We know that in order to avoid the most significant and devasting impacts of global warming, we must limit the temperature increase to no more than 1.5 degrees Celsius above pre-industrial temperatures. According to the Intergovernmental Panel on Climate Change’s sixth annual report, for a 50% chance that we stay under that the 1.5C threshold, we can only release 460 Gigatons of CO2 (GtCO2) of additional CO2 into our atmosphere. This is oftentimes referred to as our ‘carbon budget’. This budget could be depleted in as little as 11 years if we continue at our current annual CO2 emissions rate. Think about what that means – no more GHG emissions could be emitted across the entire planet after 2033!
The building and construction segment is responsible for nearly 40% of all annual CO2 emissions; 10% coming from emissions related to manufacturing of building materials used in new construction and 27% coming from the operation of existing buildings. We must drastically reduce the amount of carbon and other greenhouse gases (GHGs) we emit into the atmosphere every year. This means we must change the way we construct and operate our buildings, adopting the highest possible energy codes, use less fossil fuels to produce building materials, and reduce emissions on jobsites. And we must start now.
Creating a Culture of Decarbonization
I attended the Advancing Construction Decarbonization
conference organized by US Green Building Council, held in Chicago, IL, and what I learned blew me away. I was thrilled to see a passion and determination to drive change in the entire construction industry to tackle climate change.
Construction companies like Pepper, DPR, and Ryan came together with architects and manufacturers to share their sustainability strategies - and they are ready to move fast. They are highly motivated to educate their employees, especially those with ‘boots on the ground’. These large General Contractor (GC) companies are actively building cultures of sustainability within their teams and across their sub-contractors, because as the insightful saying goes, “culture eats strategy for breakfast”. I loved seeing the dedication and passion for reducing GHG emissions of the construction job site. They understand that reducing carbon and other GHG emissions means a safer, healthier work environment for their employees. Most of these companies have already implemented changes to divert >95% of construction waste away from landfills. They’ve got electric work vehicles on order, eagerly awaiting for the market to catch up with the demand. Ryan and Pepper are incorporating carbon emissions into their bid documents and, soon, will use for selection of trades and sub-contractors.
Making the “Accountability” Commitment
I was impressed to learn that there’s a Contractors Commitment
initiative created by The Sustainable Construction Leaders and facilitated by BuildingGreen. Contractors realize they are in a position of influence on product and material selection, how a project gets built, how construction waste is managed, and the impact of construction sites on the surrounding landscape. This affords them the opportunity and responsibility to drive more sustainable construction practices including reduction of all GHG emissions. The Contractor’s Commitment provides a framework to identify best practices and set a sustainability benchmark for the construction industry. Currently, there are 19 signatories who, by signing on, have agreed to apply the program guidelines to at least 30% of their projects and to report annually to the BuildingGreen website. It’s a huge move that will surely drive the change we need in the construction industry up and down the value chain. This is a great place to start and I would love to see this initiative more towards quantified alignment with a 1.5C pathway. In other words, how can the guidelines be further developed to ensure resulting GHG emissions reductions will align with our 2050 goal of zero emissions?
Construction companies are thinking about whole building life cycle assessment including carbon emissions from building materials, the construction phase, and the building operation phase. It’s encouraging to see a shift in thinking to ‘whole life carbon’ where consideration is given to embodied carbon from materials and the construction phase, operational carbon during the building’s use, and emissions associated with the end of life of the building. This type of decision making will maximize energy efficiency, resiliency and durability, and minimize the GHG emissions during the design and construction phase.
Reducing GHG emissions down to zero is a collective challenge and requires accountability at all levels of the value chain. GCs like Skanska and Chandos have set aggressive net zero targets that even include their "customer's carbon". In their view, what happens on the build site and in the delivered building is their responsibility. For example, Chandos has committed to every building they build being net zero embodied carbon by 2040 “whether their customers ask for it or not”. Imagine if we see more construction companies taking this stance, it would be hugely impactful in moving the entire industry in the direction we need to go towards a zero-emissions built environment!
Tackling Emissions in the Construction Phase
There were also many ideas on how to reduce carbon emissions during the construction phase through energy efficiency and electrification. Companies like Mortenson, Clayco and Samet shared learnings from their efforts to optimize their projects with carbon at the forefront. Temporary lighting and heating of the site is a huge place to make positive gains on carbon reduction. In the case of net-zero buildings – and this is kind of mind-blowing – the temporary lighting and heating could result in more carbon emissions during the construction phase than the entire lifetime operational carbon. What are some of the ways to address this? Take advantage of pre-manufactured wall systems that can be assembled on site quickly to close up the building sooner, utilize LED puck lights and solar powered trailers, use high load battery powered tools and solar powered security cameras.
Advancing Development of Lower Carbon Materials
Some of the most inspiring parts of the conference were hearing presentation by Amanda Kaminsky from Lendlease, Scott Barton Smith from TimberLab, and Christie Gamble from CarbonCure. They each shared details of reduced carbon construction materials: options like circularity in gypsum, cement replacement with ground glass pozzolan, CO2 injection into concrete for cement reduction, and mass timber with strategic forestry practices. These improvements may be small on their own, but they can add up to a meaningful reduction in the total embodied carbon of a building. Given the fact that emissions associated with building materials accounts for 10% of global CO2 emissions, we must adopt these successful innovations into practice and continue to push for continued embodied carbon reductions from manufacturers.
Making Steps In the Right Direction
We all know that climate change can’t be solved with a simple solution. There are a tremendous amount of steps that need to be taken to keep us to 1.5C warming and avoid the most severe environmental impacts as we face this climate crisis. It is clear that builders are motivated to do the work. All the great ideas and actions that were shared at the conference are part of a larger puzzle that will be a complex solution to climate change. Our construction industry will need to adopt a new way of building in a collaborate and creative way where multiple iterations in the pre-construction phase allow the most carbon reduction possible with the most current options. We need to see GHG emissions reduced by 50% or more by 2030 in order to be on track, which will take consistent reductions every year. If we keep sharing what works, celebrate the small wins, push everyone up and down the value chain to do their part, consider carbon cost as carefully as financial cost, we may have a fighting chance to stay within our ‘carbon budget’ before it’s too late.