Greater Greater Washington

Will Green Area Ratio green DC or just hinder urban living?

Washington, DC may adopt a "Green Area Ratio" requirement for multi-family and commercial buildings in its new zoning code. It's an attempt to promote sustainable practices in large projects, but its ultimate effect might just be to make environmentally friendly urban living more expensive with limited actual benefits.


Photo by atomicShed on Flickr.

The newly-released draft of the zoning code contains very promising changes, like reducing parking requirements and allowing homes on narrow alley streets after a decades-long ban.

It also introduces "Green area Ratio," modeled on similar laws in European cities such as Berlin and Malmö. Seattle has already implemented a version of the same idea, called the "Green Factor," where it has drawn praise and some criticism.

The basic idea of the GAR is this: in order to address a perceived imbalance of paved/built to green space in urban areas, the zoning code must mandate dedicating a certain proportion of each lot to landscaping or permeable surfaces.

According to its proponents, the GAR will push buildings to better treat stormwater, improve air quality and reduce urban "heat islands." However, the draft regulations do not appear to contain any standards to determine whether landscaping elements actually aid in stormwater retention or treatment. Nor is there information about whether the estimated benefits are large enough to matter regionally or city-wide.

Existing research also raises potential concerns that nobody will monitor the environmental performance of these features once built. George Washington University professor Melissa Keeley, whose work the draft documents cite, sounds a cautionary note about "policy deficits and the lack of adequate outcome monitoring" in her 2011 study of Berlin's green ratio.

Some of the benefits seem questionable, like the statistic that "1,000 square feet of green roof can supply 110 people with oxygen." While this is beneficial, that the carbon monoxide-emitting motor vehicle creates much more pollution in urban areas than the lack of landscaped surface.

Berlin's air quality, which some sources estimate is the cleanest in Europe, largely owes its success to car restriction zones and policies that encourage traveling by foot, bicycle and mass transit. Cities are unlikely to substantially improve air quality without confronting the role of the car.

Additionally, GAR does not appear to distinguish between non-green ground coverage. An asphalt-covered surface parking and a 10-story apartment building with no parking and which covers its entire lot both receive a GAR of zero. On the other hand, it appears that the same apartment building with a 160-car garage but with a green roof could earn a high GAR.

The most notable element of the GAR is, perhaps, what it does not include. Single-family homes receive a special exemption from the proposed regulations because, the hearing report states:

Implementing this standard would impose an undue financial and logistical burden upon homeowners. Properties with one-family dwellings typically maintain higher standards of landscaping and retain more green area.
Imposing expensive mandates on multifamily housing while exempting single-family homes from regulation creates a perverse outcome in which dense, space-efficient housing suffers penalties for being environmentally unfriendly, while low-density homes occupying a small portion of their lot enjoy rewards for "retaining more green area."

While the GAR is compatible with high density urbanism, regulations which apply differently to various densities can make some types of housing more expensive, especially small apartment buildings.

In old cities, the highest art is often maximizing visible greenery while minimizing GAR. That creates streetscapes of intense greenery at low cost. The tools of this approach are not bioswales and rain gardens, as useful as these may be, but window boxes, hanging pots, climbing vines and clay urns:


Eguisheim, Alsace, France. Image by Ela2007 on Flickr.

Ultimately, certain landscape elements, green roofs and other innovations may have an important role to play in Washington, but residents deserve to learn more about the long-term costs and benefits of such a large scale, mandatory and relatively untested regulation before adopting it as part of the zoning overhaul.

Cross-posted at Old Urbanist.

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Charlie Gardner writes the blog Old Urbanist

Comments

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What would this do to NoMa, which is rapidly converting every inch of space to 12-story building with no apparent plan for plantings or parks?

by Ward 1 Guy on Feb 15, 2012 2:31 pm • linkreport

I am concerned about the green area ratio. First, I think it could lead to bigger setbacks and useless green space in front of buildings (meaning less residential units or office space) and take away from street vitality. This could give buildings a more suburban format. Second, if buildings statisfied the green-area ratio with rooftop gardens or green roofs, this could come at the expense of solar panels.

by Ben on Feb 15, 2012 3:28 pm • linkreport

Ward 1 Guy, Larger setbacks are the solution.
Ben, Green roofs are the solution.

Glad no one from DCSUN asked a question.

by Rayful Edmond on Feb 15, 2012 3:36 pm • linkreport

@Rayful:

Doesn't become zero-sum with green roofs and solar, although I know someone who has both on his roof? I think the District and the Office of Planning should be neutral in that.

by Ben on Feb 15, 2012 3:44 pm • linkreport

IIUC pervious surface relates to specific questions about run off and stormwater capacity - its a water quality capicity issue, NOT an air pollution issue (though greenery has a GHG impact). Lots of window box plants are good for CO2, but don't address the run off issue.

I am also dubious that this will result in the retention of SFH's in the district in lieu of redevelopment - most redevelopment is taking place on properties other than existing SFH's. And I doubt there are more than a few places where higher density is legal, where SFHs (even THs) will be built.

