In this photo a ten-foot long 2x4 hits a sample concrete wall section with a brick formliner surface finish at 100 mph. Resilient structures provide a safe place for occupants without being destroyed. Credit: Joe Nasvik
After deciding to build a house, the next crucial step is determining the construction method. The optimal building system benefits both current and future occupants by adhering to sustainability and resiliency guidelines.
When constructing a home, consider the greenhouse gases (GHGs) emitted during construction, the building's safety amid increasing climate change risks, the energy required to maintain living conditions over time, the waste and toxic materials produced upon demolition, and the home's adaptability for future owners.
Once it was established that global temperatures rise with the amount of carbon dioxide (CO2) and other heat-trapping gases in the atmosphere, scientists began to focus on their sources and quantities. Consultants like Emily Lorenz, owner of SevGen Consulting in Chicago, calculated the GHGs produced during product manufacturing. The sustainability movement advocated for using materials with lower GHG emissions. "Green" products, such as wood (since trees can be replanted) and straw bales (a byproduct of food grain production), were favored. However, the term "sustainability" has become a marketing tool for various materials. Evan Reis, executive director of the U.S. Resiliency Council in San Francisco, notes that sustainability has traditionally been defined as "green design" aimed at minimizing environmental impact.
The front portion of a 10 ft long 2x4 is reduced to a cluster of fiber when it hits a concrete wall panel at 100 mph. Credit: Joe Nasvik
In the realm of sustainability, the production of portland cement is often criticized due to its high GHG emissions. Limestone, the primary ingredient, must be heated to approximately 2,800 degrees Fahrenheit, releasing CO2 both from the fuel used and the calcination process. Despite improvements, producing a ton of portland cement still emits about 0.8 to 0.9 tons of CO2. Since cement is a key component of concrete, some advocate for alternative materials.
Resiliency
Reis emphasizes that focusing solely on green design is insufficient; true sustainability also requires resilience-building structures so that the environment has minimal adverse effects on us.
Resiliency considers the entire lifespan of a building—its safety amid unpredictable climate events, the energy needed for heating and cooling, combustibility, and the use of toxic materials. While U.S. sustainability practices often focus on GHG emissions during production, resiliency adopts a long-term perspective. Both resiliency and sustainability are vital.
A 10 ft 2x4 traveling at 100 mph passes half way through brick veneer in front of a standard wood frame wall section. Credit: Joe Nasvik
Life of the Structure
Considering resiliency involves evaluating GHG emissions throughout a structure's lifespan. Focusing solely on cradle-to-gate sustainability assesses only the GHGs emitted during production. For instance, manufacturing lumber emits less GHG than producing concrete, suggesting wood is more sustainable. However, if a wood house burns down, producing toxic debris that must be landfilled and then rebuilt, the total GHG emissions may surpass those of constructing a non-combustible concrete house once.
Safety
The resiliency movement values structural safety, emphasizing that homes should remain habitable after disasters to minimize life disruptions. However, safety standards must evolve as extreme events like fires, hurricanes, and tornadoes increase in frequency and intensity due to global warming, necessitating continual updates to construction codes.
A standard wood stud frame construction with ¾ inch plywood sheeting and aluminum siding offers almost no resistance to a 10 ft 2x4 traveling at 100 mph. Think about the resilience of the construction method you use when you build. Credit: Joe Nasvik
Energy Use Over Time
Resiliency assessments account for the energy required to heat and cool a building throughout its life. Lorenz notes that in the U.S., the majority of GHGs stem from the energy needed for heating and cooling, rather than construction. The materials used significantly impact this energy consumption. Studies comparing insulating concrete form (ICF) homes to standard wood-frame houses found that ICF homes require less energy for heating and cooling. Although ICF homes produce more GHGs during construction, their total GHG emissions over their lifespan are comparable to wood-frame houses due to better energy efficiency.
Toxic Debris
Reis highlights concerns about debris left after fires. Los Angeles, for example, faces substantial amounts of toxic debris from the 2025 fires, which must be safely stored in landfills indefinitely. However, "there is no such thing as forever," he adds, noting that water leaching through landfills can spread toxic materials over larger areas.
It’s easier now and less expensive to make crushed rock on construction sites from demolished concrete, thanks to advancements in technology. Credit: Joe Nasvik
Repurposing
Buildings are often constructed to meet specific owners' needs. When sold, new owners may demolish structures to suit their preferences, resulting in significant material waste deposited in landfills. Future designs might focus on creating adaptable structures that retain their core while allowing aesthetic changes. Notably, concrete can be recycled into aggregate for grading beneath new concrete and asphalt, and its steel reinforcement is also recyclable. Most landfill sites don't accept concrete, encouraging recycling.
Closing Thought
Sustainability is relatively straightforward to measure, with researchers quantifying GHG emissions during material production, often reported in equivalent tons of CO2. Buildings can also receive scores for their environmental friendliness. Additionally, it's now possible to assign resilience scores to buildings. For more information, visit the U.S. Resiliency Council's website at www.usrc.org.
When building a house or business office, it's essential to consider both sustainability and resiliency, benefiting both yourself and your community.
RELATED:
Part 1: The Case for Fire-Resistant Concrete Homes
Part 2: Concrete and Fire
Part 3: Reinforcement for Concrete Homes
Part 4: Resiliency
About Joe Nasvik
Joe Nasvik has been a prominent figure in the concrete industry for over four decades. Before transitioning to editorial roles, he owned and operated a concrete construction company for nearly 20 years. In his editorial career, Nasvik served as a senior editor for Concrete Construction magazine, contributing extensively to the field through articles and insights.