By: John Hyde, Senior Sustainability Manager for Banker & Tradesman
Buildings are a significant contributor to climate change. Accounting for 39 percent of global greenhouse gas emissions, they produce more carbon emissions than either the transportation or agriculture sectors.
Generally, building emissions are classified into two categories – operational emissions and embodied emissions. Operational emissions result from purchased electricity onsite, combustion of fossil fuels, and fugitive refrigerants used to heat, cool, light, and power our buildings. Embodied carbon emissions result from the mining, manufacturing, and transporting of building materials, construction activity, deconstruction and disposal of the building at the end of its useful life.
Fortunately, there are many things we can do to reduce both types of greenhouse gas emissions from buildings.
The construction industry is currently focused on increasing energy efficiency and reducing operational carbon emissions. Many regions of the country are stretching building codes to include proven methodologies that increase building performance. Some typical strategies include improving air tightness and insulation, avoiding thermal bridges, using more efficient equipment, appliances, and lighting, avoiding fossil fuels and incorporating renewable energy. As building efficiency increases, operational carbon emissions are reduced, minimizing the impact of buildings on the local environment and climate.
There is a movement afoot to ban fossil fuels and require full building electrification. Fully electrified buildings have many advantages over those that utilize fossil fuels. Electric equipment is easier to maintain, simultaneously heats and cools, has a higher coefficient of performance and is cheaper to operate. A building that utilizes fossil fuel-fired equipment will always produce operational carbon emissions. In contrast, operational emissions from an electric grid tied building will eventually go to zero, as the grid becomes cleaner due to the increased supply of renewable energy.
Benefits from Less Embodied Carbon
The industry has been slower to turn its attention to reducing embodied carbon, but the momentum is increasing. Most embodied carbon emissions are present in the atmosphere by the time building construction is complete, making them more immediately impactful on the climate. Luckily, many ways exist to reduce embodied carbon emissions to mitigate climate change.
The most effective way to reduce embodied carbon emissions is to reuse existing buildings instead of building new ones. Structural components such as concrete and steel have very high embodied carbon. By reusing an existing building, we avoid the need to produce new building materials and generate the emissions associated with their installation.
When you do build, use natural materials that sequester “biogenic” carbon during their lifecycle, are responsibly sourced and minimally processed. Some examples of these biogenic building materials include wood, cross-laminated timber and natural fiber insulation. These materials have low embodied carbon: They remove CO2 from the atmosphere and store it within the building. In addition to the environmental benefits, their biophilic design can reduce stress and improve overall well-being.
You can also avoid or limit high embodied carbon building materials such as cement, steel and glass. Use durable and long-lasting materials with high recycled content, instead.
Another source of embodied carbon emissions is construction activity, such as those from heavy equipment, temporary power, electricity usage and temporary heating. Consider implementing anti-idling policies and scheduling deliveries to reduce waiting time. Control your temporary heating system with sensors and thermostats, lower setpoints and minimize air leakage.
New Requirements Lack Clarity
We do have several challenges that are working against us. High-performance energy codes are regional instead of nationwide. There is not enough environmental product declaration data to properly compare materials. Emissions data from construction activity is scarce and very inconsistent. Industry knowledge of embodied carbon is limited. Performing a full life cycle assessment is challenging and time-consuming. Reporting protocols are vague and inconsistent. Federal and local regulations do not address embodied carbon. Secondary markets for salvaged materials are poorly established, making material reuse more difficult to coordinate and expensive.
Here are some practical steps we can take to reduce greenhouse gas emissions from our buildings and help fight climate change:
- Advocate for and support policies that promote embodied carbon reduction.
- Pressure manufacturers to generate environmental product declaration sheets, also called EPDs, toallow comparison of the environmental impacts of various products.
- Install continuous air barriers and insulation.
- Electrify buildings and install renewable energy systems onsite.
- Track, measure, and minimize jobsite emissions.
Decarbonizing buildings can be complex, but the benefits are undeniably worth it since climate change is a global problem. Decarbonized buildings have lower operating costs, increased comfort, improved resiliency, and increased property values. More importantly, they improve air quality, mitigate climate change and contribute to a more sustainable future.