Buildings and construction are responsible for almost 40 % of global carbon dioxide emissions associated with energy use. These emissions fall into two main categories: operational emissions (approximately 70 %) and built-in emissions (remaining 30 %)To meet the goals of the Paris Agreement, which seeks to keep global warming below 1.5°C, the construction sector must halve its emissions by 2030 and reach net zero emissions by 2050.

The main priorities include:

• An overview with Lifecycle Carbon Assessments: Document explains that until recently, decarbonizing the building industry focused mainly on operational energy. However, as operations become cleaner, Embedded carbon, which comes from the production of materials such as concrete and steel, transportation and demolition, is becoming increasingly importantMaterials such as concrete and steel alone account for almost a quarter of global emissions. Therefore, it is recommended to use Whole Life Carbon (WLC) frameworks, such as the World Business Council for Sustainable Development (WBCSD) framework, which helps track emissions from the entire life cycle of a building. These assessments provide a better overview of carbon hotspots, which are often structural systems and interior finishesThe European Union (EU) has already included a requirement for life-cycle carbon footprint reporting for all new buildings in its Energy Performance of Buildings Directive, and other jurisdictions are expected to follow suit.
• Cleaning high-impact materials: The document highlights the need to address the largest sources of emissions in the construction industry: cement, steel and aluminum, which together account for approximately 30 % of the sector’s emissions. However, there are new technologies and production methods that are significantly reducing their carbon footprint. These include:
  • Cement: Alternatives to traditional Portland cement, which is carbon intensive due to limestone calcination, such as geopolymer cement made from industrial by-products (fly ash, slag), which completely bypasses this process. Another option is carbon-hardened concrete, which absorbs CO2 during hardening and can reduce emissions by up to 80 %.
  • Steel: The transition from coal-fired blast furnaces to electric arc furnaces, which, when powered by renewable energy sources, enable steel production with lower emissions. Also promising is direct hydrogen-based reduction, which replaces carbon with hydrogen in the reduction process. Both approaches also facilitate scrap steel recycling, thus reducing energy consumption. Recycling steel uses approximately 75 % less energy than producing it from raw ore.
  • Aluminum: Aluminum production is energy intensive, so it is important to switch to low-carbon smelting powered by renewable resources and expand closed-loop recycling systemsIn addition to new materials, it is important reduce the total amount of materials used through smarter, lighter designs and modular building systems. Also important are reuse strategies, such as salvaging wood, bricks or steel from demolished buildings, thereby avoiding emissions from mining and processing. The US Department of Energy (DOE) also highlights in its plan to decarbonize the construction sector circular economy as a key strategy and calls for the expansion of policies and incentives to promote reused and recycled materials.
• Renovation and electrification: Renovation of existing buildings offers a direct and scalable path to reducing emissions. Improvements such as better insulation, high-performance windows, and more efficient HVAC systems, can reduce operating energy consumption by 50–75 %. Electrification, replacing gas systems with electric ones, such as heat pumps, further increases these savings, especially if the electric grid is powered by clean energy sources. San Diego is implementing these strategies to reduce natural gas use in buildings by 90% by 2035 and is piloting large-scale microgrids powered by solar energy and backed up by batteries. Nevertheless Scaling recovery is not easy due to high upfront costs, uneven incentive programs, and disparities in access, especially in low-income communities. That's why DOE launched the Affordable Home Energy Shot initiative to cut retrofit costs in half and expand access to upgrades. It's important to note that approximately 80 % buildings that will exist in 2050 are already standing today, which means that the focus on reducing emissions must also shift to the modernization of existing buildings.
• Policy, partnerships and long-term strategy: Achieving zero emissions in buildings depends not only on better materials or smarter technologies, but also on the right policy frameworks, financial incentives and long-term coordination between sectors. Building Performance Standards (BPS), which require existing buildings to meet specific energy or emissions targets over time, are among the most effective tools that governments use. More than 30 U.S. cities and states have already adopted BPS policies, including San Diego, where the local standard sets a goal of zero operational emissions by 2035. At the corporate level, initiatives such as Science-Based Targets initiative (SBTi), which help companies align their climate commitments with actual emissions trajectories. Politics also plays a key role in shaping the decarbonization economyCurrent fossil fuel subsidies distort the market in favor of carbon-intensive options, while low-carbon technologies often face financial barriers. Redirecting subsidies and introducing carbon pricing can help level the playing field. According to the International Energy Agency (IEA), around 70% of the % of emissions reductions needed by 2050 depend on stronger price signals and financial incentives. To address this challenge, different sectors must work together through public-private partnershipsInitiatives such as Advancing Net Zero program of the World Green Building Council brings together more than 100 national green building councils to exchange tools, data and best practices. There is also a growing effort to harmonization of standards, such as the UK's Net Zero Carbon Buildings Standard.
• Innovation + Workforce = Real Impact: The document highlights the importance innovations in areas such as advanced energy storage systems, direct air capture (DAC) technologies and smart grids. It also emphasizes that even the most advanced technologies cannot be scaled up without a skilled workforce. San Diego Gas & Electric (SDG&E) actively partners with local colleges to train workers in solar installation, building electrification and energy efficiency, while also focusing on engaging underrepresented communities. It is important to invest in research and development because Almost half of the emissions reductions needed by 2050 depend on technologies that are still in the early stages of development today.

Finally, the document states that the path to zero emissions in buildings is not about one solution, but about systemic approach, which combines smarter materials, efficient design, clean energy and inclusive policies. Although there are obstacles, The plan is in place and with bold and coordinated action across the construction value chain, the sector can become a significant part of the solution to the climate crisis.The document also links to other sources of information related to the decarbonization of the built environment. Spring

Document published on azobuild.com

Glossary of key terms

• Net-zero emissions: A state where the total greenhouse gas emissions produced by a particular activity or sector are offset by their removal from the atmosphere, thereby achieving net zero emissions.
• Operational carbon: Greenhouse gas emissions that occur during normal building operations, such as energy consumption for heating, cooling, lighting, and operating appliances.
• Embodied carbon: Total greenhouse gas emissions associated with the production of building materials, their transportation, the construction of the building and its final disposal (including demolition and recycling).
• Whole Life Carbon Framework assessment: A methodology for assessing all carbon emissions associated with a building throughout its life cycle, from raw material extraction to the end of its useful life.
• Retrofitting: Modernization of an existing building to improve its energy efficiency and reduce energy consumption and greenhouse gas emissions.
• Electrification: Replacing fossil fuel-based systems (such as gas boilers) with electric alternatives (such as heat pumps).
• Building Performance Standards (BPS): Policy measures that set mandatory energy efficiency or emissions targets for existing buildings, with the aim of gradually reducing their environmental impact.
• Geopolymer cement: An alternative type of cement that is made from industrial by-products (such as fly ash or slag) and produces significantly fewer CO₂ emissions compared to traditional Portland cement.
• Carbon-cured concrete: An innovative type of concrete that absorbs carbon dioxide from the atmosphere during the hardening process, contributing to carbon sequestration.
• Circular economy (Circularity): An economic system that aims to minimize waste and maximize resource use by keeping products and materials in circulation for as long as possible. In construction, this includes, for example, the reuse and recycling of building materials.