Architecture 2030 states that the built environment generates 40 percent of global greenhouse gas emissions annually. Building operations, which includes lighting, heating, and cooling, are responsible for 27 percent of those emissions. Building materials and the construction process – which is often called embodied carbon – are responsible for another 13 percent every year.
When looking at landscapes, the share of embodied carbon as a percentage of total emissions changes. For landscape architects, approximately 75 percent of project emissions come from materials.
But one major benefit of landscapes is they can store carbon through trees, plants, and soils while also reducing climate impacts and improving ecological and human health. Landscapes are a key part of the broader effort to reduce emissions and drawdown more carbon.
“We know the built environment is more than just buildings. We need to start thinking about whole projects or whole sites instead of whole buildings when we discuss climate solutions,” said ASLA CEO Torey Carter-Conneen, at Sustainability Week US, organized by Economist Impact in Washington, D.C.
In a discussion moderated by Carter-Conneen, government, non-profit, and corporate built environment leaders discussed the collective actions driving down emissions from both buildings and landscapes.
Electrification of the millions of buildings in the U.S. and worldwide is seen as an important next step to reduce operational emissions.
Peter Templeton, CEO of the U.S. Green Building Council, noted that an increasing number of new buildings are now “electricity ready,” meaning they weren’t built with oil or gas-powered furnaces or boilers.
These buildings simply need to be connected to a “green grid” powered by renewable sources, like wind and solar, instead of fossil fuels, like coal, oil, or natural gas. Utilities need to accelerate the shift to renewable energy so the power used in all-electric buildings is clean.
More financing is needed to make the transition to electric buildings and renewable energy happen, said Joe Rozza, chief sustainability officer at Ryan Companies.
To receive private financing from the markets, companies need to show a return on investment with their electrification and energy efficiency improvements. This calculus is complicated by evolving building performance standards in different U.S. state and city jurisdictions.
For companies developing or managing millions of square feet of real estate, one common strategy amid the regulatory flux has been to make incremental improvements to decarbonize each year while also reducing climate and water risks.
But Gina Bocra, chief sustainability officer, New York City Department of Buildings, argued the time of incremental change will soon be over. New government mandates will significantly speed up the decarbonization process.
New York City government is now implementing a “robust new building energy code” — Local Law 97 — a “landmark building performance standard that mandates carbon reductions in our 50,000 largest buildings.” In addition, the city’s recent building electrification law will “restrict fossil fuel combustion in new buildings” starting in 2024. Bocra said these new regulations will help the city become carbon neutral by 2050.
“The city is now obligating building owners to make reductions in their climate impacts each year. 20-30 percent of building energy is wasted every day. Fixing these problems will create jobs, economic opportunities, and improve public health,” she said.
And it is not just NYC taking action: 40 other cities are creating similar regulations.
As cities and developers tackle operational emissions, it’s important not to forget about embodied carbon, Carter-Conneen said.
“We know that concrete and steel are major sources of embodied carbon in buildings. That is also true in landscape architecture projects,” he said.
“We can scale up low-carbon steel and cement and the use of timber and integrated solar panels. We can also reduce the amount of cement required in our buildings,” Bocra said, explaining a few solutions New York City is exploring.
Susan Uthayakumar, chief energy and sustainability officer at Prologis, a logistics company that manages 1.2 billion square feet of real estate worldwide, sees opportunities to reduce embodied carbon through economies of scale.
$40 billion in concrete is procured each year from giant companies like Cemex. Through advocacy and aggregating demand, companies can “accelerate the transition to low-carbon concrete.”
Templeton also urged the audience to think about “whole life carbon” — to look at it holistically as a resource. He noted that environmental product declarations (EPDs) are key to measuring the life cycle of embodied carbon in materials — from extraction to creation and reuse. The idea is to achieve a circular approach, leveraging the carbon in materials again and again.
Architects, landscape architects, developers — and the governments shaping their projects — are also now looking at how to maximize the many co-benefits of decarbonization.
Templeton noted that the Sustainable Sites Initiative (SITES) — which is a result of a partnership between ASLA, the U.S. Botanic Garden, and the Lady Bird Johnson Wildflower Center at the University of Texas at Austin — offered an early framework for decarbonization while also increasing the environmental and human health co-benefits of landscapes.
SITES showed developers the value in “investing in green infrastructure, public rights of way, building sites — they are all part of the solution,” he said.
Rozza also sees the landscape around buildings as critical to realizing co-benefits. “With green infrastructure and focusing on biodiversity and water, we can extend the value of the experience of the property.” There is a return on investment from creating “immersive landscape experiences for tenants.”
Since 2019, New York City has required new buildings and significantly renovated ones to add green roofs or rooftop solar. Green roofs reduce stormwater runoff. But what many don’t realize is that stormwater management has a carbon connection. “It takes a lot of energy to move and treat stormwater in waste water treatment plants.” So less water treated means less energy used and lower emissions.
And Uthayakumar said many of her company’s facilities are extending renewable energy co-benefits. Rooftop solar on their logistics centers is now powering their electric vehicles, which means cleaner air for surrounding communities. And their rooftop solar is also powering neighboring homes. “This just makes sense from a business perspective.”
“When we talk about decarbonization, we also need to talk about equity. As we know, not everyone has access to the benefits that come with green buildings and healthy landscapes that store carbon,” Carter-Conneen said.
To address this, the “Biden-Harris administration has focused on increasing investment in underserved communities through the Infrastructure Investment and Jobs Act, Inflation Reduction Act, and implementation of the Justice 40 initiative.”
“How can we make sure more communities reap the rewards of decarbonization?” he asked.
For Bocra, those federal funds have helped implement NYC’s decarbonization plans in a more equitable way.
“We have 1.1 million buildings in the city. We need to decarbonize 130 buildings every week until 2050. We have affordable housing and building owners in disadvantaged communities. We seek to lift up these building owners through training, direct assistance, and financing.”
And looking at the global scale, Templeton said “we need to bring green buildings to all. Green building councils are active in 180 countries. With significant investment, we can help developing countries leapfrog developed countries, learn new skills, and create new jobs.”