The possibility of an exemption for roof top solar (though solar also does not address the run off issues) might be considered.

by AWalkerInTheCity on Feb 15, 2012 3:55 pm • linkreport

Excellent article. Multi-family and commercial buildings are so much greener than the alternative -- parking lots and single-family homes -- that we should be leery of any regulation that makes it harder to build high-density urban buildings.

by tom veil on Feb 15, 2012 4:30 pm • linkreport

"Multi-family and commercial buildings are so much greener than the alternative -- parking lots and single-family homes --

It's funny how the concept of wanting to be green has been so been turned on its head that some people think paving over the land from lot line to lot line can is being 'green'. There was a time when being green meant 'being one with nature' ... We stared with bio-degradable detergents, advanced to cars that burn cleaner than the ambient air, cleaned the rivers, etc.

I don't see how wanting people to live like rabbits in stacked cages is possibly a part of the green movement I know. It's a wolf in sheep's clothing. A developer's wet dream masquarading as 'green'.

by Lance on Feb 15, 2012 7:55 pm • linkreport

Multi-family and commercial buildings are so much greener than the alternative -- parking lots and single-family homes

Very implausible. Tall buildings have a number of features that make them less green than single-family homes:

- Tall buildings need much more energy-intensive construction materials (steel, reinforced concrete, glass, etc.) and equipment/techniques (cranes, hoists, backhoes, welding, etc). In contrast, single-family homes use low-energy materials and construction techniques.

- In addition to private living space, tall buildings must provide large enclosed common areas for access (lobbies, hallways, stairwells, elevator shafts, etc.) These common areas require additional energy and materials not only for construction, but also for daily operation (lighting, heating, cooling, cleaning, maintenance). In contrast, no common areas are required for access to single-family homes. The entire building is private living space.

- Tall buildings require energy to move people, water and other materials to higher floors. Water pumping alone can consume a significant amount of energy (water is heavy). In constrast, single-family homes rarely exceed 2 stories and require little or no energy for pumping or moving against the force of gravity.

- Tall buildings have a low ratio of roof area to volume. This makes them very unsuitable for solar power installations. In contrast, single-family homes can provide a significant amount of their energy requirements from rooftop solar panels. This advantange will become increasingly important in the future, as the price of solar panels continues to fall.

by Bertie on Feb 15, 2012 8:02 pm • linkreport

@Bertie

You're ignoring the fact that per capita energy consumption is lower for people living in denser areas and taller buildings. And by denser areas, I'm not just referring to Manhattan-esque densities.

Read "Green Metropolis" by David Owen if you want to know how denser communities are the true key to environmental sustainability. He thoroughly debunks the myth that a detached single family house -- with green roofs, solar panels, a hybrid car in the garage, and energy efficient appliances -- is hardly being "one with nature". Nice try, Lance.

by Tyler on Feb 15, 2012 10:41 pm • linkreport

You're ignoring the fact that per capita energy consumption is lower for people living in denser areas and taller buildings.

No I'm not. There are lots of reasons why per capita energy consumption might be lower for people living in denser areas that has nothing to do with the "greenness" of buildings. One is the fact that dense housing tends to be smaller. They're not reducing their energy consumption through "greener" buildings. They're reducing their energy consumption by sacrificing living space.

Read "Green Metropolis" by David Owen if you want to know how denser communities are the true key to environmental sustainability. He thoroughly debunks the myth that a detached single family house -- with green roofs, solar panels, a hybrid car in the garage, and energy efficient appliances -- is hardly being "one with nature".

It's a lot closer to "being one with nature" than living in a high-rise apartment in an urban jungle and getting around in underground tunnels. But I'm not sure why you think "being one with nature" is the goal here anyway. The issue here is environmental costs, not some new-agey state of being. If "being one with nature" is your goal you should give up modern technology altogether and live like people did in the paleolithic era.

by Bertie on Feb 15, 2012 11:06 pm • linkreport

Read "Green Metropolis" by David Owen if you want to know how denser communities are the true key to environmental sustainability.

[Deleted for violating the comment policy.] He ignores the kind of factors I just described that make dense buildings, and other aspects of dense urban living, environmentally costly. And he ignores the beneficial environmental effects of advances in technology and energy efficiency for low-density living.

[Deleted for violating the comment policy.]

by Bertie on Feb 15, 2012 11:28 pm • linkreport

@Bertie
The being "being one with nature" phrase was clearly lifted directly from your buddy Lances post above. So if you want to give anyone crap about it ought to be directed at him, he agrees with you though that somehow living in a world where you are entirely dependent on a giant mechanical machine to transport you miles for the slightest of tasks is environmentally friendly. As said by others above it's about density, yes by definition that means more human beings in less square feet, deal with it. I personally feel that green space is a lot more usual for everyone when condensed into parks and forests rather than some idiots lawn that he is going to waste all the more energy on mowing and dumping fertilizer all over. Most lawns are an environmental disaster. One gas mower running for an hour emits the same amount of pollutants as eight new cars driving 55 mph for the same amount of time. The lawn fertilizer people use causes massive algae blooms and fish kills in the Chesapeake bay and other local waterways.

