an irreversible cycle of climate change and devastation, we have to aggressively start to remove the 2 trillion metric tons of carbon we’ve already pumped into the atmosphere.” She added, “We’ve got to reduce new emissions and sequester carbon – a carbon-negative building is a big step in the right direction.”
So, we got to work planning our first ever carbon-negative campus.
We understood immediately it would need to be a huge team effort. We pitched our partners* and they are fully on board, contributing their expertise and environmental commitment each step of the way.
Our approach is just one solution. We hope to inspire you and your partners to find additional ways to construct carbon-negative buildings.
Here’s our plan:
Step One – Use Materials with Low Embodied Carbon
Step Two – Sequester and Store Carbon in the Concrete
Step Three – Procure Carbon-Negative or Neutral Finishes
Step One: Start with Low Embodied-Carbon Materials
Those of us in the construction business have more responsibility than others to slow climate change. Building operations and construction globally are responsible for 39% of all carbon emissions, and concrete (approx. 19,000 tons are produced every minute) is typically the biggest source of carbon emissions in most commercial construction projects.
Why does the traditional concrete process emit so much carbon? Two reasons. 1) Superheating limestone in a kiln and grinding it to bits to make cement (the key ingredient which gives concrete its strength) uses tremendous amounts of energy and 2) it also releases CO2 from limestone (formed from the remains of the marine life millions of years ago).
In our building plan, most of our emissions savings will come from sourcing materials with low embodied carbon – choosing concrete, steel, aluminum and glass that have a lighter footprint associated with manufacturing. Innovative concrete mixes in particular, are the real game-changers. If you built our planned 295,000 SF office building the traditional way, the emissions from manufacturing the materials and from the construction process itself, would generate over 11,000 tons of embodied carbon. Instead, our choice of construction materials means we are sequestering more than we are emitting.
Step 2: Use Carbon-Sequestering Concrete
To take the project from zero emissions into carbon-negative territory, we plan to use emerging concrete technologies that promise to lock up CO2 in the built environment. For example, the company, Blue Planet, has developed a system that captures carbon dioxide exhausted from large emitters, like power stations and cement plants, and combines it with calcium extracted from waste concrete to form calcium carbonate — otherwise known as limestone. The company is effectively recreating and speeding up the mineralization process that made natural limestone a carbon sink in the first place. That synthetic limestone, as well as Upcycled Concrete Aggregate (a byproduct of extracting calcium from concrete), substitutes for the sand and gravel in concrete, which would otherwise be mined from quarries and blasted into bits.
“The process of concrete sequestration allows you to build a carbon-negative structure, you then have an embodied-carbon credit to use toward interiors,” said Jennifer Mitchell, who initiated the carbon-sequestering concrete building challenge. “I think a carbon-negative building is actually possible with promising sustainable concrete solutions in the market and an industry that’s adapting to climate change.”
“There are game-changing technologies in the market now that allow us to have conversations about low-carbon design that we simply could not have had several years ago,” said AS+GG’s Director of Sustainability, Dr. Chris Drew.
At LinkedIn, we now aim to start every new building with low embodied-carbon materials and carbon-sequestering concrete.
Step Three- Procure Carbon-Negative or Neutral Finishes
With the carbon “credit” we earn from the carbon-capturing concrete, we will carefully track the embodied carbon for the interior of the building. This puts us on the path to a carbon-negative building.
There’s lots of industry talk – and debate – about Cross Laminated Timber, too. CLT is a fairly new framing system for buildings – an alternative to steel or concrete framing. We’ve definitely looked into it, but we’re waiting on how the scientific community interprets its environmental impact. Microsoft is investing in it, and it looks beautiful.
Some finishes are unavoidably carbon intensive. Others can be carbon neutral. For those carbon-intensive products, like metals, plastics, aluminum, the American Institute of Architects recommends you review Environmental Product Declarations and use lower carbon alternatives.
Some current products that have a light carbon footprint include recycled fiber carpet tiles, natural insulation products, and bio-based materials from rapidly renewable resources like engineered bamboo. That said… the more we ask for them, the more products we will see come to market… so, demand carbon negative options on your next project from your team and your suppliers.
With all the best new technologies for carbon reduction coming to fruition, sometimes the best option is still to just avoid using new materials in the first place and remind yourself – reduce, reuse, recycle. For example, I created a program I called the Woodchuck Challenge, in which I asked my team to select, specify, procure and install ONLY waste stream wood products–those that are reclaimed, recycled, or repurposed. This is much more challenging to successfully pull off than it sounds, but it is certainly a challenge that could have a very positively reductive and potentially inspiring impact if more people decide to take it on. For our part, we now plan to formalize this 2020 global challenge and make it part of our design requirements for all projects going forward.
It’s Past Time to Make our Industry Carbon Negative – Join Us!
To get to carbon neutral by 2030 we also must continuously reduce our energy-use intensity on campus — our operational carbon footprint. We do this in many ways, including installing meters and Demand Response software systems in our offices to fine-tune our energy use. We also buy or generate electricity from renewable sources.
I feel good about our carbon-negative building plans, but LinkedIn is just one company and this urgent climate crisis demands a global response. Scientists say we have less than 10 years to avoid triggering an irreversible cycle of extreme climate devastation – a scenario in which the systems that support life on our planet would start to fall apart.
I think our civilization has a fighting chance because some companies are trying to renovate old buildings rather than construct new, and more companies are pursuing and creating carbon-negative or carbon-neutral construction options.
Those of us in the building business have an opportunity to make an outsize impact. At LinkedIn, we’ve created one roadmap to reverse our climate footprint. What’s your plan?
by Brett Hautop
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