Category Archives: Energy

Energy Use and Pollution of Travel Modes

The report Life-cycle Environmental Inventory of Passenger Transportation in the United States bills itself as “the first comprehensive environmental life-cycle assessment of automobiles, buses, trains, and aircraft in the United States.” The report, by Mikhail V. Chester of the Institute of Transportation Studies at Berkeley, goes far beyond counting the fuel consumed by vehicles. It considers the energy and materials used to build stations, terminals, roadways, runways, tracks, bridges, tunnels and parking, as well as maintenance, heating, lighting and more. A full life-cycle accounting of travel modes has been a long time coming; it is critically needed and tremendously welcome.

The findings on life-cycle energy use are summarized in this chart:

Read on for a summary of the findings, and a discussion of how the results are affected by urban design context.

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Sustainable Property Development and Carbon Offsets

There are a variety of actions that property developers may take to help solve global warming. One is the purchase of carbon offsets — financial credits representing renewable energy or other facilities that reduce greenhouse gas emissions. Developers may purchase carbon offsets to offset the vehicle emissions associated with their land development projects. This is undoubtedly better than no action at all; however, offsets suffer from a number of functional and philosophical shortcomings that render them less-than-optimal as a solution. There are more direct and effective actions available, and those are what the sustainable development industry should encourage.

There have already been flaws uncovered in the carbon offset industry, ranging from obvious cheating and scams, to sincere firms using flawed calculation methods. For the purpose of this discussion, let’s ignore all of that. Let’s assume that all carbon offsets adhere to a high standard like the Gold Standard.

Even so, there is something less than ethical about paying somebody else to solve the problem you aren’t solving yourself. Especially when they happen to be halfway around the world. Whatever happened to “Think Globally, Act Locally”? That saying is drawn from a distinguished philosophical tradition (Leopold Kohr, E.F. Schumacher, Rene Dubos, etc.) and it is still relevant today.

Carbon offsets perpetuate the fiction that we can pay others to solve global warming while doing nothing to change our own patterns of energy use. All energy experts recognize that it will be extremely difficult to replace the current level of energy production with clean, carbon-free sources. Many claim it is impossible. The task of converting to carbon-free energy will be far easier if it is accompanied by a reduction in the demand for energy. Especially here in the U.S., we cannot simply expect technology to fix all of our carbon emissions. We are so profligate in our usage that some degree of demand reduction will be required. Our challenge is to reduce energy demand while maintaining a high quality of life.

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Reuse Buildings, Reduce CO2

For old brick houses, it’s as energy-efficient to renovate — and possibly more so — as it is to tear down and build new. That’s the conclusion of a study by the Empty Homes Agency, a UK nonprofit that works to bring empty homes back into use.

Large homebuilders in the UK claim that new construction is many times more energy efficient than older properties like Victorian houses. That’s true for operating energy, counter the environmentalists, but what about “embodied” energy — the energy it takes to manufacture building materials? Until this study, no one had calculated the relative importance of each. After analyzing three renovated and three new houses, the conclusion was this:

Previous studies and much of the accepted thinking on domestic CO2 emissions have suggested that demolishing existing homes and building new homes to replace them will contribute to an overall reduction in CO2 emissions. This study suggests that this is not so, and that refurbishing existing homes and converting empty property into new homes can yield CO2 reductions by preventing emissions from embodied energy that would arise from new build.

In the extended entry, more quotes from the study “New Tricks With Old Bricks.”

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APTA Study on Transit and Land Use

The recent study Growing Cooler, coordinated by Smart Growth America and published by the Urban Land Institute, found that “Typically, Americans living in compact urban neighborhoods where cars are not the only transportation option drive a third fewer miles than those in automobile-oriented suburbs…”

On March 10, 2008, the American Public Transit Association released a closely related study that supplemented those findings. APTA’s study, The Broader Connection between Public Transportation, Energy Conservation and Greenhouse Gas Reduction, tackles the same topic from a different direction. It asks, How does the availability of transit affect land use, its energy efficiency, and its greenhouse gas emissions — not only for transit riders but for those who don’t ride transit?

