The threat climate change poses is existential, and buildings are hugely complicit—even more so than the automobile. Buildings consume 40 percent of our energy annually, and they emit nearly half of the CO₂, through greenfield development, cement production, and the burning of fossil fuels. As the earth’s average temperature continues to rise, so do efforts to take steps to fight the effects of climate change. Lately those efforts are zeroing in on how to reduce CO2, in both emissions and embodied carbon.

According the study, Estimation and Minimization of Embodied Carbon of Buildings: A Review. The authors of the study warn that “without major improvements in the energy efficiency of buildings, the current surge in urbanization may lead to a doubling of GHG emissions associated with the building and construction industry in the next 20 years.”

The issue of carbon was front and center at the recent Global Climate Action Summit in San Francisco, which highlighted several initiatives aimed at carbon reduction.

The World Green Building Council launched its new Net Zero Carbon Buildings Commitment, which challenges businesses and organizations globally to eliminate operational carbon emissions from their building portfolios by 2030. The goal is to meet the benchmark of the Paris Agreement to keep global temperature rise to less than 2 degrees Celsius.

“This new Commitment is a huge step forward on the path towards net zero,” said Terri Willis, CEO of the World Green Building Council. “Our vision is ambitious, but we know that the building industry has the knowledge, the technologies and the capability to deliver. The Commitment will help to create unprecedented demand for green design and construction, stimulating the market to deliver net zero carbon buildings at scale.”

A total of 38 entities quickly signed on as founding signatories—12 businesses, 22 cities and four states/regions. Each committed to require that all new buildings within their jurisdictions operate at net zero carbon starting in 2030, and that all existing buildings become net zero carbon by 2050.

California has taken an even bolder step, setting a goal of 100 percent carbon-free power by 2045. Governor Jerry Brown signed an executive order essentially requiring the state to become carbon-negative starting in 2046.

“That’s the most ambitious goal of anywhere in the world,” Brown told Global Climate Action Summit attendees.

Hawaii has taken a similar path, passing legislation that requires the state to be fully carbon-neutral by 2045. Massachusetts, New Jersey, New York and Washington D.C. are considering similar mandates.

In the UK, more than 50 business leaders have called on the government to enact more stringent energy efficiency targets in order to reduce carbon emissions. In a letter to government officials, the group wrote:

The construction and property sector stands ready to deliver on bold targets for energy performance and low carbon solutions. But we urgently need both medium- and long-term policy certainty to drive significant investment and catalyse innovation. This would work hand in hand with the industry’s drive to boost productivity and skills through the new Construction Sector Deal.

In addition to being good environmental policy, the group also feels the tougher restrictions would drive investment and innovation.

Categorizing Carbon Emissions

To reduce or eliminate carbon, the first step is to determine the source. The Greenhouse Gas Protocol Corporate Standard puts GHG emissions (including carbon) into three ‘scopes:’

• Scope 1 emissions are direct emissions from owned or controlled sources; this includes emissions from stationary combustion, mobile sources, refrigeration and AC leakage, fire suppression systems, purchased gases and waste gases.
• Scope 2 emissions are indirect emissions from the generation of purchased electricity, as well as purchased steam or heat.
• Scope 3 emissions are indirect emissions that result from a company’s supply chain and include both upstream and downstream emissions—simply put, anything that’s not Scope 2. This includes purchased goods and services, business travel, employee commuting, waste disposal, use of sold products, transportation and distribution (both upstream and downstream), investments, and leased assets and franchises.

For businesses categorized as low-emitters—office-based organizations, small businesses and public institutions—the United States Environmental Protection Agency created an inventory guide that provides tools for an organization to document its GHG emissions and develop an inventory, collect data and track annual progress towards an emission reduction goal.

To make a real impact on reducing carbon emissions, companies need to focus on Scope 3 emissions; those often make up the bulk of a company’s carbon footprint. And until recently, Scope 3 emissions have been largely overlooked.

Reducing Scope 3 emissions takes the highest level of commitment, as you’re encouraging suppliers, partners and even employees to take actionable steps to reduce their carbon footprint. High performance energy codes, net zero new builds and retrofit projects, and even zero carbon builds will still not prevent us crossing the +2  degrees Celsius mark.  This can only be prevented by including a major focus on lowering the embodied carbon in the building material used.

Nearly 500 companies have joined the Science Based Targets Initiative (SBTi) that helps them take science-based action and work towards science-based targets to reduce GHG emissions.

Companies Taking Action

Kellogg’s has committed to reduce its Scope 3 emissions by 20 percent from 2015-2030, as well as a long-term target of reducing Scope 1 and 2 emissions by 65 percent by 2050. The company is actively engaging with its suppliers, which includes having them respond to a CDP Supply Chain questionnaire on GHG emissions, as well as working with farmers to implement smart agricultural practices that focus on emission reduction and resilience.

Regarding the benefits it has seen so far, Kellogg’s says:

The benefits are huge. We are one of just a few companies that have set holistic Scope 3 targets for all our suppliers. This is so powerful and yields a real leadership dividend. It’s a demonstration of how quickly we have upped our game since 2008 when we first set emission reduction targets. This kind of acceleration leads to recognition from internal and external stakeholders, which is really valuable.

Dell has committed to reducing its Scope 1 and 2 emissions by 40 percent by 2020, using 2010 as its base-year. The company is looking downstream and focusing on reducing the energy consumed by the laptops, desktops, servers and networking equipment it produces; that reduction in energy can serve as a proxy for reducing emissions.

Kingspan has committed to reducing its Scope 1 and 2 emissions by 10 percent by 2025 (using 2017 as its base year), as well as a 10 percent reduction in Scope 3 emissions through its purchased goods and services, business travel, transportation, distribution and end-of-life treatment of sold products.

GHG assessments aren’t just for major corporations, but can—and should—be done for any building project, big or small. Fortunately, there are several online tools available to help calculate a footprint, find ways to cut emissions or save energy. Energy Star has a variety of options, including a list of average CO2 emissions from an average U.S. office building and ways to set goals for reducing energy use.

The International Living Future Institute has introduced ILFI Zero Carbon Certification, the first worldwide Zero Carbon third-party standard. The certification recognizes buildings that offset 100 percent of their energy use through on- or off-site renewable energy. Projects must also account for the total embodied carbon impact through a one-time carbon offset from an approved source.

Google is taking carbon emission estimates to another level with its new Environmental Insights Explorer. Implemented in partnership with the Global Covenant of Mayors for Climate & Energy, this new tool provides a city’s estimate of carbon emissions from transportation and buildings, rooftop solar energy potential and NASA climate forecasts.

There is tremendous momentum building—from countries to businesses to individuals—to take action and implement policies in support of the Paris Agreement, and one of the primary goals is the reduction of carbon.