While run off from impermeable is a real issue, this law should be modified so it doesn't discourage the kind of density that is urban livings biggest environmental benefit.

by Doug on Feb 16, 2012 2:44 am • linkreport

Article on health effects of air pollution in the NYT

http://well.blogs.nytimes.com/2012/02/15/air-pollution-tied-to-heart-and-brain-risks/?ref=health

may add to the discussion. It's fine to talk about Berlin. But how realistic is it? I wish it were realistic. But we can't even get dedicated bus lanes that can push traffic lights. I'm not sure how much success we will have at making car-free zones.

by Jazzy on Feb 16, 2012 6:56 am • linkreport

All other things being equal, high density living is greener than low density. In the real world, looking at energy people actually use. Not assuming that apartment dwellers have the same sq feet as SFH dwellers PLUS common areas (and why do we assume that all low density dwellers are in SFHs - thats neither apples to apples, nor reality, in a world filled with low density suburban apt complexes and condos - those developments typically have common areas)

But the DC code is not about that. Its about buildings that arent equal. Getting a ten story apt building to be more green than it would otherwise be. Thats only offset by lowering average densities to the extent A. The green area requirements impose significant costs and B. the demand for density is SO price sensitive that that leads to a significant change in urban form as a result.

Im not convinced of that.

And the rhetoric of making density trump ANY other environmental consideration only plays into the hands of those who, out of misunderstanding or dishonesty, want to make density sound anti-sustainable.

There are lots of people out there, architects, engineers, developers, trying to create DENSE green buildings. Lets celebrate that and encourage that, instead of picking needless fights between density and other sustainability concerns.

by AWalkerInTheCity on Feb 16, 2012 9:30 am • linkreport

@Bertie makes a very good point. If each single family home was built using the same materials and techniques as we use to build 20 story condo buildings, they would be much more expensive, measured in money and carbon footprint. All other things being equal, a McMansion is more "efficient" than a skyscraper.

Of course, if everyone bought a city bus and drove it to work alone, that would be less efficient than driving an SUV. All good points, and not ones I would have immediately thought of.

by oboe on Feb 16, 2012 10:40 am • linkreport

I live in a building with a green roof, and boy am I glad I don't live on the top floor. We might as well live in a thatched hut the way that thing keeps out water.

by dcredhead on Feb 16, 2012 3:39 pm • linkreport

Do tell, DCRedhead. I've always been very very curious, and frustrated with the way people throw around "green roofs!" "bioswales" as The Answer. Muuuch more thought, please.

There's never any thorough, engaging analysis. It's either or. Ugh. I'd love to hear your perspective. Does it seriously leak? What about the additional weight. Who lives underneath? Do they complain? Any measures taken to compensate that person? What's been done about it? What will be done? Who maintains it? Who decided it would go in? Which city agency is responsible for regulation?

As you can see, lots of questions!

I think people see dollar signs when they hear these new initiatives, and thought - WHOOSH! - goes out the window.

by Jazzy on Feb 16, 2012 7:10 pm • linkreport

you are entirely dependent on a giant mechanical machine to transport you miles for the slightest of tasks is environmentally friendly.

People who live in suburbs are not "entirely dependent on a giant mechanical machine to transport [them] miles for the slightest of tasks." Dense cities, of course, also use "giant mechanical machines" (buses and trains) to transport people. Studies have repeatedly found that mass transit is only modestly "greener" than private automobiles. It is very unlikely to be any greener at all than the super-efficient cars we will be driving in the future. The basic problem for transit is that in order to provide an effective alternative to cars for general transportation it must operate at times and in places where demand is low. This means that buses and trains are often mostly empty. On average, transit buses carry only about 10 passengers. More than two-thirds of the seats are empty. Burning fuel to haul around so many empty seats is obviously not very "green."

by Bertie on Feb 16, 2012 7:47 pm • linkreport

@Bertie "The basic problem for transit is that in order to provide an effective alternative to cars for general transportation it must operate at times and in places where demand is low. This means that buses and trains are often mostly empty. On average, transit buses carry only about 10 passengers. More than two-thirds of the seats are empty. Burning fuel to haul around so many empty seats is obviously not very "green."

This is so self-evident that I'm frankly surprised it needs to be explained. I suspect some mass transportation lobby did an effective campaign to get people to think that the inflexible, limited-reach, high-sunk-costs mass transit is more efficient than personal transportion. Use an analogy like computers and networking, and people understand that YES in the early days of self-propelled transportation you had to do it 'en mass' like you had to have big massive centralized Big Blue computers, but that as the product matures, individualized pieces bought by the users (think laptops, iPADS, smartphones) become the most efficient means to provide more options and especially more flexible options to more people. The transport of people is no different from the transport of data and information in that way.

by Lance on Feb 16, 2012 9:55 pm • linkreport

Actually, the transport of people is more like cloud computing. Rather than individualized pieces bought by the users we're actually moving towards "massive" farms of centralized computers (e.g. Google apps), and away from everyone "rolling their own".

