In response to the focus on sustainability within the built environment and driven by a growing discussion about climate change, the industry has started thinking beyond the construction phase, to the building’s entire lifecycle.
“The emissions that result from the renovation and demolition of buildings should be accounted for, as much as for the manufacture and construction of them,” writes Blaine Brownell, architect and materials researcher, and director of the School of Architecture at the University of North Carolina in Charlotte.
Carbon costs from material deterioration
Many buildings that exist today, will still be in existence in 20 years’ time. These will have gone through many stages of the material lifecycle:
- sourcing the raw materials
- product manufacture
- deconstruction of the building.
The carbon cost resulting from material deterioration over time should be part of the discussion about the carbon footprint of that buildings’ materials.
Based on existing knowledge about material longevity, it is generally feasible to predict the CO₂ emissions of the future replacement of building components, but it is less certain when this replacement would happen.
Structures can be demolished for reasons other than deterioration, so calculating the timing of a building’s demise is likewise challenging. Recommendations for emissions reduction strategies are developing, as researchers start seeing a clearer picture of how maintenance and end-of-life scenarios influence the carbon footprint of materials.
New vs existing buildings
According to a 2016 Preservation Green Lab report, “it takes 10 to 80 years for a new building that is 30% more efficient than an average-performing existing building to overcome, through efficient operations, the negative climate change impacts related to the construction process.”
Calculating the total energy and CO₂ rating
In a study on steel corrosion, it is explained that while information on the economic cost of corrosion has existed for more than half a century, little is known about the impact of its emissions. Using current steel industry emissions, between 4,1% and 9,1% of the total CO₂ emissions are attributed to corrosion.
This gives rise to a recommendation that a total energy and CO₂ (TECO₂) rating should be used, which includes this replacement cost in material estimates. Although initially more expensive, this comprehensive measure could encourage the increased use of corrosion-resistant alloys, resulting in a lower overall TECO₂ rating.
Evolution of design and specification
The architectural design and specification process will likely evolve, as awareness of embodied carbon extends beyond new construction to encompass the entire lifecycle of buildings. Materials will be viewed with regards to their initial CO₂ and their lifetime embodied carbon.
This could give rise to the use of longer-lasting materials to reduce maintenance-related impacts, but considering that the lifespan is not predictable, multiple scenarios should be considered. Material reuse and design for disassembly at the end of a building’s useful life may finally receive the attention it deserves.
Brownell notes: “Finishing may symbolically end construction, but construction – just like weathering – is never really finished.”
Issue: Managing materials’ carbon footprint.
Solution: Thinking beyond construction, to the building’s entire lifecycle, could give rise to the use of longer-lasting materials.
Full acknowledgement and thanks go to https://www.architectmagazine.com/ for the information in this editorial.
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