The conclusion: Not only is the land use effect significant, it is major. Below the fold, some excerpts from the study and key findings.

Image credit: APTA

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Fun with Density and Transit Statistics

Conventional wisdom holds that the U.S. is too spread out for workable mass transportation except in a few high-density cities. Urban planning expert Anthony Downs offers this explanation:

But in 2000, at least two thirds of all residents of U.S. urbanized areas lived in settlements with densities of under 4,000 persons per square mile. Those densities are too low for public transit to be effective. Hence their residents are compelled to rely on private vehicles for almost all of their travel, including trips during peak hours.

Traffic: Why It’s Getting Worse, What Government Can Do

Is that accurate? It all depends on statistics and assumptions, both of which are endlessly susceptible to manipulation. For instance, Downs uses “settlements” as the geographic unit of analysis and calculates how many Americans live below a certain density threshold.

That’s one approach, but there are many different approaches. We could use other geographic units and find out the average density in each of them.

Geographic Unit Population Population
% of U.S.
Land Area
(sq mi)
Land Area
% of U.S.
United States 281,421,906 100 3,537,438 100
Metropolitan Areas 225,981,679 80.3 705,790 20
Urbanized Area 192,323,824 68.3 72,022 2

Source: U.S. Census 2000

Looking at the entire United States, what impresses is the vastness and diversity of the land. It’s the America of spacious skies, amber waves of grain, and purple mountain majesties; of trackless tundra, sizzling deserts and rocky badlands.

But look at the urbanized area of the nation and a different picture emerges. Sixty-eight percent of Americans live on just 2 percent of the U.S. land area. Seen in this light, the large majority of the U.S. population is remarkably concentrated on the land. What implication does this have for population density?

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Connectivity Part 3: Latter Half of the 20th Century

This is part 3 of a series. See also IntroductionHistorical BackgroundNeighborhood WalkingNeighborhood CrimeVehicle Miles and TrafficCrash Safety

Disconnected street networks were the default, entrenched pattern of development in post-WWII America. However, by the early 1960s a backlash had arisen in opposition to the conventional planning wisdom. This countermovement snowballed through the 60s and 70s, and by the 1980s the issue had filtered into the architectural profession and scholarly research.

Part II of this series described how disconnected street patterns became ubiquitous in U.S., with the mandate in particular coming from the Federal Housing Administration. By 1941, over 200 cities had instituted subdivision regulations that encouraged disconnected street patterns.

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Connectivity Part 1: Introduction

This is part one of a series. See also Historical BackgroundLatter Half of the 20th CenturyNeighborhood WalkingNeighborhood CrimeVehicle Miles and TrafficCrash Safety

Thoroughfare network connectivity is the single most important element of sustainably-built cities and towns. That may sound like an odd statement, particularly if you’ve never even heard of it. Connectivity has so many interrelated effects on so many urban functions, and more people should recognize how truly essential it is.

Why is connectivity so important? There are many steps to trace, so in this post I’ll start with a definition and overview.

The thoroughfare network is simply the system of arterials, collectors, boulevards, avenues, streets, roads, etc., in an area. Connectivity refers to the directness of travel routes between any two locations, and the number of alternative routes available for traveling between any two locations.

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Energy Use vs. Living Standards

Nationmaster is a terrific resource for world statistics and country comparisons. I was interested to compare energy use with living standards. Is it possible to maintain a decent quality of life with low per capita energy consumption? Which nations are leading by that measure?

Here’s a scatterplot of primary energy consumption per capita vs. the Human Development Index (a combination of life expectancy, literacy, education, and GDP-based standards of living).

I tend to give the HDI axis a bit more weight. The best performer, then, is Portugal. Argentina and Chile are close with lower energy consumption but also lower HDI.

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