(And, yes, before someone chimes in, both my and Lance's analogies are rather silly,)

by oboe on Feb 16, 2012 11:25 pm • linkreport

dcredhead, which building do you live in?

by Neil Flanagan on Feb 16, 2012 11:39 pm • linkreport

roads and Interstate = 'the cloud'
cars, trucks, bikes = PCs, laptops, iPADS, and smartphones ...

by Lance on Feb 16, 2012 11:56 pm • linkreport

On average, transit buses carry only about 10 passengers. More than two-thirds of the seats are empty. Burning fuel to haul around so many empty seats is obviously not very "green."

As long as cars are less than 8-10X as fuel-efficient as buses, this isn't a problem. And the FTA did a study and found that transit is more efficient, even at average occupancy.

It is very unlikely to be any greener at all than the super-efficient cars we will be driving in the future.

As car technology improves and becomes more efficient, so will the technology that runs transit. Isn't this obvious? Buses have gotten more fuel efficient just like cars have.

Transit has a dual mandate - move lots of people during the peak period, and move people who can't use other modes for whatever reason. During the peak period transit is massively more efficient than auto travel (since each auto contains on average 1.15 people during peak) and the rest of transit use is a social obligation.

Bertie, I have to ask, why the heck do you even continue to read this blog?

by MLD on Feb 17, 2012 8:07 am • linkreport

Right, and what about the unused capacity of AUTOMOBILES? Don't they carry something like 85% unused occupancy most of the time? What about that???

by Jazzy on Feb 17, 2012 8:25 am • linkreport

@Jazzy:
That's the sound of FREEDOM!

by Matt Johnson on Feb 17, 2012 9:22 am • linkreport

@Jazzy, but if the cars had green roofs and solar panels...

by Miriam on Feb 17, 2012 9:24 am • linkreport

Right, and what about the unused capacity of AUTOMOBILES? Don't they carry something like 85% unused occupancy most of the time? What about that???

Unimportant, because cars take you wherever you want, rather than where Stalinist urban planner Agenda 21 UN liberal Keynesians want to socially engineer you to go!

by MLD on Feb 17, 2012 9:27 am • linkreport

roads and Interstate = 'the cloud'
cars, trucks, bikes = PCs, laptops, iPADS, and smartphones ...

Au contraire...

transit system="the cloud"
subways & streetcars=fiber optic trunk line
individual travelers=arbitrary client-side devices
private autos=IBM PC 8080s and Compaq Portables.

by oboe on Feb 17, 2012 10:14 am • linkreport

Quoted from above: "This could give buildings a more suburban format. Second, if buildings statisfied the green-area ratio with rooftop gardens or green roofs, this could come at the expense of solar panels. "

Not entirely true. Planting shade-tolerant plants on a green roof (certain sedums/sempervivums, dwarf hostas, etc.) actually INCREASES PV output from the solar panels. This is because all PV cells are rated at 25-degrees Centigrade with a loss in power equaling 0.25% - 0.5% per degree increase. Even white reflective roofs which will only see 55C. during the summer months in the DC climate will create a loss of 5-8% of PV output, compared to similar installations under which a green roof resides. The latter will only have a temperature rise at the roof level of 2C., even in the hottest summer months.

Better yet, at the membrane/waterproofing level, the temperature will be 3 - 6 C. below ambient temperature. This means that on a 90-degree F. summer day, the waterproofing and insulation will only have to cope with 75-80 degrees F. Combine that factor with the low thermal transmissive properties of a green roof (combined transpiration and brute thermal mass) and one saves a bundle on regulating the building's temperature, particularly in the summer months.

I have worked on one building further south that experiences an average 42% savings in energy attributable solely to the addition of a deep/intensive green roof.

If anyone would like to discuss this further, please feel free to contact me, username 'info' at the listed web address.

www.metrogreenvisions.com

by Williams on Feb 17, 2012 4:01 pm • linkreport

The goals to better treat stormwater, improve air quality and reduce urban "heat islands" should be addressed with requirements to better treat stormwater, improve air quality and reduce urban "heat islands" not a prescription of how to reach those goals through a GAR. This is already covered in LEED certification (which is mandatory in DC) and doesn't really require a new zoning application.

But saying that this solution is bad because another solution (reducing driving) can better meet one of the goals doesn't quite hit the mark either.

On the other hand, it appears that the same apartment building with a 160-car garage but with a green roof could earn a high GAR.

Right, because it's not about driving. It's about stormwater management, clean air and heat island effect. Getting people to drive less only addresses one of these issues. You're hitting on the fact that GAR, at best, should be part of a complete breakfast, but as a measure in of itself this way of measuring green area makes sense.

The real flaw is that a building with giant underwater tanks that store stormwater for use watering plants and grass, for example seems to get no credit. Ditto with a cool roof. Or some, as of yet uninvented solution. Legislate the goals, not the solution. Let the market find the solution.

Instead we should set goals about x% of stormwater needs to be managed onsite, and a building of x people should only produce y air pollution and that buildings should have smart roofs (green, cool or solar) etc... or produce only z amount of heat island effect....

We have kind of done this - goal oriented laws - with LEED building requirements and taxes on impervious areas. Taxing stormwater runoff is a better solution that GAR. Taxing air pollution is a better solution than GAR. Taxing heat island contributions is a better solution than GAR.

