Building height and density are not one and the same. You can have tall buildings configured in a low-density way (think post-war towers in the park). And you can have low/mid-rise buildings configured in a high-density way (think Paris and Barcelona). This is one of the reasons why it is important to decouple density and tallness when thinking about our cities.
This line of thinking is the approach that a recent study took when trying to determine the optimal built form for minimizing climate impact. In the study they define four building typologies: 1) high density, high-rise, 2) low density, high-rise, 3) high density, low-rise, and 4) low density, low-rise.
What they found was that taller environments tend to have higher life cycle GHG emissions, but that lower-density environments are (obviously) far more land consumptive. To determine life cycle GHG emissions they looked at both embodied and operating emissions, which is why the taller stuff didn't score as well under their methodology. There's typically a lot of concrete and steel in tall buildings.
This lead the team to conclude that if you want to optimize around climate impact, you should probably aim for that perfect middle ground: dense, but not super tall.
But as Joe Cortright (City Observatory) rightly pointed out in his email newsletter, one of the big limitations of this analysis is that it does not consider transportation-related impacts. And since we know that transportation is one of if not the largest source of GHG emissions and that how we get around is heavily dependent on land use patterns, it is probably an important piece to consider.
Photo by Alfons Taekema on Unsplash
One of the reasons why I remain so bullish on cities is because we know that new ideas disproportionately come from cities (typically big and dense ones). Matt Clancy does an excellent job of explaining this in a recent post. In it, he cites a number of studies that suggest density is pretty good. It's good for not only increasing innovation, but also for increasing the diversity of innovation.
One of the studies found that, all else being equal, doubling the number of jobs per square mile resulted in 20% more patents per capita. Matt argues that the reason for this is that density allows us to meet and collaborate with new people. With this is mind, what do you think that working from home (which is the opposite of job density) might do to innovation/patents?
Another one of the studies that Matt cites in his article deals with the correlation between patents and street grids. Denser street networks seem to have a marginally positive relationship with innovation.
But Matt surmises that this may not be because it means we're all serendipitously bumping into each other all over the place; instead a denser street network is likely symptomatic of other things -- namely an increase in "third places." Because if you consider which census blocks have a concentration of restaurants, cafes, and bars, the number of patents then goes up meaningfully.
As further evidence of this, Matt cites a fascinating paper from 2019 which looked at the effects of early 20th century prohibition on patents. Turns out that this is a pretty good experiment, because you can examine the impacts of prohibition, as well as compare counties that were already dry (i.e. unaffected by prohibition) against counties that were wet prior to prohibition.
What the study found was that (1) prior to prohibition wet counties were producing more patents per capita (where they bigger and denser?) and (2) wet counties saw a meaningful drop in patents right after prohibition. Previously dry counties went unchanged in terms of innovation.
If you're skeptical of the relationship between bars and innovation, I would encourage you to check out Matt's full post. But know that there is overwhelming research to suggest that new ideas tend to flourish in the big and dense places that we call cities.
Building height and density are not one and the same. You can have tall buildings configured in a low-density way (think post-war towers in the park). And you can have low/mid-rise buildings configured in a high-density way (think Paris and Barcelona). This is one of the reasons why it is important to decouple density and tallness when thinking about our cities.
This line of thinking is the approach that a recent study took when trying to determine the optimal built form for minimizing climate impact. In the study they define four building typologies: 1) high density, high-rise, 2) low density, high-rise, 3) high density, low-rise, and 4) low density, low-rise.
What they found was that taller environments tend to have higher life cycle GHG emissions, but that lower-density environments are (obviously) far more land consumptive. To determine life cycle GHG emissions they looked at both embodied and operating emissions, which is why the taller stuff didn't score as well under their methodology. There's typically a lot of concrete and steel in tall buildings.
This lead the team to conclude that if you want to optimize around climate impact, you should probably aim for that perfect middle ground: dense, but not super tall.
But as Joe Cortright (City Observatory) rightly pointed out in his email newsletter, one of the big limitations of this analysis is that it does not consider transportation-related impacts. And since we know that transportation is one of if not the largest source of GHG emissions and that how we get around is heavily dependent on land use patterns, it is probably an important piece to consider.
Photo by Alfons Taekema on Unsplash
One of the reasons why I remain so bullish on cities is because we know that new ideas disproportionately come from cities (typically big and dense ones). Matt Clancy does an excellent job of explaining this in a recent post. In it, he cites a number of studies that suggest density is pretty good. It's good for not only increasing innovation, but also for increasing the diversity of innovation.
