Environmental impacts from the demolition and construction cycle can be mitigated
———
Staggering environmental consequences of demolition and construction debris are leading construction and development firms, as well as government agencies and industry organizations, to advocate for waste reduction and recycling.
Total building-related demolition and construction waste in the nation is estimated to be 135.5 million tons — a figure that represents, at 30%, the largest single source in the waste stream, according to Buildings Magazine. Impacts of new buildings are significant:[i]
- The average new construction project yields 3.9 pounds of waste per square foot of building area. Example: A 50,000-square-foot building = 97.5 tons of waste.
- The average building demolition yields 155 pounds of waste per square foot. Example: A 50,000-square-foot building = 3,875 tons of waste.
Worldwide, between now and 2050, embodied carbon in buildings is expected to account for over half of total greenhouse gases from new construction, according to a 2021 World Green Building Council report. Architectural Record reported[ii] that figure is dramatically high from a short-term perspective – accounting for 72% of the global building sector’s total over the next 10 years.
Retrofits extend a building’s life, reducing waste
“The most effective way to reduce embodied carbon is to reuse a building,” Walter P. Moore concluded in the firm’s recent report, “Embodied Carbon: A Clearer View of Carbon Emissions.”[iii] That’s especially true when an older structure is demolished to make way for something new – a common occurrence in urban communities. The same holds true when an unsafe structure is destroyed in an earthquake or other natural disaster.
Retrofitting structures to withstand threats from earthquake, fire, hurricane, or flood prevents the emission of greenhouse gases associated with disposing of a damaged structure and building an entirely new one.
Building reuse provides a green alternative to demolition. Mechanical systems such as plumbing, electrical and HVAC can be upgraded for efficiency. Rooms can be redefined to create spaces adapted to modern lifestyles. But no matter how much you improve a building to make it clean and green from a technological standpoint, there’s no benefit if the structure is not able to withstand an earthquake.
The 1994 Northridge quake destroyed 13,800 dwelling units and buildings. Scientists say California is long overdue for an earthquake that could bring up to 45 times the destruction of that quake.[1][iv]
Some jurisdictions are encouraging adaptive reuse. The City of Los Angeles offers density bonuses, relaxed parking requirements, and other incentives to developers who choose to repurpose an existing building rather than demolish and replace it. Massachusetts is offering guidance on how to plan and implement a building reuse project. Portland now requires the deconstruction of buildings that must be taken down, requiring pieces to be moved one by one to maximize the recycling of the materials.[1] The Carbon Leadership Forum has developed an online tool at caretool.org that builders and developers can use to calculate the embodied carbon in their projects.
The sustainable choice
The sustainability aspect of preservation lies not only in the reuse of resources – averting the environmental impacts of breaking down, transporting, and dumping debris in a landfill – but also in a reduced CO2 footprint, researchers determined in a report produced by the National Trust of Historic Preservation. That report, titled, “The Greenest Building: Quantifying the Environmental Value of Building Reuse,” says the reuse of buildings with an average level of energy performance consistently offers immediate climate-change impact reductions compared to more energy-efficient new construction.[v]
“It is often assumed that the CO2 reduction benefits gained by a new, energy efficient building outweigh any negative climate change impacts associated with the construction of that building,” the study found. It also noted it takes between 10 and 80 years for a new building that is 30% more efficient than average to make up for the greenhouse gas emissions resulting from the demolition, disposal, and construction of the new building.[vi]
The Life Cycle Analysis methodology compared environmental impact reductions of building reuse and renovation versus new construction over a 75-year lifespan. The study showed:[2][vii]
- Building reuse almost always yields fewer environmental impacts than new
construction when comparing buildings of similar size and functionality. - Reuse of buildings with an average level of energy performance
consistently offers immediate climate change impact reductions
compared to more energy efficient new construction.
Businesses and other organizations are encouraged to develop resilience and sustainability plans that incorporate provisions for targeted reuse of buildings to extend their useful lives, reduce lifecycle costs, and mitigate harmful impacts on the environment from unnecessary use of natural resources. Contractors involved in demolition projects can also modify their practices to recover as much of the material generated on the site for reuse as possible.
Developing these plans and acting upon them can help your business to be seen as part of the solution to our carbon footprint and other environmental issues rather a part of the problem.
[i] Buildings Magazine, https://www.buildings.com/articles/34719/diverting-construction-waste
[ii] Architectural Record, https://www.architecturalrecord.com/articles/15481-continuing-education-embodied-carbon-adaptive-reuse
[iii] Ibid
[iv] Los Angeles Times, Aug. 31, 2017 Houston offers grim vision of Los Angeles after catastrophic earthquake. http://www.latimes.com/local/lanow/la-me-quake-la-houston-flooding-20170901-htmlstory.html, also: A section of the San Andreas fault close to L.A. overdue for a major quake. www.latimes.com/local/lanow/la-me-ln-earthquake-san-andreas-grapevine-20170307-story.html
[v] Carbon Leadership Forum, file:///C:/Users/dhust/Downloads/CLF-Hub-Policy-Series-Presentation-Reuse-and-Deconstruction.pdf
[vi] National Trust for Historic Preservation, https://living-future.org/wp-content/uploads/2016/11/The_Greenest_Building.pdf
[vii] Ibid
Coming Next
Part III of this 3-part series will address how building reuse offers environmental benefits by cutting the carbon footprint of new construction and reduces project costs.
(posted 2/9/23)
___
About the Author
Recently appointed to Los Angeles Mayor Karen Bass’ Transition Team, Ali Sahabi, previously received the California Governor’s Environmental and Economic Leadership Award for taking a sustainable approach toward community development and environmental restoration in the 543-acre Dos Lagos mixed-use development in Corona, CA. A licensed General Engineering Contractor (GEC), Sahabi is an expert in building resilience and sustainability. He is Co-Founder and Chief Operating Officer of Optimum Seismic, Inc., which has completed more than 3,500 structural retrofit and adaptive reuse projects for multifamily residential, commercial, and industrial buildings throughout California. Contact Optimum Seismic at 833-978-7664 or visit optimumseismic.com to learn more about your adaptive reuse options for your building.