AwalkerInTheCity's first comment is dead on.

Bertie's comments are deceptive and wrong.

by David C on Feb 17, 2012 4:40 pm • linkreport

roads and Interstate = 'the cloud'
cars, trucks, bikes = PCs, laptops, iPADS, and smartphones ...

Actually, bikes = spiral bound notebooks, which will be the only thing that still works when the electricity runs out. :)

by Ward 1 Guy on Feb 17, 2012 5:13 pm • linkreport

As long as cars are less than 8-10X as fuel-efficient as buses, this isn't a problem. And the FTA did a study and found that transit is more efficient, even at average occupancy.

From your link:

Pounds of CO2 per passenger-mile:
General automobile trip: 0.59
Bus transit: 0.65

On average, buses emit more CO2 per passenger-mile than cars. Most transit is buses.

Rail transit does better on average than automobiles in operational CO2 emissions, but that ignores the enormous emissions created by rail transit construction, especially tunneling. It also ignores the environmental costs of non-fossil fuel sources of electricity, most importantly nuclear waste from nuclear power and ecosystem destruction from hydroelectric dams.

The bottom line is that, overall, transit is, at best, only modestly greener than today's cars. It is unlikely to be any greener at all than the much more efficient cars we will be driving in the future.

by Bertie on Feb 17, 2012 8:13 pm • linkreport

But Bertie, as has been pointed out here repeatedly people who use transit generally travel fewer miles per day. The average car commute is 12 miles. The average transit commute is only 10 miles. And commute trips only make up 30% of all trips. The average driver drives 30 miles a day. The average urban resident will travel only 23 miles a day, but a rural resident will travel 34 miles a day.

Creating 10% less CO2 per mile isn't worth much if you travel 50% more miles than a transit user.

by David C on Feb 18, 2012 12:38 am • linkreport

I think there's a lot of back and forth going on here without much citing of facts. What kind of buses are we talking about for starters? What are they running on? David C with all due respect, I want a much stronger argument for transit than just 'transit users travel fewer miles.' As a transit user, and current non car owner, I want the option to travel more miles. And, to do so, I'd rather not pollute more than a car owner. OTOH, it might turn out you are correct. To travel as many miles as a car user using transit, I simply might not have a life because I'd be traveling all the time!

Nevertheless, I find it intuitively hard to believe that transit pollutes more than solo driven cars. I'm just not sure it is true. So can we get some hard facts on the table?

by Jazzy on Feb 18, 2012 7:31 am • linkreport

@Jazzy

Hard facts were already posted by me, here:
http://www.fta.dot.gov/documents/PublicTransportationsRoleInRespondingToClimateChange.pdf

The average for transit is better than both single-occupancy vehicles and the average for work car trips. In the peak period (when vehicles are full or close to it) transit wins easily.

Bertie likes to pick and choose and point out that a "general" car trip is better than the average for buses (because car occupancy is higher on those trips). But it seems to me that even if you look at just those trips, the difference in distance traveled evens things out.

Most transit trips are work trips. Compare work trips to even the transit average and transit looks good.

by MLD on Feb 19, 2012 11:37 pm • linkreport

But Bertie, as has been pointed out here repeatedly people who use transit generally travel fewer miles per day. The average car commute is 12 miles. The average transit commute is only 10 miles.

So what? Taking the bus instead of driving isn't going to reduce the length of your commute (or any other trip). In fact, you'll probably end up traveling further, because buses have to follow fixed routes. And, of course, it'll also probably take much longer. The average transit commute takes more than twice as long as the average car commute, despite the shorter average distance of transit commutes. The enormous amount of time people save by driving instead of waiting around for buses and trains is one of the reasons driving is so much more popular than transit.

by Bertie on Feb 20, 2012 3:20 pm • linkreport

The average for transit is better than both single-occupancy vehicles and the average for work car trips. In the peak period (when vehicles are full or close to it) transit wins easily. Bertie likes to pick and choose and point out that a "general" car trip is better than the average for buses (because car occupancy is higher on those trips).

Huh? You're the one who is cherry-picking. You're comparing the worst-case car trip with the average or best-case transit trip. That's apples to oranges.

If you're advocating transit as a replacement for driving ONLY for commutes, instead of for general urban transportation, then the per-passenger-mile environmental costs of transit infrastructure become much larger, because they are spread over many fewer passenger-miles of travel. The direct economic costs also increase, because transit infrastructure would be mostly idle outside of commuting periods.

by Bertie on Feb 20, 2012 3:27 pm • linkreport

jazzy and Bertie, the point is that transit is one part of a choice. A choice to live closer to work and in a neighborhood where walking is an easier option. So talking about per mile comparisons of transit versus driving makes as much sense as using the comparative cost of a hotel room in Angor Wat to one in Baltimore and using that to decide which weekend trip is cheaper.

Choosing to live in a dense, walkable community makes car ownership more expensive because there are fewer places to park it. But it also makes walking "cheaper" because trips are shorter. So it means relying on other forms of transit and "consuming" less travel total. If you replace enough driving trips with walking it makes ones total transportation budget cleaner, faster and cheaper. But one needs transit to fill in the longer trips. It's very hard to go car free without transit. That's why transit is cleaner - it makes car free living possible for so many people.