One of the studies found that, all else being equal, doubling the number of jobs per square mile resulted in 20% more patents per capita. Matt argues that the reason for this is that density allows us to meet and collaborate with new people. With this is mind, what do you think that working from home (which is the opposite of job density) might do to innovation/patents?
Another one of the studies that Matt cites in his article deals with the correlation between patents and street grids. Denser street networks seem to have a marginally positive relationship with innovation.
But Matt surmises that this may not be because it means we're all serendipitously bumping into each other all over the place; instead a denser street network is likely symptomatic of other things -- namely an increase in "third places." Because if you consider which census blocks have a concentration of restaurants, cafes, and bars, the number of patents then goes up meaningfully.
As further evidence of this, Matt cites a fascinating paper from 2019 which looked at the effects of early 20th century prohibition on patents. Turns out that this is a pretty good experiment, because you can examine the impacts of prohibition, as well as compare counties that were already dry (i.e. unaffected by prohibition) against counties that were wet prior to prohibition.
What the study found was that (1) prior to prohibition wet counties were producing more patents per capita (where they bigger and denser?) and (2) wet counties saw a meaningful drop in patents right after prohibition. Previously dry counties went unchanged in terms of innovation.
If you're skeptical of the relationship between bars and innovation, I would encourage you to check out Matt's full post. But know that there is overwhelming research to suggest that new ideas tend to flourish in the big and dense places that we call cities.
Here are a few interesting stats from a brief report that New York City published this month about their supply of new housing units:
From January 1, 2010 to June 30, 2020, New York City delivered 205,994 net new housing units across the five boroughs.
This total includes 202,956 units from new construction and 29,161 units from the alteration/conversion of existing buildings. However, it also factors units that were lost as a result of demolition (-17,400) or alteration (-8,723).
Brooklyn saw the most supply, followed by Manhattan. The four highest-growth Community Districts were responsible for 1/3 of all new housing additions. These CDs are all formerly non-residential areas that were rezoned to allow living.
Manhattan saw the greatest loss in housing units as a result of alterations (people combining units). This was most prevalent in wealthy neighborhoods such as the Upper East Side, Upper West Side, and Greenwich Village.
What is interesting about this last point is that it shows you that cities are far from static. New York City lost 26,123 housing units during the above time period, with 8,723 units being lost to alterations and people combining units.
The orange areas on the above map are neighborhoods which actually became less dense over the last decade. And of course, this phenomenon is not unique to New York City. We are seeing the same thing play out in some/many neighborhoods in Toronto.
What this mean is that the role of new development is really twofold. It allows a city to grow (i.e. house new New Yorkers), but it also replaces lost housing and relieves some of the pressures on the existing housing stock. I don't think many people appreciate this dynamic -- or perhaps they don't care.
For a copy of the full report (it's only two pages), click here.
Here are a few interesting stats from a brief report that New York City published this month about their supply of new housing units:
From January 1, 2010 to June 30, 2020, New York City delivered 205,994 net new housing units across the five boroughs.
This total includes 202,956 units from new construction and 29,161 units from the alteration/conversion of existing buildings. However, it also factors units that were lost as a result of demolition (-17,400) or alteration (-8,723).
Brooklyn saw the most supply, followed by Manhattan. The four highest-growth Community Districts were responsible for 1/3 of all new housing additions. These CDs are all formerly non-residential areas that were rezoned to allow living.
Manhattan saw the greatest loss in housing units as a result of alterations (people combining units). This was most prevalent in wealthy neighborhoods such as the Upper East Side, Upper West Side, and Greenwich Village.
What is interesting about this last point is that it shows you that cities are far from static. New York City lost 26,123 housing units during the above time period, with 8,723 units being lost to alterations and people combining units.
The orange areas on the above map are neighborhoods which actually became less dense over the last decade. And of course, this phenomenon is not unique to New York City. We are seeing the same thing play out in some/many neighborhoods in Toronto.
What this mean is that the role of new development is really twofold. It allows a city to grow (i.e. house new New Yorkers), but it also replaces lost housing and relieves some of the pressures on the existing housing stock. I don't think many people appreciate this dynamic -- or perhaps they don't care.
For a copy of the full report (it's only two pages), click here.
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