In the sustainable building industry today, decarbonization is the hot topic. But what does this mean for the future of our buildings? Decarbonization is directly related to the science of global warming. The discussion includes both embodied carbon and operational carbon. Embodied carbon refers to the emission of greenhouse gases (GHGs) related to extraction, production, and installation of construction materials. Operational carbon is associated with the greenhouse gases produced in the creation of energy, both source and the site, used to run buildings.
California took aim at greenhouse gases in 2006 with the passing of Assembly Bill 32 (AB32). The ultimate goal of AB32 is to reduce GHGs to 80% below 1990 levels by the year 2050. To address GHGs emissions the built environment, California is attacking emissions on many fronts. Fossil fuels are being phased out as power sources for California’s electric grid. In 2019, solar accounted for 14.2% of California’s in-state electricity generation portfolio. The Building Energy Efficiency Standards, California’s energy code, continues to push the boundaries of energy requirements. California has set its sights on existing buildings too. Assembly Bill 802 requires benchmarking for larger commercial and multifamily residential buildings.
While operational carbon (i.e. emissions) are addressed through California’s building codes and AB32, embodied carbon is being addressed through other developments in the building industry.
Here are four ways how decarbonization is changing the way that buildings are being designed today:
1. More solar. With the adoption of the 2019 Title 24, Part 6, Building Energy Efficiency Standards, photovoltaics (PV) became mandatory for most new low-rise multifamily and single family homes. The California’s Energy Commission’s goal for 2030 is to include photovoltaic requirements for nonresidential and multifamily high-rise buildings. In the meantime, the code requires most new buildings to dedicate roof space and electric panel capacity to accommodate future PV.
2. The push towards electrification. Local jurisdictions are also driving the push towards electrification. Electrification is the removal of combustion appliances from building designs. Combustion appliance used for cooking, hot water heating, space heating, etc. are a major source of GHG emissions. So far, 34 jurisdictions in California have passed ordinances pushing towards electrification. These ordinances range from pre-wiring for electric readiness to reach codes requiring all-electric new construction.
3. Life-cycle impact analyses. While there may not be much codified now that addresses embodied carbon, it has the attention of those pushing the industry of sustainable design. When the U.S. Green Building Council (USGBC) introduced LEED v4, the rating system incorporated a credit for Building Life-Cycle Impact Reduction, an incentive to reduce embedded and operational GHGs and other harmful pollutants over the course of a building’s lifespan. The International Living Future Institute (ILFI) has also been at the forefront of sustainability. They first offered the Living Building Challenge which provided certifications for net-zero energy and water and low impact materials. Now both USGBC and Living Future are offering certifications for net-zero carbon buildings. In addition to net-zero operational carbon, ILFI’s Zero Carbon Certification requires that projects demonstrate, through life-cycle impact analyses, a 10% reduction in embodied carbon. These rating systems are compelling builders to consider the life-cycle impacts of the materials that are used to construct buildings.
4. Mass timber high-rise. While it is debated just how much carbon is actually sequestered in timber products, the science is clear: concrete and steel emit carbon during their production, yet carbon is stored in lumber. This means that wood construction will have less embodied carbon than concrete and steel. Coincidentally, mass timber is a more cost-effective means of construction as well.
Mass timber high-rise pushes the height restrictions of building codes. Mass timber includes products allowed for Type IV construction such as cross-laminated timber, composite and glue-laminated products, and large section sawn lumber. The International Code Council (ICC) approved provisions that will allow mass timber buildings up to 18 stories in the 2021 International Building Code. This will be included when California adopts the code. Over the last few years, an 18-story student housing mass timber building was constructed in Vancouver, BC, and another 18-story mixed-use building was constructed in Brumunddal, Norway. In the US, a 12-story mass timber high-rise received approval in Portland, OR. There now seems to be a push to see who can build the tallest wood structure. One of the projects at pushing this envelope is an 80-story tower proposed for Chicago, IL.
There is little doubt that the concept of decarbonization is having an effect on how the industry builds. From code minimum to cutting edge, electrification is driving building codes now. As we move forward, carbon embodied in the materials will become more of a consideration. However decarbonization may be impacting your projects, VCA Green is here to help bring out the best in every building. VCA Green can provide energy modeling to show compliance with all-electric reach codes, perform life-cycle impact analyses, and guide your project through third party certification programs like LEED. If you have any questions or need pricing, contact Moe Fakih today. VCA Green’s sister company, VCA Structural, has been researching and staying current on the possibilities of mass timber. For more information, contact Tom VanDorpe.
Contributing Writer: Glen Folland, Director of Sustainability at VCA Green
Moe Fakih, Principal at VCA Green
Tom VanDorpe, President and CEO at VCA Consultants, Inc.