Even if transit is a loser compared to driving per mile, it facilitates a lifestyle of less energy consumption, more walking and less total travel. The correct comparison is the total transportation budget of those who drive and those who use transit. Those who drive consume more. A 5 mile bus ride breaks even compared to the 6 mile drive. And someone who walks 1 mile and rides the bus 10 miles every day uses much less than someone who drives 23 miles a day. Even if the bus is "dirtier".

It's not that the bus gets you from the suburbs to the city faster or cleaner or cheaper than driving. It's that the bus lets you live in the city without a car.

by David C on Feb 20, 2012 10:49 pm • linkreport

jazzy and Bertie, the point is that transit is one part of a choice. A choice to live closer to work and in a neighborhood where walking is an easier option.

No it isn't. Using transit is not at all the same thing as choosing to live closer to work or in a walkable neighborhood. Those are separate choices. A large share of transit is used for suburb-to-city trips, especially commutes.

You're conflating two different kinds of change: substituting transit for driving, and moving from a low-density urban environment to a high-density urban environment. The first kind of change isn't likely to reduce passenger-miles of travel at all. Since transit is, at best, only modestly cleaner than automobiles per passenger-mile, substituting transit for driving would have little if any environmental benefits, even if we made the absurd assumption that cars will never get any greener. And the second kind of change would require an enormous shift in current urban development practises and lifestyles to produce any significant environmental benefit. Neither kind of change is remotely plausible. The only realistic way of achieving a substantial reduction in the environmental cost of urban transportation in the foreseeable future is through cleaner automobiles. There is enormous potential for dramatic reductions in the enviromental cost of autos over the next few decades through increases in fuel efficiency and the substitution of alternative fuels for gasoline. The Toyota Prius already gets 50 mpg, more than twice the fuel efficiency of the average automobile. Plug-in hybrids and pure electric vehicles get the equivalent of around 100 mpg when operating on electrical power. These are enormous improvements in efficiency, and we're just at the beginning of the revolution in automobile efficiency.

by Bertie on Feb 21, 2012 1:47 am • linkreport

Using transit is not at all the same thing as choosing to live closer to work or in a walkable neighborhood.

I never said it was. I said it was part of that choice. Just a a tortilla is part of a burrito, but it is not a burrito.

You're conflating two different kinds of change: substituting transit for driving, and moving from a low-density urban environment to a high-density urban environment.

That's correct. The two are interlocked, you can't have the latter change if you don't have the former change.

And the second kind of change would require an enormous shift in current urban development practises and lifestyles to produce any significant environmental benefit.

I might quibble with the word "enormous", but that is again correct. If we want things to be different, we have to change things.

The only realistic way of achieving a substantial reduction in the environmental cost of urban transportation in the foreseeable future is through cleaner automobiles.

I disagree. It is a this/and situation, not either/or. Cleaner buses and cleaner transit, for example, will make a big difference. Moving to more walking and biking will make things cleaner. In some cities, 50% of all commute trips are by bike. If more cities moved to that point, that would do a lot to make things cleaner. And it would make people healthier and safer too.

by David C on Feb 21, 2012 9:03 am • linkreport

The two are interlocked, you can't have the latter change if you don't have the former change.

No, they're not "interlocked." Many people live in low-density suburbs, use transit to commute to work in the city, but use a car for almost all of their other traveling.

I might quibble with the word "enormous", but that is again correct. If we want things to be different, we have to change things.

"Enormous" is an understatement. Transit's share of the urban transportation market is so tiny that even a doubling or tripling of its share would have only a negligible impact on carbon emissions. It just isn't remotely plausible that we could produce any significant environmental benefit by shifting from autos to transit/walking/biking in the foreseeable future.

I disagree. It is a this/and situation, not either/or. Cleaner buses and cleaner transit, for example, will make a big difference.

No they won't. They'd make a NEGLIGIBLE difference. Transit accounts for about 1.1% of total passenger-miles of motorized transportation in the United States. So even if you could wave a magic wand make all transit carbon-free tomorrow, it would reduce carbon emissions from transportation by only a tiny amount, and total carbon emissions by an even tinier amount. A small increase in the average fuel efficiency of automobiles would produce a much larger environmental benefit. In order to produce a large-scale reduction in transportation emissions, cleaner cars is the only realistic option. Everything else is just noise.

by Bertie on Feb 21, 2012 10:13 pm • linkreport

"Many people live in low-density suburbs, use transit to commute to work in the city, but use a car for almost all of their other traveling."

and of course those people typically use transit thats at well above average occupancy. Average occupancy on transit is pulled down by the reverse commutes, weekend and night trips, etc that are mostly done by car free folks - either those living in high density, or the poor. We provide non rush hour transit to the poor to provide mobility, more thant to save GHGs.

by AWalkerInTheCity on Feb 21, 2012 11:01 pm • linkreport

Many people live in low-density suburbs, use transit to commute to work in the city, but use a car for almost all of their other traveling.

