Technology

What cities can do to combat climate change?

 By RP Siegel

Cities are responsible for as much as 75 percent of all global greenhouse gas emissions. Recognition of this fact has led to action…

The Global Covenant of Mayors for Climate & Energy, has recorded pledges by cities alone that could reduce annual CO2 emissions by 1.3 billion tons by 2030.
Cities have a unique opportunity to address climate change for a couple of reasons. Besides being responsible for a significant amount of emissions, as former NYC mayor Michael Bloomberg pointed out in the book Climate of Hope, cities tend to be more in touch with the needs of their citizens, and have a far more streamlined decision-making process than states or national governments. That means they can be far more responsive to emerging concerns.

What to do?

What are some of the actions cities can take? Perhaps the first question is, “where do most city emissions originate?” While most studies have focused on the local impacts of buildings and transportation, a recent study undertaken at the Potsdam Institute for Climate Change Research found, somewhat surprisingly, that emissions resulting from the production of goods purchased by residents, far from the city’s borders contribute as much emissions as those generated locally. The paper argues that taking actions within the city limits can avoid significant emissions in distant places around the world. For example, encouraging public transport and walkability, could reduce the demand for vehicles that would likely be produced in another city far away, using a great deal of energy in the process.
Another study, written by David Hsu of MIT, looks at the opportunities that city planners have to reduce emissions. He finds that far more can be done at the local level with buildings than with transportation, which can be impacted far more with national policies like fuel economy standards.
In the study, which developed computer models for 11 U.S. cities, Hsu compared three scenarios to the current baseline. These included: the implementation of new energy-efficient construction standards, the building of more multifamily homes and the retrofitting of homes with energy saving features.
Improved construction standards led to a 6 percent improvement by 2030, on average. However, faster growing cities like Houston and Phoenix would see improvements of 10 to 13 percent, while cities with slower growth rates like Boston, Chicago, Cleveland and Philadelphia would only see improvements in the 3-5 percent range.

More efficient houses

Significantly more can be done with energy retrofits. Upgrading residential homes across the 11 cities studied would yield a 19 percent decrease in emissions over and above the 6 percent gained by updated standards.
Surprisingly, there were no significant improvements found in moving to higher density housing (except for Phoenix). “Shifting people to multifamily buildings is what planners have always wanted to do, but that’s actually not as effective as most advocates would have thought,” Hsu says. That’s primarily due to the fact the single-family homes have become more energy efficient.
For more specific ideas that cities can do implement now, the Carbon-Free City Handbook, produced by the Rocky Mountain Institute, goes into quite a bit of detail, along with numerous examples. The book is focused on recommendations for 22 “no-regrets actions” that cities can take. These are arranged across five categories, starting with buildings and mobility, and then going on to include electricity, industry and biological resources.

Buildings, streets, industries, nature and waste

In the buildings section, standards are divided into two types: net-zero and progressive. Net zero standards typically require that all new buildings in a given category (e.g. city government) meet a net-zero, or net-zero-ready standard. Progressive standards involve a trigger event such as a change of ownership that would require an efficiency upgrade to meet the current municipal standard. Smart LED lighting also figures prominently in this category. A major lighting upgrade program in India is expected to save $5.9 billion and 100 million kWh of energy annually. Finally, disclosure and transparency can also play a role, when building owners are required to report energy usage, which can be compared to other similar buildings.
For mobility they have: fleet electrification (starting with municipal vehicles), combustion vehicle access reduction, freight delivery reduction, EV charging, car-free downtown, mobility alternatives and public transit.
The electrification section includes LED streetlighting (250,000 installed in Chicago, 225,000 installed in Madrid), and the establishment of electric-only districts (e.g. Amsterdam). In addition, they described municipal solar installations (Kansas City, Denver) and municipal renewable supplies (Houston, Copenhagen, Philadelphia). Microgrids can also be effective way to keep the lights on during natural disasters and during other times of infrastructure stress.
The study also suggests that cities partner with heavy energy users in the industrial sector, an idea that also speaks to the concerns raised in the Potsdam report. Many industries utilize heat in their processing and there are numerous ways to better utilize that heat including: conversion to low-carbon fuels, making process heat generation more efficient by doing things as simple as insulating steam lines, repairing heat-distribution infrastructure, and making productive use of waste heat through district heating or co-generation. Examples are given in China, Sweden and Vietnam. Electric motors are another area of opportunity. Motors represent nearly 70 percent of industrial power consumption, yet efficiencies have improved dramatically in recent years. Improving worker knowledge can also reduce energy consumption.
Finally, there are a number of recommendations that involve partnering with nature within a city limits. We discussed the value of green roofs in a previous post. Urban forests can add significantly to those benefits as demonstrated in Minneapolis. Diversion of organic waste can also have a substantial impact. Unless handled properly to encourage aerobic breakdown, through methods such as composting, food and yard waste will emit large amounts of methane, a far more potent greenhouse gas than CO2 as they decompose. A success story in Alappuzha, India, utilizing both composting and biogas production reduced emissions and saved money at the same time. Finally, encouraging residents to shift to a predominantly plant-based diet, can also do a great deal to reduce emissions, particularly at the source of food production. Cities in Italy, Brazil, China and the U.S., have introduced programs that encourage meatless meals one day a week.

READ MORE: Green spaces in cities by RP Siegel

about the author
RP Siegel
Skilled writer. Technology, sustainability, engineering, energy, renewables, solar, wind, poverty, water, food. Studied both English Lit.and Engineering at university level. Inventor.