In many parts of the world, there is growing concern about the environmental impact of the construction sector. An example of this is New York Local Law 97 of 2019, which sets emission limits for buildings over 25,000 square feet starting in 2024. All buildings covered by this law will face a fine of $268 per metric ton of carbon equivalent. CO2 above its respective limit, calculated each year.
Even when operational emissions are reduced, there is another challenge – reducing embodied emissions in buildings. Architecture 2030 estimated that three materials alone are responsible for 23% of global emissions when considering the total impact of their supply chains: steel, concrete and aluminum.
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Without specific actions, embodied carbon could exceed operational emissions from buildings in the coming decades. According to Architecture 2030, embodied carbon could be responsible for 57% of emissions from new construction between 2020 and 2040.
Building Operational Carbon: Reduction Strategies
There are many measures that reduce carbon emissions from existing buildings. However, they generally follow two main strategies:
- Reducing energy consumption: Using fewer kilowatt-hours, cubic feet of natural gas, gallons of heating oil, gallons of diesel, etc.
- Switching to cleaner energy sources: Replacing grid electricity with on-site renewables, switching from combustion to electric heating, etc.
The first strategy reduces the units of energy used by a building, while the second reduces the carbon footprint of each unit of energy. However, both strategies achieve a common objective: reducing emissions from the construction sector.
Every property is unique – carbon reduction measures that are very effective in one building may achieve limited results in another property in the same city. The best starting point is to get a professional energy audit and simulate the effect of carbon reduction measures with energy modeling software.
Energy bills and building emissions go hand in hand. Carbon technology is not just about protecting the environment – there is also an attractive return on investment for building owners and there are many financing options for green upgrades. PACE loans offer a repayment period of up to 30 years and can be easily transferred to other owners in the event of a building sale.
Embodied Carbon in Buildings: Reduction Strategies
Unlike operational carbon, which can be reduced by improving a building, embodied carbon has already been released when new construction is completed. Architecture 2030 proposes three strategies to deal with embodied carbon:
- Reusing construction materials when buildings reach the end of their useful life.
- Reducing the initial carbon footprint when materials are first used in new construction.
- Sequestration of carbon that has already been released into the atmosphere.
There are many technologies that focus on energy efficiency and renewables, but more innovation is needed to address embodied carbon. There are many promising concepts that can be applied in the construction sector: design for deconstruction, low-carbon and zero-carbon materials, carbon sequestration materials, carbon sequestration sites, etc.
Another way to reduce embodied emissions is to minimize the use of materials from the design phase. BIM modeling software can be used to optimize the layout of building systems, and methods such as prefabrication and modular construction can be implemented to reduce waste.
Considerable growth is expected in the construction sector in the coming decades and rapid action is needed to avoid a large impact from embodied emissions. According to the United Nations, 68% of the global population will live in cities by 2050 , which represents an increase of 2.5 billion from the current urban population. The large volume of new construction will double the global real estate stock by 2060 – equivalent to 2.4 billion square feet of built area.
In the case of New York, Local Law 97 penalizes only operational emissions, based on energy benchmarking of the construction sector. However, this does not mean that embodied emissions should receive less priority. Additionally, consider that stringent laws for embodied emissions could be enacted in the future – developers who are already mitigating the impact of construction materials and processes will be better prepared.
Final Observations
Carbon emissions are often associated with transport, but the impact of the construction sector is often ignored. However, buildings are responsible for embodied and operational carbon, and different strategies are needed for each type of emissions. The window of opportunity to reduce embodied carbon is also smaller – when a building opens, these emissions have already been released.
Operational emissions can be targeted with a combination of energy efficiency measures, conversion to cleaner sources and on-site renewable generation measures. Embodied emissions must be minimized during the design and construction process, while reusing as many materials as possible and sequestering emissions that have already been released.