Again you've misunderstood. The point is not that you can't live in the suburbs and use transit - clearly you can. The point is that you can't have a dense, urban walkable community without transit. That's why transit matters and that's why it's green. It makes a lifestyle of walking and short trips possible.

It just isn't remotely plausible that we could produce any significant environmental benefit by shifting from autos to transit/walking/biking in the foreseeable future.

What a pessimist you are. We could easily make American cities match the modal splits in Europe. Or at least as quickly as we can change over our whole auto and energy industries to accommodate electric cars. I'm proposing that American cities become more like cities that actually exist and you're proposing that they look like cities that don't exist anywhere in the world and never have. Which is more plausible or foreseeable?

Transit accounts for about 1.1% of total passenger-miles of motorized transportation in the United States.

So what? We're not talking about the United States as a whole, we're talking about urban transportation. In DC, almost as many trips are by transit as are by car (37% vs 43%). So a reduction in the emissions in DC would make a big difference. And it doesn't take too many people switching from cars to transit to make transit significantly cleaner. No technological advance needed (unlike cars). All that's needed is to make parking and driving more expensive.

by David C on Feb 21, 2012 11:18 pm • linkreport

Grateful for all the comments and feedback here. As to David C's response:

Right, because it's not about driving. It's about stormwater management, clean air and heat island effect. Getting people to drive less only addresses one of these issues. You're hitting on the fact that GAR, at best, should be part of a complete breakfast, but as a measure in of itself this way of measuring green area makes sense.

I agree with this, but what I was getting at was that these issues simply can't be looked at in isolation from driving habits. There is no evidence that I could find in the supporting literature that a hypothetical mass of green roofs in downtown Washington will have much more than a de minimis effect on air quality so long as traffic levels remain constant (consider that the business and apartment districts are a fraction of the city proper, and 40 percent of that area is devoted to public streets, which do not fall under the GAR).

All these impervious dark streets, in turn, exacerbate the heat island effect and contribute greatly to stormwater runoff issues, both in quantity and quality (due to pollutants from car traffic on the roadbed which are picked up by runoff). This is another element ignored in the favoritism shown to single-family homes, which have a far greater area of roadbed/person than the apartment districts.

The real flaw is that a building with giant underwater tanks that store stormwater for use watering plants and grass, for example seems to get no credit. Ditto with a cool roof. Or some, as of yet uninvented solution. Legislate the goals, not the solution. Let the market find the solution.

Performance-based standard would be preferable, I agree, but if you read the GAR documentation closely, there are signs that the planners were concerned with aesthetics as much as results (see 1300.3 – the GAR promotes "attractive … landscapes"). A bioswale is literally green, and visible. An underground water tank is not. A green roof is a "landscape," while a cool roof is not. That is the essence of the GAR, to maximize space that is literally the color green, not that which is substantively "green."

by Charlie Gardner on Feb 22, 2012 10:50 am • linkreport

"All these impervious dark streets, in turn, exacerbate the heat island effect and contribute greatly to stormwater runoff issues, both in quantity and quality (due to pollutants from car traffic on the roadbed which are picked up by runoff). This is another element ignored in the favoritism shown to single-family homes, which have a far greater area of roadbed/person than the apartment districts."

is the area devoted to streets in the district really at issue? There are no new streets being built there, and no serious proposals I know to remove streets. Similarly there are no new SFH developments, and few serious options to bull doze existing SFH areas.

Those are more issues for the suburban jurisdictions. There total impervious area ratio metros WILL incentivize denser growth. But I don't see how that is relevant to a jurisdiction with little vacant land.

The only relevance I can see is that GAR standards will add some costs to new high density projects, and so slow them down. That sounds like an argument against any standards of any kind for new development. I don't think that will win friends for urbanism.

by AWalkerInTheCity on Feb 22, 2012 10:58 am • linkreport

The point is that you can't have a dense, urban walkable community without transit.

You wrote "the point is that transit is one part of a choice ... to live closer to work and in a neighborhood where walking is an easier option." And my response is that this just is not true. Lots of people use transit without living closer to work and without living where walking is an easier option. Choosing to use transit and choosing to live close to work and in a walkable area are not "parts" of the same choice. They are separate choices.

What a pessimist you are. We could easily make American cities match the modal splits in Europe.

No we couldn't. American urban areas are dramatically more sprawly and car-oriented than European urban areas. Only a handful of American cities, primarily in the Washington-Boston northeast corridor, are remotely as conducive to mass transit as the typical European city. But you seem to have an exaggerated view of the role of mass transit in Europe, anyway. Urban rail transit in the U.S. accounts for about 0.5% of total passenger-miles of travel. In Europe, the figure is about 1.5%. The difference is about 1 percentage point of total travel. Even in Europe, mass transit accounts for just a small share of the total travel market. The overwhelmingly dominant mode is automobiles.

So what? We're not talking about the United States as a whole, we're talking about urban transportation.

