Where do global emissions come from? Planes, power stations, cars and big industrial plants are easy to point to as the world’s dominant sources of greenhouse gases. However, one of the biggest contributing factors to carbon emissions is all around us: buildings and infrastructure.
Construction, manufacturing materials and the electricity demand of daily operations in what’s known as the built environment, together account for as much as 50% of all global CO2 emissions - 39% is just buildings, about 50% for buildings and infrastructure (roads, sidewalks, parking lots, etc.).
This places a huge responsibility on the building sector to address these emissions. It’s also a pressing need for countries signed up to the 2015 Paris Agreement aiming to reduce all emission to zero by 2050, in order to keep global temperature well below 2°C and avoid dangerous climate change.
It’s a daunting task for the industry, but Edward Mazria, Founder and CEO of Architecture 2030, an environmental NGO focused on the built environment, believes the game plan for cutting emissions is already on the table.
Titled ZERO Code, the guidelines are designed for adoption by cities and jurisdictions as a set of regulations for building efficiency and incorporating renewable energy.
But how do you construct a zero carbon building?
Aiming for zero carbon
By Edward Mazria’s estimation the building sector can cut emissions by 50% by 2030. The key: a combination of increased building efficiency, growing adoption of renewable power and reducing the carbon footprint of the construction materials. Good news: the sector is already moving in the right direction.
“Emissions in the U.S. building sector are down almost 19% and the reason is that building energy consumption has been flat since 2005,” says Edward Mazria. “Globally, emissions peaked in 2015 and declined slightly in 2016 and 2017. Building efficiency is getting better every year, the good news is we’re making progress, but we’re not yet moving fast enough.”
The real challenge is both getting to a 50% emissions reduction in 2030 and what’s known as zero emissions (or carbon neutral) by the middle of the century, in line with the commitments of the Paris Agreement.
While steps, such as replacing fossil fuels with renewable and modern insolation, can drastically cut the emissions associated with buildings, there are of course emissions that remains. The manufacturing of building materials and machinery needed in construction, for example.
However, it is possible to address these emissions though steps like using cross laminated timber sourced from sustainably managed forests for building structures, to sequestering carbon dioxide from the atmosphere in materials or capturing and storing emissions from material production.
Cutting embodied carbon
One of the toughest barriers on the road to zero carbon is tackling what’s known as embodied carbon – the emissions associated with the extraction or manufacturing, and transport of building materials and construction.
However, Mazria is hopeful about how quickly the building sector can reduce its impact. According to the IEA (International Energy Agency), of all global emissions, about 20% come from just three materials: concrete, steel and aluminum.
“Looking at billions of buildings, products, and construction choices, it’s easy to get overwhelmed,” explains Edward Mazria. “However, when we understand that just three materials are responsible for 21.2% of total global emissions and almost half of industrial sector emissions, that gives us hope this sector can be addressed very quickly."
Technology is also helping bring material production closer to carbon neutral, with carbon capture and storage offering a potential way to reduce CO2 from concrete manufacturing entering the atmosphere.
“If we can address the embodied carbon of these materials, then buildings and urban infrastructure will begin to decarbonize,” says Mazria. ”At that point, it will be much easier to reduce emissions in the entire industrial sector.”
The zero carbon cities roadmap
Edward Mazria believes the roadmap for cutting all building sector emissions to 50% by 2030 and zero by 2050 is already on the table and industry professionals are alert to the need for action. By putting in place building codes that require new buildings to be carbon neutral and then incrementally renovating existing buildings, and reducing the embodied carbon of construction materials, entire cities can become zero carbon.
The path to decarbonizing the built environment – from material production through construction to everyday building management – is clear, now it’s just a matter of increasing the pace of change.
Photo credits: Arnaud Bouissou-MEEDDM / Pascal Artur / Saint-Gobain / Valode & Pistre Architectes / Franck Dunouau / Architecture 2030 / DR