Assistant professor of metallurgical engineering Ehsan Vahidi studies how cities like Reno should build and expand to minimize greenhouse gas emissions and conserve energy. It is data like Vahidi’s that can help city planners like Marco Velotta of Las Vegas determine how to grow a city with the least impact on the environment. Here, Vahidi answers a few questions about his research and how the data he’s gleaned about mitigation strategies could help inform a more sustainable future for the Biggest Little City.
From your research, what are some of Reno's biggest challenges as an expanding city?
By 2050, the United States is projected to add 11.24 billion m2 (121 billion square feet) of buildings, which is equivalent to constructing New York City every year for the next 20 years. However, to meet climate change goals the U.S. building sector must also significantly reduce its greenhouse gas emissions. Thus, it is critical to explore the contribution of embodied (composed of the greenhouse gas emissions contributed during construction) and operational (composed of the emissions produced by living in or operating the building) impacts of newly constructed buildings while evaluating the potential for strategies to lower greenhouse gas emissions in the building sector.
In Reno, more than 320 million square feet of new buildings will be constructed by 2050. A long-time focus on buildings' energy consumption and its associated impact on greenhouse gas emissions during the use phase of building has resulted in extensive improvement in the energy-efficient operation of buildings and eventually a switch of environmental burdens towards the embodied phase of buildings. Considering that 23% of new construction emissions are generated from the utilization of construction materials, one of the challenging decisions that has to be made in all early design stages is selecting building materials with lower embodied greenhouse gas impacts.
So, what should Reno do? What does your data tell you are the best options for growing (or restructuring) our city to minimize greenhouse gas emissions and mitigate the worst impacts of climate change?
According to the results of applying this modeling approach, without implementing mitigation strategies, cumulative greenhouse gas emissions generated from the whole buildings sector in Washoe County in Nevada in 2050 will reach 1.3 million tons of CO2-eq. If implemented, mitigation strategies would lead to greenhouse gas emissions falling to 0.7 million tons of CO2-eq in 2050. As electricity is the most intensively used energy carrier in the building sector, greening the electricity grid can significantly reduce the individual environmental footprint of buildings.
Moreover, building energy codes and standards set minimum requirements for energy-efficient design and construction for new and renovated buildings, assuring reductions in energy use and greenhouse gas emissions over the life of buildings. Based on the results of this analysis, the adoption of newer energy codes in newly constructed buildings significantly reduces greenhouse gas emissions and Reno as an expanding city will greatly benefit from this mitigation strategy. Furthermore, using more efficient lighting is an affordable and accessible strategy that can reduce energy expenses in the building sector in the United States. Additionally, as more efficient appliances are continuously utilized in all newly constructed buildings, replacing older appliances will lead to more compelling efficiency gains in the whole building sector.
What can individuals do in their homes to minimize their carbon footprint?
Energy consumption in the whole building stock in the United States plays a significant role in the sector, which is why the largest opportunities for greenhouse gas emission reductions derive from the electricity grid evolution and efficiency improvement in appliances and lighting. Taken together, changes in these three attributes make up more than 85% of the cumulative greenhouse gas emissions reductions. Therefore, by utilizing more efficient appliances and lighting, individuals can greatly contribute to minimizing their carbon footprint.
This story was originally published in the 2022 'Live a Life of Discovery' magazine from the College of Science under the title, "The Biggest Little Impact: Growing a greener city."