The point is that urban mass transit accounts for such a tiny share of the total transportation market that no remotely plausible shift from automobiles to mass transit (or biking or walking) within the foreseeable future could produce anything more than a token benefit in reduced carbon emissions or other environmental benefits. You would need to increase transit's share of the market by an order of magnitude just to get a tiny benefit in reduced emissions.

by Bertie on Feb 22, 2012 7:47 pm • linkreport

And my response is that this just is not true.

You need to go back and reread our discussion. I'm saying that if one is to choose to live a walkable, urban car-free lifestyle, they will need transit. I am not saying that choosing to use transit means you have chosen to live a walkable, urban car-free lifestyle.

No we couldn't.

Yes we could. Here is one way. Step 1 - triple the gas tax. Step 2 - put extra tax money into transit. Step 3 - wait 15 years. Done.

In Europe, the figure is about 1.5%.

I'm talking about cities. Why are you not?

You would need to increase transit's share of the market by an order of magnitude just to get a tiny benefit in reduced emissions.

You're missing the point. Getting people to move closer to work and into walkable neighborhoods means they use less transportation and drive considerably less. It means shifting driving miles into walking, biking and transit and - perhaps most importantly - non-miles. So 30 miles of driving a day becomes 10 miles of transit and 5 miles of walking/biking.

But you need transit for people to make that shift. That's what makes transit green - not it's increased efficiency per se, but it's ability to make efficient living possible.

Also, pollution is, in some cases, related to concentration and measured in parts per million. A concentrated amount of pollution is usually more dangerous to health than a diffused amount. Cities tend to have high concentrations of pollution, so making transit cleaner in Washington, DC, where pollution is condensed and transit makes up a large part of the modal share, will result in large improvements in air quality and bring with it large health benefits - comparable to those one would get with cleaner cars. In contrast, completely eliminating car emissions in Clark County, ID will probably do nothing for health.

That's why I say the answer is this/and rather than either/or. We need cleaner cars and cleaner transit. We need to enable people to drive less and walk and bike more. We need to empower people to consume less transportation in general. Electric cars are not a magic bullet. They are part of a complete breakfast at best.

by David C on Feb 22, 2012 10:20 pm • linkreport

You need to go back and reread our discussion.

I just quoted your assertion and explained why it's not true.

Yes we could. Here is one way. Step 1 - triple the gas tax. Step 2 - put extra tax money into transit. Step 3 - wait 15 years. Done.

No, we couldn't. There is absolutely no evidence that a tripling of the gas tax is remotely feasible politically. Even small increases in the gas tax are deeply unpopular. Spending the additional revenue on transit would be even less feasible. And even if a tripling of the gas tax were politically possible, it wouldn't have more than a trivial effect on modal shares anyway. The real price of gasoline more than doubled between the 70s and the 80s, and again between the 90s and the 00s, but there was no virtually no effect on modal shares. People simply absorb the higher cost, use their vehicles more efficiently, or shift to more fuel-efficient vehicles. We already have the technology for a dramatic increase in the efficiency of automobiles, and that technology is gradually making its way into the nation's auto fleet.

I'm talking about cities. Why are you not?

Because all motorized transportation imposes environmental costs, not just transportation in cities. Urban mass transit is just a tiny share of total motorized transportation, so even if transit were much cleaner that would have only a tiny effect on the environmental costs of transportation. Greenhouse gases don't stop at city limits, you know.

Getting people to move closer to work and into walkable neighborhoods means they use less transportation and drive considerably less.

As I keep pointing out, getting people to shift from cars to transit is not the same thing as getting them to move. Those are two different kinds of action. For the reasons I have explained, it is not remotely plausible that either kind of action could produce anything more than trivial environmental benefits during the foreseeable future.

by Bertie on Feb 23, 2012 1:52 am • linkreport

Also, pollution is, in some cases, related to concentration and measured in parts per million. A concentrated amount of pollution is usually more dangerous to health than a diffused amount. Cities tend to have high concentrations of pollution, so making transit cleaner in Washington, DC, where pollution is condensed and transit makes up a large part of the modal share, will result in large improvements in air quality and bring with it large health benefits - comparable to those one would get with cleaner cars.

Even in DC, motorized transportaion is overwhelmingly dominated by automobiles. Not just the drivers who live in DC, but the huge numbers of drivers who live elsewhere in the Washington metro area and who drive into and within the District for work or recreation. Local air pollution from transportation emissions is therefore overwhelmingly dominated by emissions from automobiles, not mass transit. Indeed, there are virtually no local emissions from DC's rail transit, because that's powered by electricity generated at distant power plants. So even restricting the environmental analysis to local air pollution in DC, cleaner cars are still vastly more important than cleaner transit.

by Bertie on Feb 23, 2012 2:21 am • linkreport

So even restricting the environmental analysis to local air pollution in DC, cleaner cars are still vastly more important than cleaner transit.

Even if true, the cleanest car is the one no one drives, and the cleanest transit is the one with every seat filled. So by moving someone from car to transit we make both cleaner simultaneously (whereas moving someone from transit to car makes both dirtier). That doesn't require any new technology because the tools already exist. So if we really want to make cities cleaner, all we need is congestion charges in the city with revenue going to support transit, walking and biking.

by David C on Feb 23, 2012 8:36 am • linkreport

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